Babe in the woods, help.

:? Hi. I need advice. Short version of what the deal is, here goes....
42" houseboat. Diesel engine.
I "want" 3 banks. 1. Starter battery. 2. Small inverter bank to run PC (laptop) based GPS system. 3. Large inverter bank, to run major appliances.
I have... Alternator on engine, but will buy a Zena highoutput to replace stock alt.
Also have a nice Onan diesel genset. Boat is total electric. Stove, Hot water heater, 2 RV roof A/C units, microwave. I don't expect to run this stuff off the large inverter bank all the time. What I do want (if possible & reasonable) is to run the A/C or A/Cs (13 running amps when compressor is kicked in) while running the engine. Maybe poping a bag of corn while underway also.
The start battery needs topped off, the small PC inverter is "critacl" while underway and because of the humidity factor, at least 1 A/C unit needs to run.
I don't want to eat batteries obviously. Aside from a 12 V. start batt, I'm open as to the rest of the system. I've been told to use marine VSRs for regulation Do I need all 12 V.? 24? 6s in parellel? Gels, AGMs, Golfers? Panels are planned later, I can't afford the whole package now.Thanks.
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Comments

  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    without knowing alot about the details and the reasons why you want 3 banks, im guessing you could be a LOT more efficient combining the gps and appliances battery banks, at least.

    42 inches huh? ;)
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    Well I guess adding a 3rd bank (say 2 more batts?) does complicate the design a bit. It's a fail-safe issue. No matter what, the GPS must work on demand. I'm seeing that a better sine wave is needed for computers. I'd rather buy JUST that type & size and have no other loads on that system. A "lighter duty system dedicated soley to the GPS.
    The "home" inverter (6000 W), will no doubt be subjected to more use AND if there were to be a component failure, then no big deal. Just a bit of inconvienience. If the GPS system failed, then we could fall back and use the home inverter to limp in on. Belt & suspenders, that's the plan. Actually the laptop has a battery also, so there is the 3rd. layer of defence. This particular GPS "system" does way more than Lat & long, and is very important to the safe operation of the boat. This boat cruises far from home for extended periods. It's not a "week ender".
    Aw DUH! you're right.... feets not inches. Sorry bout that.
    Thanks,
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    hey Ted,
    well im by far not the battery expert here, others will chip in, but why you say that about computers? i have never had any issues running a pc on a mod sine wave.
    with the batts maybe you could still have the redundancy of separate banks by using some voltage switching to avoid separate charge controllers.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    I will add my 2 cents worth (not worth much--huh... :| )

    Generally, it is cheaper in the long run (and sometimes in the short run too) to do you belt and suspenders backup using conservation rather than just throwing more batteries/generators/AC/Inverters at the problem...

    For example, a battery based GPS and ruggedized laptop w/ gps might address the backup issues better than more AC and Batteries... Also, I assume that you will have paper charts for the areas you are navigating and not only use main GPS/Laptop for navigation (this from a guy that flew once around the US in 1976 with not much more than charts, compass, airspeed, and watch--used motorcycle battery powered NAV/COM when landing at tower controlled airports).

    Regarding AC and other heavy loads--You probably don't want to discharge your standard batteries much more than a 1/10 capacity rate--which if you only discharge to 50% would give you 5 hours at maximum discharge. You can add batteries--but you also have to add weight, generation/charging capacity, etc... When you are running heavy loads (more than 5 minutes on a microwave, etc.)--you will probably be more cost effective (and fuel efficient) if you run your main generator (again a good quality, high efficiency unit) with those loads (battery charging already costs you about 10-20% losses by themselves).

    Generally, if you have large loads, then running at a higher voltage (24-48VDC) is better because of the equation of P=I*V--if you double the voltage, you half the current (smaller wiring). Also, from Power=I^2 * R--if you half the current, you 1/4 the loss due to resistance in the wiring and such... Sometimes, you are limited to equipment for your application (you may find many marine systems at 24 volts DC, but not many marine qualified units at 48VDC).

    Battery wise, AGMs are pretty close as you will get to the cost effective, low maintanence, and most efficient battery out there... You do have to be careful that you don't overcharge them as there is no way to add water if you start to boil them (overcharging). Also, your charging equipment needs to be able to manage their specific charging voltage profile.

    Where do you motor?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    Thanks. Some things are set in stone here, others I'm flexible with. All I know is what I read, so if a mod sine inverter will run the laptop then GREAT! But... The seperate GPS bank has to stay. The A/C stays. The whole object of the HB is comfort & fun. If Mama ain't comfortable & happy, Then ain't nobody gonna be happy. A/C from the engine while underway is a given. We are getting ready for a 800+ mi. trip down the Ohio & Miss in July. It's hot & sweaty in Louisiana no matter where we go, that's a given.
    Glad to be educated about batt voltage. Looking like 24V is the way to go. AGMs huh, OK, sounds good.
    Here is the part I don't get when I get advice from you solar types. The amp hours VS load/time. I pretty much get that. The draw down % of the batts? Seems (and I could be wrong) that all advice hinges on the short period of time ya'll think the A/C could run JUST off the batts. First, I have the room and the weight carrying ability. Sorry guys but I'll leave concervation to others (in this instance). Second, while the A/C is drawing on the batts, the alternator IS pumping in high amps. While underway I see the batts as more of a resovoir than a supply.
    Here is where the figures get murky. That BIG honking alternator is feeding the A/C, No? The batts act to smooth the curve not supply the total power. I don't see a big draw down as long as the alternator is pumping in amps. What am I missing?
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.
    mattl wrote:
    why you say that about computers? i have never had any issues running a pc on a mod sine wave.


    That's my experience too. Have been running several computers for a few years now on MSW with no problems at all.
    Wayne
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    I am not raising the "Green" conservation flag--more just the practically of running large loads with batteries only.

    I am not into marine electrical systems--but I would be looking very closely at how the alternator measures it voltage when supplying the heavy loads. What you need is a charge controller / alternator that measures the voltage (and temperature) at the battery bank itself. If it simply maintains its output voltage (at for example) 29VDC at the batteries -- then you can overcharge the batteries (especially damaging to AGM type).

    If the alternator does not have remote voltage sensing--then it runs the risk of not correctly charging the battery bank because of voltage drop in the cabling from the alternator to the battery bus ([6,000 watt load + 6,000 watt charging load after you ran on battery only for a while] / 24 vdc = 500 amps running load + charging-- just making some guesses--think good sized arc welding)... That is not an insignificant load.

    If, however, you choose to run 6kW from a 240/120 vac single phase generator--that would be 6,000w/240 vac = 25 amps... A much easier amount of current to run around to the various large/fixed loads (like AC)...

    Battery wise--50% is the soft recommendation of how far you would want to discharge a typical lead/acid battery before recharging it (hopefully quickly). If you deep cycle a lead/acid storage battery, the lead sulfate (not a battery guy--I think I have the chemistry correct) that normally form when discharging tend to harden with time (like around 24 hours)... If you cycle the battery down by 80% and don't charge right away--the lead sulfates harden and never really fully convert upon recharging. Eventually reducing overall capacity (rather quickly).

    Some AGMs do specifically say that they are OK to cycle through 80% of their capacity.

    Basically, figure out how may watt*hours or amp*hours (at what voltage) you want to draw from your banks--how far you wish to discharge, and how many cycles you want (different batteries will go from hundreds to maybe a thousand or so cycles) from your bank before replacement...

    And remember, that you can get about 5-6kWhours (real rough SWAG from a good quality generator) from a gallon of gas or diesel--but a car sized storage battery only stores (very roughly) about 0.5kWhrs of useful energy--quite the difference in weight and volume for energy storage.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Babe in the woods, help.

    Get a air conditioner compressor you can run from the Engine drive belt (like in a car, or RV) while underway. Much better than trying to generate DC, store it, and then run DC-AC, while underway. Have a 2nd DC power AC unit while at anchor. This will really suck power form the batteries, have a plan to recharge them w/o frying your engine alternator.
    Alternators seldom will have enough voltage or control to properly charge AGM cells. What do you want to have happen at 3AM, when the low voltage disconnects the inverter, and the Air Conditioner shuts down ? Do you want to manual start someting to charge batteries, or auto start ? Fresh water ? If not saltwater, you could try a water loop condenser stage, instead of a air cooled one. Or run them in tandem.
    Just ideas, I have no idea how practical they will be for you.

    Mike
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    And, obviously, I would run the questions past your boat yard / chandeliers and see what they would recommend--I would have some concerns about running an A/C compressor from your main engine(s) (refrigerant leaks and just plumbing in general) if you have the AC power available to power a standard sealed system.

    For a craft in your class--would it not be normal to have a house AC generator?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    Great. Thanks for all the imput.
    No, I'm not buying a different type A/C unit. I've got what I've got. It draws 13 amps, not an excessive load. I read how whole houses are off grid. I want just 1 A/C unit. Yes I have a good generator but 1 gal. of diesel fuel is $3.00. Besides , if talking about conservency, I need to harness the wasted energy of the running engine. Not even 1/2 its power is used while slowly cruising.
    Not that I also don't worry about over charge, but for the moment lets give the manufactures the benifit of the doubt. They say their regulators deliver a safe voltage. Wire resistance is a non issue. The distances are short & I will oversize the wire. No need to talk about lead acids, I've been told AGM are best so that is what I'll buy. Some I have bookmarked claim a 400 cycle rcomplete recharge garuntee. I'll get the biggest amp hr. capacity they sell & buy as many as needed' And forget a boat yard (I don't make enough money to shop at anything that says "Chandlery" on the door) You are the go to guys. The ones "doimg it", I value your input more.
    We are still hung up on battery life & drawdown %. Why will there be any? I mean I know I can't hook the A/C directly to the alternator. I need a buffer (like a batt bank) BUT... help me see what I'm missing here.
    The A/C is running full out, drawing say 1500 watts. BUT the alternator is putting in say, 200 amps. Where is the drawdown problem.? I could indeed weld with that much power. I ought to be able to run a 1500 watt load.. Or what else raises it's ugly head I don't know about (plenty I fear). Thanks again,
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    Ted,

    I guess I am getting a little confused... I thought that you were trying to run the (large) equipment from the batteries when the boat engine/genset is turned off... And trying to size the batteries based on those loads.

    If you are not running heavy loads without running an alternator/generator of some sort--then you would not need a huge battery bank to buffer the energy.

    But anyways, back to the basics... First your Air Conditioner appears to be a 120 VAC 60 Hz unit running at 13 amps (not a DC powered unit--so I presume that this being a house boat that this is probably must a nice home A/C type unit?). So, you will not need (or want) an air/conditioning compressor on your main motor.

    And, AGM batteries are still lead acid type--they just don't have a cell filled with sulfuric acid--the electrolyte is held captive in a mat with the plates. The reason they are a "nice" battery is that they don't spill or (normally) release Hydrogen gas and fumes (unless you overcharge them). They can be mounted in any position, don't require water to service, and don't require cleaning like standard "liquid cell" batteries. Because you can't refill them--they are much more sensitive to over charging (hence the importance of the exact voltage and temperature at the battery and monitoring of charge state).

    You can look anywhere on the web at various manufacturer's sites and read about AGM and other type of batteries... Here is one site (picked at random) that you can read through about AGM's:

    http://www.lifelinebatteries.com/

    Next, wiring size, AC vs DC current, and such are big issues... AC at 25 amps (or 15 amps) is much easier to wire and protect against shorts/failures using standard breakers than trying to manage 250-500+ amps of DC current (DC is much harder to break without self sustaining arcs--requires different breakers and much more copper to manage the current and voltage drops). So you will want to keep loads that are at high voltage/low current (and AC) when you can...

    And, by the way, usually a dedicated generator set producing 120 VAC at 60Hz will be more fuel efficient than, for example, running an alternator on a belt off of your main engine... There is no free power--so if you are generating 1,500 watts (approximately 2 horse power at 746 watts per HP)--The alternator running off of your main engine may use upwards twice as much fuel for the same energy (because of belt friction and DC to AC conversion) as a dedicated AC genset... There is no free energy...

    Now, if you have a very large engine (say 100 horsepower at 1/2 power your approximate fuel flow may be; SWAG; ~4 gallons per hour), you may not notice a fuel flow variance of 0.25 gph (est. genset running at 1,500 watts) to 0.5 gph (est. worst case main motor running belted alternator at 1,500 watts)... But there will very likely be a penalty by trying to run power from your main engine (in this example, up to 0.25 gph or ~$0.75 per hour penalty).

    The other reason to run a genset is that you can size the unit for optimum power generation... For example, if your maximum 120 VAC power requirement is 3,000 watts--you probably would be looking at a 4-6kW genset--or about 15-20 HP... Running at 50%+ load a 15 HP gas/diesel motor is much more efficient than running a 100 HP motor at 7.5% (from looking around earlier, it seems that gensets running at 25% or less of rated capacity use roughly the same amount of fuel whether or not they are generating 25% capacity or near 0% of capacity.

    If, you are running your main propulsion engine at less than 25% fuel flow when slowly cruising and your fuel flow is well over 1.0-2.0 gph--you may not see the additional 1,500 watt load (actually more--addressed further down) causing increasing fuel flow (so--technically it would be free power).

    By the way, the numbers above are very rough --more biased toward gasoline (and aviation) engine numbers--as that is what my experience tended to be in... But they do give a pretty good idea of the range of power/fuel flows that I would expect for those rated power... Diesel fuel flows should be a bit less.

    Now, back to your craft. I would humbly suggest that you first divide the power requirements into several circuits:

    1. 12/24 VDC Emergency/Navigation lighting/cabin backup
    2. 120 VAC Emergency/Navigation
    3. 12/24 VDC house lights/power/fresh water pump/sump pump/fans/etc. (if any requirement)
    4. 120 VAC things that would be nice to run on batteries--house lights, stereo, TV (no large loads like A/C)
    5. 120 VAC power for A/C and anything that would run when the GenSet is on (including battery chargers for battery banks)...

    So, you have a good generator--but is this a separate genset (diesel?)--hopefully rated as for continuous duty--prime mover--at 120 VAC 60Hz and xxKWatts of power?

    So, once you have classified your load (both in average/maximum power required--and how long you want that power--i.e., Watts*Hours or Current*Hours at xx volts) and their voltages (12/24/120 -- AC and DC)--you can start sizing the genset (you have this already?), the battery bank(s), Main Motor Alternator (assumed to be 12 or 24 VDC), and any other equipment (like 12/24 VDC to 120 VAC inverters).

    There are several efficiency/capacity issues... For example, the generator/inverters need not only to be able to supply the required voltage and current, but able to supply starting power too (like starting the compressors in the A/C and Refrigerator, domestic water pumps, etc.).

    Also, when converting from DC to AC, the inverters are only 60-80% efficient (some are better)... As an example, your 1,500 watt A/C unit may require about 3,000 watts (could be more or less) to start... And for how much current your battery bank would have to support:

    Inverter Power Input = Load Power / efficiency = 1,500 watts / 0.80 = 1,875 watts continuous
    Inverter Power Input (starting) = 4,000 watt sized inverter / 0.80 = 5,000 watts max-inverter input power

    Assume that a 24 volt battery bank will run down to 20 volts under instant load/pretty much dead

    Inverter Current (4kW) = 5,000watts/20 volts=250 amps.

    NEC (don't know boat requirements) require a circuit to run at 80% capacity, so:

    Inverter Circuit (4kW) = 250 amps / 80% = 312.5 amps (note, this is required for ~4kW--if the inverter load is less, you can size the circuit for less).

    Continuous load for your 1,500 A/C unit would roughly be (note that inverters tend to be constant power devices--if their input voltage goes up, then their input current goes down: i.e., P=I*V)

    Inverter Current (1,500 watts) = 1,875watts / 24 volts (nominal battery voltage) = 78.125 amps @ 24 VDC

    So, if you were going through a 24 VDC inverter to power your 1,500 watt A/C, you would need ~80 amps from your main engine alternator at 24 vdc (nominal) to power your A/C system steady state. And, at worst case, your 24 vdc battery bank would need to be sized to safely power in excess of 312.5 amps (perhaps more or less depending on the actual A/C systems starting surge requirements) for this one load. (If this was all done at 12 VDC, your currents would double. If done at 48 VDC, they would be 1/2).

    However, if you have a 120 VAC 60 Hz genset already--it would seem to me--to make more sense to simply power your A/C directly from 120 VAC @ 15 amps, dump the "extra inverter and battery system" and the extra load on the propulsion motor.

    Obviously, from here I don't have a clue as to what your craft is really equipped with, or what is best for it... However, I think I have given you enough information that you can sort of size and partition your power requirements and come back with some more questions... I don't think that this is a do-it-yourself project for a first timer--but if 80% is already there (on the boat) and/or you have some local knowledgeable person their--it can be done.

    Am I being at all helpful here?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.
    BB wrote:
    AGM batteries are still lead acid type--they are much more sensitive to over charging, hence the importance of the exact voltage and temperature at the battery and monitoring of charge state.
    -Bill


    This is VERY important! The standard charging system supplied with engines will ruin AGM batteries.
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Babe in the woods, help.

    It might be worth researching the Ample Power website (www.amplepower.com). David Smead and Ruth Ishihara seem to have established a loyal following for their marine battery charging and power management equipment. Additionally, Balmar (www.balmar.net) manufacturers high-current alternators as well as useful looking marine charging equipment.

    HTH,
    Jim / crewzer
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    :-D :-D :-DHappy boy, me!
    Bill, you did indeed get to the meat of the design.
    T he genset is a diesel powered ONAN 6KV. Ample power and will be used to cook & on "washday". About every other day we dedicate time to heat water to bathe & wash clothes. Same with cooking. Big meals, then leftover creations. Water pumpimg is 12V as well as dual lighting system.
    The rub comes at keepomg comfortable and the refrigerator/microwave. These 3 loads are constant (almost). The A/cs are Coleman RV roof mounted. What you see on most all trailers & motorhomes. The boats engine is a Volvo 6 cyl. 130 hp. diesel. I fair a bit better than your gasolene figures, but as you say, we're "roughing in" the system.
    Aside from cruiseing, we spend alot of time in the marshs, Shrimping & crabing. This means no shore power. Would I like "free" power? Sure, but at 59, I know there isn't a free anything. Would I like to run the fridge off solar & batts? Sure. Can I? maybe (with ya'lls help). BUT (much to my sadness), it's looking like having Solar A/C is not practicle. Wouldn't it be nice to sleep without a genset banging away & just have the A/C kick on from time to time! Oh well.
    It does look like I can salvage the wasted engine excess to at least have it while underway.
    Thanks for the math (not my strong suit) and all the links. I'm looking at several brands. Raser make a good alt also. I'll read the other links and also have more specific questions on particular brands as I puzzle this thing out. Jump in anytime, especialy if you know of any miricle s I'm not aware of. Thanks,
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    Ted,

    Whoopee... I guessed pretty close on your house boat's engines (lucky).

    Anyway, yes, you are correct that it is not too practical to power your A/C from batteries... It can be done, but you will not save significant amounts of fuel due to losses in the charging/discharging/invertering processes...

    However, it it pretty doable to power your refrigerator and freezer either with batteries or propane. Their power requirements are only, roughly 1kWhour per day +/- per appliance. And, there is another couple threads here for people that have converted chest freezers into refrigerators (using a separate temperature controller, and I would recommend a AC or DC "muffin" fan to stir the air when the compressor is running)... Those units get down to 0.3-0.5 kWhrs per day.

    The new energy star Fridges/Freezers are pretty close in efficiency as the SunFrost and others--at about 1/3 the purchase price--and usually include nice options like frost free and ice cube makers that the SunFrost and others do not.

    The other option--if you already have propane for cooking--is a propane powered fridge (from RV industry and Amish too)... Not as nice as electric (you need to vent or place outside), but they are also not too expensive to operate, are quite, and use something like 1lb of fuel or less per day (a small tank will last quite a few weeks).

    You can certainly use solar to help provide for a quiet boat--but it will have to be weighed against your other power requirements (like A/C)... Basically, if you are using A/C for more than a few hours per day--You are probably better off running battery chargers from your 6kW Onan than going through the expense (and having to anchor in full sun) of Solar.

    One option for solar that may be of interest would be to think about thermal solar panels (hot water)--If you guys like to take lots of warm showers, you can save the costs of hot water heating. And thermal solar panels themselves are about 1/10 the cost of solar PV electric panels for same "kWHr" of heating and require about 1/4 the space of Solar PV panels (still need to plumb them in and add hot water storage tanks/etc.). Of course--you can probably use the waste heat from your boat engine (and Onan if water cooled) and skip the solar thermal panels--if the engines are running often enough.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    :-)I doubt it was a much luck as it was educated guess. Sounds like you have read a book or two and been to the North Pole & fed peanuts to the elephants there.
    This HB was a dock Queen. Always on shore power and dainty little trips round the lake. She is total electric. No propane' Well now she has a NEW captain! She's gonna work for her keep.
    They (previous owners) just put a new water heater and fridge. Not sure if they were Blue Star. Probably not Can I even ADD a HWSP to a regular HW tank? I thought the tank had to have a seprtate set of fittings. Good idea if doable. The controller at Total Power looks interesting.
    Thanks,
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    Ted,

    If your boat is currently 100% electric--you need to perform some conversions... Electricity is about the most inefficient and costly way to convert diesel/propane/solar PV into heat for cooking and hot water (probably excluding a microwave)...

    For example, say 1 gallon of gasoline produces about 5 kWhrs of electricity. At $3.00 per gallon, that would give you an electric rate of $3/5kWhrs = $0.60 per kWhr--excluding the maintenance costs for the genset (compared to $0.07 to $0.15+ for shore power around the country--for lower tier power usage)...

    Using this handy tool:

    http://www.hearth.com/econtent/index.php/articles/fuel_cost_comparison_calculator/?id=47_0_1_0_M7

    You can compare costs of xx$ Million BTU.

    Solar panels with an electric water heater is nice--you can take out the lower electric element and replace it either with direct cold/warm water circulation or install an internal heat exchanger, or use an external heat exchanger (generally, if you have hard or "reactive" water, you would not want to circulate that water directly through the solar panels as they would tend to develop deposits and corrode). If you use a heat exchange, generally a double wall type is used to prevent mixing of antifreeze (recommend a bio-friendly type) with domestic water if leaks occur.

    You can install another insulated tank (for more storage) and/or still use the upper element to heat the water on cloudy days.

    Your two major choices for alternative fuels are alcohol (used in ships for stoves/heating because alcohol fires can be put out with water) or propane/butane... Adding either fuel to a boat may require good understanding of Coast Guard regulations (venting, bulge fans, explosion detectors, etc.).

    It would probably make a lot of sense to replace the stove ASAP (even if you get a cheap one for awhile before getting a nice one).

    And for hot water, the most fuel efficient will be a tankless water heater. There are quite a few out there (and some that can be mounted on the exterior of a "building"--they are lighter and save space too. The down side is that the hot water will not be quite as easy as to use as a tanked heater. Generally you have to have the "hot water faucet" turned on pretty close to full flow to get hot water and if you need to temper it--if you crank down the hot water flow rate below a 1/2 gpm flow, many heaters will shutdown the fire (going back to cold water).

    I guess that you also have electric heat (if you need it in your region)? Changing to propane/diesel would be a good idea too.

    Whether to bring propane/butane onto your boat vs trying to find diesel fueled appliances rated for boat use may be an interesting exercise. (do some kerosene appliances run on diesel too?--would diesel smell worst for unvented appliances?)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    While I don't disagree with your figures, there are other issues at work. First is time. This trip HAS to be done. It can't be posponed. Then if I did spend my money to convert, there wouldn't be any for batts, inverters , etc.. The 3rd. is space. As you might imagine, converting over would require a major remodel. Something I'm loathe to do right now. 4th. The drawbacks to propane and especially diesel appliances. The amount of storage for the propane is limited aboard. Tanks of suitable size would be in the way. Diesel appliances STINK, plain & simple.
    Someday, little by little, we will convert, but not for the foreseable future. I've got what I've got and I will make do for now.
    http://www.batterystuff.com/batteries/rv-marine/agm/LS3100.html
    These are the batts I'm looking at
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    Sounds good... You know your needs better than I ever can from a monitor and keyboard.

    And again--AGM batteries are highly sensitive to being overcharged. You need a good adjustable (or one with AGM settings) charge controller, remote voltage sensing, and battery temperature monitoring too... If you don't, you will destroy your batteries in very short order. If you can't install those now, you would be better with standard flooded cell batteries for now (you will just have to check the water levels every 2-4 weeks.

    Have Fun!
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: Babe in the woods, help.

    Ok, just caught up here. I used to do a lot of cruising on a 42' plaining boat (great uncles), with twin 454 and 600 gallons of fuel. Anyway it had a couple of neat things, a "cold plate" basically a huge chunk of metal that got cold either from 120vac or 12vdc and once cold could easily keep the fridge cold for 24 hours. The second was the water heater, when under way it heated the small 20 gallon hot water tank from the radiator line from the engine. You could have hot water for ever while the engine was running.

    It had 2 starting batteries, one for each engine, a small starting battery on the 12kw genset and then the house bank of four 8D sized batteries, oddly enough no inverter, just a lot of 12v appliances. The AC was water sourced and worked great in the great lakes and only ran on 120vac at 10 amps. I toyed with the idea of getting them to install an inverter, but they never got around to it.

    My big concern with your intended setup is the alternator. I find it hard to believe you will get an alternator to actually put out 200 amps consistently. Most are rated for peak and will comfortably put out half that. On some of the larger boats I worked on sometimes had 2 or even 4 (200 amps) alternators running. Realistically they would put out about 100 amps each. Just something to keep in mind.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    :-DI considered a cold plate. Still considering it. Again, the time factor. Would be nice to keep dem shrimps cold till we could tote em home.
    I'm not far into the alternator choise yet. You may be right, the duty cycle may not be as high as I think. On the other hand, when the batts charge up (it won't take long at high inputs) then the alt gets a rest? It's not like continious welding with one.
    Clue me in (somebody) on what function batt temp plays. Is it an indicator of some sort? A ratio of what to what? When ya'll say "get a good this or that (charge controller), That's why I'm here. Name a good one, cuz I sure don't know the good from the bad (hype).
    The thing is, the prev. owners JUST bought NEW fridge & HWH. Not what I would have done but... done it is. How sad.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    Regarding Alternators... Sorry, don't have any useful experience to suggest a brand... However, assuming you want a 100-200 amp alternator, you will need the large frame style (the "car" sized alternators are probably only good for 50 amps or so continous use).

    Part of the reason that they can crank high current out of small alternators is that these alternators usually have internal voltage regulators that back down the output current (and voltage) as they begin to run hot.

    For your needs, you need an alternator that (probably uses) and external regulator that directly monitors the battery voltage and temperature. A small frame alternator at high current would just overheat because of the lack of alternator temperature to the charge controller.

    And why do you need to monitor the battery voltage and temperature--take a look at this chart:

    http://www.lifelinebatteries.com/marinegraphs.php

    You will see that a cold battery produces relatively high output voltage (but low current/capacity), whereas a warm battery's voltage drops (output and charging).

    So, as an example as to what can happen using a non-compensated charge controller: Cool morning, cool batteries and charge controller mounted away from the batteries. Crank up the motor, 55 degree machinery space (charge controller set to charge at 13.7 vdc. You start dumping several hundred amps into the batteries and they begin to warm. Get up to 104 degrees (warm banks) and they want to finish charging at 13.1 vdc--but your controller is still set to 13.7 vdc and may even begin to up the current--batteries get warmer, their voltage drops, current goes up--and you have "thermal run-a-way"--hence the need for a battery temperature sensor and a compensated charge controller. Notice that this battery company measures the voltage to 1/100 of a volt (13.xx).

    Notice that we are only talking about ~0.5 volt or so between accurate charging vs inaccurate charging... We also have the same issues with voltage drop in cables... It is not unusual to see a 5 volt drop or more in 120 VAC home wiring--that much drop in a 12 VDC system will kill the operation of almost anything. So, you have the choice of running ridiculously heavy cable from the alternator to the battery bus to try an keep the voltage drop down to a ten of a volt or so--or, run smaller wire (that can still handle the current without overheating), but may have 1 volt drop at those heavy currents (so, if you crank up the regulator voltage by 1 volt so that the battery voltage is correct--then when they are charged and the current drops, the regulator is now set 1 volt too high and you will cook the batteries)--and use a pair of small wires from the battery bus to the charge controller to accurately measure the battery voltage, at the battery (virtually no current flows in the sense leads so that there is no V=I*R voltage drop.

    Also, when charging a battery, you want high current as it charges (temperature compensated) so that it charges quickly (to like 80% capacity)--then you will want to hold the battery voltage until the battery is fully charged (charge current tapers down), and eventually, you will want to drop the battery voltage by ~1 volt (12 VDC bank) to keep the battery full, but not overcharge it for weeks on end--eventually boiling the electrolyte dry. Also, depending on the battery type--you may also once or twice a month need to "equalize the batteries" (overcharge them a bit to mix the electrolyte and ensure that every cell is fully charged--not normally done to AGM batteries since you cannot refill them).

    Here is a quick chart of a sample charging program:

    http://www.balmar.net/page67-ars5.html

    Each battery vendor will (probably) have a different set of voltages/temperatures/profiles for their particular model/type of battery.

    OK--so this is a system, and depending on your needs/wants and craft's configuration, there are multiple ways to get this configured to your needs--but you will probably want to do this in steps (time/cash/wife/etc.).

    So, I guess the first question still comes back to what is the basic function that you need for this upcoming trip? Are you still set on running 1-3 large frame alternators on your propulsion motor to run your A/C through inverters? If you are planning on running your entire A/C load (plus other stuff) all at the same time through a 6kW inverter--you are probably looking at near 6000w/20 volts = 100-300+ amps max continuous load (not necessarily including battery charging) and pulling 4-12 hp from your propulsion motor to run this.

    If you are planning on creating a new 24 VDC electrical system to run these loads from your main engine--If you can, you should plan what loads you will operate, measure the running and starting loads pretty carefully, and determine exactly how far (money/space/time) you want to go with this part of the installation/upgrade.

    It is doable--but will require great care in equipment selection and installation to ensure that it all operates trouble free.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    Yeh, I still want to run at least one A/C off the engine. I know I will have the 4-12 extra hp. We have to maintain "steerage", as we come down with the current. Diesels don't like to idle, so more throttle is applied than needed to prevent loading. Wasted.
    It looks like 24V is a better plan.
    Man, thanks for the detail on this stuff. Things I'd never thought about.
    In another conversation with a fellow HBtr., who has had a solar setup for a few years now. He "says", after trying both types, he now uses 6V golf car batts. Claims in the long run they 1. cost less than 12s. 2 perform better (says their more honest in amp delivery claims). 3. Are tougher and live longer when abused. He claims every system gets "some" abuse and GC batts actually give him less trouble (moe forgiving?). His claim that there are thousands of golf cars using them STILL, this is proof that nothing new can do as good an overal job, or else they wpuld have been phased out by now. Hmmmm? Me? what do I know.
    Thanks,
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Babe in the woods, help.
    ted655 wrote:

    In another conversation with a fellow HBtr., who has had a solar setup for a few years now. He "says", after trying both types, he now uses 6V golf car batts. Claims in the long run they 1. cost less than 12s. 2 perform better (says their more honest in amp delivery claims). 3. Are tougher and live longer when abused. He claims every system gets "some" abuse and GC batts actually give him less trouble (moe forgiving?).

    True - they are pretty rugged, but they still need weekly water checking, and care. The AGM, if you Properly set the charge controller for them, will be nearly maintenance free. Check cable tightness every now and then. Or water the GC batteries, clean up acid mist, fix corroded terminals and such.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Babe in the woods, help.

    "His claim that there are thousands of golf cars using them STILL, this  is proof that nothing new can do as good an overal job, or else they wpuld have been phased out by now."

    food for thought............
    golf cart batteries are ok batteries, but if they are all that, then why are cell phone companies using agms? more cell sites than golf carts i would imagine. golf carts are used primarily in the warm months by golfers and cells are used year round even in cold remote towers. so what does all of that tell you?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    Perhaps Jim/Crewzer can (or somebody else) can address how accurately one needs to hold the proper battery voltages (temperature/float) for long battery life---Is it less than 0.1 vdc, or if it is +/- 0.3 vdc OK (I would tend to try and design for the less than 0.1 vdc range).

    Also, here is an interesting read--some postings from various email lists:

    http://www.geocities.com/bill_dietrich/BoatACPower.html

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.

    BB, are you trying to REALLY give me an ulcer? (smole). That site had every opinion range there could be! Great reading but confusing pointd of view. They couldn't even agree on the shape of a sine wave. (chuckle). I bet there were real nuggets of wisdom there, but I'm not the one to know the BS from the gold.
    I like it here better. That talk is typical of what you get anytime you say "solar" on a forum. Everybody's an expert.
    I'm going to research GC batts and try to weigh the life/replacement costs of both GCs & AGMs. I usted to maintain about 30 Taylor-Dunns rhat we rented out. It wasn't that bad (as I remember). Out gasing would be a problem. I "wanted" to put them under the salon floor to keep the weight low & centered.
    Thanks,
  • System2
    System2 Posts: 6,290 admin
    Re: Babe in the woods, help.
    ted655 wrote:
    . I like it here better. That talk is typical of what you get anytime you say "solar" on a forum. Everybody's an expert.


    I've found the same thing. Having checked out several other forms, I always come back "home" to this site. Guess I'm too old to put up with idiots any more. I love a joke anytime, but not BS.

    "my solar panels charge my batteries, using the ultra violet light that bounces off the full moon at midnight, hey, UV is UV" - -"Hook a 12 volt zeener in series with a 12 volt starter solenoid coil and when the voltage reached 14, the solenoid snaps in and puts a shunt load on the batteries, preventing overcharging" " put up a long wire antenna and hook one end to the HV terminal of an automotive ignition coil, then in a lightening storm, you get 12 volts out of the primary winding of the coil, which charges your battery." That kind of thing. Sorry, but I don't have the patience for that stuff.

    Wayne
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Babe in the woods, help.

    wow, sci fi stuff.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Babe in the woods, help.

    Yep--you will find that 10 different people have 11 different experiences and opinions. :roll:

    I like to look around and check out brands/products that I may not have heard of before--also, it gives a good idea of the problems to watch out for...

    But, it does get pretty funny when you get "I had A, it failed, got B--I am happy" and somebody else says "I had two B's and they failed with no vendor support--got C and I am happy" ... etc. :-P

    Anyway, you will get your money out of the GC batteries and--if nothing else--they are great "training batteries" and once you get your system dialed in, you can replace them when they eventually wear out.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset