A little advice perhaps?

JaybirdJaybird Posts: 19Registered Users
Hi all,

Tis my first post on the site. Time and time again I find myself at this site getting really good info (Thanks bill you've been a help). I have many questions but first I'll weigh in on the specifics. I have 10 , 195 watt suntech panels ground mounted (homemade treated lumber), 2 outback FM 80's, I use ac breaker boxes for my combiner boxes and landscape wiring (10/2) from my panels to my breakers. 0 gauge every where there after into 4 maxx 29's @ 12 volts ( I know they suck I'll soon be upgrading) and into a cobra 2500 continuous MSW inverter. I use a power strip and a killawatt out of that into a breaker box (neutral not bonded to ground) which supplies 80% of my houses power ( Not the oven, dryer and a few outlets in convienient places to switch after I run out of battery juice ( 50% Dod of course ). and a 20 amp battery charger (cheap)

Now the questions

I'm considering a xantrex prowatt 2000 watt inverter to replace my cheapo cobra. Am I wrong in my research that I will not be able to bond ground to neutral with this particular true sine inverter. I haven't found a straight answer. Is what I'm doing safe? I've been doing it for six months with no problems but want to ask people with more experience. And before you start preaching about codes. I live in the country in the middle of a mile in which I own half of and am not worried about insurance, etc. Just want to be safe. There is a difference between what's safe and what's code (sometimes).

Next, I don't have DC breakers between the battery bank and the charge controllers (expensive ones)? how critical is this lack of safety. I have my inverter fused at 200 amps. Could I put in some 100 amp fuses inline between the FM's and batteries or is my logic flawed in the sense they may not trip fast enough (using heavy duty car audio fuses, JL audio). What could potentially go backwards into the Charge controller to deal damage to it?

Next, I've read all about batteries and Have decided eventually when I get some decent crops I'll go with NIFE batteries. I know some of you don't like these. And that's ok. I will debate until you convert me or I surrender or who knows, convert you:) Till then, how many 6 volt GC batteries( say 200 amp hour) do I need to carry 1000 watts for 14 hours? I plan on adding 2 more panels to the array this fall and perhaps a GC 450 wind turbine.

Would this setup take me down the road for a decade or more without much trouble. So far six months into this thing and everything is OK (batteries suck though) No hot wires, everythings grounded to earth (except battery bank)

Should I ground my battery bank. My logic says no with a MSW inverter. And even so with a prowatt. I don't like fried inverters or drained dead batteries.

Thanks in advance for the help, I'm sure I'll get few WTF was he thinking responses with the redneck of it all. I use woodgas engine for backup, and homemade solar water heater. Am attempting a homemade wind turbine with cieling fans (got a bunch of super well built ag fans from our retired turkey barns).

Thanks again guys..... :)

Comments

  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?

    I'm kind of fading here but I'll toss out some info which has at least some probability of being accurate.

    If this is the Xantrex ProWatt with built-in GFI, the problem is that there is already a neutral-ground bond in the inverter before the GFI circuitry. Adding an external bond duplicates this and creates a pathway around the GFI that causes it to trip.

    You need some form of circuit protection between the charge controllers and batteries. Fuses will work, and as this is a 12 Volt system automotive types will do. But you might want something just a tad better that allows you to use it as a disconnect as well. Look at these: http://www.solar-electric.com/mr60ampdccib.html

    You want to supply 1kW for 14 hours? On 12 Volts? Are you kidding me? That's 14 kW hours. That's like 1200 Amp hours being used, or a minimum 2400 Amp hour battery bank. This is definitely the time to increase the system Voltage if you need that kind of capacity. Golf cart batteries don't enter in to it: you'd have to parallel up so many that you'd never keep the current flow even. Really.

    The trouble with MSW inverters is usually the neutral-ground bond on the output. There really isn't a need to bond the negative to ground either (some have problems there too). If there were instructions with the inverter it should explain this clearly. Hahaha! That's the funniest thing I've said today. You're lucky if the instructions are in broken English these days! :p

    Seriously; if you're looking at new inverter, new batteries, adding fuses, et cetera ... stop before you spend any more money. Re-evaluate the load requirements. Look at increasing the system Voltage. 12 Volt set-ups can only be stretched so far before they become impractical.
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    Thanks for the input.

    My wiring from the inverter to a breaker goes as such. Black to breaker, white to nuetral buss bar and ground to chasis which are all linked to chasis ground on inverter, and then to earth. I don't suppose I'll have trouble when going to the prowatt truesine with that configuration?

    At what point does a guy abandon 12 volts? I've geared other things for the voltage. Giving up, or converting my 300 amp woodgas generator would be a shame. But I'd prefer to not have to use it if I don't have to. Gotta load wood, then start fire. 10 minutes later you can startup, but 300 amps at 15 volts is no slouch. I was anticipating putting 24, 205 amp GC batteries. So even with same cable lengths and multiple leads to my bussbars I'll still have an uneven drain? 24 Volts would not be out of the question as I can probably make that work. Just hate to give up the use of alternators and generators already in service. What would you do with this? I knew when I started the disadvantages of 12 volt (hence 2 FM 80's instead of one) but wanted redundancy and options of easily available stuff. At a bit of a cross roads I guess.
    Thanks again
  • BB.BB. Posts: 28,088Super Moderators, Administrators admin
    Re: A little advice perhaps?

    My personal recommendation--I like to recommend to keep your DC/Battery loads to around 100 amps maximum... if you go higher than that, you are looking at some pretty heavy cabling and breakers/fusing. Also, you have to keep the DC runs very short to keep voltage drop reasonable (around 0.5 to 1.0 volts maximum)--Or your loads may stop working correctly when the battery bank drops below 11.5 volts and your loads are at, or below, 10.5 volts.

    So--That means around 1,200 watts maximum for an AC inverter at 12 volts, 2,400 watts for a 24 VDC battery bank... And over 2,400 watts, a 48 volt battery bank.

    But, there are people here who are very happy with their 2kW 12 volt inverter setups.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?

    People who are happy with their high capacity 12 Volt systems generally do not use twelve parallel strings of golf cart batteries. They use the big L16 2 Volt cells, which are pretty expensive.

    So let's look at it from the start: the loads. There's two factors to consider here: one is the maximum Watts needed and the other is the total Watt hours. If your maximum Watts is consistently over 1k you start thinking about going to 24 Volt. If your total Watt hours is over 1kW hour you start thinking about going to 24 Volt. If your total Watt hours is 14 kW hours you think about 48 Volt. It would look something like this:
    14kW Hours on 12 Volts = 1166 Amp hours, 2332 Amp hour battery bank minimum
    14kW Hours on 24 Volts = 583 Amp hours, 1166 Amp hour battery bank minimum
    14kW Hours on 48 Volts = 292 Amp hours, 583 Amp hour battery bank minimum
    For 220 Amp hour golf cart batteries that's 11 strings in parallel on 12 Volts, 6 strings in parallel on 24 Volts, 3 strings in parallel on 48 Volts. That last one would work, the other two will be a nightmare of constant checking to make sure the batteries all stay evenly charged.

    Here's a different plan to think about that would mean you wouldn't have to change out everything and eliminate your existing generators: divide the loads up into separate 12 Volt systems. If you don't have any one item that uses large amounts of power, there is nothing wrong with having multiple redundant systems. You even have an extra degree of safety there because if one system goes down you can switch over to another temporarily. You've already got two FM80's: that would work for two very large 12 Volt banks (like 1000 Amp hours each). But even at that, golf cart batteries aren't the way to go to get that kind of capacity: you'd still have five parallel strings in each bank. It wouldn't meet the total Amp hour requirement either, but it would be close.
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    Thanks so much guys.

    Didn't anticipate the battery bank problem. I think I can split the my circuts up and keep twelve volts feasible (at least for a while). In the day time right now we typically run about 1000 watts per hour. As the evening comes I switch to grid power for the big stuff (freezer,fridge, big screen)Although I would never actually use 1000 watts an hour through the night, I thought it would be good to have the battery to carry me if needed.
    I will go research 24 and 48 volt inverters.

    Do you guys see a safety problem with the ac side of my wiring?


    Edit- I would imagine you guys are probably a little reluctant to the last question for liability reasons or whatever, so apologies for that. However, know that I make the final decisions and what I do in my house is on me :)

    Hoping to double my array over the next couple of years to be able to run an air conditioner or two (during the day) so 24 volts is looking good with multiple banks. The info here is much obliged...
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?
    Jaybird wrote: »
    Do you guys see a safety problem with the ac side of my wiring?

    In respect to what, specifically?

    I do see a problem with your homemade wind turbine: even Ag fans aren't meant to run out in the weather. Besides, motors don't make good generators. Are you sure you have enough wind available to make it worthwhile to try this?
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    basically my inverter has a heavy extension cord coming out of an outlet an into a breaker in which instead of bonding neutral to ground I went to chasis with it. All circuts that are coming in the breaker panel are wired the same. With the chasis ground ( round bottom prong on a recepticle) going to earth. This will not hurt my inverter as I understand it cause I'm essentially just replicating what it already has (made a big power strip basically) When I hook a pure sine wave inverter up to this will things change, or can I safely get away with doing what I am doing?
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?

    The safety grounds should be connected to Earth ground as you have it.
    The issues arise with the neutral-ground bonding, which you don't have. That isn't a problem; it just means both sides of your AC are "hot", as they would be from a portable generator. The MSW inverter should not have the N-G bond. It will not hurt a true sine inverter to not have it either. But if you switch to sine wave you might want to add it as it is an additional safety measure.
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    Yes there is definetely enough wind in my part of the world. Sometime it blows 25-30 miles an hour for a week. Sometime not at all. Nonetheless It is an experiment. The Ag fans are totally sealed. They had been in service for about 12 years (finally got out of the turkey business) and look like new inside, bearings good. I don't expect them to make more than 2 or 3 amps @ 12 volts. I'm basically recycling, or repurposing things I already have. I have A BUNCH of them. The question is- Do they pay out with the main investment being magnets. That's what I intend to find out. I do alot of "experiments". I would like to try this fall to take my deep well water and pump it into a heat exchanger ( Semi radiator or two) with a plenum around it and some squirell cages to cool the house (de humidification may be an issue). I figure it might be a considerable amount less power than an ac... Just an experiment :)
  • vtmapsvtmaps Posts: 3,738Solar Expert ✭✭✭✭
    Re: A little advice perhaps?
    Jaybird wrote: »
    Next, I don't have DC breakers between the battery bank and the charge controllers (expensive ones)? how critical is this lack of safety. I have my inverter fused at 200 amps. Could I put in some 100 amp fuses inline between the FM's and batteries or is my logic flawed in the sense they may not trip fast enough (using heavy duty car audio fuses, JL audio). What could potentially go backwards into the Charge controller to deal damage to it?

    When controllers fail they may become a short circuit across the battery. Look at your outback wiring diagrams. They show a very important 80 amp circuit breaker between controller and battery.
    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    Thanks vtMaps I'll get some protection there. I had started this project with some working knowledge of small scale stuff and as time has passed it's been a journey of learning. Time to face the fact that my arrangement is no longer a little experiment. Against my previous post I believe I've determined to stay 12 volt and make seperate systems. This is contrary to popular thinking but I like the idea of redundant systems and easily obtainable 12 volt stuff. By dividing my loads on seperate inverters and battery banks I can keep from an insane battery baink size, While all the while doing the same job. Is it cheaper, NO. But I feel a little safer knowing a single point of failure can't bring me down. Can't go to walmart and buy a 48v inverter if I have to. Can't charge the bank off a car alternator. This logic is usually not feesible, but with woodgas efficiency matters not. As 16 pounds of wood makes a gallon of gas, I have many tens of thousands of gallons of gas respectably. And no, that's not cutting a single "living" tree down :) That alone is the only thing that turns the tide at this point.

    You guys have been alot of help.
  • waynefromnscanadawaynefromnscanada Posts: 3,009Solar Expert ✭✭✭✭
    Re: A little advice perhaps?

    Originally Posted by Jaybird:
    "(using heavy duty car audio fuses, JL audio). ?"


    I've been down the road of both automotive and car audio fuses and their holders, and in both cases I was lucky to not have a fire!
    Apparently, these fuses work OK with light to intermittent loads as would be expected in their intended use. To my shock, when subjected to hour after hour of heavy loads, yet still well below their blowing point, the buildup of, and sustained high temperature causes some changes in the metal to metal connections between the blades of the plug in fuses and their holders. These gradual changes increase slightly the resistance in those connections, which increases even more the temperature. Eventually the fuse blade and it's holder connection arcs, welds the connections, continues to heat, melting and scorching the holder and finally burning off one of the fuse legs. Not a pretty sight. I'm very thankful both cases were enclosed within a metal box, so a spreading fire was hopefully unlikely. I now have bolt on fuses with the fuses securely bolted to their holders. Just a heads up to what can happen.
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?

    Wayne, you've just got to stop buying that cheap stuff from Canadian Tire! :p
  • waynefromnscanadawaynefromnscanada Posts: 3,009Solar Expert ✭✭✭✭
    Re: A little advice perhaps?
    Wayne, you've just got to stop buying that cheap stuff from Canadian Tire! :p

    Worse, it was Wal*Mart! :( :( :(
    Reminds me, I have some automotive and automotive audio fuse holders and fuses for sale, never used, won't ever be used by me, not ever! Hahahahaha
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?

    You already revealed there from Wal*Mart: no one will buy them.

    If anyone is wondering, there can indeed be a difference in quality in these things. I bought some bargain blade fuses once; every one I tried popped instantly. Tossed them, and went back to stealing what I needed out of other people's cars. :p
    (Yes, I have been known to strip junkers in the yard.)

    And I have used auto fuses on 12 Volt systems with no trouble. But you do have to remember what kind of application you've got: I sure wouldn't trust one of those auto 30 or 50 Amp breakers on say a Morningstar 300 Watt inverter.
  • mike95490mike95490 Posts: 7,970Solar Expert ✭✭✭✭
    Re: A little advice perhaps?

    With NiFe, you have to watch your DC vlotage limits. Battery charge is higher, you need a programable charge controller. And your inverter needs to be able to work with the wide voltage swings w/o shutting down.

    And now I hear of the carbonite issue, bad chemical packaging likely delivers it pre-loaded with Co2 :(
    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 ,

  • ywhicywhic Posts: 612Solar Expert ✭✭
    Re: A little advice perhaps?

    I did the 250 AMP ANL fuse thing from battery to 2K inverter with some 3/0 wire and a BlueSea battery switch.

    And I did an inline 60 amp breaker from the controller (TS45) to the battery with the 6 AWG wire..

    I'm doing the 12v thing so I hopefully will be safe..
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    Hadn't heard of the nife failures before. The prowatt I'm looking at should be able to handle those swings and the outbacks should handle them ok as well. Most of my other stuff will have a problem tho :( I too had a cheapo fuse holder melt. Hadn't had any trouble thus far with the audio stuff but will most likely upgrade them this fall as I'll be doing alot of work to the system anyways. Amazing this cobra inverter was in my farm truck for 3 years working hard starting an air compressor and knock on wood it's still kicking after all the abuse it has been through. I figured it would toast by now.

    Just curious ywhic. You sure that morning star will handle the 700 watts your after at 12 volts? I'm sure you got it figured out, just sounds like to much for a 45 amp charge controller at 12 volts. Although I have a c35 and was surprised what it would do. But still.
  • ywhicywhic Posts: 612Solar Expert ✭✭
    Re: A little advice perhaps?
    Jaybird wrote: »
    Just curious ywhic. You sure that morning star will handle the 700 watts your after at 12 volts? I'm sure you got it figured out, just sounds like to much for a 45 amp charge controller at 12 volts. Although I have a c35 and was surprised what it would do. But still.

    Yup.. the max amps from the panels * 6 panels & 870 watts (IMP) is 46.5 amps.. 1.5 amps over the 45 amp limit... the TS45 book says there is a 125% overage allowance on the 45 amps.. The ISC is 50.2 amps which is .2 over the max for that rating.. The Morningstar Calc said 725 Watts PV max (5*145w) for the TS45 (PWM).. (based on the amps).. I put another breaker after the combiner/breakerbox and before the controller, as well as one after the controller before the battery bank to make sure things stay in check..

    step2.jpg

    After talking to Cariboocoot (on here) (and checking the MS String calc) we both agree I could go to 870 PV max on the 12v in parallel (or double in a 24 setup).. Cariboocoot seems to think I will never hit optimum numbers to cause the clipping or 'max out'.. The worst case I turn off 1 panel if I notice alot of clipping..

    The other option is I do 3 double and run with a 24v system.. the MS calc said I can go to upto 725*2 worth of panel (1450) on the TS45 (PWM) with 5 strings of 2 of the same 145w panel..
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    I figured you guys had it penciled out. I hadn't thoroghly read over the morningstars capabilities. I kinda wish I'd bought midnite controllers but I had read on here that the outbacks are a little more seasoned and tried and true. I was just a click away from staying pwm and using c 60's but with 30 volt panels that don't make sense after I learned some more.

    Does your MS get warm with that setup?
  • mike95490mike95490 Posts: 7,970Solar Expert ✭✭✭✭
    Re: A little advice perhaps?
    Jaybird wrote: »
    .... Does your MS get warm with that setup?

    Morningstar 60A MPPT - Mine gets warm running 40A @ 60V output, but not bad enough that I'd want to stick a fan on it.
    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 ,

  • ywhicywhic Posts: 612Solar Expert ✭✭
    Re: A little advice perhaps?
    Jaybird wrote: »
    I figured you guys had it penciled out. I hadn't thoroghly read over the morningstars capabilities. I kinda wish I'd bought midnite controllers but I had read on here that the outbacks are a little more seasoned and tried and true. I was just a click away from staying pwm and using c 60's but with 30 volt panels that don't make sense after I learned some more.

    Does your MS get warm with that setup?

    Sorry for the delay.. grad day for my nephew..

    Not setup yet... still waiting on panels to come in next week.

    I'll be testing with 1-2 panels.. not all 6 till I get back to TX.. sucks being in NJ/PA and not there.. soon..
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    Any body have any luck with forklift traction batteries. After your guys recommendation on not get gc batteries I seen these.

    http://gbindustrialbattery.com/Forklift_Battery_Sizes_and_Specifications_Zone15.html

    Thought maybe 3 or 4 of the smallest 12 volt ones might work.
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?
    Jaybird wrote: »
    Any body have any luck with forklift traction batteries. After your guys recommendation on not get gc batteries I seen these.

    http://gbindustrialbattery.com/Forklift_Battery_Sizes_and_Specifications_Zone15.html

    Thought maybe 3 or 4 of the smallest 12 volt ones might work.

    Actually nobody said don't get golf cart batteries. What was warned against are those "pseudo deep cycle" Marine/RV batteries.

    Some of the forum members run industrial/forklift batteries with great success. They have a discharge capacity of up to 80%. The down side is they are monster monoliths and you can have a lot of trouble moving them into position. Having a forklift helps. :p But if you have the right set-up for them, they work fine.
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    People who are happy with their high capacity 12 Volt systems generally do not use twelve parallel strings of golf cart batteries.

    Golf cart batteries don't enter in to it: you'd have to parallel up so many that you'd never keep the current flow even. Really.


    Ok....... I can move the monstrous batteries around with no problem. Just thought maybe they'd be an alternative to worrying about the above quotes. What's the max amount of GC batteries per charge controller/inverter you would recommend @ 12 volts? The fact of uneven charge and discharge hadn't crossed my mind until you said something. My plan before looking into bigger batteries was as such = say you have 12 batteries sitting side by side with 3/0 connections. Just put the positive on one end and the negative on the other. Or bring that arrangement in say 3 batteries on each end are blank with the positive on the next adjacent one and the same way for the negative. I could split loads and inverters and have multiple battery banks. But it'd be handy to have a nice big inverter to run the place and one breaker panel, etc.

    Any thoughts are much appreciated
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?

    Okay, different issue; it isn't the golf cart batteries that are lacking here, it's having to parallel up so many to get the amount of power capacity you want.

    Usually you do not want more than two parallel battery strings. You can have more, but it gets more difficult to keep the current flow even. That's why if you really need that kind of Watt hours you should increase system Voltage, rather than the Amp hour capacity.

    Your twelve parallels of 220 Amp hours makes 2640 Amp hours. At 12 Volts that's 31,680 Watt hours of capacity.
    Problems:
    1). Too much current needed to charge the battery bank (264 Amps, necessitating 4 or more controllers and arrays).
    2). Too difficult to keep current flow through batteries even due to the many parallel paths available.
    3). Enormous number of interconnecting wires, each a potential problem.
    4). A lot of individual cells to check for SG and electrolyte level.

    Solutions:
    1). High Amp hour 2 Volt cells. 2550 Amp hours times 6 batteries. Cost $1,372 each.
    2). Industrial batteries. Two 1375 Amp hour 12 Volts in parallel. Cost $3,204 each.

    These two choices do not solve the multiple charge controller issue.

    3). Higher system Voltage. At 24 Volts, 31,680 Watt hours is 1320 Amp hours. At 48 Volts it's only 660 Amp hours, which can easily be obtain using common 6 Volt cells (two parallel strings of Trojan L16A's for example).

    One charge controller (like an FM80) can handle the current for 660 Amp hours @ 48 Volts. The batteries are cheaper. The connections fewer. The cells to check less. The current flow easier to manage. 48 Volt systems are more efficient than 12 Volt systems.

    I hope that gives you some idea of the options for supplying the power. Buying those big 12 Volt batteries would offset the cost of the higher Voltage system. Frankly I'm boggling at the total stored capacity you're looking at and wondering why you want/need it. Is there some reason you want to stay with 12 Volts? It has its uses, but large stored energy capacity is not one of them. Nor is high load current demands.

    As a side note, one of the advantages of splitting loads into multiple systems is the redundancy factor; one system goes down, its loads can be powered by the next system if critical. This is not always a necessary criterion.
  • JaybirdJaybird Posts: 19Registered Users
    Re: A little advice perhaps?

    Mostly the woodgas generator. I can obtain high output 24 volt alternators and perhaps increase system voltage, but I have a very large generator welder and couldn't replace it cheaply. I had considered doubling my array size and adding 2 more charge controllers, but am currently looking into some wind power (so far the small wind turbines don't seem to durable) My abundance of firewood make fuel (biomass) very easy to obtain in large quantities. However, commonly found items that run at higher voltage are harder to come by. I looked at the battery calculator on the link I posted and came up with about 5000$ for 4 or the 12 volt forklift batteries. Their chart shows that would cover my needs. Now to be able to charge that amount. Understand that I've built a healthy buffer for my 1000 watts for 14 hours. Realistically more like 600 watts for 14 hours would be the max I would draw. But I don't mind spending some extra on a good buffer. Staying 12 volt will be a priority as it's very easy to take a small engine and hang an alternator off it, load 100 lbs of wood in a hopper and let it rip all night if need be. Wood gasification is a very old technique that really needs some light brought back onto it. Especially for land owners. Not for everyone, but for those who own some timberland. They often have an inexhaustable amount of fuel and don't know it.
  • Ken MarshKen Marsh Posts: 114Solar Expert ✭✭✭✭
    Re: A little advice perhaps?

    Jason,
    Would like to hear more about your wood gas fired gen set,
    something about burner geometry and gas processing.

    I have a 2 stage outside wood burner.
    Am considering taking a stream off the first stage to run an engine.
    It would be dual fueled with the other fuel being propane.
    In general we have poor wood.
    Its usually wet and low btu.

    On your DC generator, usually welder generators are 30-50 volt.
    Perhaps you could go with a higher voltage battery stack.
    Or maybe the engine will not spin the generator up enough?
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?

    I agree with Ken; we'd like to hear about your wood gas set-up. These days those things are only found in museums under "this is how we ran the car during the war" followed by the question "what war?" Might even go for one myself, as I've got more beetle-killed pine here than you could cut in a lifetime. Well, more than I could in mine.

    There is a bit of a problem with the plan of running a small engine & alternator off the gas and using that to charge the battery: the size of the battery. The more massive your "buffer" becomes the less effectual the small generator is for charging it.

    Now if the battery capacity can be switched in and out you could use smaller banks in batches. This would make it easier to keep them charged properly without all the current flow nightmare. The problem is that 1000 Watts continuous on 12 Volts is 84 Amps, and you need a fairly sizable battery bank to support that in the first place, let alone run it over time.

    I'm thinking it might be easier to find a way of increasing the available charging Voltage. For instance using an alternator from a 24 Volt industrial application (heavy equipment often uses 24 Volt).

    This gen-welder you have: is it used as a main power source or what?
  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: A little advice perhaps?

    Jaybird, Ken, et al;

    I've moved the wood gas posts to here: http://forum.solar-electric.com/showthread.php?15990-Jaybird-s-wood-gas-thread
    It's quite a different topic so it deserves its own thread. :D
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