Share the pain

rbtrrer
rbtrrer Registered Users Posts: 22
Hi folks,

As im new to computers,(as well as RE) beware it might take awhile for me to respond to questions not only due to excruciating slow typing technic but also stumbling around where's the right buttonz to push.

I am once again using a Honda EU 2000i genset to power my few (at this point) electrical needs.

Only recentlly did i figure out from reading forums such as this, i could cut the fuel by ~ 1/4-1/5 by charging battery.....run low consumption loads from inverter

That cost ~$240 for battery, charger,inverter initialy. I think the genset was
~$1,100 in 2004.

BTW I realise that this is a solar forum, at this time, this is a more practical/finacially feasable way for me to go.(not to mention way simpler
for me to comprend and more within budget.

Just as alot you, expanion/optimizing plans are on the board and bonifide battery moniter on the way.

My imidiate question is. To get the best "bang for the buck" can I charge multible batterys with same output of generator.


Example-2 parralle 12v batts take half as long to charge as 1 12v batt same load.

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Share the pain

    This was my reply via PM to Pat--As a start:
    BB. wrote:
    rbtrrer wrote:
    My main curiosity is at this point is to determining if i can charge multiple batteries with the same output of the genset.

    There are several ways of connecting batteries together... For example in a camping van, you may have two 12 volt batteries. 1 for the motor and vehicle power; the second for powering the RV section. And there is a big solenoid (automatic electric switch) that connects the two batteries in parallel so the vehicle engine can recharge both batteries... And if the RV battery goes dead--the second engine battery is still fine to get the engine started.

    Otherwise, if you have a set of common loads (like a RV trailer), you may want to connect two (or more) 12 volt batteries in parallel and simply treat them like one big battery.

    Lots of options--It is better for your to clearly state your needs (larger battery bank, or separate batteries for separate functions in one vehicle/home/etc.).
    if i'm understanding correctly, it seems There's a "magic" number that is practicable to obtain that i have no clue how to determine.
    There are lots of magic numbers (rules of thumb) we can use...

    Normally we start with the loads and then define the size of the battery bank.

    Although, many people have a battery bank (or limited space for batteries)--So we can start there too.

    Really need to know the Amp*Hour Rating of the battery (like 100 AH at 20 hour rate) and the bank voltage (12, 24, 48 volt etc.)...

    I can guess or give examples--but it is easier if we use your numbers so you understand your system design instead of someone else's system.
    My current needs are such that 1 batt is sufficient, if i can charge more battery capability with same generator output.
    In the "old'en days" (you are 2 years older than I), people though the best thing to do was have as many batteries (Amp*Hours) of storage as possible.

    Today, we actually try to size the bank as small as practical for your needs (typically 1-3 days of no-sun and 50% maximum discharge). The reason for this is batteries are expensive and need quite a bit of charging current to properly (and quickly) recharge.

    A too large bank can cost you a lot of extra money--and the battery bank will not last any longer (and in some cases, may die sooner).
    Would it make sense, if I added another equivalent battery, same usage, it would take give or take 1/2 time to charge?
    Do you have an idea of the AH and voltage rating of your current battery? How much power do you use in a typical day (Amp*Hours or Watt*Hours) or how many days this battery lasts you (1,2,5, etc. days between recharging)? Is this a deep cycle battery or marine battery, or just a car battery?

    The battery is the "heart of your system" and you need to understand how to "keep it happy"--or else it will not last very long... A couple of things to read:

    Deep Cycle Battery FAQ
    www.batteryfaq.org

    And here is a nice thread with video from Kevin in Calgary Canada that shows designing and installing solar PV in a small RV trailer.

    Our host has a website you can look around and get an idea of what is out there and the general pricing.

    If you purchase from Northern Arizona Wind & Sun does not matter to us--purely your choice (nobody here except the two Admins are connected with NAWS). They have good quality equipment and reasonable pricing--not a bad place to start looking.

    Sincerely,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Share the pain

    Welcome to the forum.

    You'd be amazed at how often we suggest people use generators instead of solar around here! :p

    Can you charge more than one battery at a time? Certainly. But know the limitations.
    First of all, if they are different types of battery or discharged different amounts they will not both recharge properly from being paralleled to one charger.
    Second, whether you use one charger or two there will be an increased draw. One charger will reach its current supplying limit sooner and (as with two) will load the generator more resulting in greater fuel consumption.
    Third, the generator will not be able to supply beyond its limit and could be overloaded with too much battery charging capacity plugged in to it.
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    My mind works in mysterious ways.

    I understand that methodology.

    I have a counterintuitive manner of processing how or why something makes sense for me. I dont have a choice about that.

    I'm trying to undestand the potential.
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    Cariboocoot,

    I'm not so amazed. Iv been reading on this and other forums much about this subject over the coarse of the last three weeks.

    I was refering to charging 2 same type batterys 12v 115ah in paralel.

    I'm looking for specif details that I can translate to real world conditions as for me thats how I might be more able to understand
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Share the pain

    Well if you leave out the trickier bits about losses and the Peukert effect you get this sort of thing:

    One 115 Amp hour 12 Volt battery, 10% discharged, needs 11.5 Amp hours "replaced". With a 10 Amp charger this will take 1.15 hours (not really, due to items mentioned above).

    Two 115 Amp hour 12 Volt batteries, each 10% discharged, need 23 Amp hours "replaced". With a 10 Amp charger this will take 2.3 hours (not really, due to items mentioned above).

    So the same rate of charge for twice as much battery charging takes twice as much time. In generator terms, this is twice as many Watt hours and more fuel.

    Or, you can run two chargers or a larger charger - either capable of an output of 20 Amps - and accomplish the same charging of the two batteries in half the time.

    The first example represents 326.6 Watt hours: 14.2 Volts charging * 10 Amps * 2.3 hours.
    The second is also 326.6 Watt hours: 14.2 Volts charging * 20 Amps * 1.15 hours.

    In reality this does not work out so neatly. Particularly about the fuel consumption. It is not simply 2X, because a generator has to use a certain amount of fuel just to run under no load. They become more efficient when loaded 50% or more.
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Share the pain

    Buy a good battery charger and power it with the Honda. The 12v output on any small generator is really only good for emergency battery charging.

    Most are limited to 8 amps, which is not a lot, and all of them have no control to make them stop charging when the battery is full, so you have to really watch them. Also, you usually have to turn off economy mode and run the generator at full speed to use the 12v for battery charging. Better to just plug in a battery charger to the regular power and use econo mode.

    Putting two batteries in parallel is okay depending on the charger. Any charger that just works by voltage (like any cheap car battery charger) it's fine.

    With an expensive 3-stage charger - no, two batteries is not good unless the batteries are always paralleled so they are always drained the same amount.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Share the pain

    Ah--Some numbers.

    Two x 12 volt @ 115 AH in parallel become a 12 volt @ 230 AH battery bank.

    Parallelingbatteries will add current/Amp*Hours.

    Placing batteries in series will add voltage.

    For solar, the typical recommendation (not knowing your loads) would be 5% to 13% rate of charge and a derating factor of 0.77 (solar panels + charge controller):
    • 230 AH * 14.5 volts charging * 1/0.77 derating * 0.05 charge rate = 217 watts of solar panel minimum
    • 230 AH * 14.5 volts charging * 1/0.77 derating * 0.10 charge rate = 433 watts of solar panel good sized array
    • 230 AH * 14.5 volts charging * 1/0.77 derating * 0.05 charge rate = 563 watts of solar panel maximum (cost/performance wise)
    For a battery charger on utility power or a genset--There is some really large variability because of how battery charger 120 VAC input may be designed... Skipping the details--For a 230 AH battery bank, you would like to see somewhere around 5-13% rate of charge again (~25% maximum):
    • 230 AH * 0.05 = 11.5 amps minimum
    • 230 AH * 0.13 = 29.9 amps good sized charger
    • 230 AH * 0.25 = 57.5 amps about maximum
    For Non-Power factor corrected power supplies, you can easily run on your Honda eu2000i:
    • 1,600 watts * 0.80 efficiency * 0.6 Power Factor * 1/14.5 volts charging = 53 amps maximum
    So--you can easily run a 40-45 amp Iota (example) 12 volt battery charger on your Honda.

    Or, if you want to share the Honda with other AC loads, you could use a smaller 20 amp Iota too (will take longer to recharge your batteries).

    wind-sun_2155_22681404Iota DLS-45 12 volt 45 amp regulated battery charger
    Price: $150.00

    If you are interested in finding the "Optimum" battery charger for your Honda eu2000i--there is this thread where "Stevek" did a bunch of research to find one that works well for him.

    Question about battery charger selection with EU2000 generator.

    In the end, for your 12 volt system, this "Meanwell 12 volt 60 amp PFC 120 VAC supply" would be a very good match for your eu2000i--even for a much larger battery bank (note Jameco is out of stock right now--not sure when they will get them in again--13 ARO for awhile).

    Of course--we have not discussed how much energy you use in a day--so sizing the battery bank, solar panels, and battery charger--is all a guess.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    For me, you guys are talking around what I'm trying todefine. That's not to be taken as critisism. I'ts how it is and hence the title of this thread.

    Specifics my current "system" details/some numbers to follow.

    I stumbled across this forum the other day and like to say right up front you guys are awesome!

    I'ts been really good to see what I feel is an outpouring of good will on all ya alls part. So even if I don't get to where I'm going, Thanx all the same
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    I'm way behind give me some time to catch up.

    I read the thread you refered to is probably the reason I am motivated to persue
    further.

    If I can trust my V meter or go by KaW, my cuurent usage is appox. 0.10 kw per day noon to late evening

    V meter ~12.2v shut down
    Charge 1 1/2-2 1/2 hrs V=~13V+

    Typical Loads 14" laptop, brodband card, batt, 8w florecent
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    I looked at that and maybe be others as well but i need to do things on the cheap at this point
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    Apology Cariboohott

    I did not read your entire post. After going back I realized you answered the one partEven though I Know it's correct and to the point The ahHa moment, Wellsee

    In my defence, if you had read my mind, you might have put it closer to the top.
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    Apologe CaridooCoot

    What if I asked it this way?

    eu2k eco off===max amp chrger to max practical 12v batts and not pushing
    generator to greater than whats not yo hard on it
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    BB

    Inpost #8 you nailed it but once again, I had to find that specific nth that brings it closer to clarity

    was that maximum 50 odd max amp chrg rate you noted at max (eco off)
  • BB.
    BB. Super Moderators, Administrators Posts: 33,433 admin
    Re: Share the pain

    Pat,

    You really need to read through the Battery FAQs (frequently asked questions) and understand them.

    Lead acid batteries are pretty simple... But they need to be correctly charged (and not discharged too deeply) for a long life...

    Typically, you charge them (solar, AC battery charger, etc.) around 14.2 to 14.5 volts or so--You want the charging voltage a bit "high" to really pump in the current to the battery bank (you don't want a 1,600 watt generator burning fuel while pumping only 20 watts into the batteries for 20 hours). You want 20-50 amps or so while the generator is running (over 50% load is very fuel efficient).

    Many of these Honda eu (and other similar genset from other vendors) do have a small (typically around 8 amp) 12 volt output you can connect to a 12 volt battery for charging (like needing to charge your car battery in an emergency).

    For various reasons, these 8 amp 12 volt battery charger outputs are not useful. They are very low power (100 watts or so), unregulated, and require the genset to run at full speed (eco throttle off)--so waste lots of fuel.

    From the bit of testing I have read here--With a regular AC battery charger, you can run with ECO Throttle ON and the genset will change engine speed as needed to power the chargers.

    The Meanwell charger that SteveK is using--It is a very efficient power supply (you can get 60 amps out of the 12 volt Meanwell instead of 40-45 amps from an Iota on a Honda eu2000i) but requires ECO Throttle to be OFF when first powering up the Meanwell AC battery charger--However, I think, once the Meanwell is up, running, and charging the battery bank, you can flip to ECO Throttle ON (it was just the startup of the Meanwell that needed full throttle ON).

    Try to take it a step at a time... Focus on the battery as the "heart" of the system.

    For the most part, each other major piece is (solar, AC charger, AC inverter) does not care about the other devices (i.e., solar+battery; then AC charger + battery; etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rbtrrer
    rbtrrer Registered Users Posts: 22
    Re: Share the pain

    I think I've pretty much got it for the time being. Do us all a favor and round file this one.


    Thnx much