question on replacing 6 L16HC batteries with 6 golf cart style batteries

Sams Club has 6 volt and 8 volt deep cycle golf cart type batteries. I now have 6 L16HC deepcycle batteries that are bad but still hooked up to my small pv system.

Please explain to me can I hook up 6 of the 8 volt batteries in my present system that is is set up for 6 volt batteries or do I have to stay with the
6 volt gold cart types? Do I gain any advantage by using the 8 volt types?

If I can use the 8 volt batteries would you explain how to set up my system
to function properly with them.?

I have 7 pv modules with a total output rating of 640 watts, a Statpower 1800 full sinewave inverter and a Pulse Energy Systems PSC 500 control panel. These were installed in 1999.

I hope that I have given you enough information to be able to advise me, if not please advise me what else you need.

Thanks a lot for your help.


Jim

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: question on replacing 6 L16HC batteries with 6 golf cart style batteries

    Jim,

    You have to define your "system"... What is the working voltage of your charger, inverter, loads...

    The "standard" systems that you will see around are 12, 24, and 48 volt systems... You will see a few 36 volt systems (marine, some military?).

    So, the simple question is what combinations of "8 volt" batteries will make a useful battery bank for your needs.

    Most people start with 12 volt systems. Works OK, perhaps up to around 1,000 watts of power (~100 amp maximum current). 2x 6 volt batteries works, but 1x or 2x 8 volt will not. If your charger is 12 volt, your inverter is 12 volt, and your loads are 12 volt--then an 8 volt battery will not work for you... a single 8 volt battery is too low of voltage. 2x 8 volt in series is too high of voltage (will probably blow most loads with over voltage).

    24, 36, 48 volt battery banks all can use 8 volt batteries just fine (2x, 3x 4x are all integer multiples of the bank voltage). Of course, 6 volt and 12 volt batteries are also integer voltage of 12, 24, 36, and 48 volt banks.

    So--if this is your first system, and you want to support fairly large loads (12v < 1,000 watts, 24v <2,000 watts, 48 volt ~4,000 watts)--then you can use 8 volt batteries for 24-48 volt battery banks.

    For a 12 volt system--then you are stuck with other cell configurations that add up to "12 volts".

    In general, I like to connect series strings of battery/cells--better sharing of current between . If you need more current/AmpHours of storage, go with one string of bigger cells. Rather than placing a bunch of small cells in parallel (probably, three parallel strings of cells is about the maximum for a long life system unless you are careful about wiring, maintenance, and possibly swapping cells around every year or so to even out "wear"). Basically, the wiring and voltage drop between batteries should be balanced out to much less than 0.1 volts (probably 0.01's of volts) to ensure that all batteries are equally charged and discharged).

    However, our host here (WindSun / North West Arizona Wind & Sun) has posted before that he has not seen any marked difference in battery bank life between those systems with battery banks wired in parallel vs wired in series--so you have quite a bit of leeway in design of your battery bank.

    So--what are your needs/what do you already have? And what battery(ies) will meet your requirements?

    -Bill

    PS: Sounds like you got close to 9 years of life out of your current batteries... Where you happy with them? Are they heavily used, or was this just for an emergency backup system? Do you want sealed (AGM) batteries so you don't have to check water levels or clean as often?
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: question on replacing 6 L16HC batteries with 6 golf cart style batteries

    how are your l16s wired, ie. 12v, 24v, or 48v? if it's a 12v battery system you use then you can't use the 8v batteries, but in 24v or 48v systems they can be used. 3 8v batteries in series = 24v and 6 8v batteries in series = 48v. i would not advise you to mix different batteries as this doesn't work out very well for your batteries unless you are replacing all of the l16s with the newer batteries.
  • System2System2 Posts: 6,290 admin
    Re: question on replacing 6 L16HC batteries with 6 golf cart style batteries

    Thanks a lot for the prompt answers, you cleared it up for me. Mine is a 12 volt system so I will be getting the 6 volt golf cart batteries at Sam's Club.

    The L16's were just for emergency backup and hardly used, they just died
    of old age, I guess.

    Thanks again,


    Jim
  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: question on replacing 6 L16HC batteries with 6 golf cart style batteries
    The L16's were just for emergency backup and hardly used, they just died
    of old age, I guess.

    Old Age is > 5 years. Anything less is abuse of the battery.

    Even in "emergency backup" applications, the batteries need at LEAST, a weekly charge to top them off. You CANNOT ignore them, if you need batteries you can ignore for a couple (2) of months, maybe the very pricey AGM's would work.
    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

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  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: question on replacing 6 L16HC batteries with 6 golf cart style batteries

    mike may be hitting the nail on the head as you can't just let them lie around without even being float charged. even if they were the main batteries you are a bit low on the charge current as this is about a 3% charge rate. either too much battery or not enough pv, take your pick.
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