Buying used batteries

Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
I found some 4 year old MK 220ah 12v deep cycle gel batteries for $50 each.

I don't think I can pass this deal up, seeing how they run around $600 a piece brand new. I think it can't hurt to buy a couple of them and test them out.

Is there anything I should watch out for when buying these used ones?

I'm sure these type of questions get asked a lot, if so is there a thread that widely discusses this?

Does any body know about these MK batteries and their life expectancy?

Thanks.

Comments

  • mike95490mike95490 Solar Expert Posts: 9,320 ✭✭✭✭✭
    Re: Buying used batteries

    GEL batteries don't generally have a long life in deep cycle applications. Mostly for float for backup.
    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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  • BB.BB. Super Moderators, Administrators Posts: 31,884 admin
    Re: Buying used batteries

    Have they been kept charged during this time? If not, them they are probably scrap.

    Gel batteries do not take over charging well either.

    Figure out how much you can get/cost to dispose the batteries. Don't get to far out of pocket if they turn out to be bad.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • FrxddyFrxddy Solar Expert Posts: 113 ✭✭✭✭
    Re: Buying used batteries

    Mind you, I am new to solar, but I have played with MK batteries. I have a home made electric motorcycle that uses them. The ones I have came from electric wheel chairs and are deep cycle for sure. The one trick is charging them. They do not like to be charged with a "normal" charger. I use a "smart charger" and have never had a problem. My gut says if you are going to use them for solar back up and charge them from solar panels you'd need to use an inverter to power a smart charger. As mentioned, they do not like overcharging at all, not one bit. I've heard stories of them bloating like a beached whale in the hot sun.
    Once charged they do hold a charge very well. I park my bike & let it freeze all winter with no attention at all. Come spring it takes 5 minutes to top them off. It amazes me how they don't die!
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Buying used batteries
    Frxddy wrote: »
    Mind you, I am new to solar, but I have played with MK batteries. I have a home made electric motorcycle that uses them. The ones I have came from electric wheel chairs and are deep cycle for sure. The one trick is charging them. They do not like to be charged with a "normal" charger. I use a "smart charger" and have never had a problem. My gut says if you are going to use them for solar back up and charge them from solar panels you'd need to use an inverter to power a smart charger. As mentioned, they do not like overcharging at all, not one bit. I've heard stories of them bloating like a beached whale in the hot sun.
    Once charged they do hold a charge very well. I park my bike & let it freeze all winter with no attention at all. Come spring it takes 5 minutes to top them off. It amazes me how they don't die!

    They have "smart" charge controllers, no need to use an inverter powering a "smart" charger, besides that probably wouldn't even work.

    As for buying "used" batteries, at 4 years old those batteries are probably worn out even if they were well cared for and you have no idea whether or not they were well cared for.

    You can buy brand new Golf Cart batteries at Sams/Costco for not much more than that.
  • Will2020Will2020 Solar Expert Posts: 62 ✭✭✭✭
    Re: Buying used batteries

    Ok, scratch that! I'm not wasting any cash on them. The guy said they had been sitting for a "while now" and may be discharged.

    I think I'll just stick to my Lifeline agms.

    If I were take care of these batteries, never overcharging, or going under say 70%, what do you think the life expectancy could be?
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Buying used batteries
    Johny wrote: »
    MK 220ah 12v deep cycle gel batteries are really cheap here in my state. $28.99 each! That's why we use only this type of batteries . And I can't count on the fingers, how many advantages these batteries offer.

    That seems pretty low, it is below cost in fact.
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