My electric lawn mower two 12V SLA 20AH batteries died what is the best replacement?????

rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
I bought a homelite mower about a year ago
http://www.homedepot.com/p/Homelite-20-in-Electric-Lawn-Mower-UT13124/202050696#.UengAm3AFOQ
Attachment not found.

Basically it runs off of two 12V 20AH SLA batteries that weight about 30 pounds together wired in series.
It is charged with this
Attachment not found.

The batteries died after about a year of use. I'll call them on Monday and see if they are still underwarranty.
Let's assume they are not.

What is the best 24V battery to replace them with? What is the best charger to use?

And I should note it needs to be idiot proof because I am letting my renters use it to mow the grass on a 1/4 acre lot. I'd guestimate that the grass that needs to be cut is probably 1/8th acre or less.

When the mower was working, it would take two charges to cut the lawn. One to cut the front, then it would charge overnite and then the next day to cut the front, so a more powerfull battery woudl be good.

I thought about buying two 12V lawn/tractor type batteries and hooking them up in series.

The lawn gets mowed about once a week from May to October. November to February is dormant.
Or maybe I should just scrap it and buy a gas mower?
I've already killed 3 gas mowers. They tend to last about 2 years before they won't start. My renters don't take care of them and clean the filter, put fuel stabilizer in it, etc. that is why I switched to the electric one.
thanks for advice.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,601 admin
    Re: My electric lawn mower two 12V SLA 20AH batteries died what is the best replacement?

    20 AH is a pretty small battery... Could you take a larger battery like one of these?

    http://www.batterymart.com/c-deep-cycle-marine-batteries.html#2

    And if you get GEL, you would need a GEL capable charger:

    http://www.batterymart.com/c-gel-cell-battery-chargers.html

    I got the BatteryMinder charger (not cheap) from NAWS when they sold them for a while... Works well on my in-laws' car that sits more than it drives.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: My electric lawn mower two 12V SLA 20AH batteries died what is the best replacement?

    yeah 20ah is tiny. I can make some kind of enclosure, so what fits isn't that important, though I think the total weight should not be more than about 60 lbs otherwise it's gonna get harder and harder to push. and for econmic reasons I'd like to keep the cost below $200, otherwise it just doesn't make financial sense to fix.
    how about two wheel chair batteries hooked into series?
    http://www.batterymart.com/p-12v-35ah-sealed-lead-acid-battery-group-u1.html
    like this one?
    I just don't want to make something that doesnt charge easily or is so hard to charge that the tenants kill the battery
  • BB.BB. Super Moderators, Administrators Posts: 32,601 admin
    Re: My electric lawn mower two 12V SLA 20AH batteries died what is the best replacement?

    Why not--The batteries are much larger and AGM are going to be good for quick discharging.

    You need to check the charger... Many small/cheap chargers (in my limited experience) really over charge lead acid batteries.

    To get around that, I was placing lead acid chargers (to float car batteries, charge small batteries for portable use) with a lamp timer. Just turn it on and it will turn off 24 hours later--And I would set it to turn on around 1-2 hours per day to keep the batteries floated.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: My electric lawn mower two 12V SLA 20AH batteries died what is the best replacement?

    when dealing with people that do not take care of things it is hard to preserve the integrity of anything and making things idiot proof proves to be difficult. it sounds as if the batteries were drained to far too often and it killed them. if 20ah does half then 40ah does all, but that is still in killing the batteries. to preserve the battery lifes one would need to double it to 80ah and this makes for a very heavy and larger area to house the batteries in.

    one possible solution is to get batteries like rollandelliot mentioned and still only do half the yard at a time with charging it overnight as before to bring it to full capacity again before doing the other half of the yard. the charger must be compliant with the battery type and capacity.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: My electric lawn mower two 12V SLA 20AH batteries died what is the best replacement?

    Hi,

    We got a 24V electric lawnmower and love the thing. It has a 24V battery in it that looks like this and it lifts out the top

    100_2947.JPG

    A replacement battery for it is a little over $100 and you can buy them on Amazon dot com
    http://www.amazon.com/Earthwise-BS80002-24-Volt-Battery-Cordless/dp/B001PTG9D2

    This is a 12-cell battery and does not have two 12V in series in it. I don't know if it could be adapted to your mower or not.

    Typically 20ah is plenty big for electric lawnmowers. Ours easily runs for an hour and a half on one charge before the indicator lights show it is down to 50%. The manual for ours says to not draw the battery below 50% because it will wreck it.

    It also says in the manual to unplug the charger when the light turns green on it and do not leave it plugged in all the time. The charger for our mower is not a bulk/absorb/float charger - it is a constant current charger that slow charges the battery for bulk, then gradually takes it up (absorb) to (31.0 volts) and holds it there for about an hour (finish stage) before the green light comes on. It will hold the battery at 31.0 volts indefinitely and does not shut off. Excessive time at 31.0 volts will damage the battery. So we have a timer that we plug the battery charger into and we have learned how many hours to set the timer for, based on what the lights on the mower show for SOC, so it shuts off the charger when we recharge it.

    I suspect the people using your mower did not pay attention to any of this stuff, or even know about it, and probably just run the battery dead all the time before recharging it, then leave it plugged in all the time when not in use. So it didn't last very long.
    --
    Chris
  • northernernortherner Solar Expert Posts: 492 ✭✭✭✭✭✭
    Re: My electric lawn mower two 12V SLA 20AH batteries died what is the best replacement?
    The lawn gets mowed about once a week from May to October. November to February is dormant.
    Or maybe I should just scrap it and buy a gas mower?
    I've already killed 3 gas mowers. They tend to last about 2 years before they won't start. My renters don't take care of them and clean the filter, put fuel stabilizer in it, etc. that is why I switched to the electric one.
    thanks for advice.

    If they are renters of yours, I would have them look after that lawn mower purchase. That way, if they screw it up, they will be paying for the next lawn mower, and will give them incentive to look after it. I have seen this happen all to often here. Best thing is have them get their own mower.

    If the carburetor does get gummed up, you can clear it out with a carb cleaner. Just spray the carb cleaner into the air intake. It will usually start after a few pulls, and then continue to spray until the engine runs smoothly. If it's really gummed up bad, you may have to take the carburetor apart for cleaning. Good luck!

    BTW, I would consider purchasing a mower with a good engine (such as a Honda), if you are looking at getting longer life out of the mower.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: My electric lawn mower two 12V SLA 20AH batteries died what is the best replacement?

    I saw that exact product recently in a thrift store, asking price was $75. Of course the charger was missing, and I am sure the battery was toast. I passed it by not knowing if having to purchase battery and charger would cost more than new.

    ChrisOlson wrote: »
    Hi,

    We got a 24V electric lawnmower and love the thing. It has a 24V battery in it that looks like this and it lifts out the top

    100_2947.JPG

    A replacement battery for it is a little over $100 and you can buy them on Amazon dot com
    http://www.amazon.com/Earthwise-BS80002-24-Volt-Battery-Cordless/dp/B001PTG9D2

    This is a 12-cell battery and does not have two 12V in series in it. I don't know if it could be adapted to your mower or not.

    Typically 20ah is plenty big for electric lawnmowers. Ours easily runs for an hour and a half on one charge before the indicator lights show it is down to 50%. The manual for ours says to not draw the battery below 50% because it will wreck it.

    It also says in the manual to unplug the charger when the light turns green on it and do not leave it plugged in all the time. The charger for our mower is not a bulk/absorb/float charger - it is a constant current charger that slow charges the battery for bulk, then gradually takes it up (absorb) to (31.0 volts) and holds it there for about an hour (finish stage) before the green light comes on. It will hold the battery at 31.0 volts indefinitely and does not shut off. Excessive time at 31.0 volts will damage the battery. So we have a timer that we plug the battery charger into and we have learned how many hours to set the timer for, based on what the lights on the mower show for SOC, so it shuts off the charger when we recharge it.

    I suspect the people using your mower did not pay attention to any of this stuff, or even know about it, and probably just run the battery dead all the time before recharging it, then leave it plugged in all the time when not in use. So it didn't last very long.
    --
    Chris
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