Geo-TH,In

Well-known Member
Guido,
I ended up with my late mother's electric wheel chair. It has 2 12v sealed lead acid batteries. One is a strong 12v the other shows 10v, but when you put a small load of it, the voltage drops to 6. I would have thought these batteries would be Ni-cd, but it says sealed lead acid.

Both batteries are wired in series. Both are charged in series too, making 24v.

Lately the one battery self discharges extremely fast, a few days.

Well I decided to flat line the bad battery by using a 12v tail light bulb. After that battery is dead, I plan to wire the good battery in parallel with the dead battery, so the good battery will discharge and recharge the bad one, equalizing the charges. I'll monitor the charging/discharging rate and keep it under 3 amps, the charging current of the charger.

Then I may charge each battery using a 12v charger and limit the charging current to 2 amps.

I may try using a batteryminder12248 and run it through a desulfating cycle. What are the chances of this will bring the dead battery back to life? I don't have much hope.
George
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I am not Guido,but I used to work for one. I have dealt with a few of these. You are better off spending the money for gell cells, so they don't wind up eating holes in the carpet. Ebay is the cheapest I have found by half, with free shipping.
 
First, I was surprised they weren't jell or Ni-
cd's. These are 22 amp-hr and those I've found
are all sealed lead-acid selling for about $90
for a pair. Definitely getting a pair if or when
someone needs the wheelchair.

There isn't much of a resale for these things
when insurance or medicare will pay for one. My
mom had to have one and paid the full price for
her's.

So now I have one good 12v battery and no idea
what I'm going to do with it. Good chance the
other will go to the recyclers or traded in as a
core.
 
Hello Geo-Th,In,

Assuming the voltages were taken at 70*+ neither battery is up to 100%charge. The problem with charging multiple cell is series is, that the weakest cell exhibits the most potential and stops the charging process. So the cells with the most capacity get partial charge, so capacity is lower then rated. When ever possible charging should be done on individual cell/s. That is why Lithium pack are so strong. All cells are individually charged to the same potential, no weak link. You should charge the two batteries individually. This will give you the most charge on each one. A fully charged Lead acid battery should exhibit a voltage of 12.6 or better @70*F



Guido.
 
Those batteries look like they could be standard size motorcycle batteries, use in cycles, snowmobiles, etc, or are they deep cycle batteries? You might be able to find replacements at less cost through www.dennisKirk.com or other retailers like that.

Yuasa was a brand that lasted longer than other brands for me.
 
I decided to pop the top off the battery and take a look see. On the top of the battery it says lead acid. On the side of battery it says non-spillable. So lead-acid, therefor the acid must be some kind of a paste or jell. On the side of battery it says life is 3-5 years and this battery is about 4 years.

So, what do you all know about a UB12180 battery?

It not very expensive. Because it has a short life expedience, I'll order a pair if and when someone has a use for the electric wheelchair.

I have both batteries on a 12v charger. Each is getting 1 amp. Plan to bring up the charge slowly before increasing the output from charger. Then when up to speed, I'll put the batteries on the batteryminder for a little desulfating. Then test the CCA.

Of all else fails, I'll have a spare 12v for generator or may even try it on the pressure washer.
UB12180 found on ebay.
 
Hello Geo-TH,In,

Charging the batteries in parallel will also charge the weakest the most and leaving the better one undercharged. Using the battery in parallel has the same power output disadvantages. The weak one will produce lees power and will bring down the good one. The nature of the beast!
Fun chat...........
Guido
 
Guido,
I've found the opposite to be true when charging batteries in parallel. I had a old battery wouldn't take a charge on smart charger or batteryminder. I put it parallel with 3 lawn mower batteries and a motorcycle battery. Set the batteryminder to 8 amps. The sick battery now has a good bill of health for it's age and all cells have the same good hydrometer reading. All the rest of the batteries showed improvement after the desulfating cycle was complete. Kinda of goes against the common wisdom many post here.

On the other hand, I had a very sick battery with 2 dead cells. Then I don't care what you would do, how you charged it, nothing will work, except the sick battery will even produce a smell sick, hydrogen suflide gas.
 
Hello Geo-TH,In,

The only way that would old true if the BAD one was only discharged. Never discharge a wet cell 100% No battery thrives with that kind of abuse except NiCad'S. Even Lithium self protect below 2.5 volts.

Guido.
 
Be cautious buying no-name replacement gel cell batteries on eBay. I bought some that were supposed to have the same specs as the name-brand batteries I was replacing but when they arrived they weighed far less than the originals. The maker apparently skimped on the lead content which it seems would also limit capacity.
 
The good one is putting out 200 cca. I popped off the top of the bad battery. It like there is a white cloth like material between plates that is damp.

I added about 25 cc's of water to each cell of the bad battery. That brought the water level up to the top of the white stuff. Used a load and slowly drained it to 6 v. Then I placed the good battery in parallel with the bad battery. The two batteries are charging at 7 amps. I don't have much hope for the bad one. Not sure what I'll do with the good one. Will replace both when a family member needs to use the wheel chair.
 

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