Power wheelchair batteries ...

In message , T i m writes

Probably. Talk to Angela:-)

AFAIR it is a bolt on adaption for a standard wheelchair.

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Reply to
Tim Lamb
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Will do. ;-)

I was just thinking if it was actually likely to end up in the scrap ... but had a 12/24V motor and gearbox, I could probably make use of it (for 'something'). ;-)

Cheers, T i m

Reply to
T i m

Chris Green wrote on 08/01/2018 :

Even a float voltage will produce some slight gassing, I use a regime of bringing unused batteries up to a full charge every month or two. I find batteries do survive much longer that way.

Reply to
Harry Bloomfield

'Much longer' than what? I've got batteries that have been kept on 'float' when not in use (sometimes months at a time) which are many years old now.

It's quite difficult to test properly, one would have to have identical batteries and keep them using the two different regimes for some years.

Certainly the leisure and deep discharge batteries I have seem to recommend keeping them on float (manufacturers' literature).

Reply to
Chris Green

The SLA in my alarm had a very long life indeed - somewhere in excess of

10 years - and was rather obviously on float charge all that time. You're not going to get a 10 year life from batteries used for traction.
Reply to
Dave Plowman (News)

I think you may need to ask what the pros and cons are (for the battery) by keeping it in a particular stat of charge might be to be able to really answer that.

Some facts that we can probably all agree on (re LA batteries).

1) Stronger acid is more corrosive than weaker acid. 2) The internals of lead acid batteries do suffer from acid corrosion. 3) Sulphation can occur (soft and hard) if a battery is left uncharged for a period of time. 4) Over discharging is as bad as overcharging (especially with sealed / GelVRLA).

So, I bought 3 x

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... last September and outside of a few tests cycles at the time, I've not touched them since. Yesterday I stuck them on my Optimate2 (.8A) smart charger and it said they were all fully charged within about 30 minutes (and I think it takes that long for it to go though a test cycle etc).

So, in this case, I'm not sure what advantage it would be by leaving them on even a smart charger in maintenance mode for the last 3+ months and further, if there was *any* gassing (a by product of overcharge especially), I'm not sure that would be considered a 'good thing' (especially Gel / sealed batteries).

I also have a couple of 17Ah classic mobility scooter / UPS sized SLA's that have been left untouched similarly and I'll stick them on the charger and see if they are any different.

Now, if a battery is old and / or has a higher level of self discharge (or a parastatic load) then a continuous compensating charge would be a good thing.

I wonder if 'manufacturers literature' recommending the use of a constant / maintenance charge is really because that is generally better (less damaging) than allowing the batteries to go flat?

Cheers, T i m

Reply to
T i m

I wonder what the capacity was at say 5 or 7 year points? I think I replace the one in Mums house alarm not that long ago (maybe 5 years?) and it tripped the other day with a 'Low battery' indicator. I replaced all the batteries in the PIRs and door switches and when I tested the SLA with my ACT tester it failed because it couldn't test it (even though the tester goes down to 1.2Ah batteries). It was able to hold a 21W indicator lamp illuminated for as long as I could hold it so it wasn't 'dead' as such.

I'm guessing you may have replaced it because it (finally) failed?

You might, depending on how often you use them, how deeply you discharge them when and how you keep them in between uses. ;-)

My 60Ah MK Gel traction battery is around 10 years old and is still a good 60Ah (tested). ;-)

Cheers, T i m

Reply to
T i m

I end up with 4 x 12V 7AH SLA batteries every ~5 years when I change them in various burglar alarms. Mostly their capacity is well down, but I've hung on to a couple over the years which seemed fine, and have stayed fine in spite of sitting for probably 2+ years between charges. Occasionally, you get a good'un.

Reply to
Andrew Gabriel

If you get a bad battery then of course you may well find it's self-discharge rate is quite high.

I think that can be key, the 'good'un' bit. ;-)

I just hooked my 2 x new 12V 22Ah scooter batteries (that have sat on the shelf since last September or so) onto the Optimate2 and again, both indicated as fully charged before half an hour or so (and much of that is it in it's 'test' phase where it turns the charge current off and watches the voltage drop and if it's low enough, considers it as 'charged').

Cheers, T i m

Reply to
T i m

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