Power wheelchair batteries ...

Bought SWMBO a little powered wheelchair last year, which helped enormously.
As instructed it was kept on charge when not in use.
Expect when it was put away for 4 months (grrrrrrrrrrrr!)
Batter(ies) went completely flat.
Managed to recharge, and it works, but with a range of 200m, rather than 4-5 miles.
Is there anything to be done, or are they ****ed ?
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They're probably dead though a really 'intelligent' charger *might* improve things a bit by doing equalisation and/or de-sulphation. To some extent what can be done depends on the battery type - is it a sealed lead-acid battery of some sort? If it's sealed then the possibilities of resuscitation are rather limited.
Any lead-acid battery left discharged dies quite quickly.
--
Chris Green
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If they are the common SLA types, likely fooked. This type of battery doesn't like being fully discharged.
If you can find someone with a decent SLA battery tester - like the ACT - and they use it honestly, you can get a pretty good idea of their condition.
--
*How does Moses make his tea? Hebrews it.*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Mon, 8 Jan 2018 14:30:30 -0000 (UTC), Jethro_uk

They can bee a real life changer.

Depending on the battery chemistry and charger, that may or may not be a good thing.

Ok ...

Hmm, assuming no parastatic load, that does seem a bit of a short period from fully charged to flat? ;-(

Assuming sealed lead acid, probably sulphated. Any signs of bulging in the battery case itself?

Before writing them off completely (and the still have scrap value, even if they are dead), I'd be tempted to pull them out and charge / test each separately, as 2 x 12V instead of 1 x 24V etc (assuming that is the geometry).
Not that it makes much difference to the final outcome, it may be that one battery has gone 'bad' and the other is still fine but because of the bad battery, the good battery isn't getting charged properly.
I get given a lot of bad / old batteries and quite like to test / play with them before (typically) scrapping them.
Sometimes you will get one good battery (from say a pair) that could be used as a solar PV store for a shed LED light or test supply or even a small jump starter battery.
It's funny, whilst I was typing this the new / replacement little 1.2Ah 12V SLA battery for Mums house alarm has finished being tested / charged and it seems to be on spec (for an un-cycled LA etc). ;-)
http://i65.tinypic.com/5jsisx.jpg
Cheers, T i m
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On Mon, 08 Jan 2018 15:36:31 +0000, T i m wrote:

Cheers for all that ... I'll dig deeper.
The main reason for a power*chair* as opposed to SWMBOs mini-scooter was the ability to rotate the seat - made car transfers possible.
Now SWMBO has had her operation, that's not needed - we can go back to the mini scooter. Which means it's a PITA trying to keep the chair operational "just in case" ... buying new batteries for example, which may never be used.
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With a good charger lead-acid batteries will last a *long* time if they are not used but just kept at the right 'float' voltage by the charger. It's discharge/charge cycles that actually wear a battery out.
--
Chris Green
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writes

For what it is worth... the one used on our old power assisted wheel chair is a gel battery. Chair due for scrap (tyres, arm rests etc. perished) motor driver assembly and battery charger OK but battery has had no attention for several years:-(

--
Tim Lamb

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On Mon, 8 Jan 2018 18:44:47 +0000, Tim Lamb

Hmm, would there be room for that and the XP box in the boot of the Meriva (when my Mrs is looking ....) ... ;-)
Cheers, T i m
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Probably. Talk to Angela:-)
AFAIR it is a bolt on adaption for a standard wheelchair.

--
Tim Lamb

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On Tue, 9 Jan 2018 09:14:37 +0000, Tim Lamb

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
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On Mon, 8 Jan 2018 15:42:51 -0000 (UTC), Jethro_uk
You are welcome. ;-)

Could be handy.

Ok. Dads Mini Scooter (3 wheeler) had a seat that could rotate either way 90 degrees so that sounds like it might have also done the job? (TGA Superlight (fwd model)).
http://easternmobility.co.uk/images/superlight.jpg

Excellent (that the op has helped?). ;-)

Well, it needn't be, depending on if you are willing to either spend some money or time yourself?
Whilst lead acid batteries have less issues being held fully charged than say some Nicad or Lithium cells, they still don't particularly like being charged all the time either. So, if you can put the batteries somewhere in the dry and not too cold (understairs cupboard?) and a note in your diary to clip them onto a good quality charger (Optimate 2?) once every month or so, they should be good (and ready) for years. I am still concerned your have gone flat (to a point beyond recovery) in just 4 months. Is there any way a light could have been left on etc? [1]
https://www.optimate.co.uk/products/optimate-2
Since I bought the 3 x LA batteries for use on the electric outboard at the end of the last season I've not really touched them <checks> but they are still holding a good charge (27Ah & 12.6V at 10 DegC).
You have reminded me though that mum still has a pair of fairly unused batteries in Dads old scooter that I really should bring home and charge / test for her (again, individually, rather than in series with the scooter charger).
Cheers, T i m
[1] An elderly neighbour we help and 'keep an eye on' decided she wanted to go out on her big mobility scooter after it had laid unused in a shed for at least two years (could be 5) and it still had sufficient charge in it to take me round the block and have been used a few times since for fairly long trips out with the Mrs (walking beside). Now it's quite possible one of her children put it on charge now and again but I doubt it (but I'm also unsure any LA would retain a good charge for that length of time)? ;-(
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I think they're better off with a charger that drops to 'float' voltage when fully charged. I've got batteries that are still good which have been kept this way rather than disconnecting completely. If the batteries *are* damaged/worn out by being left connected to the charger then it's not a very good charger IMHO.
--
Chris Green
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Agreed. They are better on a 'Smart Charger' than one that just drops to a trickle etc.
However, reading the long term storage instructions for my MK Gel traction batteries it suggests they *aren't* best left constantly on a charger (even a smart charger) but allowed to just sit and just be charged before use (the OP's scenario).
Of course if you are using the batteries regularly / daily and or need them ready for use with no notice then leaving them on a smart charger 24/7 may well be the best solution.
I think the logic is that even a smart charger will hold the battery at very high levels of charge (duh) and in that state the electrolyte will be at the highest level of acidity and therefore more corrosive to the grids / plates etc. So, by allowing the battery to sit / self discharge over time (within safe levels) can improve the life span of any battery that isn't required to be 'online'.
It could also however be a good idea to keep a 'Smart charger' connected all the time if you do intend or think you may need to use the battery at short notice, rather than say putting it on a once-per-month time switch, as that saves them from going though their startup / test phase each time (that could increase the level of charge above that when left in maintain mode (dependant on the charger etc)).

I have a 60A MK Gel Traction battery that has only been checked / re-charged once every few months when not being used and is also giving full capacity at over 10 years old. ;-)

Agreed. What I am suggesting here is that *if* the battery is going to be left in store for a pre-determined period then reducing the strength of the acid can help the internals. I also accept that there can be a gamble between the battery being over-charged (for store) or left uncharged and become damaged etc.
I built one of these:
http://picprojects.org/projects/chargeshare/index.htm
It switches a single charger around up to 4 batteries and whilst I would / will use it on the motorbikes (that are left outside, may have small parastatic loads and are often in the cold etc), I wouldn't use it on my 3 small new Gel batteries, bought for use on the electric outboard motor (for the above reason).
Cheers, T i m
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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.
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'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).
--
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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 http://www.mkbattery.com/images/8GU1H.pdf
... 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
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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.
--
*My wife has a slight impediment in her speech. She stops to breathe.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Tue, 09 Jan 2018 10:51:20 +0000 (GMT), "Dave Plowman (News)"

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
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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.
--
Andrew Gabriel
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On Tue, 9 Jan 2018 20:04:54 -0000 (UTC), snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote:

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
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