Powerchair batteries

[Biscuitgazer]

The fellow from the local mobility shop told me that I mustn't leave my powerchair battery on charge all the time as it would overcharge and "essentially cook the battery and maybe stretch the case" and I think he's talking through his hat. I think these days they trickle charge harmlessly for as long as they're plugged in. Which I read on that incomprehensible site wheelchairdriver.com (lol he might not have been saying that, though!)
I am disposed not to like the shop assistant's opinion, it's irritating. He's supposedly (unless I cancel the appointment) going to service the chair and I think he's angling to tell me that my chair stalls because I've overcharged it. Does anyone here know whether I am right or the shop assistant is right?

[Lighttouch]

My hybrid electric wheelchair runs off a Lithium battery. I leave it on charge overnight but only need to plug it in once a week.

From a Health and Safety point of view they wouldn't endorse batteries that could overheat and explode as it's a fire risk.

Once a battery is fully charged it will turn off and trickle charge to top it up.

[Biscuitgazer]

Yes that's what mine does, though it's not lithium. Neither of my batteries even gets slightly warm after sitting on charge for days while I use the other battery. It will never explode without dynamite. It's gel, not prone to exploding as lithium sometimes is.

[Sky]

Standard wheelchair and mobility scooter batteries are cheap and nasty rubbish and cannot be trusted - in many (if not most) cases they will prematurely destroy your batteries due to their appalling design. I would not trust them to be left on indefinitely that's for sure.

I have two identical 'standard' chargers; one for my wheelchair (Puma 40) and one for my mobility scooter (Breeze 4). Both the chair and scooter have a pair of 80Ah gel batteries and are supposedly charged at 8amps by these chargers.

The variations between the two chargers is quite impressive if you look at the technical specs, but I won't go into that and bore you all to death.

Rather than repeat on here what is published already I would suggest you read the following:

http://www.wheelchairdriver.com/powerchair-charger.htm

http://www.wheelchairdriver.com/charging-batteries.htm

[Biscuitgazer]

Lol notice the place where wheelchair driver days "I'm not going to tell you how, because if you have to ask then you are really not safe doing it" this is why I'm no fan of that site, he is full of photos of metal and wire and little loopy things. He's technical, I read instructions a lot but with electrics I'm clueless and it looks like spag bol.
Anyway I have a 3A charger. It's not going to cook my batteries. They may be a bit disposable though because I run them far down. But the chair and its batteries came to me with problems. The chair came with a cheap 2A charger that did nothing, I thought my batteries were dead until I tried my 3A Pihsiang charger.

[gothitjulie]

Lol notice the place where wheelchair driver days "I'm not going to tell you how, because if you have to ask then you are really not safe doing it" this is why I'm no fan of that site, he is full of photos of metal and wire and little loopy things. He's technical, I read instructions a lot but with electrics I'm clueless and it looks like spag bol.
Anyway I have a 3A charger. It's not going to cook my batteries. They may be a bit disposable though because I run them far down. But the chair and its batteries came to me with problems. The chair came with a cheap 2A charger that did nothing, I thought my batteries were dead until I tried my 3A Pihsiang charger.

What John over on that site is trying to tell you is that it isn't about the maximum amps that the charger can put out, but the voltage.

I have a Sterling 30A 24V charger with numerous complicated settings, two of them being for different gel types (different voltage profile), yes, I can charge at 30A & it puts most of the charge back in very quickly, but it's all about the long float charge that balances the batteries & keeps them topped up, & before that the balance charge takes at least 8 hours after the main bulk charge has completed (that's just how long lead batteries take, you can do little about it). The float charge keeps the batteries topped up & switches on & off forever.

If you leave your wheelchair charging using a charger that puts out too high a voltage, over time it will kill the batteries. If you leave your wheelchair charging forever with a charger that puts out the correct voltage then your batteries will last a very long time indeed.

Alas, most mobility chargers put out too high a float voltage, which is why John used that Sterling marine charger at the time.

The other reason John used a "12V" charger was to make certain that the batteries were properly balanced without having to do the 8 hour balance charge cycle. Having the 12V charge setup also allows him to connect the wheelchair to his car battery directly (with heavy cable) so the car charges the chair whilst he drives. After charging he used a "link" cable on the chair in place of the twin charge cable to bring the chair back to 24V.

Complicated? not really. Fiddly? yes, kind of, until you get used to it.

If you want complicated, look at his chairs with LiFePO4 Headway cells, but even they are fine once you get your head around it all.

[Sky]

Nicely put - a good explanation.

[gothitjulie]

Well, worth a try, I find John's explanations very "male", which I suppose can make him come across as overly technical to many.

I'm female, but very technical, so everyone runs away from me

As an aside, it's useful to individually charge each battery in a wheelchair before you install them. This makes certain they are fully charged & helps the balance charging process.

However, bear in mind that something like an MK gel battery needs to be charged with a charger that is for a gel battery, a normal car battery charger will charge at a little too high a voltage.

[reddivine]

I was told that lead batteries as in the mobility scooter - take an overnight charge. NEVER use any other charger than you were give to start with.
LT and I have lithium ion batteries which is a completely different kettle of fish. (Sorry LT, but try not to confuse the masses)

[gothitjulie]

Yes, lithium ion batteries tend to have a BMS, so you need to use the charger provided & hope the BMS does its job.

My PW-1000XL is lithium polymer, just as tetchy. Making up a replacement LiFePO4 pack for it at the moment since I don't want to go up in flames.