WheelchairDriver

Recently, my OG permobil sla/agm batteries are only lasting like 3 hours from a "full charge" (lol).

I will be putting in a lifepo4 pack soon but I remember last time I had such terrrible battery issues, it was the motors draining it and the wheelchair dealer checked the motors instead.

My question is, what did they check in the motors, just the resistance? How do I check them? What should the values be?

If the batteries are only lasting three hours around the house you probably have a battery problem. That might dependent on your weight and your wheelchair's plus the type of flooring in your house. Outside on rough terrain at 8MPH or a lot of turning or stopping and starting can murder batteries.
What is the capacity of the batteries and has it been checked? How old are they and have they been looked after? is your charger changing the batteries properly? It can take eight hours plus to charge a battery to 100% though it will get to 90% charged before that.

I would say that your batteries are toast. Does your chair freewheel ok? Your motors being the problem is low on the list of probabilities.

Dan wrote:If the batteries are only lasting three hours around the house you probably have a battery problem. That might dependent on your weight and your wheelchair's plus the type of flooring in your house. Outside on rough terrain at 8MPH or a lot of turning or stopping and starting can murder batteries.
What is the capacity of the batteries and has it been checked? How old are they and have they been looked after? is your charger changing the batteries properly? It can take eight hours plus to charge a battery to 100% though it will get to 90% charged before that.

I would say that your batteries are toast. Does your chair freewheel ok? Your motors being the problem is low on the list of probabilities.

yeah the batteries are definitely the problem lol, they used to last all day on an 8-10 hour charge, now just a few hours. 2.5 years old. Wooden floor in the house, no different than before. They are 75Ah. I was just wondering what the "motor checking" the wheelchair people did was.

2.5 years is actually good. I had to change mine every 6 months. That's because I only charged them about 7 hours. Lead acids like being charged and to get that last %, it must be plugged in over 12h.
I switched to Lithium, charge once every 3 weeks. Been 6 months and only charged like 10 times.

Recently, my OG permobil sla/agm batteries are only lasting like 3 hours from a "full charge" (lol).

Depends what you do.
7mph for 3 hours on the street means 21 miles... Most chairs in real world conditions only get 10 or 11. Because the streets are not smooth or flat. I can kill a set of lead batteries in an hour is leaf blowing the driveway for e.g with continuous left right swinging. It EATS power.

I will be putting in a lifepo4 pack soon but I remember last time I had such terrrible battery issues, it was the motors draining it and the wheelchair dealer checked the motors instead.

I a motor runs smoothly and doesent make odd noises or get very hot its fine.

My question is, what did they check in the motors, just the resistance? How do I check them? What should the values be?

You cant check them that way. Only by stripping and examining. They just listened and drove it. Or swapped them just in case...

Literally just driving it around the house. Can barely get 3 hours worth of battery. Just didn't realise batteries can get this bad. Motors sound/feel fine

What battery. What have you been charging with?

How old?

Knowledge is power. I used to eat a set every 9 months. The NHS said they would stop replacing them so I did what I should have done from the start. And looked after them properly. Now they lasted 4 to 5 years. Then I went lithium.

If using those "permobil" branded batts and their charger you ill likely cook the batteries fast. DETAILS and technique matter.

Burgerman wrote:What battery. What have you been charging with?

How old?

Knowledge is power. I used to eat a set every 9 months. The NHS said they would stop replacing them so I did what I should have done from the start. And looked after them properly. Now they lasted 4 to 5 years. Then I went lithium.

If using those "permobil" branded batts and their charger you ill likely cook the batteries fast. DETAILS and technique matter.

Had a really weird experience today. All stock permobil batteries and charger. My batteries have been getting worse and worse, dying every 20-60 mins, so I was charging multiple times a day. Last night when I was charging, massive burning smell coming from somewhere in the chair and the charger was flashing. Since then, the battery has lasted me all day without needing to charge. What is going on here? what was burning? why are the batteries ok now? Thought it was the XLR port on the rnet joystick that was burning, but looks fine to me, no? I put some WD40 in it to clean and charged for an hour, no burning smell, no heat.

Superchunk wrote:

Burgerman wrote:What battery. What have you been charging with?

How old?

Knowledge is power. I used to eat a set every 9 months. The NHS said they would stop replacing them so I did what I should have done from the start. And looked after them properly. Now they lasted 4 to 5 years. Then I went lithium.

If using those "permobil" branded batts and their charger you ill likely cook the batteries fast. DETAILS and technique matter.

Had a really weird experience today. All stock permobil batteries and charger. My batteries have been getting worse and worse, dying every 20-60 mins, so I was charging multiple times a day. Last night when I was charging, massive burning smell coming from somewhere in the chair and the charger was flashing. Since then, the battery has lasted me all day without needing to charge. What is going on here? what was burning? why are the batteries ok now? Thought it was the XLR port on the rnet joystick that was burning, but looks fine to me, no? I put some WD40 in it to clean and charged for an hour, no burning smell, no heat.

WhatsApp Image 2026-02-25 at 12.17.06.jpeg

But we still do not know any of the above that I asked. Is this permobil BRANDED battery? Is it a permobil "special" branded charger tat they claim is needed? Because if boh these things are true they have 2 problems.

Burgerman wrote:

Superchunk wrote:

Burgerman wrote:What battery. What have you been charging with?

How old?

Knowledge is power. I used to eat a set every 9 months. The NHS said they would stop replacing them so I did what I should have done from the start. And looked after them properly. Now they lasted 4 to 5 years. Then I went lithium.

If using those "permobil" branded batts and their charger you ill likely cook the batteries fast. DETAILS and technique matter.

Had a really weird experience today. All stock permobil batteries and charger. My batteries have been getting worse and worse, dying every 20-60 mins, so I was charging multiple times a day. Last night when I was charging, massive burning smell coming from somewhere in the chair and the charger was flashing. Since then, the battery has lasted me all day without needing to charge. What is going on here? what was burning? why are the batteries ok now? Thought it was the XLR port on the rnet joystick that was burning, but looks fine to me, no? I put some WD40 in it to clean and charged for an hour, no burning smell, no heat.

WhatsApp Image 2026-02-25 at 12.17.06.jpeg

But we still do not know any of the above that I asked. Is this permobil BRANDED battery? Is it a permobil "special" branded charger tat they claim is needed? Because if boh these things are true they have 2 problems.

yes, a permobil branded battery and permobil branded "voltpro" charger. What could be going on that explains all of the above?

1- Are they Gel batteries?

2-Is the charger for AGM batteries?

martin007 wrote:1- Are they Gel batteries?

2-Is the charger for AGM batteries?

1. They are permobil's gel/agm batteries.
2. Yes

The batteries are either Gel or AGM.
Batteries cannot be both Gel and AGM...

Yes they can.
Permobil and many other gel batteries use the same AGM matt seperator as batteries with plain old acid/water/

Permobils battery is just a gel battery like many others. They just choose to market it by actually mentioning that it uses a AGM seperator material. And call it a AGM GEL...

Whats wrong?
2 things.

1. The fancy permobil rebranded charger does (ORIGINALLY) not have a genuine connector and used a cheap generic branded one. That was not very good quality and it added a resistance that cause the contacts to get hot. That in turn oxidised them. Causing ever more resistance and bad charging and ever more heat. In many cases it actually melted the joystick connector too. Permobil was forced to recall and replace many joysticks, and replace the chargers.

And I quote PG Drives that make these things!

Only chargers fitted with Neutrik NC3MX plugs should be connected into the Joystick Module.
CAUTION:
The maximum permissible charging current for both methods is 12A rms.

WARNING:
Do not exceed the maximum charging current of 12A rms. Always use an Off-Board Charger fitted with a Neutrik NC3MX
plug. Failure to observe these conditions could result in poor contact resistance in the charger connector resulting in
overheating of the charger plugs. This presents a potential burn hazard for the user. Curtiss-Wright accepts no liability for
losses of any kind arising from failure to comply with this condition.

And thats why permobil melted lots of joysticks and ruined many batteries through undercharging.

2. The algorythm on those chargers charges at too high voltage and the batteries dry out, go high resistance and in many cases swell up and die a very early death too. Take a look at an example on dans youtube page. He isnt exactly knowlegable on batteries but shows the result!

Its for all of these reasons that I always throw away mobility chargers. They are usually complete overpriced junk. And I use MANY other chargers that allow me to set the CORRECT voltage, float voltage, tail current, CV time etc. The ZXD for e.g. Below. And I always add a heavier charge cable, and an ANDERSON 50 connector. If I do charge a chair without an Anderson connector fitted I limit the charger to 12A max, and use a genuine Neutrik connector rated to 16A.

Burgerman wrote:1. The fancy permobil rebranded charger does not have a genuine connector and used a cheap generic branded one. That was not very good quality and it added a resistance that cause the contacts to get hot. That in turn oxidised them. Causing ever more resistance and bad charging and ever more heat. In many cases it actually melted the joystick connector too. Permobil was forced to recall and replace many joysticks, and replace the chargers.

I am aware of this issue, was in 2021 but they solved it by changing manufacturers/spec to actually use properly rated XLR connectors. I don't think the joystick connector is melted in my case, looks fine, see pic above.

Burgerman wrote:2. The algorythm on those chargers charges at too high voltage and the batteries dry out, go high resistance and in many cases swell up and die a very early death too.

This can explain things, high resistance built up pressure which popped battery vent caps and released it. Why are the batteries performing better after last night's event though, that's what I'm trying to understand.

Beats me.

Batteries only get worse unless they are undercharged which atually means sulfated.

The ONLY way to charge a lead battery properly is to charge it at the CORRECT voltages, for the correct length of time. And that is never less than 12 hours. If its heavily discharged you can put MOST of the charge back in 6 or 8 hours. But that last tiny bit is the part that makes them LAST and not die.

In order to PROPERLY check a battery you carge it CORRECTLY and then leave on float for 48 hours. At the correct charge and float voltages.

Then you connect to a device like my PL8 and set it to do a 20 hour discharge at the rated level. At 20 to 25 centigrade. And you discharge it to the level that the manufacturer specifies. This is usually 10.8V. Can be 10.5. Then the PL8 couts the Ah and mAh and gives you an exact reading. To test the internal resistance you need a 4 wire high frequency impedance meter. I have both. Theres no other way to reliably tell anything unless they are so ruined that its obvious.

I updated the post above, go read!

Are you saying that the caps on your battery cells have opened as a result of charging...?

This one measured 74Ah when new + 10 cycles. And still does a year later used occasionally! MK gels, pair, in a chair tested via XLR socket.

This is the ONLY way to know.
As for resistance, or rather impedance, JUST as important you need one of these. Measuring a lithium cell here.

martin007 wrote:Are you saying that the caps on your battery cells have opened as a result of charging...?

He is saying the caps that shouldnt ever come out were popped due to too high pressure caused by gassing, caused by a stupid CV voltage setting in the charger that murders the gel battery... Yes.

I would charge at 12A not 10, via a correct neutrik connector, or at 15 to 20A via an Andrson connector, instead. But at 28.2V CV and for around 8 hours. Plus a float stage at 27.4V for another 8 hours. Or get up and use it sooner if you must.

That takes a ZXD or other user adjustable charger. Or a simple power supply set to 28.2V and 12A limits. Charge till you get up 8 to 10 hours later.

martin007 wrote:Are you saying that the caps on your battery cells have opened as a result of charging...?

I'm thinking/hoping that that's what happened, haven't looked yet (won't be able to for like a week due to carer issues), I really don't want to have to replace a connector or a cable. If you have any other suggestions that could explain, let me know.

Burgerman wrote:

martin007 wrote:Are you saying that the caps on your battery cells have opened as a result of charging...?

He is saying the caps that shouldnt ever come out were popped due to too high pressure caused by gassing, caused by a stupid CV voltage setting in the charger that murders the gel battery... Yes.

Exactly, does the caps popping affect performance? Am I ok to keep using these batteries for like another week? Could them popping cause that burning smell?

The batteries if you were to MEASURE performance will be ruined. If that affects your usage, I dont know.

The battery is VENTED and designed to run at a max 2psi so the caps do not need to pop. You get bad smells anyway from the vent if the voltage is too high. Somtimes smells sulfurous or like bad eggs too! But too high charge voltage costs electrolyte over time and so battery resistance increases.

Throw that charger away. Or at very least measure what it does!