New batteries

[wes4dbt]

Well, it looks like I need too replace the batteries on my Permobil M3. I only use this chair when I go to the dentist because they can work on me while I'm in the chair. It's been about four months. Don't know why they wont hold a charge but I went about 10ft and the power indicator started dropping like a rock. I check the voltage and it was at 24v. I've had the chair @ 3yrs, bought it used, they guy said the batteries were new but who knows. I've never pulled the batter case out.

My question is since I hardly use this chair should I just use a cheap set of group 24 batteries? I see them for $130 each but if I search for M3 replacement batteries they are $200+ each.

[Burgerman]

I would. If you only use it occasionally, just buy something cheap. But keep them topped up, charge 8 hours every 2 weeks or sooner. Even if it didnt move a millimeter.

Leisure batteries are super cheap. Especially if wet acid types... Get the biggest that will fit. They are not deep cycle, even is it says they are. They are for intermittent use, and discharge to 50% or 70 max a few times a year. Thos are sold here for around 60 each now and again. Junk, but for a dentist trip? Who cares.

Something like these for e.g. https://www.tayna.co.uk/leisure-batteries/leoch/sfl-85/
Don tell them what they are for...

Description
Adventurer SFL batteries are a high quality flooded lead acid range from Leoch.
They offer strong deep cycle capabilities and are made up of 99.99% pure lead inside.

Some features of the Adventurer series are:-
Rugged Construction
Fast Charging
Top up facility
Tried and tested lead acid technology

I got a set of these a few years back as they had a 3 year warranty for a laugh. They lasted around 5 to 6 weeks of heavy chair use. Better than expected. REPLACED free of charge 4 times. Until the boss saw what I was doing with them. He refunded the money and refused to replace the 5th time!

THEY told me that they would be fine. I told them that they wouldnt. But who am I to argue with the experts at the shop.

[wes4dbt]

I would. If you only use it occasionally, just buy something cheap. But keep them topped up, charge 8 hours every 2 weeks or sooner. Even if it didnt move a millimeter.

Thanks for the reply.

I had left the batteries on a Victron Smart charger with storage set to 26.2. The chair in the garage and it get very hot during the summer months but I had set the temp compensation so I was a little surprised the batteries went bad.

Sometime I wonder if there's something wrong with this Victron. It always has a trickle current or .2 to .3amps during storage. I have another Victron I use for my everyday chair and it goes to 0.

[Burgerman]

At that float voltage there should be a tiny current. A few mA.
Unless the victron is faulty. Or the battery is old and sulfated.

The problem with the victrons is that they are a pig to configure in a way you want and keep on fighting you and reverting to what hey think is best which includes restarting the charge and reconditioning etc.

You have a fight to do a full custom setup that it will stick to.

Also, heat murders batteries. Every couple of degrees halves the lifepan.

Probably better to use cheap ones and swap when they die if you cant avoid the heat. Be careful of the age when you buy a the dealer may have had them sat in the heat too!

[martin007]

Be careful of the age when you buy a the dealer may have had them sat in the heat too!

Some sellers are scammers...

[Burgerman]

This might depress you...

If your battery, with a nominal 10 year float life, is seeing 50c in summer then it will last about 14 months. I keep mine cool. I keep hobby batteries in the fridge.

[wes4dbt]

I guess I was luck to get 3yrs. That is depressing because I really don't have any space in my house for the chair.

As far as the Victron goes, I agree it is a pain to setup. But as far as I know there isn't another programable charger in the $100 - $200 price range. I could go a little higher.

[Burgerman]

You got a few years because its not 50c all the time. And because long after it reached the 80% capacity point (end of useful life), you keep on using it.

Cant you just have the batts indoors?

[martin007]

I only use this chair when I go to the dentist because they can work on me while I'm in the chair. It's been about four months.

Is it a reclining powerchair?

This might depress you...

If your battery, with a nominal 10 year float life, is seeing 50c in summer then it will last about 14 months. I keep mine cool. I keep hobby batteries in the fridge.

Does the LiFePO cells also deteriorate at those temperatures?
Do you keep them in the fridge or in the freezer?

As far as the Victron goes, I agree it is a pain to setup. But as far as I know there isn't another programable charger in the $100 - $200 price range. I could go a little higher.

Have you reviewed a PSU ZXD2400?

[Burgerman]

All batteries deteriorate faster with accelerated calender life as storage or usage temperatures increase.

But lifepo4 has around 30 years calender life at 20C and 30 to 70% charge, to start with. So its not as important. And 2k to 5k cycle life if looked after.
But lead if very high qualiy, can be stored on a low float voltage for a decade before its ready to replace. Or 500 cycles if its a true deep cycle gel. Not both together.
Other lithium chemistries like my lipo packs for hobby use last 25 cycles, or 400 depending on usage. And iF stored at a mid 30 to 70% charged can last 2 or 3 years. Or 5 or 6 in the fridge. Not freezer.

The ZXD is massive overkill for storage. All you really need is a 5 or 10 watt wall wart that sits at say 13.35V regulated indefinitely. Or double that for a pair in series. A tiny 0.5A one is enough. Bigger will work but not needed. Or the same with a solar panel, and a solar charger. I have one on my van set to the same voltage. That odyssey batt is now about 16 years old! Still good enough for a van. Set to 13.5 in winter. 13.2 in summer.

[wes4dbt]

Is it a reclining powerchair?

Yes, fully reclining.

Have you reviewed a PSU ZXD2400?

I didn't understand any of the description. lol

Saw one review and it said the menus were in Chinese.

[wes4dbt]

You got a few years because its not 50c all the time. And because long after it reached the 80% capacity point (end of useful life), you keep on using it.

Cant you just have the batts indoors?

That's true it's only 64 degrees here today. I also had never seen the power indicator come off full charge. Those batteries probably had less than 10 miles on them.

I could keep them in the house but it would require me getting someone to take them out of the chair and put them back in everytime I needed to use it. I avoid asking for help as much as possible. So I'll just have to pay the price.

[wes4dbt]

Burg,

The link you provided was for a UK company I think. I'm a Yank. lol

To bad, that was a good price. The cheapest group 24 size was this, https://www.amazon.com/Battery-Trolling ... 255&sr=8-8

But couldn't I use any 12 SLA that fit's in my tray. I saw a 50ah for @ $73.

[Burgerman]

The link was to show the cheapest grp 24 that was deep cycle capable, ish... Ie the type. Not to order from the UK.
Its a wet, leisure battery. Search leisure battery grp 24. You should find something cheap.

Trolling battery? Same type of thing. Probably better quality / dearer.

[Burgerman]

For storage you can use one of these. Set to say 13.5V in winter. 13.2V summer. For long safe storage. For a single battery or your van. (TWICE THAT if in a chair in series obviously)

https://www.ebay.co.uk/itm/405108313343

3 to 36V output, 100 to 240V ac input regulated DC out. 2Amps, 60W max 95% efficient.
£10
Fit XLR for whelchair and AC connector of your own country.

[martin007]

I keep hobby batteries in the fridge.

Do you have a waterproof box to keep them isolated from moisture?

[Burgerman]

No. They are in plastic bags though.

[wes4dbt]

For storage you can use one of these. Set to say 13.5V in winter. 13.2V summer. For long safe storage. For a single battery or your van. (TWICE THAT if in a chair in series obviously)

https://www.ebay.co.uk/itm/405108313343

3 to 36V output, 100 to 240V ac input regulated DC out. 2Amps, 60W max 95% efficient.
£10
Fit XLR for whelchair and AC connector of your own country.

You think something like that will do a better job than my Victron set at those voltages?

I looked at the description and others on Amazon and didn't see any with the XLR connector.

Thanks for the reply

[Burgerman]

They dont know what you will use it for so its not going to have an XLR...

But those take 1 minute to add, cost a couple of dollars.

Will it work better than a victron? Not as a charger. Too weedy and 1 stage... But as a device to hold your battery at the voltage you decide then yes! And in storage thats all you need.
I have one similar from years ago, connected to my van over winter. It is in the house, long extention cable goes to the van with an anderson connector. It holds my vans battery at 13.35V most of the time.
In hottest part of the year I drop that to 13.1V. In COLDEST winter I increase to 13.5V

It just does what you tell it without going off on its own and doing aomething like restart charge or recondition... You cant tell what those victrons are going to do! And it takes very little power, and it gives YOU control over long term storage.

I set to 27.4V and top up a few chairs for 24 hours that are sat unused in the house every 2 weeks too. As well as a string of old batteries in parallel at 13.7V.

A useful gadget for pennies. Add a Anderson, an XLR, and a you get a choice.

Will it charge a dead battery? Yes. If you have till about xmas...

[martin007]

The XLR connector can be easily added with a bit of tin.

[Burgerman]

Remember that all a charger is is a power supply where some programmer has chosen all the wrong parameters! And that thinks you are too stupid to choose these yourself. Generally since the programmer has no idea what battery or usage you are looking at this isnt actually even possible!

So as always some USER KNOWLEDGE and an adjustable gadget is everything.

[wes4dbt]

Got my son to pull the battery case out and the battery size seems strange. They were 10.1W x 6.5W x 6.75H.

The M3 specs say it can use a group 24 or group 34. The length and width are close but the height is way off. Group 24 is 8.8 and group 34 is 7.8. Maybe these specs include the battery post?? These don't have posts, it's a flush connection.

I guess I'm going to have to pull the battery tray back out and figure what's the tallest battery possible. Shouldn't have told my son to slide the case back in. lol

[Burgerman]

Normally grp 24 but height is very close on permobils.

[wes4dbt]

Got the battery out and measured. It was about 8.3 high clearance. It was a group 34 battery. I found a group 24 with a 8.3" height but didn't want to take the chance so I order a set of cheap group 34. They actually cost more than the group 24.

If these don't last I'm thinking next time I'll just get a cheap set of U1 33ah. You can get those for about $70 a piece. All I need is to go into and out of the dentist office. About 100 yards each way.

[Burgerman]

You can buy 2 50m meter extention cables (110 yards) for less than the price of a set of batteries...

[wes4dbt]

You can buy 2 50m meter extention cables (110 yards) for less than the price of a set of batteries...

lol

Not sure even my dentist would agree to that.

[Burgerman]

OK.
THIS will easily do it. https://nexusmodels.co.uk/products/over ... e-pro-3369


And will go in your pocket.

Fit chair with an anderson or a XT90 connector.
Throw away its battery!

Plug this in when its time for a dentist.

Tiny hobby battery.
Will do about 2 miles with loads of reserve. (you use 1.5 to 2 Ah per mile?
And its 100C (so 500Amps capable) so can easily power a chair, or probably 6 of them at a time!

[wes4dbt]

That's an interesting idea. Keep it the house until I need it, probably would last a lot longer.

I'll see if I can find a US equivalent and come up with a manageable way to create the interface with the chair.

Thanks

[wes4dbt]

I found this, https://hrb-power.com/products/hrb-grap ... 1tW1ROShx6

It has two connectors attached, not sure what's going on there. How would I charge it??

Also, the batter break in they describe, not sure I'd do that either.

[Burgerman]

All hobby lipos are similar. Its exactly the same as all the hobby chargers, and my own powerchairs etc.

You have 2 wires to charger and discharge. The blue connector. You can use that, and put a matching one on the chair. Or make an adapter for an anderson, or an XT 90 which I much prefer. Or cut it off and fit one of those yourself. Or you can just buy an adapter.

The other connector is just a common balance connector. It plugs into the chargers balance port, balance board, etc.

Any cheap hobby grade charger will charge and store a lipo.

Also you dont actually need a 100C pack. Anything LiPo, from about 5Ah upwards, 7S, from say 50C (or even less if its a bigger Ah one) will easily do the current we need for a powerchair. Which can be cheaper. The LiPo batteries are quite amazing.

But lipos do not last a long time like LiFePO4 do. Say 50 cycles, to a couple of hundred depending on how they are stored and how much current you pull from them.

These are common advice for all LiPo.

BATTERY SPECS
Balancer JST-XH THE BALANCE CONNECTOR!
Capacity (mah) 6000 6AH
Cell count 7S (7S isnt common, harder to find, matches the lead we use in a chair)
Cell Voltage 25.9V Nominal. Will be 4.2V per cell charged full. And dont discharge below 3.5V or you will kill! 3.7 is a safe figure.
Charge Rate (2C recommended) 5C Charge at 2C which is 12A recommended, or faster 5C which is 30A Which is a 0 to 100% charge in 20 mins.
Connector EC5 I prefer anderson or XT90 (some have XT90 as delivered)
Dimensions 155x48x63mm 6 inches x 2 inches, x 2-3/8th
Discharge Rate (C) 100C (Up to 100x the 6A or 600A which is overkill!

Battery Care
Warning! Always follow manufacturer warning labels when handling Lipo batteries.

In addition there are some common practices a user should follow to not void the warranty:
Break-in new packs by gently cycling them 3 to 5 times on a charger/discharger or in the model from full charge to no less then 50%- 60% of full mAh capacity.
You will already be doing this just by using them in a chair if careful not to run them too low.

Always check for excessive heat after a couple minutes of runtime depending on the battery mounting location, and power draw of the model.
Let battery cool to ambient temperature prior to charging.
Always charge on a non-conductive surface to avoid shorting the battery or charging equipment.
Avoid running Lipos heavily during hot seasons where the outside temperature exceeds 95F/35C

Do not keep Lipo batteries fully charged while not in use. Always discharge to storage (60%) until the next run time. This avoids premature "aging" of the cells.
Essenial with lipos. Advisory with all lithium, but not quite so important.
Avoid discharging below 20% capacity. Doing so degrades the cells leading to high IR and reduces charge capacity.
As all lithium types. But lipos are not about lifespan. We hammer them and fly to about 1% remaining in hobby use! And at very high currents.
Do not exceed recommended charge rates. A 5C charge rate implies a max input charge current of 25A on a 5000mAh battery regardless of the cell count.
Never charge unattended.
Use Lipo safe bags for charging/discharging and transportation/storage, and discontinue the use of batteries that are puffing or physically damaged no matter how small.
Lipos can burn when charged. I charge in my bedroom, in an old metal box just in case but as long as they are dot damaged and charged accurately with a hobby balance chargerthey are 99.9% safe. I store mine in the fridge in plastic zip lock bags after doing a "storage charge" on a hobby grade balance charger.