NEW Charger for our LifePo4 - ToolkitRC M8D

[elryko1992]

That price seems very cheap to me.

just learn from this forum BM, Woody, Expresso, Shirley etc

[martin007]

That's what I do every day.

[Burgerman]

Martin. Its not expensive to convert to lithium. Its massively cheaper than lead.

A big lead battery like https://www.wheelchairdriver.com/board/ ... 30#p205943
Which is 230Ah or 244Ah measured actual, will only ever need charging every few days if used hard. Every week if used normally. It offers 5x as much range as a set of 70Ah lead bricks. With a complete set of lead batteries in reserve!

But it offers 10s of thousands of cycles exactly because its a huge battery. Because:

If you charge it once a week it already lasts 7 times longer than lead if it had the same 400 to 500 cycles. But it has 2 to 3 thousand cycles if fully discharged. 5,000 to 7000 cycles at say 70% discharge. Thats more YEARS of use than you probably have left at the weekly charge rate!

So it costs the same as decent lead or less initially.
Gives 500% to 600 the range compared to 70Ah lead.
Lasts at least 2 decades maybe a lot more. Instead of 1 to 2 years. So at LEAST 10X LONGER!
Charge it weekly in normal use...
Its a little lighter.
It charges faster.
When its at "end of life" after say 20 years it will have only 80% of original range remaining, which is still about 4 to 5x as far as new lead!

NOBODY can or should afford lead batteries in 2025.

[martin007]

One question elryko1992.

What container do you have for the lithium cells?

[Burgerman]

I can tell you what theres room for. Duct tape.

[shirley_hkg]

Everything you have bought costs a lot of money; even for someone who lives in Spain.

Then make the most value of your money.

Save €400--500 for a set of LiFePO4, that will outlast your chair/chairs, even the rest of one's life.

[shirley_hkg]

What container do you have for the lithium cells?

youtu.be/B8WvRpH3EvM

[shirley_hkg]

I was going to buy one but then I went with the ISDT P20 because it was a bit cheaper. It had firmware upgrades too. It charged my battery for about 30s then went up in smoke.

I bought something similar, because it can balance @4A.
Though it's working still, one of the channels cannot balance and its accuracy sucks.
When doing regenerative discharge, it balances at the bottom, but you cannot stop it.
PL8 is far more reliable and user friendly.

JK bms @2A balance is good too. Use it for charging only , and drive chair from battery direct.

[Burgerman]

One problem with a BMS is that if it is actually "strong" enough for a powerchair without chopping off power of failing, then its physically huge. And theres usually no place to put it unless you fit smaller cells.
For e.g. I could have done this with my new pack. But instead of using the beautifull 230Ah (244Ah) cells, I would then be forced to use the 160Ah ones. As they are same basic cell, but about an inch shorter in height in order to get the BMS on top, and into the chair. Since you still need to have about the same number of miles in reserve then that would literally half the usable range, and run the cells at too high C rate for best longevity.

It would work, defeats a lot of the gains. And adds a complex fire hazard on board.
(Thats partly why all the the drop in bricks suck. Because they also try to use a plastic familiar battery box, so now we cant even get the 160Ah cells in!)

But you could use a BMS - (with the ZXD as the charger) - externally (not fitted on the chair at all) for charging only.
ZTE ZXD with Anderson, via Shirley. Also Cinese auction sites etc.
https://www.wheelchairdriver.com/board/ ... 20#p206668
JK BMS - any and only spec thats important in this case is balance current and charge current 50A or better.
https://www.fogstar.co.uk/products/jk-s ... 8s-12v-24v

And that removes all the issues with the BMS safety nazi stuff we dont want or need, on board too. Its not an elegant solution, doesent balance as well as a PL8 but it gets there eventually. But you can sort of make your own powerful charger that way. And I am tempted to try it myself with a JK balancer (the rest suck) that has high balance current. Shame theres no PC control though as phones also suck... I think shirley already did this? seem to remember it being mentioned elswhere?

[shirley_hkg]

Is it what you are referring to ?



https://www.wheelchairdriver.com/board/ ... =2&t=12583

[Burgerman]

Yes.

[emilevirus]

Yea i have 2A JK BMS. Works great. It's big but it fits over the cells, then added a XT90 lead that plugs directly in the ZXD.

[Burgerman]

Which cells?

Peronally I wouldnt want a BMS on the chair. But if I did want that it would mean replacing the 230Ah cells with much smaller in height 160Ah ones. Same measurements otherwise. But thats a huge loss of capacity just to add a BMS that I dont need. Its worse than just the capacity drop, as you end up realistically with half the range, or double the amount of charge cycles. And much greater load on the cells anyway so faster.

Here was my layout, to replace the the GRP 24 lead.

Exact same layout with the 160 and the 230 cells. Only height changes.

[emilevirus]

Which cells?

Peronally I wouldnt want a BMS on the chair. But if I did want that it would mean replacing the 230Ah cells with much smaller in height 160Ah ones. Same measurements otherwise. But thats a huge loss of capacity just to add a BMS that I dont need. Its worse than just the capacity drop, as you end up realistically with half the range, or double the amount of charge cycles. And much greater load on the cells anyway so faster.

Here was my layout, to replace the the GRP 24 lead.

Exact same layout with the 160 and the 230 cells. Only height changes.

230Ah but Magic X8 had enough space for it.

[Burgerman]

I see. But once you backed off all the safety nazi stuff on that BMS, then all that nonsense no longer does anything. If it did then you would relax it yet more right?

So other than as a charge cell balancer, whats it actually for? Wouldnt it be better to use a hobby type charger, or a ZXD and have that BMS firestarter external in the charge cable?

[emilevirus]

JK BMS has a screen to see state of charge. So that's useful. The BMS uses 22awg wires so wires would melt before catching on fire (IMO). It's easier for carers. One cable, ZXD on autostart. Do you ask your carers to mess with the PL8?

[Burgerman]

No. All my chairs PL8s are BT and fully controlled by my laptop. (If they were not, its just a USB cable.)

I set the settings as I want, analise it, choose start, then graph and watch real time as it draws 8 curves and gives me the figures as it does its thing from my bed. I am never without the laptop in bed anyway so no equipment needed and no godawful smartphone or android/apple spyware nonsense. Or if up I use my desktop PC. And a PL8 also works in my van as I drive. All my carers do is connect its single chair connector. And it only goes in one way!

As for logging or watching cell voltages, I never bothered after the first few days even with a small 120Ah battery decades ago because it goes way further than I ever could in a day. After a few days you lose a couple of lights as with lead so you know not to leave town! So no need.

I do carry one of these in the event I do somehow get caught out 10 hours from home!

[martin007]

What container do you have for the lithium cells?

youtu.be/B8WvRpH3EvM

You haven't understood me.
How do I place that package on my powerchair?

[Burgerman]

Remove old batteries first.
Replace with new one...
Plug it in.
Drive away.

Seriously, I dont see any difference other than you cant charge it via a XLR port (unless it has a BMS but its too slow realistically) and so needs a seperate charge plug someplace instead.

[shirley_hkg]

I just use the original battery box most of the time, unless I need to put in much much Ah.

Look for the most suitable cell, that fits in.

You have a good power supply, a €35 BMS will be a full list.

[slomobile]

Just in case anyone is looking to build the next great charger, I feel it will look something like this. Though for our voltages GaN is probably better than SiC.
https://www.wolfspeed.com/knowledge-cen ... -chargers/
Bidirectional onboard charging so that we can just plug in any extension cord. No extra boxes. Either for putting power in or taking power out. And power doesn't need to go in or out as AC. It can be AC, or we could tap in between the DC-DC and DC-AC to pull out a large range of DC voltages to charge any old chair from ours at whatever voltage they require. Or put 56v into our large 48v onboard battery sourced from a 12v car without having to pull plugs to reconfigure any battery series/parallel situation.