PL 8 - Q and A section - How to Set up - Use etc,

[wheelchairer]

obviously can't get The balance cables for the PL 8 now, but I need a balance cable that is longer than the one I have. I know the cables on the balance cable supplied by PL 8 is high quality, so what cable would people recommend to buy to extend the balance cable by soldering the new cable to the balance cable?

[Burgerman]

Any really. Seperate strands are fine as you are making longer cables. So best to go up a fraction in size. Be sure to label each one as you go! Dont mix them up. Its possible to damage the charger if you do.

Try to find ribon cable. I never did but I never looked.

[shirley_hkg]

Damn. I might have a bad PL8 that can kill batteries.

On my recent 2 consecutive charges on two battery packs . It caught my attention that both packs were shown as cell 2 low - cell 3 high. (by 20 mV)

Multimetre shows all cell volts are close .

Hope it is the charge cables. Will resort to another PL8 for comparison tomorrow .

[Burgerman]

Doubt it. I have 4. And when tested with a good multimeter all are extremely close.
Also remember your bare copper bus bar? That wasnt accurate because you were connecting dissimilar metals. Which forms a kind of battery or thermocouple at the joins. And it gave all kinds of problems.


20mV isnt anywhere near enough to kill batteries though.

P.S. I tested mine with very short wires, and a hobby lipo. And my fluke. All within a couple of milivolts.

[shirley_hkg]

I really wish you were right , but sadly it itsn't.

The other PL8 shows the right things.

Want the contact for repair.
Anyone has it ?

[shirley_hkg]

The magnitude of the voltage differences are the same , Δv +/- 23.

Maybe a cap /resistor of that 2_3 node has changed value .

Could be a simple fix for someone familiar with electronics.

[Burgerman]

If we knew how it could be calibrated in software. But its not supposed to change. Its plus/minus 3mV as stock according to the manual. Which is pretty much increadible if its true.

This is one of the reasons I dont trust a BMS that tries to correct voltage all the time. If it reads voltage at say 3 to 10mV wrong, which it probably does, then it will spend all day long UNBALANCING the pack.

But even your 23mV is perfectly safe above 3.45V. It may mean your 3.600V cells have one thats just 3.023 low or higher. Thats so tiny it doesent matter. Its just 0.02 of a volt! Far more accurate than almost every volt meter is.

[steves1977uk]

In Dev mode, there's a calibrate oscillator option. But I'm guessing this needs special equipment to calibrate the PL8.

Steve

[expresso]

I really wish you were right , but sadly it itsn't.

The other PL8 shows the right things.

Want the contact for repair.
Anyone has it ?

[shirley_hkg]

Thank you.

[Burgerman]

You realise how little 23mV actually is? Not sure its worth the expense of shipping for repair.

Once above say 3.5V, up to 3.65V then 0.023 of a volt either way is still 100% charged.

Email and see if he will allow you to have whatever schematic or software that is needed to set calibration. It might be useful to us here too. Then all you need is a GOOD multimeter.

[steves1977uk]

I wonder if there's a PCB diagram and parts list of the PL8 somewhere? It should be open sourced now Revolectrix is defunct, as I'm sure hackspaces could improve on the PL8's design and be able to repair them locally.

Steve

[Burgerman]

Repair is too difficult as you need to remove things from the board to be able to test/measure them. Unless its just mosfets or something. If you do that it will also need calibration. And that isnt as simple as you may think.

[steves1977uk]

Yeah, I figured that BM. Ah well, it was just an idea...

Steve

[YellowBuzzaroundEX]

So I'd need a PL8 hobby charger? What brand and model? Is there a thread or webpage somewhere with that info? I'm new to lithium and this forum. I know there's lots of good lithium info here, but I'm having difficulty knowing where to look.

My scooter has a charger point on its tiller with 20 guage charging wires running approx 4.5 to 5 ft to battery box. I think that limits my fastest safe charging to approx 7A at 24V, but for safety for my wires I'd like to charge at 5 or 6 amps.

I would like to be able to continue using my scooter's tiller charging port without rewiring the scooter. My scooter uses two U1 batteries. 1 battery per battery box. Two boxes.

[daveonwheels]

the PL8 is no longer made

[daveonwheels]

and i suspect a lithium conversion isnt a good idea for a scooter with u1 batteries. you wont be able to fit enough Ah's to make it useful

[Burgerman]

I would disagree and it may be more simple because its a scooter. Because he can get off it. Unlike us powerchair users. Meaning that the reason we use lifepo4 (fire safety) is not needed here. So a pack made from tesla style lithium ion cells, 7s and greater energy density with a bms instead of a hobby type charger is a practical solution. So lithium cells 18650 or 21700 sizes are possible although not cheap.

[YellowBuzzaroundEX]

I would disagree and it may be more simple because its a scooter. Because he can get off it. Unlike us powerchair users. Meaning that the reason we use lifepo4 (fire safety) is not needed here. So a pack made from tesla style lithium ion cells, 7s and greater energy density with a bms instead of a hobby type charger is a practical solution. So lithium cells 18650 or 21700 sizes are possible although not cheap.

I can eventually get off it, but it's a slow painful process to transition to standing. I have to do 3 minutes of knee limbering therapy exercises before I can begin to slowly transition to standing. So I'd rather go with the safest non-flammable option, which sounds like LIFEPO4.

Surely I could build a LIFEO4 battery that would fit into my plastic battery box that's designed to hold one U1 battery? I have two such boxes. If it had 45 AH or more, I'd consider that excellent. Though I'd rather have 60+ or 70 AH if it'd fit.

I only weigh 145 lbs. It doesn't take much electrical power to move me around.

[Burgerman]

In that case then yes. Your best option is 8S and lifepo4 as they are at least as safe as lead.

The difficulty is that unlike big group 24 battery areas on a full sized powerchair or scooter, yours is much harder to find the correct sized cells that will take full advantage of the battery area volume. And you must fit more Ah - usually 1.5 to 2x as much to make a lithium conversion successful for a bunch of reasons.

So measure carefully and start looking on the chinese auction sites for 8 cells that will fit, and increase capacity over what you have now.

[YellowBuzzaroundEX]

OK. Thanks.

What is 8s referring to? Does 8s mean 8 cells?

[Burgerman]

8x lifepo4 or 7x lithium ion as in tesla/camera/laptop type cells all give a workable voltage close enough to 2x 12v lead that it works correctly with mobility controllers.

But that is just series. You can have as may cells in parallel in each group as you want or need.

But with lifepo4 you will need a hobby style balance charger rather than BMS.

[shirley_hkg]

I can eventually get off it, but it's a slow painful process to transition to standing. I have to do 3 minutes of knee limbering therapy exercises before I can begin to slowly transition to standing. So I'd rather go with the safest non-flammable option, which sounds like LIFEPO4.

Surely I could build a LIFEO4 battery that would fit into my plastic battery box that's designed to hold one U1 battery? I have two such boxes. If it had 45 AH or more, I'd consider that excellent. Though I'd rather have 60+ or 70 AH if it'd fit.

So , you didn't heard an add-on neither.

This is the easier and failproof way for beginners.

Once connected , it will fuse with your U1 batteries as ONE. You won't need a new charger too.

No more PL8 for late comers now, *so move on and post you threads here .
https://www.wheelchairdriver.com/board/ ... f=2&t=6873

[shirley_hkg]

Gonna buy used ones . Shall I avoid old firmware versions, say 3.31 and old 1.9X units ? ?

[Burgerman]

The last 3 firmwares were ok. Not earlier.

[shirley_hkg]

3.1X --- 3.3X

[Burgerman]

You want 3.3 onwards. Not earlier.
So, 3.3, 3.4, 3.5 (probably the most common, and the latest is 3.6! Which is the same as 3.5 with a few tiny changes and some new chemistries added.

[fishinjunky]

Gonna buy used ones . Shall I avoid old firmware versions, say 3.31 and old 1.9X units ? ?

i was tempted to purchase this used pl8

https://www.ebay.com/itm/325120633919?m ... olid=10050

[shirley_hkg]

Here are around £45 --- £90.

[Burgerman]

I have updated firmware with my laptop at the flying feild for a dozed different people. And with my desktop PC at home harbe 50 times with many of those beta firmware while trying to get revolectrix to sort out the charge algos for lifepo4 and lead. And would never be scared of doing it. So buy any 3.x ones and update to latest version.