PINNED - Lithium battery conversion/info

[Burgerman]

Those are what I want. A genuine 200Ah in the Salsa.

Give me 1 month. Then I will send you some money!

[Dan]

Is there a good place where 16 of them can be bought now?

[Burgerman]

Those PARTICULAR cells, right now, only SHIRLEY who was testing them for us.

But take a look at a few thtreads. Theres a lot of places to get cells siilar quite cheap. But mostly china. So you have to order and wait.

[Scooterman]

Only 1 mV , while discharged to the last 0.1 . . . . amphere hour.

Top banana shirley!

You've achieved perfection, best graph ever!!!

[shirley_hkg]

Those extra pouch cells just gave me the most messy balance ever .

[Scooterman]

Ooh that's a bit wiggly Shirley .

Why only charge to 3.5v?

Is it not 4.2v for all non-lifepo4 lithium cells?

It's probably mentioned in previous thread, but........... how do you connect pouch cells, spot welds?

[shirley_hkg]

They are LiFe too , with copper cathode that I can solder .

Anode is aluminum . Seller laser welded nickel strip on it, so I can solder too.



LTO is 2.4----2.7V.

Is it not 4.2v for all non-lifepo4 lithium cells?

[Scooterman]

Silly me! It’s says LIFE chemistry on the graph

still learning

[funkykeyboard]

Okay I have this battery pack. To be fair it was sat around for 2 with 3 years before it was fitted. And because I wanted to experiment to make it easier for ordinary people to use the wheelchair, I fitted a balancer. However for whatever reason this has not been successful.

Out of this current battery pack on this wheelchair I am only getting about 6 miles, and then it just stops dead. Secondly, it has developed a problem recently, of when you put the charger on it only gives you the option of "one cell". This battery pack when it is charging normally has 8 cells. I messed about with it the other day and it worked, providing 8 cells charging again, and today I had to take it out of the wheelchair before it would do 8 cells charging again.

So in the long run I would like to build a new battery pack, so was the webpage created explaining in detail how to make a 24 V battery pack to fit the BM 2 battery box specifications?

I'm a tetraplegic and the guy who is doing it for me as a tiny bit more electrical knowledge than I do. So we need a "for dummies" guide please.

Any advice appreciated, Tremulous Tetra. :-)

[Burgerman]

Okay I have this battery pack. To be fair it was sat around for 2 with 3 years before it was fitted. And because I wanted to experiment to make it easier for ordinary people to use the wheelchair, I fitted a balancer. However for whatever reason this has not been successful.

Thats not a surprise. Thats exactly what I expect to happen with a BMS. And no understanding.

Out of this current battery pack on this wheelchair I am only getting about 6 miles, and then it just stops dead.

Thats because - BMS. It has likely discharged a cell group too low. Or allowed a group to discharge over time too low. And now its too feeble to balance it in under a week or so. This may or may not have been low enough to damage that group. So you now have a wildly out of balance pack. And possible a damaged group(S) of cells. So one group runs out long before the rest, the BMS cuts off power to protect the low group.
This stuff happens because BMS are crap. And because you do not KNOW what is happening as its all hidden.

Secondly, it has developed a problem recently, of when you put the charger on it only gives you the option of "one cell". This battery pack when it is charging normally has 8 cells. I messed about with it the other day and it worked, providing 8 cells charging again, and today I had to take it out of the wheelchair before it would do 8 cells charging again.

No clue. What pack? What charger? BMS still fitted? Are all cells balanced above 3.500V?

So in the long run I would like to build a new battery pack, so was the webpage created explaining in detail how to make a 24 V battery pack to fit the BM 2 battery box specifications?

Every chair, pack, battery option, and solution is different depending on chair, space you have available, and if you are going to be doing it properly with a PL8 or not? Plus theres a multitude of threads explaining how, on this forum. Everything from full packs to addon batteries that extend range.

What you need is the knowledge of whats required and why. And then decide what to order, then do your own thread where you can ask specific questions. Its impossible to do a painting by numbers for dummies, too many details.

I'm a tetraplegic and the guy who is doing it for me as a tiny bit more electrical knowledge than I do. So we need a "for dummies"

You tried the dummies way. Doesent work.

So start at the begining.
1. What chair, and what size is the battery space to the MM ?

[foghornleghorn]

Range testing my pack on the same route I used testing the lead batteries previously going out and doing 2 hours, home for rest, then continuing.

Have a 4 digit voltmeter wired in which was there whilst PL8 was discharge testing before pack fitted to wheelchair, so confident it is accurate enough to believe. Been looking at voltage while pausing at the mile markers, also been checking the voltage drop regularly while moving.

Got to the point now where stationary voltage is 26.02, driving along at a very sight incline (69ft height increase over a mile) it drops to 25.75, and driving up the hill to my house (10 degrees) it drops to 25.08 then bounces up again once stopped.

In terms of when to give up the test and call it far enough is it the voltage when I stop that I should concentrate on, or under load?

[Burgerman]

Under load it can drop to about 2.5V lowest. About 2.9V when at rest means that you have very little left. x8 obviously.

[snaker]

Have a 4 digit voltmeter

Do not forget to give it a fuse. I knew why

[Scooterman]

Range testing my pack on the same route I used testing the lead batteries previously going out and doing 2 hours, home for rest, then continuing.

Have a 4 digit voltmeter wired in which was there whilst PL8 was discharge testing before pack fitted to wheelchair, so confident it is accurate enough to believe. Been looking at voltage while pausing at the mile markers, also been checking the voltage drop regularly while moving.

Got to the point now where stationary voltage is 26.02, driving along at a very sight incline (69ft height increase over a mile) it drops to 25.75, and driving up the hill to my house (10 degrees) it drops to 25.08 then bounces up again once stopped.

In terms of when to give up the test and call it far enough is it the voltage when I stop that I should concentrate on, or under load?

Can you see the voltmeter display while driving along? Where have you mounted it?
As a test to double check voltmeter you can always monitor voltage with the pl8 while riding along.
Are you using one of them bg-bs checkers to check pack voltage? They have LCD which easier to see in sunlight. I had to shield my led dvm.

[Scooterman]

BM - In emergency tavel situations away from home when charging on the fly. Would a couple of bulk charges without balance phase unbalance a pack too much? I think my pack would probably be okay but that's just a guess...

[foghornleghorn]

Can you see the voltmeter display while driving along? Where have you mounted it?

On the end of a long snake that is tucked under my knee or up in my hand for looking at. Not found anywhere to permanently fix it that is easy to view.

[Scooterman]

On the end of a long snake that is tucked under my knee or up in my hand for looking at. Not found anywhere to permanently fix it that is easy to view.

no it's not easy fitting anything in view on a powerchair. I want to fit a rear view mirror but haven't worked out where I can mount it yet

When I convert my powerchair I'm planning on mounting one of these on bodywork somewhere

https://hobbyking.com/en_us/turnigy-180 ... tore=en_us

[shirley_hkg]

BM - In emergency tavel situations away from home when charging on the fly. Would a couple of bulk charges without balance phase unbalance a pack too much? I think my pack would probably be okay but that's just a guess...

I noticed pack voltage starts to accelerate after 27.4V

Therefore , it is safe to bulk charge a balanced pack couple of time @not_exceeding_27.4V

Your pack will certainly be alright .

[Burgerman]

Provided that it was in balance prevuiously. I do that regularly.

[Scooterman]

Thank you both

Yes it stays pretty well in balance between charges. The current by-passes all start balancing roughly around the same time.

Lithium is brilliant, I try and do lots of long rides while whether nice. Although after a round trip of 28 miles yesterday, I couldn't wait to get off it and on the bed

But it woz good fun whizzing past all the cars stuck in traffic during rush hours

[Burgerman]

he real advantage isnt going on long trips because you can. But that all range anxiety and worries about not getting back if you go out again in an evening for e.g are gone. You know that you wear out first.

Yesterday, typical example. I chose NOT to go into town in the evening to meet freinds in a pub. Why? I was in the salsa chair, still lead. And it was showing most of the important battery lights out already. After a trip into town a couple of miles away, plus a days shuffling about indoors and cleaning house/garden and van.

It may have "made it" but you cannot know. So the limited lead range is further reduced because we are scared to use the last half anyway! Thats why we never actually run out. Its built into your head not to test it to the limit. Years of mental lead brain conditioning. Swap out 70Ah lead (35Ah of which is usable if still healthy) for 180 to 210 Ah of usable lithium and all that worry is just gone. Even if you charged 2 or 3 days ago.

[Gnomatic]

When I charge I have my CV set to 3.55v ...



But when the charge is complete, the PL8 says the average cell is 3.653v ...



This is typical in my experience, but why?

[Burgerman]

Because it hasnt measured anything yet. Its waiting to start. Should read ------ instead.

Choose monitor. Or charge. Or discharge. And it will guess at an average voltage. Based on many things. But you can read the actual cell voltages instead.

[Gnomatic]

That's the CCS screenshot right after I disconnected the charger in the morning.

[Burgerman]

Yes, but it says "waiting to start" so its ended everything. Including monitoring volts. That reading isnt your battery. Its just some random voltage on the floating line somewhere inside the charger. It really should read blank. But I didnt write the software...

As soon as you choose monitor, charge, or discharge, and click start it will correctly read battery volts.

[snaker]

When charging is finished, the button is "STOP" and the software still monitors and displays the cells and pack voltages. If you click on that STOP button, it will become "START" and the software stops monitoring. It should clear all info in this case. That 3.65V is meaningless, maybe a random value or a software's bug. PL8 software was not well designed, it seems written by an unskilled student.

[LROBBINS]

PL8 software was not well designed, it seems written by an unskilled student.

Maybe the same one who keeps trying to make InstallShield Pro (a VERY expensive Microsoft product) compatible with the ever changing Windows OS ways of doing things. Or the one responsible for its 5,000 page un-organized manual.

[steves1977uk]

That's the CCS screenshot right after I disconnected the charger in the morning.

Once the charge is complete, the charger monitors the cells and cell voltages drop very slowly until the STOP button is clicked. Maybe a bad/dirty connection somewhere Gnomatic?

[Gnomatic]

That's the CCS screenshot right after I disconnected the charger in the morning.

Once the charge is complete, the charger monitors the cells and cell voltages drop very slowly until the STOP button is clicked. Maybe a bad/dirty connection somewhere Gnomatic?

Won't hurt to give my charge connectors a spray of DeoxIt.

[expresso]

Do you use SubD dust cover over the charge cable ends ? If not - you can give it a try - i been using covers since day one on all charge cables i make . they are cheap and seem to work.