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Re: Step by step lithium conversion?

Postby Burgerman » 26 May 2015, 23:41

Probably a few minor things. But you wont know till you do it.

Like a set of cables to take power for your chair?

Cable ties? Soldering irons, flux, solder, etc.

The orange building blocks come with the cells. And I think some Allen bolts do as well now rather than x head screws.

You need to be sure you can fit 2x 6 x 6 40mm block batteries in your chair too. That's 240mm tall. You need to measure your battery bay.

But I suspect that if you need serious hand holding and details on how to connect it all up it wont end great...

What's needed is some UNDERSTANDING of what you are doing. Then a painting by numbers kit of parts will not be required. Because you will understand what you are doing - before the smoke and sparks, blown chargers, melted wires, unbalanced packs, settings cockups etc. happens!

READ the whole thread here.
READ the PL8 charger manual 3 or 4 times. http://www.revolectrix.com/support_docs/item_1377.pdf Anything you don't understand? So that you know it all? Because 99 percent of what you need is here.
MORE: http://www.revolectrix.com/downloads.htm

Download the PL8 CCS software, and choose the advanced tab. Then study the way it (and the charger) works. And examine all the settings and options for A123 batteries in detail. Don't understand anything? Ask!
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Re: Step by step lithium conversion?

Postby Burgerman » 27 May 2015, 00:01

The D covers you link to are chromed plastic. You really need quality metal ones if you are doing a neat professional job.
The cables already have fuses. I used small automotive ones and soldered the wires, and cut off the excess so it would fit in the sleeving.
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Re: Step by step lithium conversion?

Postby FJC10 » 28 May 2015, 15:27

Burgerman wrote:Probably a few minor things. But you wont know till you do it.


Ok, thanks for your reply. ;)

I forgot the battery low voltage tester buzzer alarm.

http://www.ebay.co.uk/itm/Cell-Checker- ... 1273777416

How I can edit my previos menssage for add it?

Burgerman wrote:Cable ties? Soldering irons, flux, solder, etc.


I have all these tools; soldering irons, flux, solder, wire stripper, cutter, crimping tool, Mannesmann tool set, cordless screwdriver, Dremel multi tool...... and I know how to use, more or less. :) I build, modding and watercoling various PC's, video games console, smartphones... but, this is slightly different, obviously!

Burgerman wrote:READ the whole thread here.
READ the PL8 charger manual 3 or 4 times


Ok, nice idea. RTFM. ;) I start by reading the PL8 manual. Nice manual!

One question, where did you purchased the PL8? In Europe/UK or the US/Singapore store?

Burgerman wrote:The D covers you link to are chromed plastic. You really need quality metal ones if you are doing a neat

professional job.


All are plastic or metalized. Where can I find metal db25? Please, if you have, send me link for one better D25 cover. Thanks.
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Re: Step by step lithium conversion?

Postby Burgerman » 28 May 2015, 16:44

Metal covers?

All over. Inc RS Components, Farnels, etc.
http://www.canford.co.uk/Products/44-02 ... etal-cover many types

I have these. Well made. http://www.canford.co.uk/Products/20110 ... try-nickel
>>>Singapore store?
Yes.
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Re: Step by step lithium conversion?

Postby maker102 » 06 Jun 2015, 21:42

I am going to user the Hyperion Charger and am making up my pack. Can I split up the balance wires between connector A and B? As I see it I need the Black Wire and 8 balance wires, can I put 4 balance wires on connector A and 4 on connector B. or do I need to keep them sequential 1-7 on connector A and a single wire on connector B. Thanks
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Re: Step by step lithium conversion?

Postby Burgerman » 06 Jun 2015, 23:27

Either.

Probably best to keep it sequential though.

and a single wire on connector B


Well it would be 2 wires. The neg goes first, then the last cells pos. (8 pins for 7 cells remember).
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Re: Step by step lithium conversion?

Postby maker102 » 07 Jun 2015, 01:09

Will do. As always thanks for the help.
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Re: Step by step lithium conversion?

Postby DeeDee » 09 Jul 2015, 22:09

Hi, I'm new on this forum.

My chair goes fast enough for me but I wish I could go farther before I have to charge.

I have been reading about building batteries with the lifpro4 cells. Can I build a battery that will power my chair without doing all the robotec changes? I guess I want a 24v battery but with more Ah. I read about the Powerlab8 and the power supply and since money is tight I'd like to make a 24 v battery that would just use one Powerlab8 and power supply. Is that possible? Could I expand the cells and add another Powerlab8 and power supply later to get more Ah? I think I have the concept down about how the batteries are built but I am not sure about making the 24V size. It shows 12v size in the diagrams in this thread but how is it bumped up to the higher voltages like 24v 36v or 45volts. The way I see it adding more cylinders tied together as one with the bus bars (9 or 8 or 7 or 6 groups of Lifepro4 cylinders.) adds Ah but the volts stay the same. Is that 12v diagram just half of the battery? Is the other half a mirror image?

P.S. My husband will be helping me set this up. He is tired of lugging and buying lead batteries. I'd also like to change to bigger tires if I could but that might come later. He knows about hubs and wheels and extender things to fit the tires to the motors.

DeeDee.
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Re: Step by step lithium conversion?

Postby Burgerman » 10 Jul 2015, 00:05

Tyres. My whole chair is severely modified to fit the wider tyres and yet still be the same width as it was before. Adding two 6 inch wide tyres to a stock chair leaves it too wide for doorways and any indoor or van use.

Batteries. You can absolutely add a 24V lithium. It means 8 cells. Or rather multiple layers of 8 cells connected in parallel.
8 cells gives the correct voltage to use in a stock powerchair.

Yes you can add as many Ah of LiFePO4 cells, as you want, and still only use one PL8 8S charger. At 24V then you never need another charger.

But at 24V you lose out on the "free" speed. You gain the range regardless.
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Re: Step by step lithium conversion?

Postby ex-Gooserider » 10 Jul 2015, 03:30

Deedee says she is fast enough, but needs more range, so it would seem like she is an ideal candidate for a nominal 24V LiFePO4 conversion... The only thing that concerns me some is the questions she asks show a limited understanding of how these things work, which can be hazardous since mistakes involve welding level currents....

However, as a quick summary - YES, almost all chairs can be converted to LiFePO4 batteries without changing any other electronics on them, as long as you (or whoever is doing the conversion) thoroughly understand what you are doing.

The big thing to remember is that batteries in series add their voltages, while batteries in parallel add their voltages. Unless you really know exactly what you are doing, you should only combine batteries of the same voltage, current and type...

Your chair is currently using two nominally 12V lead batteries in series to give 24V. (note that these batteries are actually 6 two volt cells, wired in series, built into one package) Since some chairs have battery boxes that are arranged to have the batteries separated, or even just the way the batteries are arranged, much of the discussion has involved making two 12V packs, but really it is the same as one 24V pack.

Since LiFePO4 batteries are nominally 3V each, to get 24V, you need to put them in strings of 8 cells in series, and then to get the needed current capacity, you need to put a bunch of these 8 cell strings in parallel, the more the better.... (If doing two 12V packs, you'd use 4 cell strings in each pack instead, which would give the same result)

The biggest change is that you would no longer be able to use the charger that came with the chair, instead you'd need a charger intended for lithium battery packs. This is where the PowerLab charger and power supply comes in. My recollection is that the Powerlab8 can charge 8 cells in series, so one is all you'd need. Burgerman needs to do two of the chargers in series because he is running a higher voltage pack....

The basic 'process' is to measure your battery box, and figure out how many cells you can stuff into it, and how best to arrange them, try lots of different combinations, and also the different cell sizes.... The answer MUST end up divisible by 8, or possibly 8 with a remainder that you just will leave empty.... Then purchase the cells, 'building blocks' and busbars and CAREFULLY bolt it all together...

Assuming you can fill the battery box the same as your existing batteries do, the result will be about 3X the capacity of your lead bricks, and about half the weight, so you will have about 3X the range per charge.... In addition, IF you take proper care of the pack, you will get at least 10-20 years of service out of it, which translates to a much lower cost over the pack's life span, even though it has a higher initial cost....

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Re: Step by step lithium conversion?

Postby DeeDee » 10 Jul 2015, 04:01

Thank you ever so much. The doorways in our home are w-i-d-e. Thirty six inches wide (91cm) but it might be an issue while visiting at friends homes. Maybe some tires not as wide but a tire I can run slightly soft. That is a future project. We'll see. I am so excited I am going to order the PS and PL8 tonight! Tomorrow after my husband gets home from work I get him to do some careful measuring or remeasuring and order the max number of cells that will fit plus a couple extra.

DD
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Re: Step by step lithium conversion?

Postby LROBBINS » 10 Jul 2015, 09:45

My daughter's chair is using Kenda 13 X 5.00 - 6 Super Turf tires. They are not quite as wide as what John (Burgerman) is using, but have high sidewalls so that low pressure has the nice cushioning effect. They are tubeless and need rims either made or adapted for tubeless just as the Super Turf's that John has, just narrower than his. I think that the diameter is a little less (can't tell from nominal size number as tire mfr's are very "flexible" with those ) so the chair would be a bit slower at the same pressure.
Ciao,
Lenny
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Re: Step by step lithium conversion?

Postby Burgerman » 10 Jul 2015, 10:02

If you want a sensible service life, and improved range you must be sure that you are fitting MORE Ah than the lead you remove.

Typically a pair of 70Ah powerchair lead batteries can / should be replaced with 108 or 120Ah lifepo4 cells.
There's little point fitting 70Ah in place of 70Ah. Because gains will be minimal.
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Re: Step by step lithium conversion?

Postby steves1977uk » 14 Jul 2015, 21:57

DeeDee wrote:Thank you ever so much. The doorways in our home are w-i-d-e. Thirty six inches wide (91cm) but it might be an issue while visiting at friends homes. Maybe some tires not as wide but a tire I can run slightly soft. That is a future project. We'll see. I am so excited I am going to order the PS and PL8 tonight! Tomorrow after my husband gets home from work I get him to do some careful measuring or remeasuring and order the max number of cells that will fit plus a couple extra.

DD


I'd suggest getting the COOLICE 25v 1150w PSU if you want a small and compact one as this will allow you to charge upto 25 amps with ease. If you order one of these, make sure you say you want to use it with a PL8.

Steve
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Re: Step by step lithium conversion?

Postby maker102 » 22 Jul 2015, 02:40

I have been down for a few months and finally getting back to working on my packs. Are these the correct setting for a 12 volt pack, with 4 cells comprised of 9 individual batteries:

Battery Type: LiFe
Cells: 4 each 3.3 volt Cutoff Timer: OFF
Battery Capacity: 108 Ah Pre Peak Delay: Not Applicable
Charge Current: 3 amps Trickle Current: Not Applicable
Discharge Ampere: 3.0 TCS Capacity: 100%
Discharge Volts: 3.6V TCS End Action: Continue
Peak Sens: Not Applicable TVC Adjust Voltage 3.600: 0 mV
Cutoff Temp: 50 C PB Batt Float Voltage: Not Applicable
PB Batt Charger Voltage: Not Applicable
Set Store %: 60

Thanks again for all the help
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Re: Step by step lithium conversion?

Postby Burgerman » 22 Jul 2015, 09:27

Charge current max.

Dont use store.
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Re: Step by step lithium conversion?

Postby DeeDee » 07 Aug 2015, 00:57

Thank you so much for your reply. I was so excited when I ordered the PL8charger and the batteries and power supply... etc. And then I waited and waited and waiter for the batteries to come in. I thought I had everything and my husband gathered everything together and then he smiled sweetly. "What about the cable from the power supply to the PL8?" he asked. I ordered that 10 days ago and now it is sitting in some post office somewhere-lost! So another delay (sigh) the build will start soon and I am sure I/we will have more questions.

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Re: Step by step lithium conversion?

Postby Burgerman » 07 Aug 2015, 10:03

You could have bought that from your local hobby shop, or the parts to make one. I use Anderson connectors for that.
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Re: Step by step lithium conversion?

Postby snaker » 08 Aug 2015, 11:17

After switching to lifepo4 batteries, the power gauges on my wheelchair's controller do not work. They have 5 lights (1 red + 2 orange + 2 green) and after the wheelchair runs a long distance (about 20km), all 5 lights are still on. Is that normal when using lifepo4?
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Re: Step by step lithium conversion?

Postby Burgerman » 08 Aug 2015, 11:31

Yep.

You need to either watch till a light or two go out (at which point its dead and you need to stop) or get a monitor. But voltage barely falls as you add miles. Until its really empty.
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Re: Step by step lithium conversion?

Postby shirley_hkg » 16 Aug 2015, 07:13

:D

Small cell form factors like 18650 / 26650 give flexibility to accomodate various battery compartment.

This pack is around the front shourd and above the casters. :lol:
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Re: Step by step lithium conversion?

Postby DeeDee » 19 Aug 2015, 03:23

Postby Burgerman » 07 Aug 2015, 10:03
Re: Step by step lithium conversion?
You could have bought that from your local hobby shop, or the parts to make one. I use Anderson connectors for that.


Yes, that is true Mr. B but the hobby shop here is very small and more interested in selling glue together model planes, kites, and railroad stuff. They don't even carry the kind of planes you fly. The next closest shop is 80 miles away and the internet brings supplies right to my door. Obviously we don’t live in a big city. Even to build those cables I would order over the internet. Radio Shack has kids selling stuff. They looked at me like I was crazy when I said the wire had to carry 40 amps. “Is that for a speaker?” he asked. I even showed them the red and black cables from the PL8 with the banana plugs on them. They didn’t know what an Anderson connector was used for let alone carry them in stock. (In other words they weren’t listed in his computer.) I had to chuckle. I don’t know that much and I knew more than they did thanks to you!

Reading this step by step lithium conversion forum again I realized that there are recommended settings for charging new cells using the Hyperion charger but there are no settings recommended for the PL8 charger. I am using pre-set 13 to let the group of 10 parallel cells charge to 3.6v until the m-amps go to zero. The charge amps= 2.20A and the charge voltage = 3.555V. It pauses for 5 minutes and then begins to discharge and when the capacity out reaches -3000 mAh I manually stop the discharge. The voltage at each cell is about 3.308v when I stop the discharge.

I am charging ten cells at a time and I am using the balance cable (red and black wires only). Does this look right? If there are other recommendations I could start over since I’ve only done one group of ten.

By the way all the cells now come with Allen head screws (4mm wrench) and not Philips type screws. It is hard for me to measure but I think the screw is 6mm or 7mm long. They must have heard that John B recommend replacing the Phillips head screws with Allen head screws!

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Re: Step by step lithium conversion?

Postby Burgerman » 19 Aug 2015, 09:28

You need to set all time outs for CV and CHARGE time as well as discharge time to max or off.
You need to set the termination current to a low figure like 5mA x the number of cells you have in parallel. And initial charge needs to be 3.6v.
Set balance to CV only.
Cell count to auto.


If the cell is already built into a pack charge all cells together through the charge connections at say 20A. If not then why use the balance wires?

A bit confused here.
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Re: Step by step lithium conversion?

Postby DeeDee » 19 Aug 2015, 19:57

Except for the CV time out I had everything else correct. It always reached 0mA before the 30 minute ‘soak’ time out so that wasn’t a problem. I guess it does help to read the manual four or five times. There was some discussion (somewhat heated but not very heated) between me and my husband about the balance wires. The preset has BAL in the title and he contended that the wires were needed. I said they balanced the whole big pack. He asked if ten cells together in parallel was a mini-pack. I couldn’t find anything that said the balance wires would hurt anything so he put them on his ten cell mini-pack (his words). This is the initial charge of the cells to match them before we build the pack.

What is nice about the PL8 is that if you hold your cursor over the word in the preset a question mark appears (for example under the tab for balance there are options like Balance Mode) and if you click on the word a description appears of what ‘Balance Mode’ does so you don’t have to go back to the manual to understand the function.

I have another question that really will not affect me because I am building a 24v pack. The question is how do you use two PL8’s on a pack like yours. How do you split the pack for charging and then marry it back together for running? I had a thought that maybe the two charging ports could be jumper-ed together for the running part and when you pulled the jumper they would be separated for charging. How about a third Anderson connector (maybe in between the two charging ports) connecting the two parts of the battery together. Maybe this is a dumb idea but I just can’t picture in my mind how you would split the pack for charging unless you use a switch or something—a switch that if in the wrong position could be potentially disastrous for the chargers. Even if you use one PL8 for each half there should be some idiot proof method of splitting the pack for charging. I guess the ideal solution would be a Cellpro PL16. Maybe since you are consulting with the PL8 people you could suggest adding another balance port like the Hyperion charger had. Perhaps you already have.

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Re: Step by step lithium conversion?

Postby Burgerman » 19 Aug 2015, 20:38

You jump from one thing to another.

Are you confusing parallel with series?

Your cells are how many?
Your cells are what capacity?

How many parallel, how many series?

You should charge each cell to 3.600v. That means a low power preset. You can charge 100 cells in parallel, if you want, and there are no balance wires. You have to use a single cell unbalanced preset. With at least an hour sat at 3.6v after the current drops to almost zero.
And leave for a week or two. Then charge at low current, maybe 50mA slowly, to the point where EACH CELL INDIVIDUALLY is full. Write how many mA was returned to each. It wont be much.

Then make groups of parallel cells that add up to the same total.
Then assemble these groups in series to give your 24V.
Then only ever use the high power Preset for A123 and only ever charge with balance connected. And use my preset if you can till you know what you are doing and why!
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Re: Step by step lithium conversion?

Postby DeeDee » 20 Aug 2015, 13:18

You seem to indicate that I do not have to discharge the 3000mah after I fully charge to 3.600V and let it soak for a couple hours. You stated earlier in this blog that the discharge was necessary before I set them aside for a month or six weeks.

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Re: Step by step lithium conversion?

Postby Burgerman » 20 Aug 2015, 13:59

Lithium batts generally, don't much like being full and stored. So its a good idea to take an EXACT amount out, the same exact amount for every one. But not absolutely essential. Many of these LiFePO4 batteries are used even in standby operations today. Where they sit full the whole lifespan.

I probably would bother, and then store for longer. But its up to you. The longer you store them the easier it is to see the difference in self discharge when you charge each one up again.
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Re: Step by step lithium conversion?

Postby DeeDee » 20 Aug 2015, 16:11

Thank You
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Re: Step by step lithium conversion?

Postby Scollard » 29 Aug 2015, 01:49

To anyone out there:

My first set of Lead Batteries are in need of replacing so I am going to do a LiFePO4 conversion for my Pride Pursuit XL Scooter. I have one simple question so far. Will the regenerative braking feeding back into the Li pack cause a problem for the Li batteries?

Cheers
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Re: Step by step lithium conversion?

Postby shirley_hkg » 29 Aug 2015, 02:43

No problem at all, because we've been using them for years. :)
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