PINNED - Lithium battery conversion/info

[FJC10]

Is that a 12Ah cell or a 15Ah one?

12Ah

[Burgerman]

The its good! You can also see why going lower than say 3V in use, or 2.7 to measure capacity is pointless. Theres nothing left.

[snaker]

FJC10's cells seem survived. So, how to kill a lifepo4 cell

[Burgerman]

2V is a safe round number limit. Slightly lower and discharged s l o w l y as his were, may still get away with it. But he was lucky. I saw many hobby cells totally ruined by running too low just once. And it still may not be 100% good. It may show damage sooner than the rest in a years time, or may have increased impedance/resistance.

For E.G I destroyed a brand new 5.8Ah 16.8V LiPo battery in my quadcopter. When trying to make it back home after a long range "mission". I do missions! And I am 57... I miscalculated (stupid headwind at about 1000 feet on the return for about 4 miles) and it only just made it back. To do so I had to go beyond the low of 3.65 to 3.70V where I would normally land. And after a further 1 minute of flight it was now visible. But had fallen to 3.5V per cell which is too low. By the time I landed it was down to 2.9something V. And ruined... And dropping like a rock. Out of power. It landed heavily 50 feet from me because I forced it down but it landed! About 15 seconds later it would have just shut down. Bad! But those things dont glide well and weigh the same as a brick so there was no choice.

Without access to a reliable flexible tool like the PL8 all of this testing and measuring wouldnt be possible. So the reason for having one and the PC control/graphing etc, and very flexible settings for balance and for termination, discharge capability and so on rather than a cheap hobby charger (or worse a dumb charger and BMS) is again very obvious. Once you start messing around with lithium you actually NEED one.

And of course you can charge lead properly, and everything you own regardless of chemistry or cell count. And you can do it from a car @ 12V a chair @ 24V, or a wall @ 110, 240 AC via a power supply. At a tiny 10mA up to 40A... The more you learn about batteries the more you realise how good it is. Right now, there is no other charger on the market, (even four figure professional tools), that can do close to what this does. Although its taken many years to get the firmware and a way to make better presets to allow it to do some of this.

[dEknowmight]

Hi guys..

I'm going to purchase 48 of the 15Ah Headway cells (40152S) and make 2 12v 90Ah batteries for use in my Pride Victory 10 Sport scooter.
Based on much reading here over last few days it looks like i will also be taking the PL8 charger.
And of course i'll need to get some low voltage alarms to protect.

I'm still needing to learn about matching/balancing the cells and using the PL8 properly but wondering if any advice before i purchase?
Also does anyone have accurate fuel gauges, or just the low voltage alarms?

Thanks to BM and everyone else for all the great info here! I'm excited to expand my fun zone with lithium.

[Burgerman]

Other than to read the main lithium threads on here, And the PL8 one. Not really. Much to learn/know which matters.

[shirley_hkg]

Sadly there is none , EXCEPT . . . . .

[FJC10]

The its good! You can also see why going lower than say 3V in use, or 2.7 to measure capacity is pointless. Theres nothing left.

Yes! Thanks you! And it make me see that PL8 charger is wonderful!!!! A lot of information and functions!

FJC10's cells seem survived. So, how to kill a lifepo4 cell

Well, It's time to recover the remaining seven cells... Maybe I'll only be able to recover one!

[Burgerman]

Connect all 7 in parallel neg to neg, pos to pos. . And charge at say 5 Amps or so. As a 2s nickel metal. Stop it at 2.5 to 2.7V. Seprate all cells.

Then charge each alone fully and see what they do.

[dEknowmight]

Just ordered my 48 cells from EV Assemble and about to order the PL8, PSU & cables/connectors.
Because I'm making 2 separate 12v packs I'm wondering best way to charge them and make balance cable. I made the following diagram for my physical packs and how i think i'll connect the balance cable and charge the 2 batteries in series. Not sure if good idea or not, does this look good?



Thanks!!

[Burgerman]

Looks right I think. But these diagrams are harder to understand than just looking at the pack. Why 2x 12v packs?

[dEknowmight]

2 12v's because i haven't been able to check my pride victory 10 scooter yet to confirm where i connect just as 1 24v.
Plus the spot to place the batteries will require they are separated by about 4-5 inches.
I'm also ordering a DMM tonight and once it arrives i can check the connection points on the scooter and see if i can then just jumper wire my 2 packs together as 1 24v pack.

[Burgerman]

The scooter runs on 24V so you can. Almost all do.

[robert97]

front pack

wiring diagram for two 7S 5P packs

I got my prototype chair converted to lithium over the weekend. works great.
i'll be checking the range.

I used a couple of novel approaches that I haven't seen before
on the forums. Maybe others will find some of these ideas useful.

One of the major constraints was fitting the lithium to a C350 permobil.
Because of the center seatpost I required split battery packs.
Also, the PL8 charger cannot handle more than 8 cells in series.

Given the space requirements, the desired amount of power,
and the desired voltage I chose to make a pair of
identical packs. Each is 7 series 5 parallel.

My diagram is crude but should be easy to follow. One novel
idea is how the pull loop connects the two packs in series via
the yellow wire. I get 48 volts and I get a full loop to
interrupt power. Power can also be interrupted via the contactor
which ves positive 48v to the Robotech. And
the circuit breaker which goes to the ground side of the
Roboteq.

With Anderson connectors and careful wiring it's very easy to
remove the packs from the chair. again the packs are identical
and interchangeable.

robert

[Burgerman]

You should have a ton of range.

Thats 14S and 5x 12Ah, so

3.3Vx 14 = 46.2V
X
12Ah x 5 = 60Ah. And thats 2,77kw hour pack.

[robert97]

after 2 hours of outside driving time with Ruby, i have
returned about 9000 mAh to each pack.

Ruby - the reason i built a better chair

john,
thank you and the community for everything.

thanks for illustrating that wheelchair manufacturers make pathetic
products. you always give solid reasons for the problems.

then you design, build and share solutions.
you patiently work with newbees educating us about batteries,
chargers, motors, controllers, etc.

the last 6 months have been challenging and rewarding for me
because of you and this forum.

there's still much more to do, but getting this far has me celebrating.

[Burgerman]

Ruby looks great. Sadly mine has gone now.

Wood on a chair. I actually thought about building a one bit plywood glued and screwed chair. Wool looks a bit odd but has many advantages. After all I have flown in wooden sailplanes, and they seemed strong and light. And survived 30 or 40 years of student arrivals...

T31 and T21 I am talking about. Learned to fly and repair on both! Put my bum through the fuselage nylon.

Note the bit of string side slip indicator. Not that it was needed you can feel it on your face. These things are better for learning than all the modern stuff. Other than the 800ft 3 minute flights!

T21

youtu.be/y19dxd82XCg

Shorter flights still, T31 was much smaller.

youtu.be/n50OJK61zuE

[dEknowmight]

Hitting 2 weeks now and still waiting for EV Assemble to ship my 48 cell order.
My PL8 just came in with 36" balance cable, output banana cable & the PC cable.

Still needing to order a PSU and some assorted wires/connectors. Based on reading & links provided here I'm going for;

PSU to PL8: 10AWG w/ grey Anderson SB50 connector
Battery Discharge: 10AWG w/ 8AWG copper ring terminals (1/4" stud holes)
Balance Cable: 12AWG w/ 8AWG copper ring terminals (1/4" stud holes) & 22AWG w/ 22-18AWG ring terminals (1/4" stud holes) to D SUB connector
Initial & Single Cell Charge: 12AWG w/ 8AWG copper ring terminals (1/4" stud holes) to D SUB connector
Cell Voltage Monitor: 22AWG to D SUB connector

Have yet to nail down the PSU but it's looking like the 24v47a supply from FeatherMerchantRC.com.
Also need to find the ebay link again for those cell monitors and pick a D SUB.

Any fast links to a good thread for initial charge & cell balance process for assembling my pack?

Thanks!!

[Burgerman]

Probably non that I could easily find.

The idea is that you carefully and completely charge each cell to 100% Individually (or in groups in parallel) with a sensible termination current.

Then put each in a box in a cupboard for 2 to 4 weeks.

Then repeat the charge. Very little will go in. What you are looking for is this exact number of mAh returned. Write it on each cell. This is the amount it had SELF DISCHARGED itself over time. This may vary between cells. And will also show up any suspect cells before you build.

All cells are now full. Assemble into 8 parallel groups that each have the same TOTAL discharge mAh level once all cells in that group are added together so each group will now self discharge at the same rate. Then build the pack. This prevents a large pach from going far out of balance over time, or if stored for a few months.

I will upload a SINGLE CELL profile, and a FULL PACK profile that is correct for these purposes if you wish. Theres already some in various threads here.

[dEknowmight]

Hey BM, I found the attached presets to do a single headway cell and a full pack. I'll play around with these to make sure they make sense and good for my 15Ah cells before I get started. Just ordered the rest of my bits... I went with the Chargery S1200 PSU (24v50a). It was a little more expensive but was easy for me to get it.
Now I read and wait for my cells to arrive!

[Burgerman]

This is why I keep telling people not to fit small lithium batteries.

It seems the reason tesla get such a huge battery life, and long battery warranty it is because they fit a massive battery and don't use some of it. So even when empty, its actually still got around 15 to 20% extra left untouched. They do the same on charge. They are careful to not ever use its limits.

https://qz.com/1073742/hurricane-irma-t ... n-florida/

[ex-Gooserider]

By "Battery Discharge" I assume you are talking about the cables that actually power the chair?

If so, I would be inclined to say that AWG 10 would probably work, but is on the light-weight side... I would go with at least AWG 8. Personally I use AWG 6, but that is on the over-kill side...

FWIW, BM uses Metric 10mm^2 cable on his chairs. If you look that up on some of the charts, it's about equal in theory to AWG 7, but since the only place I've ever seen odd number AWG sizes is as numbers on the charts, we have to go to either AWG 6 or 8.... Others have suggested that AWG 8 is OK for most users, but if you want the absolute maximum performance (i.e. for sports use) go with AWG 6. I figure the cost difference isn't that much to go for AWG 6, and that has the advantage of being the size of the most common pins for the SB-50 / PP-75 series shells...

ex-Gooserider

Hitting 2 weeks now and still waiting for EV Assemble to ship my 48 cell order.
My PL8 just came in with 36" balance cable, output banana cable & the PC cable.

Still needing to order a PSU and some assorted wires/connectors. Based on reading & links provided here I'm going for;

PSU to PL8: 10AWG w/ grey Anderson SB50 connector
Battery Discharge: 10AWG w/ 8AWG copper ring terminals (1/4" stud holes)
Balance Cable: 12AWG w/ 8AWG copper ring terminals (1/4" stud holes) & 22AWG w/ 22-18AWG ring terminals (1/4" stud holes) to D SUB connector
Initial & Single Cell Charge: 12AWG w/ 8AWG copper ring terminals (1/4" stud holes) to D SUB connector
Cell Voltage Monitor: 22AWG to D SUB connector

Have yet to nail down the PSU but it's looking like the 24v47a supply from FeatherMerchantRC.com.
Also need to find the ebay link again for those cell monitors and pick a D SUB.

Any fast links to a good thread for initial charge & cell balance process for assembling my pack?

Thanks!!

[dEknowmight]

Yes "battery discharge cables" meaning battery to scooter. The current cables are 10awg so I figured there wouldn't be any change in draw from battery so should be good. I'm actually going to use the same cables that are on there now. In future I plan to step up voltage and get different motor/controller combo so will definitely upgrade the cables. Thanks for the input, I'm learning a ton here and thankful for all the shared experience everyone offers.

[LROBBINS]

Cable size selection should be based on current draw, not voltage. Using heavier than 10ga. may well improve responsiveness even if the original was awg 10, but in general scooters don't draw as much current as powerchairs when maneuvering so smaller may be OK. Still, it costs very little to put in heavier wires.

[Burgerman]

I may also add that if you increase the volts, any given level of motor power used will now take only half the amps. And so the stock cable size becomes much less of a problem.

[dEknowmight]

Good point BM, and at this time most of my orders (including all wiring) have been delivered so I'll want keep the course as is. Just need those D SUBs and the cells to arrive.
I'm going to start building the cables this weekend and will keep em short as can be as i think that helps with the smaller gage wire.

[FJC10]

Well, It's time to recover the remaining seven cells... Maybe I'll only be able to recover one!

All, apparently, recovered:

Cell 2:
https://imgur.com/EPLOs5j

Cell 3:
https://imgur.com/ExEYqD1

Cell 4:
https://imgur.com/DdUfl16

Cell 5:
https://imgur.com/fTcZsQi

Cell 6:
https://imgur.com/ioH4dW4

Cell 7:
https://imgur.com/mO0CX7n

Cell 8:
https://imgur.com/6RKVU29

I said, apparently... do you think they will have any problems in the future?

[FJC10]

One more question...

This cable:

https://hobbyking.com/en_us/turnigy-hig ... m-red.html

should be fine for chair-side cable or 12AWG like PL8 charge cable is OK?

[Burgerman]

Ideally on the chair, where 200A can be demanded you need 10sqmm and it needs to be marine, tinned, and thin hard insulation.

Silicone is used by the hobby industry because it means the cables can be smaller, lighter, more flexible, because it doesn't melt. But that stuff is easily torn, or ripped and you don't want silicone cable on the chair itself.

As for future? Hard to know. But those cells are at least a little different to each other. The least capacity was 11.2 from a 12Ah cell. Compared to 11.7 from the best. Thats a half Ah difference. About a 5 percent variation. Which is a fair bit more than a set of new cells. So while they still have good capacity its not 100%. Just keep an eye on them in the future.

[FJC10]

I think I explained myself wrong ...

chair-side cable for charge and balanced, like this:

My wheelchair (Invacare TDX SP) have Anderson SB50 connector + 80 amp fuse, can you see it in this photo:

If I see that I need a longer cable, I have this cable to make one for battery->chair side:

Is ok?