PINNED - ADD ON PACK Step By Step 30ah Pack build / pictures

[shirley_hkg]

Not recommended for main cables , due to higher resistance of solder .

Bolt and ring terminals .

[Burgerman]

I disagree. I doubt theres any measurable resistance difference. And in fact would expect a soldered connection to be just as good initially, and the crimp to get worse as things oxydise over time even if it was as good to begin with. I have seen so many bad crimped connections that I never consider using crimping alone as secure enough on anything thats bigger than balance wires. So yes!

[expresso]

why even bother with Fuses on the Main pack in the chair - why not just use a Breaker - wouldnt that be best ?- if it ever trips - you just reset it -

and not worry about fuses to change etc, i mean if you solder a fuse - its a pain to change it - i never had one blow or trip on any chair so far - so it shouldnt but in the event it did - would be easier with a breaker -

[snaker]

why even bother with Fuses on the Main pack in the chair - why not just use a Breaker - wouldnt that be best ?- if it ever trips - you just reset it -

and not worry about fuses to change etc, i mean if you solder a fuse - its a pain to change it - i never had one blow or trip on any chair so far - so it shouldnt but in the event it did - would be easier with a breaker -

My dad removed the breaker away. It's weak just 50A. I had bad experience with breakers, they caused more troubles than protecting. Maybe that's because all my chairs are cheap and they use low quality breakers. I am living in a chaotic society, everything is unsafe and everybody is familiar with unsafe things. All that BM has done and showed are new and strange to people here but we all see that's better, safer. I will try to follow as much as possible. Hoping it could reach 50% at the end.

[rustyjames]

One of my chairs has a set of AGM group 24 batteries that are probably about 4 years old now. When I fully charge them and let them sit overnight the voltage is 25 volts. Would it be ok to connect the add on pack? I don't want to hurt my new investment.

[expresso]

One of my chairs has a set of AGM group 24 batteries that are probably about 4 years old now. When I fully charge them and let them sit overnight the voltage is 25 volts. Would it be ok to connect the add on pack? I don't want to hurt my new investment.

You can connect it - but your going to really be working your ADD ON pack the most - any lead battery 4 years old no matter how easy you used it or charged etc, cant be in good enough shape -

it would be best to get a New set of Lead - MK Gel if you can - and if you can - charge them first one at a time - then install - and use the ADD ON -

this would give you the best performance and last the longest - i think even any new battery would be better to use with the ADD ON instead of those 4 years old - but if you cant change the lead now - you can use the ADD ON and then change the lead when you can - you just wont get the best range out of it this way and work the lithium more since those lead you have is really dead at 25V i think -

or if you like - just use those lead till you feel they dont work for you anymore - then connect it with a new set of lead - will work either way you choose -

[Burgerman]

25 volts?

Thats basically 60% discharged voltage, or almost dead... You will just waste all the power of your lithium trying to charge ruined lead bricks.

[rustyjames]

Thanks guys, that confirms what I was thinking. I guess I'll buy a new set of MK's and start fresh.

[expresso]

yes best way to go - i just did that to my chair with the ADD ON also - got new set of MK from insurance last set for this chair - this way - you should be good for a while - if you had lead 4 years old - new MK with the ADD ON - should last you a long time

i charge it once a week if i dont use the chair at all - if i use it - i charge each time after use with the PL 8 - i also charge it before i use it if its been sitting a week and i want to use it - i would charge it first - then use it -

[Burgerman]

ALL of you guys would benefit from a power cut off link, or switch. All my chairs have them. A modern lead or lithium battery loses virtually nothing if stored as long as the thing is DISCONNECTED from the chair. Just one cable, no circuit.

An AGM like odyssey, or mk gel, have extremely low self discharge rates. So stored disconnected, they dont need a top up charge other than every 4 to6 months. Just charge very full, pull the link. Forget about them for 4 to 6 months.

The only reason you need to keep topping up is because the chair itself sucks power out all the time, even when off. 6mA to 30mA is typical if turned off. And 100 to 150mA if left on in error.

[popschief]

Lead brick question;
I have 5 powerchairs around here. Cheap ebay junkers with seat and tire and wiring changes to suit my particular needs. Every one received a new set of batteries when it arrived. Now we have completely lost track of these batteries, when they were purchased, how much they were used etc. I would like to know if it is possible to somehow check each set and determine their capacities? Can the PL8 do this and if so how is it accomplished? Would have been smart to mark them with at least a purchase date. Hindsight 20/20.

bp

[expresso]

yes thats a good idea now that i have a few chairs - and in the winter time mostly - - what would i have to do to make that happen with the Cut off etc, ?

thanks BM

[Burgerman]

Easy.

Test 1 at a time.

Set 12V 6S only, discharge at the 20 hour rate, and compare to the rated spec.
So for eg an MK grp24 is designed to give 73Ah at the 20h rate.

If you discharge at 7.3A thats the 10h rate. So you discharge at half this, or 3.65 or 3.70A and tell it to stop at 10.5 volts. Be sure to specify 24 hours or longer in safety, etc. And no CV discharge.

You can test also test faster over 10 hours, if you change the discharge level to 7.3A. But you will get less total Ah out (around 71.1Ah).

Or just use this (USE IT TO FULLY CHARGE BEFORE, AND AFTER TOO):
If you need an AGM one let me know.

[popschief]

Thanks John. Now I'll put the shiny new charger through it's paces.
bp

[Dan]

Dan - your going to make a 30ah Pack - look back from Page one here - i have pictures - you can follow them - it will show you how to arrange the Cells - attach the balance wires etc, -
when you say a BIT - what does that mean - Did you charge each Cell with the PL 8 Full and left them ALONE for a MONTH or TWO ? at least a MONTH is fine - before you continue ?

Yes I had fully charged each cell when I got them. They have now been sitting for a few weeks. I'm charging them back up. I numbered each cell when I first charged them.

I'm looking for the capacity returned to each cell? This one is 179mAh.

[expresso]

Dan - your going to make a 30ah Pack - look back from Page one here - i have pictures - you can follow them - it will show you how to arrange the Cells - attach the balance wires etc, -
when you say a BIT - what does that mean - Did you charge each Cell with the PL 8 Full and left them ALONE for a MONTH or TWO ? at least a MONTH is fine - before you continue ?

Yes I had fully charged each cell when I got them. They have now been sitting for a few weeks. I'm charging them back up. I numbered each cell when I first charged them.

I'm looking for the capacity returned to each cell? This one is 179mAh.

that seems pretty high for a Cell sitting for only two weeks - thats even high for two months sitting - Two weeks is really not enough - At least a month sitting after fully charged - - OK if you going to continue this way - i would put that Cell aside for the moment and continue with the rest of the cells and see what you get back in mAh returned -

[Dan]

It was a few weeks. Just checked the date they were charged. It was early July so they haven been sitting about eight weeks.

Highest returned so far is 275mAh, the lowest is 105mAh.

[expresso]

It was a few weeks. Just checked the date they were charged. It was early July so they haven been sitting about eight weeks.

Highest returned so far is 275mAh, the lowest is 105mAh.

if i recall mines - were all much lower - those all seem high - not sure what that means but if they are all similar - i guess you can match them the best you can - you can try to test them again - discharge one and then recharge it again to see how much it returns -

you are making a 30ah pack - 16 15ah Cells ?

[Dan]

"you are making a 30ah pack - 16 15ah Cells"

Yes, I hope so. I bought 18 15AH cells in July.

[expresso]

"you are making a 30ah pack - 16 15ah Cells"

Yes, I hope so. I bought 18 15AH cells in July.

Did you finish recharging all your Cells ? when you do - post the results - - i would want to check them again maybe - either do a discharge of each cell - remember dont go below 2.7 or 2.9 V during your discharge - i think 2.9V is good enough and then recharge and check how much each Cell is when full also -

[Burgerman]

The amount returned depends on the termination current setting. So it may well be different to yours. That doesent matter. As long as every cell was set to the same termination current. No need to redo.

[Dan]

Thats them charged using the LiFe Charge ONE 10/12/15Ah Cell preset.
Cell No. Starting voltage. Charge taken.
02 3.35V 88mAh
10 3.35V 90mAh
01 3.35V 91mAh Dropped
05 3.35V 99mAh
13 3.35V 105mAh
14 3.35V 105mAh Dropped
03 3.35V 106mAh
04 3.35V 109mAh?
11 3.35V 124mAh
16 3.34V 131mAh
18 3.34V 131mAh
12 3.35V 137mAh
17 3.34V 242mAh
08 3.35V 148mAh
06 3.34V 151mAh
15 3.35V 179mAh
07 3.34V 275mAh
09 3.33V 573mAh

Oh and I dropped one or two, theres a slim chance I forgot to charge number 9 first time around.

[Burgerman]

What is the history of these cells, thats a large spread? And no 9 at least looks suspicious? In fact any over around 150 to 200 do.

Are you sure they were all charged the same way? Same termination current etc? INITIALLY before storage.

[Dan]

They are the Headway 40152S 15ah LiFePO4 Cell bought from evassemble about 3 months ago. Charged up using the preset for a single cell that is posted in this thread somewhere then left in the same room for about nine weeks.

[Burgerman]

Well you may have had a bad connection to one or two when initially charging or when topping up. Or your power supply may be unstable and to charge rate jumping about so they terminate at random times.

Either way I would be careful with no 9. Build a pack, make each parallel group have approx equal discharge. And charge, test. Store it a week and recharge and see what the curves look like.

[Dan]

I have the graph from when they were first charged.
Cell 4. The power supply is a new Chargery S1500 V2

[Burgerman]

Forget that one. Look at these.

Volts v time
Amps v time.

[Dan]

Cell nine when I first charged it.

[Burgerman]

That shows that the line where it holds voltage steady, and where current falls, is a little uneven. So the exact point where the charger terminates the charge will vary slightly. Its caused by the power supply voltage jumping up and down slightly. Many do.

So build the pack and keep track of 9!

[Dan]

Build a pack, make each parallel group have approx equal discharge.

Just to be clear what constitutes a parallel group here. Is it four cells together?