Homemade Battery Packs

kje said:
OK so if I make this battery pack without balance cables it is still possible to "equalize" manually?
Click to expand...
Yes, as long as you can access each bank (p).
 
My motor is 750W 48V
This will maximum draw 15,6A right? (750 / 48 = 15,6)
So a bms capable for discharges ≤25A is ok?

Like this?
http://www.ebay.com/itm/Batterie-Protection-BMS-PCB-Board-Balance-Pr-13-Packs-48V-Li-ion-Cell-Max-25A-/121713481986?hash=item1c56b05902:g:tx0AAOSw~gRVtKLm
 
48V 750w motor would be nicely served by a 25A BMS.
48V 25A = 1200w input will offer efficient limitation for optimal 750w motor operation.
Recommend not exceeding a 30A controller - 1500w maximum battery input is optimal.
 
Allex said:
Open up the battery enclosure, Disconnect all of the wires, connect them to your charger, then reconnect everything together, each and every time before a charge - to you really need all that work?
And how will you charge every group? will you have 13 small chargers or wait for each to be finished? Sounds odd to me.

Just buy a BMS and a regular 13s charger - connect ONE plug and then forget about it, return after a few hours to disconnect one plug when your battery is full AND balanced
Click to expand...

What about using this method like the guy in this video?

https://m.youtube.com/watch?v=KtZXNOcZeLA

I could make two 6s packs and one 2s pack and connect them in series with series adapter? Or is there better configurations? Three 5s packs? Or three 4s packs? What is minimum and maximum voltage on the 48V 750W BBS02 Bafang?


That way I can easily balance charge them with my Imax 6s charger. I can add bigger parallel packs for longer trip. I can also connect low voltage alarm while I use my bike.
 
I will be having a crack at making my own battery in the new year.
I will be using new 18650s and a BMS. I don't want any fiddly plug/unplug drama as it will be charged/discharged twice daily. The plan will be 13S and as many P as I can stuff into a Q76R case. Undecided as to whether the controller will be stuffed in there or will be on the outside. Will decide on exact dimensions when the frame turns up.

I'm relatively confident with the idea of spot welding my own pack, just a little daunted by choosing an appropriate BMS. I understand bestechpower are considered the premium or recommended BMS. Is this correct? If so, how to choose the most appropriate BMS?

The battery will be paired to a 1500w DD Leafmotor. I don't intend to use it much above 1000w, but the plan was to overbuild the battery in it's capability so if I want more power, its just a controller swap away (I have ordered both a 12 fet and 18 fet controller). This is because it will be a daily commute bike, but may end up offroad in the hills :D

I intend to use it at 48v. 1500/48 = 31.25a. Would it be more appropriate to choose an overrated BMS, i.e. 50a discharge to ensure it definitely won't be toasting it if I swap controllers? (everything will be controlled/limited by CA v3 anyway). I am assuming the motor may attempt to draw above 32a when under strain.
 
DrkAngel said:
LVC on a 48V controller is typically ~41V.
Which makes 12s seem feasible ... especially if bank 13 and 14 have their cells added to the 12s.
14s10p will sag more volts than 12s12p, ... but not to a lower voltage.
But check your 48V controller for 14s (58.8V) compatibility. Many have a HVC!

With any pack build ... Add a fuse!!!
Can save you from a whole lot of heartache!
Click to expand...

Where goes the fuse ? Between battery positive and motor connector (the thickest wire) or between charge connector and battery positive ? Or both ?
Eventually, should be a good idea to put fuses between BMS and battery parallels ?
Where can be found 42V/20A fuse (for a BBS01 250W) and 45-50V/5A for ”charger madness” - one of the main sources of fire ?
 
Recommend fuse as close as possible to battery.
Between battery and BMS, if possible.

Slow blow fuses recommended (vs fast blow fuses)
250V/20A (very common) fuse is equally effective at 42V DC.

Blade type fuse personally recommended ... even cheap fuse holders provide positive contact.
(I have had some deterioration problems with glass tube type fuses and end contact fuse holders)

I also have begun using a copper-graphite based anti-seize compound as a electrical contact enhancer - preliminary results seem very good-effective!
Works great on freewheels also! (FelPro C5-A)
 
DrkAngel said:
Recommend fuse as close as possible to battery.
Between battery and BMS, if possible.

Slow blow fuses recommended (vs fast blow fuses)
250V/20A (very common) fuse is equally effective at 42V DC.

Blade type fuse personally recommended ... even cheap fuse holders provide positive contact.
(I have had some deterioration problems with glass tube type fuses and end contact fuse holders)

I also have begun using a copper-graphite based anti-seize compound as a electrical contact enhancer - preliminary results seem very good-effective!
Works great on freewheels also! (FelPro C5-A)
Click to expand...

Wouldnt you want a fuse with an "Max Amp Rating" closer to what you would get in terms of max amps, while riding?
Like my Lyen 18fet is rated at 65, so wouldnt I just buy a 65A, 70A, 80A even a 90A fuse?
Then when i get it up to around 100A on occasion, the slow blow would blow in "whatever time frame the fuse blows", unless its shorted then its very high amperage and blow quickly.

I just got my holders in so now, today, I am soldering my pre-charge harness. A pretty large 5W 150ohm resistor that I will shrink wrap. All thats needed would be 1W or less.
 
markz said:
DrkAngel said:
Recommend fuse as close as possible to battery.
Between battery and BMS, if possible.

Slow blow fuses recommended (vs fast blow fuses)
250V/20A (very common) fuse is equally effective at 42V DC.

Blade type fuse personally recommended ... even cheap fuse holders provide positive contact.
(I have had some deterioration problems with glass tube type fuses and end contact fuse holders)

I also have begun using a copper-graphite based anti-seize compound as a electrical contact enhancer - preliminary results seem very good-effective!
Works great on freewheels also! (FelPro C5-A)
Click to expand...

Wouldnt you want a fuse with an "Max Amp Rating" closer to what you would get in terms of max amps, while riding?
Like my Lyen 18fet is rated at 65, so wouldnt I just buy a 65A, 70A, 80A even a 90A fuse?
Then when i get it up to around 100A on occasion, the slow blow would blow in "whatever time frame the fuse blows", unless its shorted then its very high amperage and blow quickly.

I just got my holders in so now, today, I am soldering my pre-charge harness. A pretty large 5W 150ohm resistor that I will shrink wrap. All thats needed would be 1W or less.
Click to expand...


The BBS01 motor is rated at 15/18A, so 20A would be enough to protect it from sudden bursts of amperage. Usually installed BMSes are rated slightly higher than motor, just to prevent overheating and safety of operation.
 
Fuse is likely higher than necessary-recommended.
Motor controller rated at 48V 30A?
Fuse should exceed controller Amp rating by a few Amps ...
... to allow minor excesses but protect against the major.
30A fuse for 25A controller?
35A fuse for 30A controller?
Start with minimal Amp fuse and increase only if necessary - for best protection.
Best to carry spares!
 
I ordered a 40A fuse. The controller is rated for 25A.

Is 13s7p enough for my BBS02 750W? Average capacity of each cell is 1.5A (1.5 X 7 = 10.5A)

I get a spark when I connect the battery pack to the motor. Can a rocket switch in series with the battery prevent this?

http://www.ebay.com/itm/New-12V-20Amp-20A-Red-LED-OFF-ON-SPST-Toggle-Rocker-Switch-For-Car-Boat-Sales-/151476331280?hash=item2344b16310:g:VRkAAOSwYshUZbKB&vxp=mtr
 
kje said:
I ordered a 40A fuse. The controller is rated for 25A.

Is 13s7p enough for my BBS02 750W? Average capacity of each cell is 1.5A (1.5 X 7 = 10.5A)

I get a spark when I connect the battery pack to the motor. Can a rocket switch in series with the battery prevent this?

http://www.ebay.com/itm/New-12V-20Amp-20A-Red-LED-OFF-ON-SPST-Toggle-Rocker-Switch-For-Car-Boat-Sales-/151476331280?hash=item2344b16310:g:VRkAAOSwYshUZbKB&vxp=mtr
Click to expand...
10.5Ah of laptop cells will be inadequate!
Might survive a while with very moderate throttle use?

Recommend >20Ah battery

Rocker switch will spark (internally) and might have limited survive ability.
Recommend a pre-charge resistor ... if it concerns you.

Temp Pre-charge Resistor.jpg
 
DrkAngel said:
kje said:
I ordered a 40A fuse. The controller is rated for 25A.

Is 13s7p enough for my BBS02 750W? Average capacity of each cell is 1.5A (1.5 X 7 = 10.5A)

I get a spark when I connect the battery pack to the motor. Can a rocket switch in series with the battery prevent this?

http://www.ebay.com/itm/New-12V-20Amp-20A-Red-LED-OFF-ON-SPST-Toggle-Rocker-Switch-For-Car-Boat-Sales-/151476331280?hash=item2344b16310:g:VRkAAOSwYshUZbKB&vxp=mtr
Click to expand...
10.5Ah of laptop cells will be inadequate!
Might survive a while with very moderate throttle use?

Recommend >20Ah battery

Rocker switch will spark (internally) and might have limited survive ability.
Recommend a pre-charge resistor ... if it concerns you.

Click to expand...

The pack may be more like 13ah if I'm lucky. Will I destroy the battery using this pack with my 750W motor?

Normal biking conditions, the battery is pushing ~10 amps to get to speed.
 
Less than 1C (13A from 13Ah battery) is reasonable for laptop cells.
Bigger is better ... of course.
 
Lurkin said:
I will be having a crack at making my own battery in the new year.
I will be using new 18650s and a BMS. I don't want any fiddly plug/unplug drama as it will be charged/discharged twice daily. The plan will be 13S and as many P as I can stuff into a Q76R case. Undecided as to whether the controller will be stuffed in there or will be on the outside. Will decide on exact dimensions when the frame turns up.

I'm relatively confident with the idea of spot welding my own pack, just a little daunted by choosing an appropriate BMS. I understand bestechpower are considered the premium or recommended BMS. Is this correct? If so, how to choose the most appropriate BMS?

The battery will be paired to a 1500w DD Leafmotor. I don't intend to use it much above 1000w, but the plan was to overbuild the battery in it's capability so if I want more power, its just a controller swap away (I have ordered both a 12 fet and 18 fet controller). This is because it will be a daily commute bike, but may end up offroad in the hills :D

I intend to use it at 48v. 1500/48 = 31.25a. Would it be more appropriate to choose an overrated BMS, i.e. 50a discharge to ensure it definitely won't be toasting it if I swap controllers? (everything will be controlled/limited by CA v3 anyway). I am assuming the motor may attempt to draw above 32a when under strain.
Click to expand...

Anyone willing to have a stab at these qs?
 
image.jpegWhat u think? I made four. There is a bit of room for the cells to expand but not much and I've been wondering what would happen if there was no room to expand. I think I will cut the bottom face off and glue that side with a softer rubber to my skateboard.
 
Hummina Shadeeba said:
What u think? I made four. There is a bit of room for the cells to expand but not much and I've been wondering what would happen if there was no room to expand. I think I will cut the bottom face off and glue that side with a softer rubber to my skateboard.
Click to expand...

What are they? pouches? if so I think I remember reading on this forum that you want them compressed with no slack.
 
Yes they're lipo pouches. I'm now thinking this was a bad idea. Of course I research on here "lipo compression" after I already did it. I can cut it off. Think I'll cover them in soft rubber instead.

It's not compression but restraint and I imagine gas pressure will have less space to fill and will more easily blow out the side
 
DrkAngel said:
kje said:
I ordered a 40A fuse. The controller is rated for 25A.

Is 13s7p enough for my BBS02 750W? Average capacity of each cell is 1.5A (1.5 X 7 = 10.5A)

I get a spark when I connect the battery pack to the motor. Can a rocket switch in series with the battery prevent this?

http://www.ebay.com/itm/New-12V-20Amp-20A-Red-LED-OFF-ON-SPST-Toggle-Rocker-Switch-For-Car-Boat-Sales-/151476331280?hash=item2344b16310:g:VRkAAOSwYshUZbKB&vxp=mtr
Click to expand...
10.5Ah of laptop cells will be inadequate!
Might survive a while with very moderate throttle use?

Recommend >20Ah battery

Rocker switch will spark (internally) and might have limited survive ability.
Recommend a pre-charge resistor ... if it concerns you.

Click to expand...
Simple and handy switch with pre-charge capability ...
DrkAngel said:
Simple Pre-Charge - Switch
A simple, and cheap, on\off\on switch with the 2 positions shorted with a resistor makes an effective pre-charge circuit.
I position to charge, (couple seconds?) II to fully engage.
High V light bulb as replacement for resistor confirms pre-charge complete when bulb dims fully.
Proper resistor with LED would provide similar function. Might need Large resistor parallel with small resistor-LED.

file.php


Pictured switch is rated up to 15A in dual (pos and neg) disconnect and 30A as single disconnect (pos or neg).
Personally used at 25.9V and 33.3V w\35A controller on various eZips and survives hundreds of on off cycles before needing replacement.
Adding pre-charge should greatly prolong life even at higher Volts and Amps!
Also liable to prolong controller life. ... ?
Click to expand...
See - Simple-Cheap Pre-charge Switch
 
I connected this Adjustable MeanWell type 48V power supply to my 13s battery pack with a meter between that measured 7A for a second and then the adjustable power supply died. 

Any idea why it just died?

The Adjustable MeanWell type 48V power supply Drk Angel recommended me:
http://www.ebay.com/itm/271852793055?_t ... EBIDX%3AIT
 
3 Amp limit!
Output was 7 Amp.

You must restrict amps.
If no recognizable amp adjustment ...

22ga charging leads?-

Alternative, if you leave the volt amp meter attached ...
Begin at low charge voltage and adjust occasionally to 3 Amp charge rate, till desired voltage attained.
 
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