Begginers Guide to Processing 18650 Cells | Cell Database


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How to calculate pack and charger?
#11
Im talking about the balance part. Connect 2 14s packs in paralell 100% requires 15 wires!
But to hook up 2x 7s packs in series requires 2 wires Wink

Its just a matter of make sure that you always maintain them in balance in the cart and in that sense its best to make sure they all are "paralell".

If the cart draws 2000A at the start you should consider to have a capacitor bank hooked up to it as well. That will cope with the initial pull pretty well and you dont need several 1000 cells.
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#12
(08-21-2017, 04:55 AM)daromer Wrote: Im talking about the balance part. Connect 2 14s packs in paralell 100% requires 15 wires!
But to hook up 2x 7s packs in series requires 2 wires Wink

Its just a matter of make sure that you always maintain them in balance in the cart and in that sense its best to make sure they all are "paralell".

If the cart draws 2000A at the start you should consider to have a capacitor bank hooked up to it as well. That will cope with the initial pull pretty well and you dont need  several 1000 cells.

Yeah, so the idea would be the "permanently" mount these in the cart, the motor draws 200 amp on start and then 100 at full throttle, most of the time I run 75% throttle and it averages about 60amps.

What would recommend for a BMS ?

So the next challenge is BMS and balancing / charging and is that easier to do in 2 packs wired in series, or 2 packs wired in parallel?
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#13
It depends on how you going to charge? If you charge with a proper RC charger then no need to add any BMS stuff to it. Then its just enough to have under voltage protection.

Just as I said before hook the 2 7s packs up to an iCharger DUO 308 or 4010 and you can charge them with either 30 or 40A Smile
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#14
so 2 of these, (iCharger DUO 308) one to each pack and separate the packs electrically before I charge them? Looks like about 300USD for each unit, With this do you still suggest that I fuse each cell to the bus bar as I build it?

(08-21-2017, 04:57 PM)daromer Wrote: It depends on how you going to charge? If you charge with a proper RC charger then no need to add any BMS stuff to it. Then its just enough to have under voltage protection.

Just as I said before hook the 2 7s packs up to an iCharger DUO  308 or 4010 and you can charge them with either 30 or 40A Smile

so 2 of these, (iCharger DUO 308) one to each pack and separate the packs electrically before I charge them? Looks like about 300USD for each unit, With this do you still suggest that I fuse each cell to the bus bar as I build it?

(08-21-2017, 04:55 AM)daromer Wrote: Im talking about the balance part. Connect 2 14s packs in paralell 100% requires 15 wires!
But to hook up 2x 7s packs in series requires 2 wires Wink

Its just a matter of make sure that you always maintain them in balance in the cart and in that sense its best to make sure they all are "paralell".

If the cart draws 2000A at the start you should consider to have a capacitor bank hooked up to it as well. That will cope with the initial pull pretty well and you dont need  several 1000 cells.

so 2 of these, (iCharger DUO 308) one to each pack and separate the packs electrically before I charge them? Looks like about 300USD for each unit, With this do you still suggest that I fuse each cell to the bus bar as I build it?

(08-19-2017, 09:29 PM)1958 greyhound Wrote: you would need a min of 14s 160p to equal the standard 8 golf cart batteries.

if you go with high amp drain bats like in a cordless drill you could get away with half as many.

So what battery cap are you suggesting? IT may be cheaper to do it that way than to purchase the extra smaller cap batteries?
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#15
higher amp drain.
standard laptop cells have .2c - 1c drain

the 10 amp you have should work, so if max draw is 200 amps you need 100p min



why do you want 2 dif packs?
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#16
(08-21-2017, 09:01 PM)1958 greyhound Wrote: higher amp drain.
standard laptop cells have .2c - 1c drain

the 10 amp you have should work, so if max draw is 200 amps you need 100p min



why do you want 2 dif packs?

Yeah the spec is confusing to me:
http://www.tme.eu/en/Document/cf2b91a946....2P-HV.pdf
Shows .2C but below that a few lines it shows 10A (Cont Discharge).

Just figured 2 packs would most likely be easier to fit in the space below the seat in the cart, otherwise no real technical reason.

The cart does draw 200 amps when you torque it up (stomp the pedal from a dead start) and so I need to account for that.  Wow 100P is going to be a HUGE $$$ pack!
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#17
0.2C is the typical discharge for full capacity.

Nominal discharge is 1C and mach discharge continous is 5C.
Lets say your nominal should be 1C. then you need 30p roughly. For the maximum rate that you have ie 200A you need 20P to accomodate and have some safety.

I would rather go for 30p to save on the pack than 20p. 100p if you want to utilize the full pack capacity under 200A load Smile I guess that is overkill than having alot of juice over a long time.
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#18
(08-22-2017, 04:44 AM)daromer Wrote: 0.2C is the typical discharge for full capacity.

Nominal discharge is 1C and mach discharge continous is 5C.
Lets say your nominal should be 1C. then you need 30p roughly. For the maximum rate that you have ie 200A you need 20P to accomodate and have some safety.

I would rather go for 30p to save on the pack than 20p. 100p if you want to utilize the full pack capacity under 200A load Smile I guess that is overkill than having alot of juice over a long time.

Then I start to wonder if the math works out better to just do something like this https://www.imrbatteries.com/sanyo-ncr20...p-battery/

BTW, I did a paypal donation today under my work email, thanks for your help!
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#19
you can charge them at 1c
10amps discharge

capacity was checked at .2c
you will end up getting 1000-1500 mah out of them
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#20
20700 is a different size of cell Smile
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