[jr dragster]

Where going to put lithium in the first electric jr dragster in CANADA, over the winter.We are running agms 6x12=72,where starting the race with 78 volts at the end of the run we have 75 volts left in the pack, we
can make two runs with them till the 1/8 mile times drop off.Do you guys have any suggestions for us?? 72 volts would like to pull 450 amps if possible.Need to keep the weight< under 80 pounds> price under <2,500> may go to 3,000.And need to charge in 10 to 15 minutes. must have bms . Any suggestions ???????????

[jr dragster]

Found 72 volt kit at elite power solutions, gbs 40 ah 3.1 kw with bms and charger for $2,424.00 . 88.2 pounds it says on the site.Any one try one of these ??

[major]

Originally Posted by jr dragster

Found 72 volt kit at elite power solutions, gbs 40 ah 3.1 kw with bms and charger for $2,424.00 . 88.2 pounds it says on the site.Any one try one of these ??

Hey jr dr,

Be careful. 450 A is over 11C rate on a 40 Ah cell. Some types of cells will support that high rate, others will not. I've not used GBS, but do not think they would be a good choice for high rate discharge.

I'm not sure where the number 3.1 kw comes from. Are you mixing power and energy? But from your post #1, you should be looking for 30 kW.

Regards,

major

This is for a Jr Dragster. Doubtful you can stuff in a 30kw pack. He is talking pack size. My MG pack size was a nominal 12Kw pack. 120 volts of 100 AH cells. I'd go with at least 100 AH size cells because of the power factor needs or go with the smaller LiPO pouch size cells that will need a BMS and will allow high discharge and should recharge up in no time flat if you have a fast charger.


Ultra-Power Lithium Polymer Cell
P68100120F-50C
Capacity: 6AH
Nominal Voltage: 3.7V

$29.99 each

20 cells = 72 volts = $600
Need 20 AH pack
4 packs will equal a 24 AH pack for $2400

At 50C and 4 cells in parallel that would give you 1200 amps. More than enough for your needs.

Bottom balance them and don't charge them to full. Be careful of thermal issues. Maybe hook up a thermal cut off switch or a few of them around the pack. Bottom balancing will be a must at the track. No matter what lithium cell you decide to go with.

[major]

Originally Posted by gottdi

This is for a Jr Dragster. Doubtful you can stuff in a 30kw pack. He is talking pack size. My MG pack size was a nominal 12Kw pack. 120 volts of 100 AH cells.

gottdi,

Do you know the difference between Power (kW) and Energy (kWh)?

Back in post #1 he says he wants 450A from a 72V pack. That is ballpark 30 kW (~40 hp) electrical from the battery. That is power. Obviously for a jr dragster which runs 1/8th mile races, large amounts of energy (kWh) are not required.

Regards,

major

I know what he said. I took it as pack size not power. 30kw of power should be pretty easy to get with lithiums. Many of the cells can do quite high C rates. Being a race car I suspect that longevity is not as big an issue as is power out. I think 86.4kw is more than enough with what I proposed. That will still keep the cells well within the abilities of the cells and the cells will still live a good long life even with hard driving. If all you need is 30kw or 40kw of power then it would work just fine.

My proposal is just one option.

Pete