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30Ah 28s LiPo from 7s bricks

Posted: Dec 15 2018 3:33pm
by nuxland
Everybody have suggested that I should use lipo-s in my kart. So now I have made a plan to build this battery.
And actually there is multiple goals to achieve when building this.
1. It should be lighter than my current ones.
2. I want to use this for my two controller+motor 1/4 mile test insted of two lifepo4 packs.
3. Not needing to cool pack between races

Right now plan is to get 24pcs of Turnigy Heavy Duty 5Ah 7s 60C bricks. And use them in configuration 4s6p, so total of 30Ah and 28s. I think these will provide me average 200A in 8 minutes with max 640A easy. And also like 1300A for 10 seconds when using two motors.
Bought one for testing and measurements, its 50mm x 60mm wide and 160mm height with wires. I would prefer that it had 8AWG wires instead of 10AWG ones. Case would be made of 3mm hobby plane plywood so that it has 24 slots for bricks 4 in width and 6 in length. And there will be additional 50mm in the side for wires and bms and fuse and dc/dc and olimex with lcd.
So total size will be like 268mm width and 381mm length and 180mm in height.
Weight will be like this, this is my estimate.
1. 24 bricks 0,91kg a pcs will be 21,84kg
2. harnesses with 20cm 8AWG cable to each brick and xt90 and crimps and lugs will be around 2,37kg
3. two anderson 350 (one for each controller) will be 0,5kg
4. 3pcs of zeva bms + olimex + fuse + lcd + dc/dc is aprox 0,7kg
5. balance cable harnesses around 0,5kg
6. plywood will be around 3kg
so together around 28,91kg, lets round it to 30kg :) YES it will be lighter than my 25Ah lifepo4 pack that is 37kg.

will add more info and drawings when they are ready.

Re: 30Ah 28s LiPo from 7s bricks

Posted: Dec 15 2018 5:58pm
by Upperfoot
I definitely think LiPO is the best route for you for Power / Weight ratio

I know 10AWG can handle 100 amps continuously at 1 foot in length (Courtesy of Doctorbass)



And 150 amps for the XT90's !



What setup are you going for? Two Gen 4 Size 6's in Master/Slave and two Zero 75-7 motors? Your becoming a speed fiend!

Re: 30Ah 28s LiPo from 7s bricks

Posted: Dec 16 2018 7:11am
by jonescg
Happy to help if you want some screw terminations and busbars etc :)
Too many XT90s makes me shudder.

Re: 30Ah 28s LiPo from 7s bricks

Posted: Dec 20 2018 5:34am
by nuxland
Made a mock-up from cardboard to see how all the stuff will fit :)
There will be two 350A anderson just for two motor setup :twisted:
In regular races I will use only the back one (the one where there is also charger port).
Idea is that if I need to change one brick, then this can be done easily, just disconnect it and slide out :D
Top and side will be covered with plexiglass.

Re: 30Ah 28s LiPo from 7s bricks

Posted: Apr 15 2019 7:27am
by nuxland
Increased from 30Ah to 35Ah. So 28 Bricks together. Got aluminium and plywood water and laser cut.
In the process of threading aluminium and then starting to add bms and fuse and other stuff.
One brick is about 890g so 28pcs will be 27,44kg. I think it will be about the same weight as my A123 25Ah pack ~37kg.

Re: 30Ah 28s LiPo from 7s bricks

Posted: Apr 15 2019 8:03am
by Upperfoot
Nice one Nux! Can't wait to see your results, I bet you won't even notice the voltage drop when you put your foot down with this new pack!

Re: 30Ah 28s LiPo from 7s bricks

Posted: Aug 13 2019 10:30pm
by Bmr4life
Any more pics of progress?

Re: 30Ah 28s LiPo from 7s bricks

Posted: Aug 18 2019 1:53pm
by nuxland
Have not done anything from june, because have had zero time :(
But made balance wires for all the packs and started to do main outputs in may.