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Discussion Starter #1
Hi,

I am trying to get back into making a battery pack for my kart chassis which has been sitting around forever. I'm looking at using hardcase LiPo packs and stringing them together. Something like these: https://hobbyking.com/en_us/zippy-5800mah-1s2p-60c-hardcase-pack.html

They have 4mm connectors. What I'm not sure about is how these 4mm connectors can possibly discharge the current the battery is rated for. The battery is rated for 60C, which should be 5.8 * 60 or around 350A. If I use really short strings of cable or busbars with 4mm plugs to connect each pack - would that be ok? I've seen some EV bikes use off the shelf packs like this instead of individual cells.

I have a bunch of these individual cells too: https://hobbyking.com/en_us/turnigy-5000mah-1s-20c-lipoly-single-cell.html , but soldering to the tabs has been hard and they seem a little fragile for me to handle :(

My motor is a ME1003 and draws 200A continuous with 400A burst capability if that helps give context. I'm looking at LiPo for weight savings / density as this is a go-kart.

Thanks,
Aditya
 

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Hi Lost

Those 4mm plugs will be OK - remember that at 60C you will empty the battery in less than a minute

The reason people avoid LiPo is that they do have a habit of blowing up and going on fire
So keep that in mind - and never leave them alone when charging
 

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Discussion Starter #3
Hi,

Whatever I read about these 4mm plugs says they handle around 100A (like here https://hobbyking.com/en_us/hxt-4mm-gold-connector-w-protector-10pcs-set.html). So I was worried. Seems weird that they would spec these connectors when the pack is supposed to be rated at 60C.

I am not going to draw 60C - just figured having a battery rated higher than what I need would make things easier on the battery. I plan to discharge around 200A max most of the time. This kart will run smaller sprints (<1min laps) instead of longer endurance stuff.

Thanks,
Aditya
 

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Hi
Any "rating" has a time linked to it

The motor in my car is rated at 10Kw for one hour - 200 amps and 48 volts

I'm feeding it 1200 amps and 340 volts - but only for a few seconds!

The basic issue is heat build up - a "one hour" rating is essentially "forever" - it will heat up to a stable temperature and stay there

But it takes time to heat up - so you can overload something for a short period and it never reaches the temperature where it will fail
 

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Hi
Any "rating" has a time linked to it

The basic issue is heat build up - a "one hour" rating is essentially "forever" - it will heat up to a stable temperature and stay there
/QUOTE]

Nope. A one hour motor rating in a vehicle means the motor will be just below over heating in the one hour the batteries will last.

That makes the motor rating look much better than it really is. That's why stationary motors are such monsters. They are rated 24/7.
 
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