80A BMS for 75 A battery

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gdinim   1 mW

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80A BMS for 75 A battery

Post by gdinim » Oct 07 2018 11:40pm

I am building a 36V 10S 75Ah battery, I have not succeeded in sourcing a 36V 10s 75 A BMS, can I safely use a 36V 10S 80A BMS with an 80A over current protection

http://www.batterysupports.com/36v-37v- ... p-389.html

Joachim   1 kW

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Re: 80A BMS for 75 A battery

Post by Joachim » Oct 08 2018 2:18am

How many cells in total? and the brand/type cells?

Punx0r   100 GW

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Re: 80A BMS for 75 A battery

Post by Punx0r » Oct 08 2018 3:15am

I think you're mixing up A (power) and Ah (capacity).

What load is this battery going to power? This will determine how many Amps your BMS needs to be rated for.

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flippy   1 MW

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Re: 80A BMS for 75 A battery

Post by flippy » Oct 08 2018 6:39am

the bms needs to be rated for the limits of the battery, not it's application.
Lithium beats liquid dinosaurs.

gdinim   1 mW

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Re: 80A BMS for 75 A battery

Post by gdinim » Oct 08 2018 10:52am

the cells are Samsung 25R the battery is 10s 30p for 75Ah powering two 20A controller for 2 500w geared motors

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fechter   100 GW

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Re: 80A BMS for 75 A battery

Post by fechter » Oct 08 2018 1:13pm

The BMS should be rated for something above the intended load. In your case, it looks like 40A. It's good to have a little more so the peaks don't cause the BMS to trip. I'd look for a 50A or more.

The BMS normally does not limit the current. It acts like a circuit breaker if the current goes too high and cuts off. The controller limits the current, so you just want the BMS to handle that much.

The capacity of the battery is very large, so you will have no problems with the cells overheating. Most Li-ion cells can handle at least 2C discharge, so your pack could do as much as 150A if you wanted. This would be the most your BMS should be rated. You want it to trip if the load gets high enough to damage the cells.
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flat tire   1 MW

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Re: 80A BMS for 75 A battery

Post by flat tire » Oct 08 2018 1:36pm

That is a gigantic battery that could out hundreds of amps without hesitation. No problem with a 80a BMS.

The 80a means current output, not storage capacity which is the current a battery can put out for an hour before being depleted (amp hours). The entire purpose of a BMS is to protect the battery so you don't want to use one that can let your battery try to supply or receive more current than is healthy.

999zip999   100 GW

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Re: 80A BMS for 75 A battery

Post by 999zip999 » Oct 09 2018 10:35am

300 cells ? Is this a two wheel drive nature bike.

gdinim   1 mW

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Re: 80A BMS for 75 A battery

Post by gdinim » Oct 09 2018 2:36pm

I live in a rural area on Cortes Island short steep hills, I am making myself an electric bike with a long side car, all one piece.
Motors on front and rear wheels of the bike. I will be able to carry a passenger or a load of seaweed for the garden or firewood

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