Lithium battery disconnect thingy

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Lithium battery disconnect thingy

Postby beaujewel » Fri Feb 17, 2017 8:54 am

Hiya folks.
I have a Nissan leaf battery pack that I'm reconfiguring for use in a motorhome at 24v. The pack will have a 300amp fuse on it to feed the inverter but I'd like to reuse the emergency disconnect handle thing (I don't know what its really called) to isolate the pack when I need to work on it.
Any ideas on its current carrying capability? The conductor is 6mm diameter and total path length is around 100mm. According to online calculators it will have a voltage drop of around .2% but I just want to check I'm not doing something stupid...
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Re: Lithium battery disconnect thingy

Postby APR » Fri Feb 17, 2017 10:55 am

beaujewel wrote:?... but I just want to check I'm not doing something stupid...


Data I have found with Google suggests the pack is 24kWh, a nominal 360 volt, with a discharge rate of 90kW.

90kW at 360 volt requires 250 amps current flow, so I would expect the isolator you have would be rated better than 250 amps at a nominal DC 360 volt. 250 amp at 24v is 6kW, which I expect is more than you need in a motorhome.

It appears these cells are not LiFePO4 chemistry, but Lithium Manganese Oxide chemistry. I would want individual cell under and over voltage protection as well as temperature protection to maxamise safety. Is there protection on the cells incorporating various safety features?
2 x Goodwe GW5048D-ES Hybrid inverters, 13kW panels, 20kWh LiFePO4
Mk2 PV Router feeding excess solar generation to a 3.6kW 250 ltr HWS
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Re: Lithium battery disconnect thingy

Postby beaujewel » Fri Feb 17, 2017 11:26 am

Thanks. Monitoring will be in place for over and under voltage. I have a second pack coming of which I will sell half, don't need that much capacity. :)
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