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I'm trying to select an output breaker voltage for my 150/70-Tr MPPT. I know I should use a 150vdc breaker on the input (PV) side. However, I'm unclear about the voltage requirements on the output (battery) side. My battery is a 12V LifePO4. Does this mean a 0-48Vdc breaker will be sufficient, or should I use a breaker rated for 150vdc? I'm not clear if a failure could deliver PV voltage directly to the battery. That seems pretty unlikely to me, but I just wanted to confirm. Thanks.
Hi @Createthis
indeed, on the battery side your breaker (or fuse) should be rated for your (maximum) battery voltage, thus a 32VDC breaker or fuse is more than enough for a 12V system.
Hi Createthis ! Onthe PV side, I'll suggest you to use a 1000VDC / 16/32A breaker per input.
Regarding the breaker on the battery bank, usually if you load the batteries during extended periods, the breaker will heat and disconnect the load. My setup is running a 120VDC / 125A breaker. I'll suggest you using at least a 120VDC / 80A or 100A.
These breakers tend to heat with the power passing through them and disconnect in some occasions.
These pictures were taking during the modification / installation of the new breakers.
Michel
Why do you recommend a 1000vdc breaker when the max voltage for this charge controller is 150vdc?
Also, why 120vdc on the battery side? Your charge controller accepts 150vdc on the PV side. Your charge controller only accepts up to a 48vdc battery. Why not use a 48vdc breaker on the battery side?
Can you tell me where you got (and maybe provide a link to) the breaker enclosure in your picture?
Hi TexasCharlie, it comes from Aliexpress. The reseller is very serious, in Europe it is almost impossible to find such kind of breakers at a "correct" price !
https://www.aliexpress.com/store/4046040?spm=a2g0o.store_home.1000001.12.31055375D0EzkQ
I hope it helps.
Michel
