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I am interesting what is the working curve for this fuse and when will be reacting with what amperage and after what time. I saw same youtube test which shows that can hold more then 200Amps which is a bit scary unless this is time delaying breaker, anyone knows or victron can add something ?
Trying to protect my 300Ah batteries with this one and potential more then 200amp can hurt my inverter in such a case.
Best
Kris
Here is a datasheet for Littlefuse mega fuses.
The fuse is there primarily to stop the wire or equipment or battery from overheating and catching fire from short circuit not the prevention of damage to the equipment and the fuse rating is matched to the wire size and/or equipment rating. If your inverter is drawing 200A then there is something seriously wrong with it and it needs the current shut down. It is hard to force more current into the inverter without some means of failure.
Youtube is littered with people who do not understand what fuses are or how they work.
Have a read of Victron's document, wiring unlimited.
Should also have asked what batteries, fuses have something called ampere interrupting capacity, i.e. what current can they break, mega fuses can break a short circuit of 2000A, if the short circuit is above 2000A the fuse vaporises and condenses inside the fuse body and can still conduct current. For lithium batteries the recommendation is that maga fuses are not good enough and you need fuses with a very high AIC such as MRBF, Class T or NH. Check what your battery short circuit current is and make sure the fuse AIC is higher than this. If the battery resistance is quoted then calculate the short circuit current from voltage. If voltage = 14V and the battery resistance is 1 milli ohm then the short circuit current is 14 / 0.001 = 14,000 Amps
Thank you for your reply..
I have lifep04 batteries 304Ah https://batteryfinds.com/wp-content/uploads/2021/09/EVE-304Ah-LiFePO4LFP-Battery-Cell-Product-Specification.pdf, connected in 16s protected with bms 150A and my inverter is not drawing more then 100A , the wire size is 32mm2, sorry for wrongly expressing myself.
However true I have little knowledge about the DC breakers, Hance looking for help here at the community support.
So if I understand correctly my 16s set x 0.28m ohm = 4.48mohm
The battery short current would be 54 V / 0.0048 = 11250 Amps, which as you said Mega fuse would be not enough. Could you help me then to find correct DC breaker I understand it has to be non polarised as sometimes the battery is a load and sometimes inverted is the load depending on charging and discharge process. Is that correct?
Thank you for your help.
I do not know about DC breakers, for a nominal 48V 300Ah lithium.battery you would use class T fuses or NH fuses or equivalent. It will also depend on the regulations of the country you are based in. I suggest you get local electrical installer support.
