Bus bar

[robbob2112]

Actually I have 4 MRBF fuse holders, 1 for each battery. There is more surface for the fuse holder on the bus bar, therefor lower resistance connection. Prior to this forum I have never heard of mounting the fuse directly to the battery. Also haven't see it in 50 years of working with dc voltages. That doesn't mean it might not be a better way. The Bluesea 6006 switch is mounted directly to the bus which reduces connections and possible failure points. While maybe not the best the fuse holder, another MRBF, is connected to the switch protecting the down stream wiring to the inverter. Also kinda limits the ac output of the inverter to 30A. The ac side of the inverter will be hooked to a 30A breaker also.

The 4 MRBF should be mounted to the bus bars in your case if you have 4 batteries in parallel. This prevents melting the cable to 1 battery if you manage to drop a wrench across the posts there the BMS will hopefully shut it down. The other 3 will feed current through the bar down the cable to the shorted battery and melt the wire because it gets 6 times the current you size it for. A fuse at the bus bar would blow and that wire is safe.

Time to melt the insulation off the wire is 0.01 to 0.1 seconds when given that much current. Time to melt the wrench is 1.5 seconds. If you fuse directly at the battery the other 3 batteries don't care if the fuse blew on the shorted battery.

NOTE - Fuse curves for MRBF and Class T are basically the same when it comes to time to blow, 0.01 to 0.1 seconds. Mega is 0.5 to 1.5 seconds. ANL is 1 to 5 seconds. Choose wisely.

 

[robbob2112]

I've seen large system fuses commonly close to the battery. Then everything else feeds off that.

Golf cart conversions always show the fuse at the battery.

I prefer as close as possible.

Typically golf carts are using lead acid batteries. As close as possible is correct in that instance. If using a battery with a BMS inside to shut down current a fuse at the other end of the wire is a better choice.

 

[Detritalgeo]

I have just bought an Aolithium server rack battery an need cables, they're out of stock. what are the battery connector ends called?

FSP connectors from Futronics. part number: FSP800160TZ-25U1A1K 2384

125A rated, up to 25 mm2 cable (~3 AWG)

Something like this... https://www.metabee.com/waterproof-...mm2-unshielded-cable-z-key-id20220600044.html

 

[Bigrr63]

Thank you, appreciate the help

 

[Zwy]

Typically golf carts are using lead acid batteries. As close as possible is correct in that instance. If using a battery with a BMS inside to shut down current a fuse at the other end of the wire is a better choice.

For over current protection, the fuse can be mounted anywhere in the circuit, the amperage is the same anywhere in the circuit.

For short circuit protection, close to the battery is of course preferred.

Golf carts today are moving towards LFP, at least for those of us modifying golf carts for power, longer battery lifespan and longer run time.