Fusing my DIY battery but I can't answer my own Questions

[jdfrye]

My problems I cant get sleep over...
1: I have an on board Onan 4k generator that will pull a little over 200amps when starting up
2: I have limited space to add a fuse

Questions:
1: Will a 200a class T fuse be fine with a short surge or should I go 300a?
2: Can I cover the class t fuse with heat shrink like the picture below so I can fit it beside the battery without mounting the big honkin holder?

 

[sunshine_eggo]

You size wires in accordance with the maximum continuous current. You fuse in accordance with max continuous current. Slow blow fuses are designed to handle the brief surges associated with motors.

Class T fuses are designed to work best in a fuse holder. Shrink wrap like that will cause the fuse to blow early.

 

[Rocketman]

Go look at the spec sheet on the class T fuse you are thinking about.

The one I used had the spec’s when it blew. Also, get a clamp meter and see what the generator really needs for startup power and surge. It may be less than 200 amps (just a guess).

 

[jdfrye]

Slow blow fuses are designed to handle the brief surges associated with motors.

So I'm thinking I should go with an ANL fuse. Is that a slow blowing fuse?

 

[jdfrye]

Also, get a clamp meter and see what the generator really needs for startup power and surge. It may be less than 200 amps (just a guess).

Damn! All these new tools I'm buying..lol. hopefully I can use them again. I'll go this afternoon and get one and give you a boots on the ground report. Thanks!

 

[mikefitz]

Use a MRBF fuse, value suitable for the cable used and holder from Blue sea. Unless the clamp meter has a max value detect and hold it may not record the true surge current.
Any fault current should shut down the BMS so any fuse is a fail safe. The current interrupt rating of a MRBF is 10k amps at 12 volts.

Mikr

 

[Zil]

Do not use the ANL fuse.

 

[Zil]

The specification on 200A Class-T from Blue Sea shows the fuse will hold for almost a minute at 400A. Will that cover your inrush?

 

[jdfrye]

Use a MRBF fuse, value suitable for the cable used and holder from Blue sea. Unless the clamp meter has a max value detect and hold it may not record the true surge current.
Any fault current should shut down the BMS so any fuse is a fail safe. The current interrupt rating of a MRBF is 10k amps at 12 volts.

Mikr

I'll measure to see if I have enough head room to install one of those. I may have to move the plexiglass a little higher. I like that idea.

 

[jdfrye]

The specification on 200A Class-T from Blue Sea shows the fuse will hold for almost a minute at 400A. Will that cover your inrush?

Yes I'm sure it will.
I looked at the price of the amp meters.. They are expensive for me doing one test. Maybe my victron smart shut will capture the surge spike? Also like the MRBF fuse if I have room to install it.

 

[Bvillebob]

I'm doing exactly what you suggested, except I left the middle a bit more exposed, not that it matters much I suppose. My fuses are 100 amp Class T, handling 70 amp loads just fine, I have 4 of them set up like that operating.

 

[jdfrye]

I'm doing exactly what you suggested, except I left the middle a bit more exposed, not that it matters much I suppose. My fuses are 100 amp Class T, handling 70 amp loads just fine, I have 4 of them set up like that operating.

good to know. thanks for speaking up

 

[jdfrye]

Using my Victron shunt looks like after starting it 2 times i get close to a 133amp draw. not sure if it would catch a surge of a mili second (like i seen on my xiaoxiang app for a split second) but for what it worth thought I would post what I got. I cant see spending $150 for a amp meter. Guess now I'll do some online shopping for Class T or MRBF fuses @ 200 amp