T class fuses enough?

[darius7575]

Currently have 2, 48v 100ah batteries with 150 amp mrbfs at the terminals connected to a 300 amp busbar, connected to an eg4 3000 ehv. When I add more 100ah batteries i know I will need to add t class fuses on all batteries. When that happens, can I remove the mrbfs entirely? Or if I just add the t classes but don't add another mrbf at each additional battery am I creating a problem for myself?

 

[SparkyJJO]

I see no point in keeping MRBF along with the class T.

 

[robbob2112]

The MRBF at 48v doesn't have but around 2000a AIC rating - so it won't really break an arc for you... Most 48v batteries come with breakers built in, but if they don't I would put a class T on each battery as close as possible and loose the MRBF fuses.

 

[SparkyJJO]

The MRBF at 48v doesn't have but around 2000a AIC rating - so it won't really break an arc for you... Most 48v batteries come with breakers built in, but if they don't I would put a class T on each battery as close as possible and loose the MRBF fuses.

Most of those built in breakers have a low short circuit rating as well. Those miniature circuit breakers just don't have the capability of breaking a high amp arc.

 

[ScrodusGargleRotten]

The MRBF at 48v doesn't have but around 2000a AIC rating - so it won't really break an arc for you... Most 48v batteries come with breakers built in, but if they don't I would put a class T on each battery as close as possible and loose the MRBF fuses.

We need to collect and crowd fund a junk battery bank for you to test.
We need to. It's for science

 

[Dagoth Ur Does Solar]

Most of those built in breakers have a low short circuit rating as well. Those miniature circuit breakers just don't have the capability of breaking a high amp arc.

That's something I constantly think about with those server rack batteries, I too assume those breakers are probably woefully incapable of actually stopping an arc from a major internal failure.

I even wonder if it's creating a false sense of security for users? How many of these users have 5+ of these 48V 100Ah rack batteries stacked up in parallel with no Class T fuses anywhere, assuming the breakers will do the job?

At a bare minimum when I build my DIY battery and my 48V system, I'm gonna use Class Ts right off each battery.

Would be really cool if they started making these server rack batteries with like, an internal Class T fuse holder in the chassis or something. Could charge a premium for it and I bet there's people here that would buy it.

 

[robbob2112]

We need to collect and crowd fund a junk battery bank for you to test.
We need to. It's for science

Actually I have 8 damaged 314ah cells I plan to assemble and use for testing -- it isn't 48v, but should be interesting for some short circuit testing of fuses... Oscope and current probes to watch the spikes and time things...

I've seen some of the cases and kit batteries that come with an internal class T ...

And for any I build I use a DC breaker and a class T per battery...

 

[ScrodusGargleRotten]

Actually I have 8 damaged 314ah cells I plan to assemble and use for testing -- it isn't 48v, but should be interesting for some short circuit testing of fuses... Oscope and current probes to watch the spikes and time things...

I've seen some of the cases and kit batteries that come with an internal class T ...

And for any I build I use a DC breaker and a class T per battery...

Ok, we will get you 8 more