timselectric
If I can do it, you can do it.
- Joined
- Feb 5, 2022
- Messages
- 18,928
There's nothing wrong with stacking extra protection.
As long as you don't mind spending the money.
As long as you don't mind spending the money.
Is this your topo?
If yes, the short as shown would not be interuppted by the class_t fuse.
Code:positive |<->class_t_fuse<->rest_of_system |->dead_short------------------------------>| |<->mrbf_fuse<->breaker<->battery.1<->bms<->| |<->mrbf_fuse<->breaker<->battery.2<->bms<->| rest_of_system<->shunt<->| negative
Agree, and since I don't trust the bms, breaker or MRBF fuse I would put an overcurrent device in that position that I do trust.There's nothing wrong with stacking extra protection.
As long as you don't mind spending the money.
Insulated barrier between the terminals is my first thought.Whip of able from battery "+" to fuse holder mounted to insulating support, out of reach of chassis?
So just a heads up, I personally went to test this on a few batteries. 100% of the time, using the terminals the BMS shut off before the breaker (which makes sense because it's programmed for a slightly lower voltage). Manually bypassing the BMS, we were able to trip the breaker. We also have the breakers as a stand alone product (for replacements etc) and was able to duplicate that on those as well. I'd stand confident behind these breakers at this point.Agree, and since I don't trust the bms, breaker or MRBF fuse I would put an overcurrent device in that position that I do trust.
Since the breaker can serve as a switch I would choose a class-t fuse as its the least expensive option.
If there were no breaker I might choose a breaker with sufficient specs.
If @RichardfromSignatureSolar says that Signature Solar is confident that their breaker can quench a dead short then I would not require the class-t fuse.
@RichardfromSignatureSolarSo just a heads up, I personally went to test this on a few batteries. 100% of the time, using the terminals the BMS shut off before the breaker (which makes sense because it's programmed for a slightly lower voltage). Manually bypassing the BMS, we were able to trip the breaker. We also have the breakers as a stand alone product (for replacements etc) and was able to duplicate that on those as well. I'd stand confident behind these breakers at this point.
AwesomeSo just a heads up, I personally went to test this on a few batteries. 100% of the time, using the terminals the BMS shut off before the breaker (which makes sense because it's programmed for a slightly lower voltage). Manually bypassing the BMS, we were able to trip the breaker. We also have the breakers as a stand alone product (for replacements etc) and was able to duplicate that on those as well. I'd stand confident behind these breakers at this point.
Follow-up, what is the over-current trip amperage and time for the BMS?So just a heads up, I personally went to test this on a few batteries. 100% of the time, using the terminals the BMS shut off before the breaker (which makes sense because it's programmed for a slightly lower voltage). Manually bypassing the BMS, we were able to trip the breaker. We also have the breakers as a stand alone product (for replacements etc) and was able to duplicate that on those as well. I'd stand confident behind these breakers at this point.
So just a heads up, I personally went to test this on a few batteries. 100% of the time, using the terminals the BMS shut off before the breaker (which makes sense because it's programmed for a slightly lower voltage). Manually bypassing the BMS, we were able to trip the breaker. We also have the breakers as a stand alone product (for replacements etc) and was able to duplicate that on those as well. I'd stand confident behind these breakers at this point.
Follow-up, what is the over-current trip amperage and time for the BMS?
Yes, lets be explicit.Did you try a dead short, a "bonded fault" with as short and fat a connection as possible?
To be explicit, by the breaker not the bms.If I wasn't feeling lucky, I would put the largest class-T fuse I could find in series with each cable. After the test, confirm fuses didn't blow and current was interrupted by battery system.
Yes. With the addition of a third battery.[Battery #1 <-> internal 125A breaker] <-> MRBF <-> Busbar
[Battery #2 <-> internal 125A breaker] <-> MRBF <-> Busbar
Busbar <-> Class T fuse
Class T fuse <-> 250A breaker as switch
250A breaker as switch <-> system
@RichardfromSignatureSolar seems I was too charitable.Yes. With the addition of a third battery.
I'm returning the MRBF blocks and fuses. Eating the one I modified to fit the terminals. Ordered (3) 150A Class T kits.
I don't know if need is correct. Other than I need to get on with this build. I don’t think too much criticism can be levied for having a little extra piece of mind with those Class T fuses installed at each battery. I can live with "you probably didn't need those 3 Class T fuses."@RichardfromSignatureSolar seems I was too charitable.
I guess we still need class-t fuses.
If we can't be certain that chint breaker can quench a dead short I say we need to add over-current protection that can.I don't know if need is correct. Other than I need to get on with this build. I don’t think too much criticism can be levied for having a little extra piece of mind with those Class T fuses installed at each battery. I can live with "you probably didn't need those 3 Class T fuses."
I don't know if need is correct. Other than I need to get on with this build. I don’t think too much criticism can be levied for having a little extra piece of mind with those Class T fuses installed at each battery. I can live with "you probably didn't need those 3 Class T fuses."
Without those Class T fuses, you just might be giving someone a piece of your mind.