BMS Paranoia

[mcart117]

Why keep a $100 bms spare when you can have an extra $1500 battery !!!

I do actually have four spare LFP cells, which for me is half a battery. So I think it makes sense to have a spare BMS as well.

 

[mcart117]

BMS who fail and caused the battery to catch in fire, yes
I don't trust BMS's.

I'm not sure I do either.

When the battery is full and over voltage protection kicks in, it seems like a very flimsy device holding back a lot of current.

I have manual isolator switches, and if I am home I switch off one array as the battery approaches full charge and the second array when it gets there.

 

[mcart117]

It probably also helps that I oversize my BMS's. Do I NEED a 150a BMS for a 1kw inverter? No, but it's pretty much the same cost and I don't work the circutry too hard.

Good strategy.

 

[time2roll]

Does anyone else lie awake at night worrying about whether their BMS is going to fail?

And if so, do you always keep a spare on hand – just in case!

I have two batteries and could easily make do with one. Does that count as a spare?

 

[mcart117]

Same here for everything.
Nothing will ever be worked hard.

Should probably be the subject of another thread, but your reply makes me think of charge controllers. Should they be oversized to handle noon sunlight and have redundant capacity morning and evening, or made to fit the softer sun and just burst at the seems for a couple of hours midday?

 

[Rednecktek]

Should probably be the subject of another thread, but your reply makes me think of charge controllers. Should they be oversized to handle noon sunlight and have redundant capacity morning and evening, or made to fit the softer sun and just burst at the seems for a couple of hours midday?

More Power! No sense clipping any watts you don't have to.

 

[mcart117]

I have two batteries and could easily make do with one. Does that count as a spare?

I started out with one and really enjoy the luxury of having two, so I don't want either to fail or have to switched off while I wait weeks for a replacement BMS.

 

[mcart117]

More Power! No sense clipping any watts you don't have to.

Yes, I think you are probably right

 

[sunshine_eggo]

I can't afford a spare Batrium, but I do have a spare JBD in case the Batrium goes tits up.

 

[timselectric]

Should probably be the subject of another thread, but your reply makes me think of charge controllers. Should they be oversized to handle noon sunlight and have redundant capacity morning and evening, or made to fit the softer sun and just burst at the seems for a couple of hours midday?

Overpaneling is a way to get more for less cost.
Oversizing is the way to get everything including longevity. But at a higher expense.

 

[Rednecktek]

Overpaneling is also a way to deal with krappy weather too.

 

[time2roll]

I started out with one and really enjoy the luxury of having two, so I don't want either to fail or have to switched off while I wait weeks for a replacement BMS.

One = necessity
Two = redundancy
Three = luxury

Almost there May as well order the cells to go with the spare BMS...