Cells must be within X volts of each other to safely parallel them

[kolek]

Someone please fill in the X.
You don't take a totally empty cell and put it in parallel with a full cell, right?
Read somewhere on the forum they must be within a certain voltage, like 0.01V or 0.1V or something like that, but can't remember what the number was. Assuming standard 280AH cells.

 

[sunshine_eggo]

Andy of off-grid garage put a full cell in parallel with an empty cell (about 0.6V), and he saw notably high current that tapered very quickly to something within specification, and he could influence it greatly by how tight he made the fastener.

I wouldn't be concerned by anything 0.2V or smaller

.

 

[timselectric]

0.05v difference is pretty uneventful.
I have actually connected a low (48v) battery in parallel with 4 full (56v) batteries.
I don't recommend it. lol

 

[kolek]

Andy of off-grid garage put a full cell in parallel with an empty cell (about 0.6V), and he saw notably high current that tapered very quickly to something within specification, and he could influence it greatly by how tight he made the fastener.

I wouldn't be concerned by anything 0.2V or smaller

.

@sunshine_eggo Is that you with the waffle in your profile picture, or just some dude? Whoever it is just has such a high level of positivity and enthusiasm. Sorry but I've always been curious.

 

[sunshine_eggo]

@sunshine_eggo Is that you with the waffle in your profile picture, or just some dude? Whoever it is just has such a high level of positivity and enthusiasm. Sorry but I've always been curious.

LOL... no... it's just some dude... I'm not known for my positivity or enthusiasm... at least not like the kind on that guy's face... Maybe I should aspire to be like him...

 

[kolek]

LOL... no... it's just some dude... I'm not known for my positivity or enthusiasm... at least not like the kind on that guy's face... Maybe I should aspire to be like him...

I see. It's good tho. You've inspired me. I need to work on getting an enthusiastic profile picture. This is the joy I feel after spending 12 million hours on my DIY battery.