I’m running a 12s1p 6000mah 65c bat with the 80 bestech bms that has a max charge rate of 4a. My understanding is that 1c for my batteries would be a charge rate of 6a. Is a 4a 50.4v charger ok?
Yes. Although im interested to know how small your BMS is with a max charge rate of 4A
Damn, didnt know the charging current was so little on the Bestech. Good to know, thanks for the link (:
I think some of the others have a higher charge rate. And for what it’s worth the bestech can do quick charge though i’m a bit hazy on what that really means.
Charging at anything less than the maximum rated is absolutely fine. Just don’t go over either the BMS or battery rating. And make sure you have a fuse in series with your charge port.
1 Like
doesn’t the bestech have a built in fuse?
I don’t know, and I wouldn’t rely on just that. For one, it’s a much bigger pain to replace a fuse on a PCB than to replace one in a fuse holder.
1 Like
Do you have a recommendation for fuse size? I’m guessing an 80a fuse
I also have bot focboxes set at a max for 40a each
No no no no. On the charge port. It’s only going to see a four-amp charger, right? So put like an eight or ten-amp fuse on it.
1 Like
ooooo i see i see. thats jsut for if the charger fails or something? cause the charger im picking up tops out at 4a
Not so much that, but as a general safety thing against shorts. What if some idjit decides to mess with your board while you aren’t looking and shorts the pins in the charge port? Depending on the BMS and wiring, you could end up with a fried BMS or cooked wires, or even a fire. With a fuse, you’d get a small pop, a small spark and you can’t charge until you replace the fuse.
1 Like
also I’m not sure if it means anything but at first I soldered the the - and + backwards and blew a charging brick but I dont see any damage on the bms and the board still turns on fine so im guessing everything is ok
Wow 4a max charge. Doesn’t this mean you will have very weak brakes?
Doesn’t that mean you have very fast no breaks? 
I know that the values in the data sheet are for constant charging, so I assume no issues when breaking for a short period with 8-10a.
But if you for example drive down a longer hill and break for 30sec or longer, wouldn’t the bms cut off which would lead to a total loss of the brakes?
Yup you should test the brakes with that bms. I think it will cut off under hard braking
But than I don’t understand why an esk8 shop sell this configuration
I mean it even doesn’t make a sense to wire it up for charge only. Ok it makes sense but is too big and too expensive to compair to a d140 for example.
1 Like
Could it be a typo? Can’t understand it either why a eskate shop would sell it… I have a HCX-D223V1 aswell but with 20a max charge.
I’m sure it’s a typo because when looking at Bestech site it states 20A max. cont. charge and it’s not an adjustable value so don’t worry. Or is this a special version @JLabs?
The regenerative breaking with BMS is one thing which confuses me from day 1. If the BMS has different ports (P- for discharge, C- for charge) I think the max charging current doesn’t matter for regenerative breaking because the current flow goes back to P- and not C- anyway.
On a BMS with discharge and charge on same port the value for discharge and charge are the same. There are just more FETs on the C- trace (same amount as on P-) and discharge plus charge are connected to C-. There are also BMS available where all is connected to P-. Very confusing for beginner.
I have 5 BMS and all with same port because of my paranoia about a cut off due to breaking. But I’ve heard and read from experienced members that their BMS with different ports never shut off due to hard breaking so I guess it makes no difference. Would be interesting to hear the opinion from an electrical engineer about this case.
4 Likes