Ride1Up 700 Series: An upgrade journey

[amberwolf]

because i can't sleep...assumign the pack from this post Ride1Up 700 Series: An upgrade journey then with a 4p pack, 30A / 4 = 7.5A per cell. The chart from the lygte page shows that at 7.5A each cell is going to sag around a third of a volt when full, and around half a volt shortly after that until it gets toward empty. Wouldn't be much less at 25A (6.25A per cell).

My previous runs, at 30A, were to see how my BMS responds and if it’ll trip,

What is it supposed to trip at? If it is supposed to trip at or below 30A, and you're actually drawing that much and it's not, you should investigate why before you end up with cell damage from overdischarge / overcharge / etc, as that could mean your FETs have failed shorted (the most common failure mode) so the BMS can't actually turn off the output.

 

[slaphappygamer]

I don’t know about the BMS. I tried to contact the seller, and of course, they didn’t know. I did contact a seller for this style case, but wasn’t able to find out what the BMS rating is, since they didn’t sell the battery. From looking at other listings for this same case, I see a lot of 25A (with Grade A cells) and some 35A BMS come with them. I’m going off that.

I could open it and check. Maybe that’s what most people do? I didn’t see a fuse door on the battery housing, so must be an internal fuse.

 

[amberwolf]

I would recommend always verifying any battery hardware / safety devices / etc before using it, just to make sure that they're actually there, and that they actually work and have all the advertised functions, and are really built of the parts you paid for / expect, so you know they should be able to do what you bought them for.

For instance, many cheap BMS don't have balancing functions. Some batteries have no fuses (at least one posted here some time back was wired around the fuse from the manufacturer, probably by accident). Some have crappy fuse holders that don't securely hold hte fuse which can lead to overheating of the connection which cna lead to wiring damage or fires. Some BMS may be damaged or nonfunctional, or wired incorrectly so they can't actually protect the cells. Etc.

I expect most things will be what they were sold as...but there isnt' a guarantee for most of them that this will be true, since QC is sadly lacking in many companies.

 

[slaphappygamer]

I’m setting my battery max to 25A. This is sufficient for my area. 30A was also nice, but as voltage gets lower, this 30A might start to tax the cells and I don’t want that.

On my old KT system, I had a 25A controller and that worked well for me. I want my battery to last.

Also, I saw a list, at em3ev, with my cells on there. Seems like good numbers to go by.