Received new BMS today and installed it then went to charge and still had a green light indicating a full charge(which its not). I am now in the market for a good reliable charger, 48v 13s with 3 prong male barrel connector and American style wall socket. Preferably something in the U.S. so I don't have to wait 2-4 weeks for delivery. One more question, do I need a balancer/ charger or will the BMS do the balancing?
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My batt up and died. Took it apart and found a tidbit of plastic wrap in the power switch. Lucky it has holes in it so I could see before i jumped it out.Comment
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Bought a Luna 48v advanced charger, Did a hard reset on the BMS and got that working again. All batts were within 0.05mah of each other, my battery gauge on throttle showed full power and yet it is still cutting out. Could the controller be causing this?
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I think you mean they were withing 0.05 millivolts of each other, right?Originally posted by Schrockie71 View Post
If so, great, it's balanced. But is it also charged up? You didn't mention the pack voltage. Could just be low?
Guys, when asking about battery issues, PLEASE tell us the pack voltage. It gets tiring asking all the time.
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53.9v + on the pack.Comment
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Cool, charged and balanced, then, thanks. So, I think it's likely your cutouts at higher loads will stop, or be less frequent, anyway. Sag affects the weakest group, and is dependent upon charge level, too. You brought up the weak groups, so will have a bit more reserve voltage for high power pulls, now. But as noted, that looks like a high resistance pack design, so sag at high currents will tend to be an issue. More connection resistance, more sag, more cutouts at higher charge levels, compared to a pack with low resistance current paths.
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What is an expected amount of sag from a battery like this? I have a similar battery, 13S 9P, and when I go to full load (20A) my voltage meter drops from 52V to 43V. I still get good power and range, but I think that is way too much drop?Comment
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Well, that's a lot. Look how close you get to LVC with a nearly full pack. At 40A my pack drops maybe 6-7V if it's full and cold, hard to say since I just know peak current and minimum voltage, but something like that. At 20A it's just a few volts. There is no right or wrong, no 'proper sag' but the more you have, the earlier you hit LVC, so the less power you can use and still drain the pack low.
For a given pack the sag will vary mostly with current, and temperature of the cells. More current, colder, both mean more sag. And it increases with age.
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