Battery doesn't fully charge anymore

Funny it is the same vendor I bought mine :sweat_smile: I do not understand then why mine seems not work as it should do. Did you choose the one with bluetooth only? or also PC?

Both, bluetooth and pc. If you really want them at 4.2V charge them seperate with a lithium charge module, like the one in a powerbank. 1529826940372202724487 You can plug them in the balance connector, very easy

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I agree that 41V it’s ok, It’s just wierd that the charger doesn’t try to reach 42V and moreover that if I spin the moto one sec so that the bms will allow the charger to start the cycle I see onyl the same led show up, suggesting that the packs are still unbalanced. I do not know what to think, I just don’t want to open the battery pack for nothing. That’s it. Do you use it for charging only? I see that it is also programmable

I also use it for discharging. Yeah you can adjust a lot of settings, actually everything. IMG-20180616-WA0013 And you can also change the setting via bluetooth in the app so I’m really happy with it. I just like to be able to see every cell voltage, makes everything so much easier :sweat_smile: These are the settings for my Lifepo4 16S pack IMG-20180616-WA0016 I has also 4 temp sensors so you can put one in your battery pack, bms, esc and maybe one close to your motor. But you don’t need to connect them, it’s just for information or you can set a max temp. value for these.


Then I will go for it. If I can program it is the way to go. Thx!

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Hi! I finally found the bravery of open partially the battery so that I can access to the BMS. I then charged the battery al lteh way up and I am waiting the BMS finish to balance two cells (I can see it becasue it has a led light for each cell lead + that turn one when fully charged). Aftercharging I just checked the cells and these one the results 10s battery: |1|4.1| |2|4.1| |3|4.1| |4|4.17| |5|4.1| |6|4.1| |7|4.1| |8|4.13| |9|4.21| |10|4.1|

The cells group are out of balance and indeed the leds are on so seems the BMS is working, but why it allowed to get so unbalanced? I will report back in a while but I was wondering to manually discharge the single cells can I connect a small led to the single led pin (the pin that usually connect to the BMS). If it is possible the + wire goes to the unbalanced cell, but the + one should be connected to the B- pin or the pin form the previous cell group? The reason why I am asking it, is because if I measure with a multimeter placing the - probe to the B- lead and the + probe to let’s say Cell 9 + lead I get the total Voltage (around 37.8V when fully charged). On the other hand if the - probe to the pin of group 8 I get only the voltage of the single 9 cell group. So I am not sure where to place the - of the light bulb, I do not want to give it to much Voltage. Thx! I made this simple circuit for discharge the cell. IMG_20180715_203336

you should seriously consider getting a higher-end BMS and use it to balance discharge. I commute up and down some big hills in LA daily and have never had issues with balance discharging after a year. Best advice to move in this direction would be to see if @barajabali will sell you one of the BMS’s he uses. they’re fantastic and I can’t be sure he doesnt do something special to make them balance discharge at higher amperages.

Yeh, I am in EU so if I can find something locally would be better. I do not know why my BMS allowed the cell to get so unbalanced. @bartroosen12 talked about a BMS with Bluetooth that you can set it for higher overcharge protection, plus monitoring the single cell voltage. I like the idea to be able to check it without open the battery. I check all the connections, nickel strips ecc… everything looks good. really solid. I really think is the BMS :expressionless:

Even if you buy a BMS, I am a firm believer that everyone should also buy a hobby charger. BMSs work pretty well, but never seem to work quite as well as a hobby charger. 1-2 times a year it’s a good idea to balance charge your pack with a hobby charger to make sure everything is well balanced. That is why I build 2s li ion packs and connect them with bullet connectors to make a 12s pack. Much easier to troubleshoot and charge with a hobby charger.

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@kuphjr @onepunchboard @itsmikeholland New results after 1.30h of balancing

1 4.1 4.12
2 4.1 4.12
3 4.1 4.12
4 4.17 4.18
5 4.1 4.12
6 4.1 4.12
7 4.1 4.12
8 4.13 4.1
9 4.21 4.18
10 4.1 4.12
Ore 17 Ore 18.26

Now group 8 it’s better the other still not

I started to discharge some cells. I am doing like that to be able to monitor it IMG_20180715_211944

Huh, I thought problem went away. Good choice manual mode for the win

Maybe the bms had only 5a charging current and the Regen braking provided more which results in cutting out the brakes?

Yeh I will try but since it happens once I am afraid it will happen again after few charges. One of the cell ( cell 8) is lower tha the other may I charge it with this as you said? IMG_20180715_215530

I just need to connect the cell to B+ and B- right?

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The problem was that when battery nearly fully charged in the first 2 km hard brakes result in BMS cut out to prevent overcharge. So I am now using it for charge only

That is only a problem with a >12s battery (50,4v + regen Spikes) With a 10s you should not have the Problem. I still think the bms had too less charging current ability

When I remove the discharge branch than the problem went away. I also have the telemetry data and you see that just before the voltage reached 48V because the BMS cut out and current doesn’t know where to go and it’s read at the VESC level by the HM-10 module. That what I thought

That means if you do not discharge through the bms it works. That means the bms cannot handle the Regen current? It seems like that

ah ok that’s for sure. The overcharged protection starts to low. I am now balancing manually the cell and I will give it another try. Otherwise I will change it. I am sick of opening the battery

Some is discharging and some charhing :laughing: it’s a mess!


@onepunchboard Finally! Now we’ll see for along they will be stable. Thanks for the help :grin:


After one night of final balancing from the BMS

1 4.16
2 4.16
3 4.16
4 4.18
5 4.17
6 4.17
7 4.17
8 4.17
9 4.17
10 4.17

Let’s see for how long it will last this time… Thank you everyone for the help!

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