dewalt charger error but pack seem ok

[jc.maquet]

hello
I have replaced a cell in my 36v a123 pack. the BMS seem to work, I can drain 9A on bms protected output (with the voltage divider schematics connected)
when I put in the charger, the 3 led start bling after few second !
all cell voltage are about 3.3v...
the charger work ok with another pack
what is the problem ?

 

[Doctorbass]

hello
I have replaced a cell in my 36v a123 pack. the BMS seem to work, I can drain 9A on bms protected output (with the voltage divider schematics connected)
when I put in the charger, the 3 led start bling after few second !
all cell voltage are about 3.3v...
the charger work ok with another pack
what is the problem ?

The problem is your BMS.

The only way the BMS flash 3 led is:

- when one or more cells are lower than 2.5V threshold
-The BMs is deffective ( sometime caused by not respected wire connection sequence!)

If you need to reconnect a Dewalt BMS, YOU MUST connect first the negative, positive and Bms ground case little wire BEFORE to connect the Balancing connectors! Otherwise you will blow it.

PM me, I have many of them working and tested.

Doc

 

[jc.maquet]

bonjour doc
I'm pretty sure that I have respected the sequence
I have unpack the box, then I have removed de 2 side support and fixed it with a tape away from cell
then I have replaced the cell. ( I have solder the new cell with a standart Iron quicky)
then connected again the 2 side support with bms contact
did you see it before a bms working for discharge and given an error for charging ?
merci pour les info

jc

 

[Doctorbass]

bonjour doc
I'm pretty sure that I have respected the sequence
I have unpack the box, then I have removed de 2 side support and fixed it with a tape away from cell
then I have replaced the cell. ( I have solder the new cell with a standart Iron quicky)
then connected again the 2 side support with bms contact
did you see it before a bms working for discharge and given an error for charging ?
merci pour les info

jc

Salut Jc,

Parlons un peu français pour faire changement

Je vais t'avouer que non, je na'ai pas eu l'occasion de voir un BMS qui fonctionne en decharge et qui refuse de fonctionner en charge!

Mais je suis certain a 99% que ce soit le BMS et 1% que ce soit le chargeur.

As tu d'autre Batteries dont tu pourrais enlever le BMS et l'essayer avec celle qui marche pas en charge?

Doc
:wink:

 

[jc.maquet]

salut

tu avais raison, c'etait bien le BMS.
j'ai raccordé chaque cellule en parralleles sur les 2 batteries (en conservant les 2 bms)
j'ai toujours un bms qui recharge et l'autre pas.
je vais laisser cela comme ca, c'etait quand meme le but de mettre les batteries en parrallele et maintenant c'est meme plus equilibré.

merci

you right, the issue was the BMS
now all cell is linked to the other cell in second pack (keeping 2 BMS)
one BMS still fail for charging
as the aim was to put battery in //, I will leave it like this
bye

thanks