Conect dewalt packs balanc wire under discharge extend life?

[jk1]

Guys on the problem of out of balance and also that its always the battery connected to the ground terminal and maybe near the fusible link that goes dead, would it be possible to connect the dewalt balancing connectors in parallel during discharge to stop this problem in unmodified dewlat packs of 4 in parallel ? Also is it possible to maybe swap the connections so that say the + and - of the lowest battery in the chain ie the one connected to the ground terminal is connected to the highest one say connected to the positive terminal to cancel out the effect that its always the negative most battery that dies 1st. would this work ? and would the dewalt BMS handle it ?

I know people on these forums have connected dewalts packs in parallels of 4-5 packs for charging with no problems. I am wondering if leaving this balancing connected during discharge may solve this balancing issue or make it a lot better and hence longer battery life with untouched dewalt packs (APART FROM WIRING THE BALANCING WIRES TOGETHER, MAYBE THESE WIRES WOULD HAVE TO BE THICK to handle this balancing??)

I had a bad battery in my pack already and it seems the BMS cuts off if any cell if less than 2.5v this LVC was working well in my case. My theory on drained damaged packs is that maybe its because the batteries are left on the tools for too long without use, say 6 months and the very small drain of having a tool plugged on slowly kills the packs lowest battery in voltage chain 1st ?..so its better to unplug them completely if not in use, what do u guys think ?

 

[jk1]

Does anyone think its possible to parallel the dewalt battery pack balancing wires on discharge ? i know it has been done on charging.

Could this extend the life of the packs as their would be no sudden drop off of any one cell as it has an accompyaning cell that would also have to drop at the same time , so in essence it will average and slow the drop to the 2.5v cuttoff?

 

[mn_aerorider1]

Does anyone think its possible to parallel the dewalt battery pack balancing wires on discharge ? i know it has been done on charging.

Could this extend the life of the packs as their would be no sudden drop off of any one cell as it has an accompyaning cell that would also have to drop at the same time , so in essence it will average and slow the drop to the 2.5v cuttoff?

Various people here in the forum have been doing this paralleling of Dewalt packs during discharge for a while. Search Dewalt packs on this forum. I have been running 3 Dewalt Packs in parallel in two sets for a 20s3p pack. They are tied together in parallel permanently via the balancing wires using some 5 pin connectors (I bought in bulk) that match the Dewalt Pack balancing connector plug-ins (if anyone wants to buy some balancing connectors cheap - I have a bunch of these connectors left - just PM me) . Each individual cell carries 1/3rd of the load current, and the cells self-balance as they discharge. There is no problem with currents between parallel cells being too large for the thin balancing wires.

Brian

 

[mn_aerorider1]

I should also point out that by paralleling cells, the individual cells should last longer because the individual cell charging and discharging current is reduced in proportion to the number of cells put in parallel. If you look at the LiFePO4 specifications (for example the A123 specs), they can handle more discharges if the charging and discharging current is lower.

However even if the cells were not cross-linked, the discharge current would still be shared between individual packs, until one of the individual packs goes off-line, i.e. below cutoff. (This is another advantage of cross-linking the packs - you don't have to face the possibility of a single pack handling the load of the motor after the other cuts out - This is not a trivial issue - It could make the difference between being able to make it up that last hill or not.) Just the same, the primary advantage of cross-linking individual cells is that the cells self-balance each other during charging and discharging, and thus should remain balanced longer.....

I hope my explanation is clear.


Brian