WANTED - Faulty Bosch power pack battery

[Darren2018]

Hi,

I am looking for a faulty Bosch power pack battery. I believe these can be re celled but only using a particular procedure and I would like to understand the way that they work . If anyone has a faulty pack that they would be willing to sell for a reasonable cost I would be happy to buy it.

Thanks

Darren

 

[Nealh]

I believe the bms needs to be connected to a power source before old cells can be disconnected so wiring a temp source in parallel keeps the bms alive without the need for reprogramming.

 

[wheeliepete]

I am looking for a faulty Bosch power pack battery

AFAIK, as Nealh says, if the BMS losses power, it bricks (I think that's the term, hmm never used it before!). TBH, Darren there's not alot to learn from looking inside one. If it's faulty, the BMS will be US and it's only worth are the cells. This is the BMS if your up for a challenge.

 

[Nealh]

I suspect any info is contained in those two micro processors (lhs upr & lwr) so if any voltage imbalance/disconnection is felt they cause the bms shutdown.

 

[Darren2018]

I didn't know people on this forum were so involved! You guy's sound like the people over at endless sphere! Glad I posted now!

So is the BMS looking at the pack voltage or individual cell voltages? Once I know exactly what the BMS is looking for I will make a jig to keep it alive whilst I swap out the cells. Why does it have 4 charge/discharge wires? I wish I had one to test.

 

[Nealh]

Can't be precise but I expect the bms is looking for 10 cell readings so 10s , though in operation it looks after both balance and pack voltage at lvc & hvc level.
I suspect if a sense wire or cell group is disconnected it interpretates this as interference and shuts down.
Again not sure but charge discharge may be separate channels so two sets of wires.

 

[wheeliepete]

Why does it have 4 charge/discharge wires?

I stripped that one out of a 400 rack pack that would not take a charge, nothing wrong with the cell, all still well balanced. From memory it had B+, B- and P+, P-, the 4 large connections and the charge wires on the connector at the centre bottom of pic. The balance wires on the 2 connectors at the top. It's a guess, but I would hope that pack voltage would keep the BMS alive, otherwise it's a lot of temp. connections to make. Jimmy at Insat Int. knows the secret to this one, he may be willing to share.

 

[Darren2018]

I doubt anyone would revel that if they are in the business of selling them. I have also heard that they do not all use the same self destruct features which makes things even more complicated without seeing and testing all the different variants of the boards.

 

[soundwave]

there are some on the german forum that has recelled these batts and the early bms gen 2does not need power to be maintained to recell them but no idea what year it was changed board wise.
https://www.pedelecforum.de/forum/index.php?forums/bosch.30/

 

[wheeliepete]

Could it all be "Bosch/Chinese whispers"?

 

[soundwave]

Could it all be "Bosch/Chinese whispers"?

no as the bms these days has to talk to the motor so power must be kept when recelling them as if it looses power you brick it and will never turn on again bit like ram in ur pc cut the power and loose everything.

 

[wheeliepete]

I'm just questioning where this info on Bosch BMS's originated from. We all quote it, but I've never read of anyone trying to recell their Bosch pack and this happening. Gotta link anyone?

 

[Deleted member 128]

Cells can be stacked using various serial/parallel combinations to give the required voltage, current and amp/hour. Does anybody know if ebike BMS's typically monitor each cell, serial chain and/or parallel network?

 

[soundwave]

jimmy @insat told me via email and as there a pita to work on so will cost more than a normal batt recell but cheaper than buying new and can pick what cells you want and 1 year warranty.

 

[soundwave]

Cells can be stacked using various serial/parallel combinations to give the required voltage, current and amp/hour. Does anybody know if ebike BMS's typically monitor each cell, serial chain and/or parallel network?

 

[wheeliepete]

Does anybody know if ebike BMS's typically monitor each cell, serial chain and/or parallel network?

The BMS will monitor voltage in each parallel group/string during charging and keep the pack balanced, ie. each string at equal voltage. This works unless you get a defective cell/cells in any string, which often leads to the pack under charging because 1 or more strings reach full charge before the rest.

 

[Deleted member 128]

View attachment 28561

That's it, do you know if ebike BMS's typically monitor each cell, serial chain and/or parallel network?

 

[Nealh]

Cells can be stacked using various serial/parallel combinations to give the required voltage, current and amp/hour. Does anybody know if ebike BMS's typically monitor each cell, serial chain and/or parallel network?

Bms monitors parallel cell group (however many cells) via the thin sense wire this is placed on each + side of the group.

 

[Deleted member 128]

The BMS will monitor voltage in each parallel group/string during charging and keep the pack balanced, ie. each string at equal voltage. This works unless you get a defective cell/cells in any string, which often leads to the pack under charging because 1 or more strings reach full charge before the rest.

If you look at SW's series/parallel examples which cell or group of cells would typically be monitored?

 

[soundwave]

https://www.batrium.com/