WANTED - Faulty Bosch power pack battery

soundwave

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Nealh

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If you look at SW's series/parallel examples which cell or group of cells would typically be monitored?
The example is of 12v battery connection the two bottom diagrams are two rows in parallel then connected in series, each row would be monitored by one wire. Each parallel joined cell in a group is looked at as one by the Bms and all cell in parallel each receive an identical charge voltage as its neighbour.
 

soundwave

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The example is of 12v battery connection the two bottom diagrams are two rows in parallel then connected in series, each row would be monitored by one wire. Each parallel joined cell in a group is looked at as one by the Bms and all cell in parallel each receive an identical charge voltage as its neighbour.
The two bottom diagrams show 2 rows of cells each containing a serial network of cells, and the 2 rows are connected in parallel. If I understand you correctly the BMS would only monitor the voltage on the entire network?
 

Nealh

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To most it reads and sounds scary but to me and others with a diy knowledge of building batteries it reeks of scaremongering and protectionism. A pack under warranty then yes send it back for a free new one or repair but out of warranty the afore protectionism come in to play.
The Bosch batteries are only 36v and less then 25a rating, guys on ES build monster bike packs capable of 100mph in some cases, some are well over 160a and nearing 100v.
My current build a WIP is for the Swizzbee and will be a 98 cell /two 24v packs in parallel with 140a rating though only 60 -80a max is required.
 

soundwave

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1547597551098.png
b1-b3 are the sense cables you just scale it bigger for larger packs. 4s is 16.8v
 

Nealh

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The two bottom diagrams show 2 rows of cells each containing a serial network of cells, and the 2 rows are connected in parallel. If I understand you correctly the BMS would only monitor the voltage on the entire network?
Yes you are correct.
I'm a practical hands on person but when it comes to diagrams I get lost. I know in my head what happens and can put in to practical use but usually throw drawings away.

Lithium bike batteries though aren't connected series first then parallel, they are always connected as 10 parallel groups for 36v then each group is then serial connected to the next and so on, if a Bms is used it has 10+ sense wires to monitor each of the 10 groups.
 

soundwave

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watch this ;)
 

wheeliepete

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reeks of scaremongering and protectionism
Your quite right Neal and I don't like it one bit. That post was just a follow on from me asking about the "Bosch BMS Consiracy". I'm starting to see why you like your Swizzbees so much apart from the funky looks, why so many amps, vertical cliff climbing a hobby of yours perhaps?
 

Nealh

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Your quite right Neal and I don't like it one bit. That post was just a follow on from me asking about the "Bosch BMS Consiracy". I'm starting to see why you like your Swizzbees so much apart from the funky looks, why so many amps, vertical cliff climbing a hobby of yours perhaps?
The 24v Heinzman mid drive motor isn't a hub or crank drive but a brushed motor mounted (mid height) between rear wheel and seat post, it is the first I believe mass produced S-pedelecs so has a controller which can produce up to 80a output. Therefore the motor is a little beaat and consumes battery mah at a healthy rate. Currently I use a 28.4ah lithium set up which is good now for about 42 miles, the only way I to get capacity is more cells in P which ultimately means more ampacity when using Panasonic 10a cells. In all the two battery packs combined will have 14 cells in P. I have started the build and when finished will post pics on the Swizzbee thread in one go rather then bits and bobs but might not be for several week yet.
The build will be a bit different to normal welded nickel builds so that I can achieve good current flow without multiple nickel build up.

Quite honestly I just enjoy playing with cells etc,etc and like building packs and with each pack improving layout and current flow for better power use from the cells. Building bikes persay no longer really interests me it's the power source of the battery that I'm currently enjoying and what cells to try next time. The PF is my cell at the mo due to the good price of them and the power they can deliver.
I wouldn't mind trying 35E's , GA & MJ1 in the future but only if the price is right.
The last cells I got before Xmas was £128 for 100 unused PF's and £20 for 50 PD's, plus £80 for 50 MJ1's for Kirstin. The PD's are in a DASKIT case now on my town/errand commute bike and will give them their first run out tomorrow they are replacing two tired dolphins that got a bit wrecked with derestriction, that was before I knew how crappy the cells really were.
 
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watch this ;)
Interesting, thanks. That combination of cells and the BMS would provide a nominal 24.1V and 6Ah. Would you use that as a building block to create more volts and Ah, with each block having its own BMS?
 

soundwave

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no you just use a bigger bms for the hole pack that can take the extra amps you cant pull 100a from a 20a bms as it will end in a massive fire if it dont blow first lol.
 

wheeliepete

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The 24v Heinzman mid drive motor
That is a beasty little motor, I've read about Heinzmann motors being able to take big amps, they were one of the few that saw the lack of amperage restriction in the regs and made motors to suit. I'm following your pack building tips,along with blunderbus and AK with much interest as there's always room to improve things even when you think you have it worked out. I've built a few packs, not that many, but no 2 are the same as you always change things slightly with new knowledge gained. Keep up the good work.
 
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