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Cordless vacuum cleaner problem

katar83

New Member
It just this minute struck me that there are only two wire connecting to the motor. Looking closely, I can see that the coils are in the rotor. Thus a brushed DC motor.

Therefore I can simply remove the entire Bosch circuit board and replace it with a 7S BMS and and a solid state relay or similar to bypass all the Bosch planned obsolescence crap.

Cheaper, simpler and more certain than trying to restore the eeprom(s) to factory defaults.
Have you attempted this? Found this forum through google, I have same hoover here. What bosch does with this is absolutely criminal. The hoover in question works 5-10 minutes from full charge. I thought one of the cells died hence low run time, I've disassembled it and taken out ALL Samsung cells out and then tested each one of them separately and ALL of them have 90% factory capacity and ALL of them are within 30mah from each other, yet Bosch must have set up controller to only run at ~15% factory run time! at this capacity/charge cycles!

To add to insult, if you disconnect/connect the battery pack in incorrect order the atmega chip will get in blocked mode and the board is bricked.

I've purchased 7s BMS and a charge indicator, just wondering what relay to use or whether I can somehow reuse some of the components on the original board for switching ground(motor works of switched ground). It also runs at 10A(brush motor at around 1A), I was thinking to get the motor to run at full power with switch in position 1 and in 2-3 to run motor and the brush motor together. Not fussed about running it at lower voltages.

BTW
Attached is the eeprom dump for this hoover too(from a working one), in case someone decides to go that way.
 

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  • EEPROM_dump.txt
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vasia

New Member
Have you attempted this? Found this forum through google, I have same hoover here. What bosch does with this is absolutely criminal. The hoover in question works 5-10 minutes from full charge. I thought one of the cells died hence low run time, I've disassembled it and taken out ALL Samsung cells out and then tested each one of them separately and ALL of them have 90% factory capacity and ALL of them are within 30mah from each other, yet Bosch must have set up controller to only run at ~15% factory run time! at this capacity/charge cycles!

To add to insult, if you disconnect/connect the battery pack in incorrect order the atmega chip will get in blocked mode and the board is bricked.

I've purchased 7s BMS and a charge indicator, just wondering what relay to use or whether I can somehow reuse some of the components on the original board for switching ground(motor works of switched ground). It also runs at 10A(brush motor at around 1A), I was thinking to get the motor to run at full power with switch in position 1 and in 2-3 to run motor and the brush motor together. Not fussed about running it at lower voltages.

BTW
Attached is the eeprom dump for this hoover too(from a working one), in case someone decides to go that way.
Hi friend, please give the original eeprom , avrdudeprog your version of the eeprom does not perceive.
For comparison, leave in the correct format.
Or do you have a different cpu ? Not atmega328p ?
 

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  • eeprom 32V huevii 1.txt
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Last edited:

katar83

New Member
The one I've sent is from Bosch Athlet but it might be different version than yours. Anyway, I've got rid off the Bosch board and replaced it with a 7BMS, a relay and a charge indicator, all works fine and its a faily easy project, I get up to 30 minutes on full power from original batteries now but last 10 minutes when voltage drops to around 21V it runs like on a slowest setting. Because of that, if anyone attempts doing this I would suggest going for an 8 BMS and you can then use a slightly higher voltage ac adapter(original will still work and charge cells to 3.75V each, when they can theoretically be charged to 4.2V. With 8 cells, BMS will cut power at 22.4V which will mean hoover will still run at good speed at that voltage.

Was an easy project generally and original batteries should still be good for a long time. The BMS is also much better at balancing cells voltage, after multiple charges, all cells are within 10mv and they were all over the place with Bosch PCB. Clearly a rubbish design.

BMS and charge indicator cost 10 GBP. I've used an automotive relay as had a few spares but solid state relay 30V 10A would be better.

Motor runs at 10 amps so a relay is needed as switch wiring is to thin to run it directly off the BMS.
 

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