Bosch Athlet Vacuum Cleaner Lithium Battery Replacement Using Sony 18650 VTC6 Cells 

I successfully replaced the batteries in my unit. It is very important to read the previous comments. My unit was working OK, so as a precaution I decided to save the content of the EEPROM before disconnecting the cells. Some things to add: It looks the microcontroller is running at 3.3V which is cut off after like 10 seconds after switching off the cleaner. When using my adapter I provided externally this 3.3V to the power rail (TP 2 pad). It looks it causes no damage to it. I used MPLAB X to download the EEPROM and saved it as a text file. Fortunately I did not need it. I disconnected the black negative terminal first, then the wide battery connector and finally the red positive terminal. After spot welding the new cells I reconnected them in the reverse order.

Really clear pictures ands instructions, thank you. It is much more complicated than I thought. This 75 old girl will have to take it to a repair shop. One of the best instructive videos I have seen with no distracting loud music.

Hi, I just want to say a HUGE thank you for your clear instructions! I want to share that I have successfully replaced all 7 batteries of my 25.2V Bosch Athlet Vacuum Cleaner. One thing that was a bit different was the way that these batteries were connected. They were connected by metal tabs that were seemingly spot-welded onto the batteries, and the voltage sensing wires were soldered onto the centre of these tabs (halfway between two connected batteries). I have just "peeled" them off using a sharp knife and a tweezer and replaced them with soldered wire connections for the new batteries. Be careful though, as it is way to short-circuit the batteries if you penetrate the green protective film. Furthermore, the sensing wires may need to be rearranged in order to connect them to a different location (they are just about long enough). I did not touch the EEPROM as I would not even know where the JTAG connector was placed, but things work fine now....

Just wanted to say thank you for the detailed instructions and share that I have successfully changed the battery on the 18V model as well (5 batteries) - the model is BCH61840GB/01

Thanks a lot for this guide, also some comments here are really important to read. Mostly the fact to start by disconnecting the battery's GND first..

I just finished replacing batteries in my 2016 Athlete vacuum. It is the version with black battery/pcb holder. What is important: > charge batteries to the same storage voltage 3.6-3.8v, not to high not to low. > Switch off for a minimum of 30 sec > You can remove the 6 screws with a popular flat screwdriver with a neon bulb (phase detecting tool) > disconnect 2 2pin connectors DC in and something > disconnect engine (I marked polarity just for safety) > disconnect negative and isolate it > positive isolate > not neceserilly pcb connector (but it is safer not to short something trough the board just for its safety) > then remove the welded plates. Start on a negative pole and pry it up, because positive side has insulated negative on the edge and will short with positive. After disconnection of negative side just pull the positive side - you can pry it up against the black chasis not the edge of battery as written above. > Then desolder the balancing cable (it is much easier now, because the heat will not disperse to batteries, which is also not good) > You need to prepare batteries for soldering - scratch the surface in circular motion, apply flux, tin these points with pretty high temperature in order to decrease the heat transfered to battery especially on a positive side (3 seconds should be enough if not wait for it to cool down and use higher temperature). > replace batteries one by one not to forget the orientation (and keep everything together, without 10 cables flying around) > tin the new connection cables > solder negative and bms cable first to create fix points, bend the cable to positive and push the cable from the top while heating the solder until immersed (2-3seconds is enough). > check all the connections by applying some force near all of them, check if the voltage of a pack is ok = 25+ v (if something is disconnected while connecting Power supply and switching on, circuit can be locked and eeprom must be cleared ) > connect pcb connector if disconnected > solder positive (it may need to be extended) > solder negative > Connect engine and 2 x 2pin connectors > Assamble Thanks to all the people who provided this knowledge to us.

Hey thank you for your video.i used VTC5's only cos I got a good deal on 7 of them from NKON (Dutch based battery company shipped to UK all included £23.00. Thank you

15/02/2022 Another one saved. Used new batteries from 2 x Lidl 20V power packs. They are only 2000mAh but had them anyway so made sense to use them 🇬🇧

this is a great video.. i would like only say one thing in a friendly way and no way am criticising.. please, if soldering start by scraping with a sharp blade or grinding with dremmel, add flux and tin the area with solder before even trying to attach the wire, once the terminal and wire has been tinned bring them together and you will achieve a stronger cleaner joint.. it will actually need less heat on the joint overall, wipe off excess flux.. it is acid..

That video is a lot longer than 5 minutes. But very helpful:)

If anyone's interested, you can unlock 32.4V model by zeroing 2 bytes in EEPROM starting at offset 01C8 (my blocked board had 42 42 there). Make sure to read and backup original EEPROM before flashing. This method works at least with the following 32.4V boards: Facelift 9C_30Q H/W ver: R3.0 and R4.0 S/W ver: V9 Remember that bad batteries may be dangerous!

I measure a different value on C7 than on C1 - C6, is it possible that the ceramic capacitor C7 is defective? Can anyone confirm that there are failures in the capacitors and what is the capacity of these tiny SMD capacitors?

A great video to fall asleep to 😴🛌😀

Hi, thanks for the video. Which screw bit size do i need?

Really handy video but I can't unscrew the last screw - can someone please tell me the right screw driver for this task? Thank you

To remove the star screws which size screw driver do you recommend?

Hello, my battery is running for 3 minutes at full speed, and I want to bypass the battery with a surce 25v 10A (by cable). Can you tell me, how can I do this and not damage the PCB. If I cut all battery-PCB wire and then solder + and - from the surce is OK ? Thank You!

First test I got 20 minutes at full speed with brush on and no loss of bars.

Very helpful thank you. I maybe will do it but with adding the three missing batteries.

I've got the outer casing off, what tool do you use to unscrew the four bolts to access the PCB etc ? As they are not flat head/Philips

Update for all the people that replace tje 18650 cells but the vacuum does not charge after the swap of cells. It's the thermistor, it's allocated on the last cell with white goo and it's like a black tear with two poles. No reprogramming of EProm, no Jtag hacking, no coding, just replace the thermistor. Now the good question, how many ohms it is? I don't know, i just replaced with the same kind found on old laptop batteries. But if there is no thermistor the machine would not charge, belive me.

Hey what is the exact model of the athlet? What's the battery life like now after 1 year?

What is the sequence plus minus for the batteries as i cannot see it well on the paper. Thanks

Best to use T20 (Torx 20) long bit with hole. Or dremel a hole in an T20, works too.

Hi guys ! I bought from auctions bosch athlet 25,2V. It has turbo brush problem. I opened it, and F2 was blown. When I join it (short circuit), brush is always working on, independently from main switch position (brush is on even main switch is turned off). Someone knows how to fix it ?

I guess i have bricke my unit. After recelling the motor spins up for a second than stops. Also the sensor LED and the first battery led light up. Charging isnt working at all. Before removing the old cells i had disconnected the positive voltage first, could that couse my problems?

Hi,mine was stop working when i put to charge nothing hapens when turn on nothing, i was replaced batteryes end now when i turn him on only the led came on and the motors not working. And still not charging when is pluged on adapter. The adapter provides 29.5v but no led come on. is it posible that the board is in fault? Thanks

Buongiorno Ho cambiato le batterie e collegate nel modo giusto, non riesco ha capire come vanno collegati i fili sottili dello spinotto quelli di colore rosso,verde,nero, nella parte superiore e grigio,blu,bianco nella parte inferiore. Nelle batterie vecchie erano collegati in mezzo alla piastrina tra una batterie e l'altra. Grazie

I was wondering, since there seems to be room for 2 more of those 18650 cells (have worked with them before) - if it would be possible to extend the 25,2V - 7 cell configuration to a 9-cell and 32,4V configuration - as the Bosch Athlete is offered by Bosch as a 9-cell and 32,4V variant ?! If the plastic parts are the "same" it makes you think, maybe they have the same electronics board? Any way to find out/verify? that would indeed be very interesting for me, as I am very interested in buying one of those vacuum cleaners ^^

Guess mine is going in the ducking 🦆🦆🦆🦆🦆🦆🦆🦆🦆bin then….😂😂😂😂😂😂😂😂. Great video you have patience 👍🏻

Hello, I did this but it doesn't charge but if I start from the button it shows that it is charging and interrupting and charging again and stopping again .. Thank You!

the 18650s here are $10 each which means thats like $70 but im sure the charge would be $250 as the bosch athlet is $600 RRP

What are the batteries that sat as original in the vacuum cleaner?

What 18650 cells are they? Can you share the details please?

what amperage do you need in your battery? as the lower amperage batteries are a lot cheaper

There is a another place to put an extra 1865?. Is this possible?

Buona sera. Desidero sapere, quanti alloggiamenti per le batterie ci sono nello chassis. grazie.

Hi guys! After replacing the batteries, the vacuum don't charge. Then I found this video and read the comments... there is some tutorial about how to reprogramming the eeprom? I never do it before and I'm lost... Thanks!

Hey, my positive pole touched the negative pole whit my print attached... Now I don't have any power at Al at the vacuum cleaner... Fun fact I did the replacement whit the battery's and it did work, then I d see that I need to cover off the batterypoles whit tape. So I opent the vacuum cleaner then I got fault code sensor was red and no charge.... Then opend up and then I focked up my main board ( I think) Is there any solution for this?

ok done the job ,but had an accident with one of the new batteries ,heated it up too much and it set a flame (using crap solder was to blame),so had to leave 1 old battery in THought i would get away with it,but the vacuum went into charge mode for about 15mins then turns itself off could this be due to this 1 battery?

I am very struggling to do this since some(1/3) of people reported that fail. I say your comment that you go for dyson now? Why do you change since it just replaced battery for 2 years only.

Still going strong with ridiculous amount of capacity in the 18650 cells.

I changed the cells! and put all together again and all looks well! But charger lamp wont light! but it blinks when start button is on! charger wire is then plugged in! there are normal current in the cells from the factory! direct connected motor run fast! but vacum Bosch Athlet wont run by ordinary start button! and do not take more charge? no charging light! anyone have a tips on looking for the fault? before I changed the batteries they charged! but Athlet then only runned for aprox 4 minutes!

Hi I have a bosch athlet 25.2v. I replaced the battery but now the problem is it doesn't charge. The light comes on blinking for a couple of times and then it's off. I tested the slow blow fuse and nothing is broken. It just doesn't charge. I used the same replacement battery. Anyone knows what could be the problem or how to fix it

Hi I found 2 types of 18640 3.6v that I can buy. One is 2500mah with Max continuous discharge 20A. Another is 3500mah with Max continuous discharge 8A. I'm not sure whether 20A vs 8A affects what and which is the best to use. I know higher capacity 3500mah giving longer run time. Much appreciated if anyone can teach me layman on this max continuous discharge impact

Hello, How are you. Could you please tell me where to find the electronic board of that vacuum cleaner? Thank you.

18650 batteries come in all sorts of mAh. From 4200mAh down to 2000mAh. Can I use 4200mAh batteries in my Athlet? Is it safe to use the 4200mAh? Will these overheat? Will I get more run time using 4200mAh? Will the 4200 mAh hold their charge longer before wearing out?

share a link to the file 32.4V. I beg you

total how many batteries to replace ?

Hi i change the bateries and then have to flash a new firmware and now leds are blinking like they try to charge but without charger any one know what next? xD trash? or you can do something with it?

Very handy video, thanks! But please, please clean that soldering iron tip, it made me wince all the way thru ;-)

Hi, maybe, someone could help: I have Bosch Flexxo Series 4 and when charging or turning the switch on, the red led lights up for 10 seconds then it turns off (Over-/undertemperature protection - according to users manual). It uses 7x 18650 batteries and one of them has only 1.27V. Could this be the problem or is it issue with temperature sensor?

Excuse my English. Some BMSs have protection in case an item is defective or disconnected (interrupted). When changing the cells, the first time disconnection of the minus (black) wire must be considered. In case the extra one is disconnected (red) or the connector, BMS sees the intervention as a defect and it is blocked. This is the situation with some laptop batteries. Unfortunately I found out late. Can anyone point me to the 22v firmware?

Ciao a tutti volevo chiedere a voi qualche consiglio. Ho anche io questa aspirapolvere e volevo sapere che batterie devo comprare e quante. Ma se io sostituisco semplicemente le batterie funziona?!? Perché leggo che bisohlgna installare efrom o o qualcosa del genere, vi chiedo aiuto prima di comprare le battery per poi non riuscire a farla funzionare. Grazie mille

Hi, can you help me fond batteries for my Bosch atleth 18v 🙏 ?

How long does it take to fully charge?

I doing think this vacuum cleaner is worth fitting new battery cells into, it doesn't have a brushless motor to start with. It's be inlined just to remove the batteries altogether then extend the power wires outside of the unit and use a power tool battery instead, would need to buy or make up adaptors to connect to battery pack according to make and model, that way you can use a fast charger plus swap out batteries while charging another. These companies are all taking the public for a ride, no need for internal batteries or all the different mount types to supply mostly 20v DC.

What's the exact model of the vacuum?

There is no way im doing this. Its long and complicated. Im buying a new one 😂

I renew/replace only batteries and there is correct voltage on B+, but it does not charge.

After i change it no improvement. They charge but last just 4-5 minutes. After i start go directly to the last led.

Welp, guess this won't be a simple job like I was hoping.

So rhe BMS wont reset !! Nice !! Ill start mine then ... i hate when bms reset and u waste ur time

Sorry but I cannot watch anymore. Hope you improve, thank you.

Я его просто выкинул, никогда больше не куплю технику Бош, не ремонтно пригодна!!!

Oh no, soldering at battery cells ??

Stop...Bosch will disable the circuit board if it reads the cell replaced. It ruin my vacuum and Bosch I hate you and will never buy your product again!

My god what an abomination of a battery I certainly wont be buying anything bosch for a while