36V Bosch tool battery for e-bike use

[WheezyRider]

I thought I'd start a thread here for those interested in using 36V Bosch power tool batteries for powering e-bikes.

This seems to be of interest for several people on the forum who have Bosch lawn mowers, or other tools and like the idea of being able to use the same batteries on their bikes.

For me, these packs a are a bit on the small size for my needs, but for some people with lightweight bikes they are ideal. Also, as we seem to be getting to a situation where only certified batteries (and certainly not scooter or e-bike batteries) may be allowed on trains/workplaces etc, it may be easier to say, "but it's for a tool not an e-bike battery" to be able to slip it into work or so on for recharging.

@Woosh @StuartsProjects @peterjd

I'll kick things off by re-posting some of Peter's pictures of his set up:

 

[soundwave]

so why dont bosch make lawn mowers ect that can take a bosch ebike batts

 

[WheezyRider]

I know, but that would be too logical My lawn mower isn't a Bosch, it's an Einhell but it still uses a puny 18 V 4Ah battery. The charge on it isn't enough to do the whole garden and it doesn't have the grunt needed to get through wet grass. With a 36V 15 Ah e-bike battery it would be so much better.

Anyway, there seems to be quite a few people interest in using the tool batteries for e-bikes, so it seems like a good idea to bring them together to chat about the best way of doing that.

 

[soundwave]

im surprised there not can bus locked like the fkn bike batts

 

[WheezyRider]

im surprised there not can bus locked like the fkn bike batts

Fingers crossed they leave it alone. There seems to be quite a few existing batteries out there, so plenty of scope to work with what has already been made.

 

[soundwave]

gen 1 batts had no can bus gen 2 has but it has been bypassed so a recell is possible if the bms dont brick its self £500-550 500w new one is £630

the new smart frame batts will not work on any older motor and have a new bms and different connector.

so we have to hack it alllll over again lets hope it dont take 8 years

 

[StuartsProjects]

I have been testing 4Ahr Hoverboard batteries and a custom 10S1P 5Ahr battery, and that has been enough for my local trips on my eBrompton.

So for 'light' eBike use then the 36V 6Ahr Bosch power tool battery should have enough capacity for local use.

 

[StuartsProjects]

I have a working eBrompton, mainly using a 5Ahr custom battery and with the battery\controller in a handlebar bag facing rearwards.

To charge the battery in this setup gives me two choices, either wheel the bike down to my shed and plug it in for charging there or remove the battery and take it down the shed for charging and storage, I dont charge batteries in my house and dont store them there either. However I suspect that long term removing of the battery, its got XT60 connectors, is going to wear the cable and connectors plus there is the risk of damaging the battery when carrying it to the shed, its a custom battery and has no hard shell.

What would be far more convienient for me is to keep the folded eBrompton by the front door and have an easily removeable battery that is also in a robust and compact case. For sure there are a great many different removeable eBike batteries out there, but they do tend to be a bit on the long side and when you fit one its fairly obvious you have an eBike.

The Bosch 36V powertool batteries are compact and if a suitable bracket can be found or made, should be quick and easy to remove for charging. And they are in robust cases.

One other potential benefit of the Bosch batteries is that it should be possible to hide the battery in a small cycle handlebar type bag, this disguises the battery so its not obvious your riding an eBike.

 

[Bikes4two]

• So does anyone know what cells are used in the (genuine) Bosch 36v 4Ah batteries?
• I'm thinking max current capability etc
• The Bosch batteries look to be pricey at around £130 on first Google trawl.
• Can they be charged with a regular 36v charger or is a specific Bosch charger needed (that'll be pricey too I guess)?
• I saw something on YT the other day where the guy had bought the cheapest product that took the batteries he had (a torch I think it was) and cut the base off the torch to mount on his bike to hold the battery. Obviously an expensive route (which he acknowledged) but it was all for a bit of fun.
• 4Ah won't take some riders very far but it could be used to boost say, the main 36v battery on a bike, as in with both fully charged, parallel connect the two batteries to extend range on a longer than normal ride.

 

[StuartsProjects]

£130 for a 36V 4Ahr does seem expensive when you compare it capacity and cost wise with a typical 36V 10Ahr.

Small & light 36V batteries of reasonable known quality no not seem to be cheap, my 36V 5Ahr cost over £200. There are those Hoverboard batteries 36V 4Ahr that are under £60 if you want cheap.

The Bosch 36V 6Ahr is circa £230, which is around the same price for having a 10S2P custom equivalent built, that is if you can find someone available to build one.

 

[peterjd]

£130 for a 36V 4Ahr does seem expensive when you compare it capacity and cost wise with a typical 36V 10Ahr.

Small & light 36V batteries of reasonable known quality no not seem to be cheap, my 36V 5Ahr cost over £200. There are those Hoverboard batteries 36V 4Ahr that are under £60 if you want cheap.

The Bosch 36V 6Ahr is circa £230, which is around the same price for having a 10S2P custom equivalent built, that is if you can find someone available to build one.

As well as the 2.6Ah original Bosch batteries I also obtained an Exmate 5Ah look-alike from Amazon for about £85 a couple of years ago. Seems to be going well on lawnmower and Swytch-like bike conversion using the original and fast charger. But I wonder if Bosch have stopped Exmate selling a look-alike because I haven't seen it advertised recently. Peter

 

[chris_n]

I'm sure you will find a lot of similar information to what you are looking for in this old thread. https://www.pedelecs.co.uk/forum/threads/small-battery-bargain.19563/

 

[WheezyRider]

• So does anyone know what cells are used in the (genuine) Bosch 36v 4Ah batteries?
• I'm thinking max current capability etc
• The Bosch batteries look to be pricey at around £130 on first Google trawl.
• Can they be charged with a regular 36v charger or is a specific Bosch charger needed (that'll be pricey too I guess)?
• I saw something on YT the other day where the guy had bought the cheapest product that took the batteries he had (a torch I think it was) and cut the base off the torch to mount on his bike to hold the battery. Obviously an expensive route (which he acknowledged) but it was all for a bit of fun.
• 4Ah won't take some riders very far but it could be used to boost say, the main 36v battery on a bike, as in with both fully charged, parallel connect the two batteries to extend range on a longer than normal ride.

I would imagine the 2 Ah packs use a single string of 2 Ah Samsung cells (based on what is inside the 1.3 Ah packs, which seems to be Samsung 1.3Ah cells). Hopefully we can crack one open in the near future and have a look.

£130 is a lot for a 4 Ah pack, but 1) many people have these lying around in their sheds for lawnmowers etc. and you don't tend to cut the lawn every day. 2) you can get a dead 2.6Ah pack and recell it to 7Ah, which is quite respectable.

One option is to make a base from scratch, or you could buy the cheapest broken 36V tool and cut what you need from that.

My thinking is that it is best to go for an old 2.6 Ah, as it has two strings of 1.3 Ah. Then you can buy some cells up to 3.5 Ah and end up with a 7 Ah pack. Say the dead battery costs you £20 and then cells for about another £70, so a total cost of about £90, so not too bad for 7Ah.

One thing to note is that the max current for decent 3.5 Ah batteries is around 10A. This is less than for the 1.3 Ah cells, which are rated at 15 A. However, this should be fine as there are two strings, giving 20A capability and it's very unlikely you'd put this on a bike where you wanted to draw mare than 15A total. If you are worried about it, you could drop to 3 Ah cells that are 15A capable, but then the total capacity drops to 6 Ah.

You could make a double battery mount and then have the option of up to 14Ah.

 

[WheezyRider]

I'm sure you will find a lot of similar information to what you are looking for in this old thread. https://www.pedelecs.co.uk/forum/threads/small-battery-bargain.19563/

Thanks, I'll have a look.

 

[StuartsProjects]

You can buy new empty cases for the 20 Cell versions;





But not cheap, around £40.

 

[StuartsProjects]

The Bosch batteries look to be pricey at around £130 on first Google trawl.

Cheap on Aliexpress;

 

[WheezyRider]

Cheap on Aliexpress;

View attachment 53167

I wonder how they claim 8 or 9 Ah for a 2p 18650 battery? I do worry about the quality of the cells. The BMS in these batteries does not seem to do a lot of the monitoring of individual cells as you would with a normal battery, so I think it is important to have very good quality cells made to tight tolerances. Not sure what grade cells you'd get from a supplier on Aliexpress.

 

[StuartsProjects]

I wonder how they claim 8 or 9 Ah for a 2p 18650 battery? I do worry about the quality of the cells.

For sure, who knows what you would get. There must be people who are risking it though.

But if you really want to worry, you can allegadly get 2 (yes two!) 18V 6Ahr for £24 + VAT delivered.

 

[lenny]

 

[WheezyRider]

How about an 18 Ah version? Total BS, no way you could get that from a 2p pack of 18650 cells.