Do you know how it is possible to bypass the middle pin (BUS)? Is there a workaround?

I wouldn't do that. Your mower needs to know that the battery is working in its safe zone. If you gives it false information, something bad may happen.

Yesterday on BBC Breakfast, there was a call for mandatory third party testing of batteries and making compulsory that the battery talks to the charger before accepting charge to reduce risk of overcharging.

All it seems to do is monitor temperature and if that's at room temperature, it wouldn't report an error.

 

Problem there of course is that if the battery starts to overheat whatever its powering wont cut out.

I wonder if you just took a control board from a dead Bosch battery and connected it in parallel to the DIY pack whether it would provide the centre pin signal? All it seems to do is monitor temperature and if that's at room temperature, it wouldn't report an error.

 

Not at the moment.

 

My battery pack includes a BMS equipped with a thermistor, which means that the BMS will handle the temperature monitoring.

I wouldn't do that. Your mower needs to know that the battery is working in its safe zone. If you gives it false information, something bad may happen.

Yesterday on BBC Breakfast, there was a call for mandatory third party testing of batteries and making compulsory that the battery talks to the charger before accepting charge to reduce risk of overcharging.

 

I agree with you, but my battery pack has a BMS with a temperature sensor, so I assume it's safe because the BMS will monitor and handle any overheating.

You would need to replicate the control unit inside a Boch battery that the mower expects to see.

 

Sounds like a question for a lawnmower or power tool forum.

Yes, this is a good idea. I had considered replicating the BUS signal using an Arduino Nano, but I'm not certain about the signal's specifics. It would be ideal to capture the signal using a logic analyzer before attempting to replicate it, but unfortunately, I don't have a working Bosch battery to monitor the signal.

Problem there of course is that if the battery starts to overheat whatever its powering wont cut out.

 

I agree. I am assuming that the OP knows what they are doing, has built the battery to a suitable standard, to be able to supply enough current, is properly fused and has its own BMS with thermal cut out etc etc.

Yes, this is a good idea. I had considered replicating the BUS signal using an Arduino Nano, but I'm not certain about the signal's specifics. It would be ideal to capture the signal using a logic analyzer before attempting to replicate it, but unfortunately, I don't have a working Bosch battery to monitor the signal.

 

You can buy the Bosch battery style board for about £20, or you can pick up a dead battery quite cheaply and obtain a genuine board from that.

I watched a yt video last night about tool batteries. The main theme is there are 2 signals, one to start the battery and one to stop it. Those batteries can supply insane currents, much higher than those we see on E-bikes. The guy pumps 75A from his tool battery. So if you want to use your battery on tools, watch the current, otherwise you'll kill your cells in no time.

I watched a yt video last night about tool batteries. The main theme is there are 2 signals, one to start the battery and one to stop it. Those batteries can supply insane currents, much higher than those we see on E-bikes. The guy pumps 75A from his tool battery. So if you want to use your battery on tools, watch the current, otherwise you'll kill your cells in no time.

 

There is a fuse on the Bosch battery, which I forget the rating (I think it has been mentioned in this thread) although it is a lot less than 75A. But yes, the OP does need to be sure that the batteries they have chosen for their DIY pack can handle the kind of currents to be expected from the mower.

it's still worth considering using a tool battery for e-bikes.

You can build a good and cheap e-bike using my BBTS kit (£100), a motorwheel and a tool battery.

it's still worth considering using a tool battery for e-bikes.

You can build a good and cheap e-bike using my BBTS kit (£100), a motorwheel and a tool battery.

 

The concerns I have with this are that with some of the Bosch batteries (it seems particularly the older versions) have only a very primitive monitoring system that only looks at temperature, with no balance, no undervoltage protection (maybe in the COMs protocol to the tool, or the tool just senses undervoltage? But certainly no individual cell undervoltage protection), no short circuit protection (other than a high rating fuse)...and without the COMs set up in some way with the e-bike controller, there is no way to monitor temperature etc. The other thing is that the packs are not at all waterproof. They are full of vents for cooling. I've seen some people selling a waterproof sock for them, but this then covers up the cooling vents!

the risk of damaging the tool battery when used to power ebikes is much less than the other way round, using your bike battery to power a lawnmower for example. The LVC is set in the controller, usually 31.5V. The overcurrent is usually non existent, controllers are usually set for 15A max. The remaining risk is water and temperature. Temperature risk is usually non existent if ventilation is adequate, like mounting it to my Brompton luggage block or downtube.

the risk of damaging the tool battery when used to power ebikes is much less than the other way round, using your bike battery to power a lawnmower for example. The LVC is set in the controller, usually 31.5V. The overcurrent is usually non existent, controllers are usually set for 15A max. The remaining risk is water and temperature. Temperature risk is usually non existent if ventilation is adequate, like mounting it to my Brompton luggage block or downtube.

 

Over current is usually not an issue unless someone tried to run a 20 A plus controller on a tool battery not designed for that kind of draw...or a MOSFET goes down in the controller - I've had that happen before.

 

I do worry about the lack of individual cell monitoring. If one cell is weak, the others gang up on it, dumping lots of heat into that one cell until it fails with rupture/fire. This has almost happened to me when back in the early days, I ran a small pack without a BMS to power a bike. I pulled the plug when the shrink wrap started melting on some cells and caught it just in time. If there is no balancing, it is more likely that some cells may end up weaker than the rest.

 

The later Bosch packs do seem to have individual cell monitoring, so the recommendation may be to get a later one, rather than an older one.

 

Still need to solve the issue of water proofing/resistance though....

it may be still worth considering for infrequent use compared to the cost of a full kit.

it may be still worth considering for infrequent use compared to the cost of a full kit.

 

Agreed, but maybe the way to go is the Einhell route rather than Bosch. Einhell have everything contained in the tool battery and you are not reliant on tool/battery COMs. However, the Einhell set up only uses 18 V packs, so you have to use 2 in series.

I have seen the expected YouTube videos on using these Bosch powertool batteries for eBikes. However as has been mentioed a few times these batteries do not have a eBike type BMS for protection.

 

There is the battery temperature sensor, and some newer batteries do appear to have individual cell monitoring.

 

Given that the different batteries are comapatible across the range of tools, the comms protocol must simple, that maybe just signals OK or not OK. Its unlikely that an old Bosch tool would have known that some years in the futute batteries with individual cell monitoring would be introduced.

 

Using a Bosch battery as an eBike battery without the eBike controller being able to read the good battery bad battery signal seems, to me at least, to be an unacceptable risk.

 

For a Brompton, a conversion based on the single 36V power tool battery on the luggage block seems ideal. I cannot see that a Brompton conversion using 2 x 18V batteries would be very practical.

I wonder if a small standard BMS could be substituted for the Bosch control PCB in the pack.

Or maybe somthing as simple as this;

 

https://www.electronicsweekly.com/news/products/emech-enclosures/resettable-fuse-carries-20a-li-ion-batteries-2018-04/

https://www.mouser.co.uk/ProductDetail/Bourns/AC77ABD?qs=55YtniHzbhAbFzbGWRl7PQ%3D%3D

£1.71
£1.71

 

Controller lvc is variable , KT ones are set for 20/30/40v though one can also adjust the lvc value range by -2v to + 1.5v in 0.5v increments.

"Electric bike maker Aventon has dared to be bold and make the entirely logical move to enable its bikes (specifically the Pace 350, for now) to be powered by your bog-standard Worx power tool battery."

https://www.cyclingelectric.com/news/use-power-tool-batteries-to-power-e-bike-aventon

 

I can see a place for tool batteries in a very lightweight specialist kit but not for a factory assembled e-bike. The weight saving is tiny compared to the overall weight of an equivalent bike with a more suitable bag or in-frame battery, the drop in safety and yield for the battery and is considerable and there is little cost saving. If you put two tool batteries on the bike then all the advantages disappear, you are left with only disadvantages.

I think I am agreeing with the last contribution. My minimally adapted Mk1 Swytch kit using multiuse 2.6Ah 36V Bosch lawnmower batteries is still running well. I actually prefer the adapted old touring bike to my Decathlon 500E for local town use. Bike is light and reasonably well balanced and can handle moderate loads (eg shopping) even though it only has rim brakes. I have used it for longer rides with a spare battery carried in a pannier - only takes a couple of minutes to change the battery. Peter

I keep thinking about this.

Using tool batteries to power bike as I've loads just sitting about. Well about 7 18v plus 4 at 12v.

I thought today I could just fit 2 18v batteries in 2 chargers permanently then wire that up to motor.

Plug in the chargers to 240v to charge.

I guess you would need to wire the batteries together to get 36v and at only 4ah will that be enough for my commute? It's the wiring of batteries together that's the problem I guess, plus the strain on the batteries with just the 2 that will cause a problem?

I've not seen anyone use the chargers as a holder as well.

I guess it's an unknown and possible fire risk

I have been using bosch 6 amp batteries, with moultons and crank drive and front wheel motors for 4 to 5 years. I try to average over 15 mph with legal speed with 250 watts.

 

time 01:00 distance 14.0 miles average 14.1 mph ascent 1,225 ft descent 1,250 ft

I return 1 or 2 bars remaining . Some of the batteries have reduced capacity.

 

2 or 3 times the batteries have refused to charge, I'm guessing from draining to far. The solution is fit

the battery to a bosch tool and run it briefly. I found this out through reading the motorhomefun forum. I had bought a new battery by then, but was happy to restore the defunct one.

 

Graham