36V Bosch tool battery for e-bike use

[WheezyRider]

They einhell batteries have great protection inside having watched a breakdown on YouTube, although I can't say I fully understand it. I've got 5 batteries here I could use. 4 we would be enough I guess.. I'm thinking about it

The Einhell batteries seem to have everything on board and the tool just has two connector pins. The battery seems to manage itself. The third pin is only used for charging on the charger. They have taken an 18V approach to all their tools, even the 36V tools use two 18V pack in series. I suppose the tool has some kind of sensing in case one pack is fully charged and one empty.

 

[WheezyRider]

What is perhaps important with these Bosch 36V batteries is working out how to persuade a standard type eBike controller to cut-out if the battery gets too hot.

The 6Ahr batteries appear to have a BMS but there is little to suggest that the battery itself has a low volt or high temperature cut-out.

Used as a bare battery on an eBike might be OK for getting clicks on a youtube video, but for safer day to day use it would be preferable that you get some warning if the battery is overheating, such as making the motor cut out.

When used with a power tool, the tool appears to cut out if there are temperature problems with the battery, so if you could work out the signals from the battery that cause this, with an eBike you could use say a brake sensor input to cut the motor.

A clue that the charger and tool use the centre battery connector for sensing comes from an advert I saw for the 36V electronics module. Look at the centre connector, it would appear to short the BUS connector to -ve when the battery is initially inserted but when fully inserted BUS would appear not to be shorted to -ve and hence could pass temperture info to the tool.

View attachment 53325

Maybe the charger\tool when powered sends regular requests to the battery to report the temperature.

Ah interesting, the pin is plastic with a partial metal covering.

 

[WheezyRider]

They einhell batteries have great protection inside having watched a breakdown on YouTube, although I can't say I fully understand it. I've got 5 batteries here I could use. 4 we would be enough I guess.. I'm thinking about it

Have you got a link to the You tube vid for the Einhell strip down? What size packs have you got?

 

[Wayners]

I've got 4Ah

 

[Woosh]

The have just used a weird symbol for the battery and the rest of the schematic shows;

the middle button with the plastic pin works like this: the pin keeps the SW2 contact open until a device is connected. When SW2 is open, the two 18V halves are not connected, the battery does not deliver anything. When a correct device is connected, the two leaves are connected with the middle pin, closing SW2 connecting the two 18V parts into a 36V.
I love mechanical solutions.

 

[StuartsProjects]

When SW2 is open, the two 18V halves are not connected, the battery does not deliver anything.

Where is the 18V tap in the schematic ?

 

[WheezyRider]

In the video, there is no break in the 10s string to make 2x 18V strings.

 

[Woosh]

Where is the 18V tap in the schematic ?

it's the switch marked SW2.
The middle blade is connected on the charger side to BUS (K2, middle ground) and shorts the negative of the high side to the positve of the low side.

 

[WheezyRider]

Look at the pack, the two 5s parts are joined with nickel strip and folded back. There is no break or tapping point.

 

[Woosh]

Your picture does not show where the red and black wires are attached to.

 

[WheezyRider]

Your picture does not show where the red and black wires are attached to.

Watch the video and you will see.

 

[Woosh]

Which post is the video in?

 

[WheezyRider]

Which post is the video in?

Post #31. first video.

This one:

 

[StuartsProjects]

Your picture does not show where the red and black wires are attached to.

Look at the picture in post #73, two wires only connected to the PCB.

 

[Woosh]

I missed the part of the schematic in your post #78. Will try to make sense of it tomorrow

 

[Woosh]

@StuartsProjects - can you post a picture of the whole schematic or the bottom right? it's too difficult to work out without the missing part.

 

[StuartsProjects]

Do a Google search for;

bosch_al3640cv_36v_li-ion_charger_with_battery_schematics

 

[Woosh]

found it at:

Bosch Al3640cv 36v Li-Ion Charger With Battery Schematics | PDF (scribd.com)

 

[guerney]

The manual for one of the 36V SDS powertools says this about temperature monitoring;

Temperature Control Indicator

The red LED of the temperature control indicator 19 signals
that the battery or the electronics of the power tool (when the
battery is inserted) are not within the optimum temperature
range. In this case, the power tool will not operate at full capacity.

Temperature control of the battery:

– The red LED 19 lights up continuously after inserting the
battery into the charger: The battery is not within the
charging temperature range between 0 °C and 45 °C and
cannot be charged.

– The red LED 19 flashes when you press the 21 button or
the On/Off switch 10 (with battery inserted): The battery
is outside of the permitted operating temperature range.

– For battery temperatures over 70 °C, the power tool
switches off until the battery is in the optimal temperature
range again.

Temperature control of the power tool electronics:

– The red LED 19 lights up continuously when pressing the
On/Off switch 10: The temperature of the machine’s electronics is below 5 °C or above 75 °C.

– At a temperature above 90 °C , the electronics of the power tool switch off until the temperature is within the allowable temperature range again.

A four cheese early warning system:

between 0 °C and 45 °C

Cream cheese

For battery temperatures over 70 °C

Cheddar

The temperature of the machine’s electronics is below 5 °C or above 75 °C.

Gouda

At a temperature above 90 °C , the electronics of the power tool switch off until the temperature is within the allowable temperature range again.

And when the mozzarella is crispy...

the battery is cooked.

 

[StuartsProjects]

I have been able to get hold of one of the older Bosch chargers and I can take it to bits if I want.

The first obvious bit is that the central blade is one sided on the charger, see the picture below;



So when the battery is inserted the internals of the charger are connected to the BUS line on the battery controller board, the lower leaf of the central connector in the picture below.



The charger puts a 5V level on BUS line and when this is connected to the battery digital comms appears on the BUS line, this is charging progressing as normal;



And this is what happens to the data when the thermistor on the battery control board is heated;



And the charger stops charging beeps flashes the LEDs etc.

So potentially you could read what appears to be data related to temperature and use it to turn off the motor when used on an eBike.