Robonect.de

Hi

Has anyone opened husqvarna batteries or know if tge contain any discharge protection circuit(like Bms module) in the battery pack?

Or is this implemented in the motherboard of the robot?

The battery looks like this

https://www.kjell.com/se/produkter/el-v ... vyEALw_wcB

On the other side of your picture is the balancer under the plastic
LGE

That means the battery itself is protected from total discharge in case if I want to power a Raspberry Pi (with DC/DC converter of course) to batteries plus/minus rails?

I wonder the same = akku BMS for R40/R70 ... akkus.
Where is it possible to get it? Is it just "standard"BMS, ...
Any info is more than welcome.

I've done some more research, and from photos, it looks like akku for R40/R70 do not have BMS (and anyothe charhing logic?) anymore at all.
Can someone (@LitlleJohn ?) confirm this (that BMS is not needed)?

If I understand the ERFAdoc from @Fidatex then the charging logic is inside the roboter, and no additional logic is needed at the akku itself. Ok, BMS makes the life of akku longer.

I disassembled the battery and here are the pics of charging module that sits inside. There is a temp sensor between the backside of the board and batteries. Pics are high res and one can read which IC are used and therefore deduce if whats on the board.

Any thought an what it is are welcome.

From the phot looks like have the same PCB.
It contains BMS,, and charging logic(?).
As charging logic is already part of R40/70, and BMS is not so important you can get accus w/ this PCB.

I should have mentioned that photos of the battery are actually of the original Husqvarna 3200mah battery.

The most important info is missing in the pics. You may actually use any BMS system you like with the Husquarna (at least with my 310 MY2016) as long as the complete battery pack (cells plus BMS) will identify itself properly to the controller. They seem to use a dedicated resistor, that is in one of the (yellow) control wires. In my 310 this is a 3,9k resistor to ground/minus.

A 3rd party battery pack from the bay area did not work because this resistor was missing AND they used the wrong thermistor value. The original thermistor is a 10k type, they had a 20k installed.

With these corrections made the 3rd party battery pack now works perfectly.

I wonder what the resistor value is for: will different resistor values make the controller change anything? Is there anybody OUT there with a larger (original!!) battery pack who may want to identify the value of the resistor used in his pack? I remember reading about larger packs in a 330??

If a modified/enlarged battery pack can properly tell the controller its real size by using the correct identifier resistor, all the circumvents like changing the run time limitation may be unnecessary or the 4h charging time limit is increased?

One more thing about BMS: any LiIon battery pack requires a BMS to protect against overcharge, undervoltage and overtemperature. BUT these BMS are usually made with maximization of availabe energy in mind. They allow charging up to 4,25Volt/cell and discharge to 3 (or sometimes even 2,8) Volts/cell (100% DOD). Under these circumstances any LiIon cell will only last some 500 cycles. To lengthen this lifetime, Husquarna takes control and limits the charging voltage to some 4 Volts and the discharge voltage to some 3,5Volts. This reduces the available capacity up to 50% but tenfolds the lifespan of the battery pack.

Original Akku
Nachbauakku (nach der Anpassung, der NTC hängt noch in der Luft)

Der sollte wohl reichen

War für ein anderes Projekt (10p10s). Ich baue diese Packs aus alten Laptop Akkus selbst