# VW mild hybrid battery and components, teardown



## Swing (Apr 25, 2021)

This topic is not showing the listing? Still needs to be approved or something?
Edit: Ah now I notice the awaiting for approval bit.

Anyway, this is the detailed label. Showing all the info and that it is a Chinese made CATL battery.
At 43.2v divided by 12 it would mean 3.6v nominal per cell. 12s is at this point still an assumption.
Part number 5WA 915 107 or 5WA.915.107


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## Swing (Apr 25, 2021)

I think the main purpose of reuse of these batteries would be exactly the same, to convert an existing petrol car to a mild hybrid. 
I don't see many other uses, I also find 0.6kWh to little for my camper van, if I want to do more than running a water pump, lights and fridge.
And it is also heavier than my Bosch 500Wh e-bike battery. However, the casing is nice to put in some engine room (not to close to the engine/exhaust side) or similar.
And a 500Wh e-bike battery may be nice and compact, if you would use that in a mild hybrid kind of way, I think you would quickly fry it.
Would be interesting to know what the specs are on this battery, because I think they can withstand pretty high C rating, only lasting for a short time because then it is full or empty.


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## YumYum (Jul 1, 2020)

Have you tried looking at VW official repair documents and service info for a pinout?


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## Swing (Apr 25, 2021)

That would be a good start, but I don't know how to find it. It is also from a relatively new car (2020) so I am not sure how much they are already sharing that, or where to find it.

But I found some more interesting technical info on the whole mild hybrid system. 
I found that they are only using 250Wh of this 600Wh battery? Probably to allow for starting the engine, but they still have the 12v starter installed for cold starts.
Reported dimensions and weight of the battery module are 290 x 300 x 110 mm (probably without mounts) and 15 kg
The motor replacing the alternator is called the RSG.

The RSG has a peak generator power of 12kW and a peak drive power of 9kW. On a 600Wh battery C ratings are going through the roof, but that explains why you got such a bulky battery with air cooling. Because otherwise you could have 600Wh in a much smaller lighter package (like on an e-bike)
The RSG is still belt driven with its own guiders to keep tension on it.

It is reported that both the RSG motor as well as the battery are CAN bus connected.
I think this is really nice if these CAN messages were to be reverse engineered.
Because you get quite sturdy components with everything already on board (battery has BMS and contactor integrated, motor has controller integrated probably) and you can just drive them with CAN messages. 

Next to that there should be a DC-DC converter from 48v to 12v rated at 275 Amps (not sure if peak power or continues). That is quite impressive as that is over 3kW!
And probably pretty sturdy made as well. It may output a charging voltage because it probably charges the 12v battery too.
Dimensions are 220 x 175 x 75 mm and 3 kg.

And the cars are fitted with a braking system that can mix regen braking with normal braking, which is to be expected.


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## Swing (Apr 25, 2021)

This is most likely the DC-DC converter, which seems to have the same plug (on the left), probably meaning that is also CAN based, but that is a big assumption.
This is probably a very generic VW plug used in all kinds of components, perhaps always with same pinout?
Part number: 5WA 959 663
Aandrijfeenheid hybride Volkswagen Golf VIII 1.5 eTSI 16V - 5WA959663 VW-AG

I don't see the RSG motor listed, but oh well it is most likely there as well.

All in all a very interesting set to reuse, and control yourself through CAN, in converting an existing car into a mild hybrid.
DC-DC converter pretty powerful, and of course the RSG motor can be interesting components in itself.
The battery is not so impressive in terms of capacity versus size and weight, but is of course very suitable for this purpose and can clearly take very high C ratings.


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## brian_ (Feb 7, 2017)

I don't know what the "R" in RSG would stand for - perhaps something in German - but this article from VW calls it a BSG (belt starter-generator):








The new Golf: with 48V technology


With 48V technology, Volkswagen can electrify conventional drivetrains with comparatively little effort and thus offer many customers the advantages of hybrid-drives in conjunction with existing vehicle concepts.




www.volkswagen-newsroom.com




That article includes nice illustrations of the mild hybrid system components and locations.

At that power level, it might be a fun system (without the DC-DC) for a kart, but it would only have sprint range.


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## Swing (Apr 25, 2021)

Yes but that article like other articals did not give technical info, which I found later behind register wall.

Anyway, you would rather replace battery fpr something else, but it is probably one of the highest specced C rating, given the info on the motor. In the peaks it is at 20C


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## Swing (Apr 25, 2021)

I still had this battery lying around. Finally opened this up. I am not going to much with, other than reusing parts probably.
But I am sharing it here for info.

One of the interesting things is that the ground, the minus of the battery, is connected to the battery casing. And the two terminals on the connection plate are both for the positive side of the battery. Didn't really expect that. It can mean that the 48 and 12v circuits share the ground, but I don't know how it is mounted.

It consists of a main PCB which includes the shunt, and there is a 100A relay and a 300A fuse. Most this battery should do is 12kW at 48 or 49v max so it is max 250A.
The relay disconnects the positive side.

You can see the battery layout. I guess perhaps you could get away with splitting it in half to get 2x 6s.
Other than that the battery is glued to the bottom it seems. Removing the Torx bolts didn't make it come lose.
I see no easy ways to remove the cells from the casing.

This might be useful for somebody some day.

In general, the unit seems quite repairable, in that you can exchange the fan on the outside, the PCB, the relay or the fuse, and put it back together.
However, getting those battery cells out will get messy. And I already thought it was messy to prey open the top, which you would have to glue down again.

Lot of people will just opt to change the module for another one. But they can ask a lot of money for it, and if they all turn out to be unreliable for a specific reason (a fan or pcb or relay issue) repairing might be worth it.

Picture dump, including the chips used on the PCB which are MC33771BTP1 and SPC58


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## brian_ (Feb 7, 2017)

Swing said:


> One of the interesting things is that the ground, the minus of the battery, is connected to the battery casing. And the two terminals on the connection plate are both for the positive side of the battery. Didn't really expect that. It can mean that the 48 and 12v circuits share the ground, but I don't know how it is mounted.


It is interesting, but I don't think it's surprising... at 48 V.


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## brian_ (Feb 7, 2017)

Swing said:


> You can see the battery layout. I guess perhaps you could get away with splitting it in half to get 2x 6s.
> ...
> View attachment 132909


Excellent view, confirming the 12S overall configuration and showing that it is specifically 12S 2P of prismatic cells.


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## brian_ (Feb 7, 2017)

Combining the information from the label in post #2 (596 Wh and 43.2 V nominal) with the configuration (12S 2P) yields a nominal cell voltage of 3.6 V and a nominal capacity of 13.8 Ah for the battery or 6.9 Ah per cell.


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## Swing (Apr 25, 2021)

Yes. I was hoping to get them out to see the actual weight, because the casing is quite heavy.
They are probably not that energy dense.

However, they are doing 20C in this application so that is quite something.


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## urgi (3 mo ago)

#Swing Thx for this info I have same battery now home and I going try dissaseble out and try to make 24V li-ion pack for mu solar system Possibly will add some picture here later Just Q how difficult was removing top cover ? Need to be heated? Thx Urgi


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## Swing (Apr 25, 2021)

Maybe it works better with heating but lithium shouldn't never get over 60 degrees Celsius!

We just used a chisel and a hammer.
Just make sure, that you never put the chisel inside the box because you might create a short.


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## urgi (3 mo ago)

Depends on your picture I think will cut last cross BusBar and create 2x 24V independent battery 

Just wondering anyone have good Tip for Li-ion BSM 20A with B/T

My solar is small poly 500W + 40A MPPT and I generating only idle house consumption ussually 150W but gridtie inverter capable of max 350W (with present potentiometer)

Right now using 2x bank 24V 90Ah AGM 

But looks this Li-ion may be good for me


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## urgi (3 mo ago)

Than today all open and mod done Cutt cross-busbar and here I have to 2 x 24V 6S2P + connected both banks parrarelly 

Ideally will be 7S2P but this is fine for testing 

MPPT set to max V cut to 24.6V = 1 cell max 4.1V for now without BMS

Did small experiment with grid tie inverter 45V and nicely 1000W 

Tommorow will try charge to max 24.6V if Sun 🌞 be there HaHa forecast rain and ⛅ 

Some pictures


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## urgi (3 mo ago)

Just update done read out ECU and here is log

interesting - more info in VCDS LOG

28709 - HV Battery Pack 
P0A7D 00 [038] - State of Charge Low
[BMS_SOC_LL1]
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 6
Fault Frequency: 1
Reset counter: 40
Mileage: 0 km
Date: 2000.00.00
Time: 00:00:00

Unlearning counter according OBD: 255
High_voltage_battery_total_voltage: 42.80 V
Test_Program_High_voltage_battery_contactor_voltage: 0.00 V
High_Voltage_Battery_Pack_Current_1: -0.03 A
Battery temperature: 22 °C
State of charge: 21 %
Test_Program_Cell_voltage: 3.57 V
Test_Program_Cell_index: 6
Test_Program_Cell_voltage: 3.53 V
Test_Program_Cell_index: 9
Test_Program_Outlet_temperature: 22 °C
Test_Program_Inlet_temperature: 21 °C
Test_Program_Cell_state_of_charge: 0 %
Test_Program_Cell_index: 0
Test_Program_Cell_state_of_charge: 0 %
Test_Program_Cell_index: 0
Maximum_permanent_discharge_power: 2500 W
Minimum_permanent_discharge_voltage: 42.00 V
Maximum_permanent_charge_power: 2600 W
Minimum_permanent_discharge_voltage: 43.00 V
Maximum_strategic_discharge_power: 11300 W
Minimum_strategic_discharge_voltage: 39.00 V
Maximum_strategic_charge_power: 13850 W
Minimum_strategic_charge_voltage: 46.00 V
Maximum_peak_discharge_power: 13450 W
Minimum_peak_discharge_voltage: 38.00 V
Maximum_peak_charge_power: 16350 W
Minimum_peak_charge_voltage: 46.00 V
Maximum_voltage: 50.00 V
Minimum_voltage: 36.00 V
Maximum_discharge_current: 380 A
Maximum_charge_current: 380 A


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## Swing (Apr 25, 2021)

@urgi 
How did you open them? With a chisel, or with heating a bit?
I didn't try anything on the CAN bus. How did you do the read out? Connect something directly to can bus of the module and then used a Volkswagen app?

It would be interesting to get all the CAN commands. And especially for the other components. The motor/generator (alternator) and the 48 to 12v converter. And how to operate them.


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## urgi (3 mo ago)

#Swing

Open with hammer and chisel few time on side and pry by screwdrivers 🪛 and folow arround.

I did communicated by VCDS over CAN 500kbps powertrain just hook up 4 wires on PCB 

If you have all (I believe need as well Gateway ) system may works as in car but need to have all sensors ect


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