PowerPack 400/500 (second generation)

It is possible to transfer BMS between these batteries if done carefully. Take care that the power connectors are NOT identical on all of them!

Some housings have 4 screws, other 6. They use different power connectors from the Bosch plug to the BMS, and you must change them if for some reason you really cannot find a fitting pair.

The BMS is programmed to know if it belongs to a 400 or a 500 pack. They will work on the other, but it should be avoided as for example the diagnostic machine will only show 400, even if the battery pack is really 500.

How to open

1. Test with the button if the BMS is working okay!
2. Remove the either 4 or 6 T15 screws on the bottom side
   1. The two screws holding on the small metal plate can stay
3. Use the orange-colour thin metal pryers to pry the handle apart a little
4. Insert a large flat screwdriver as shown on the photo
5. Place the battery on the table
6. With one slow but steady and strong prying pop open the 8 plastic tabs that hold the battery together.
   1. You need a fair amount of force.
7. Flip it upside down, and the battery will slide out. You may need to wiggle a little.
   1. Be careful with the three short wires that connect the plastic tub to the BMS!
   2. Be even more careful with the button on the BMS - it is easy to break it off if you force the pack out!
8. Disconnect the BMS from the connector in the plastic tub
9. Test with the button that the BMS is still working!

How to tell if the BMS is good

No lights come on

If the battery does not charge, but there is no visible sign of damage on the board or the cells, measure the B- to B+ voltage. In most cases, it will be something very low, below 10V. If it is below 25V, that is deep discharge, and the cells are not suitable for reuse.

However, we are interested in the BMS. So we:

• Charge the battery to 30V
• Check if the lights come on
• Check if it is possible to charge with the original charger
• Check capacity on the Bosch tester

If it passed all, that BMS is ready to be used!

Lights come on, but it does not charge

Most likely it is water damaged or out of balance. Open and check. If it is the balance, the tester should also read it out. The BMS can be used!

Putting it back together

Sliding the pack back into the bottom part of the housing is challanging due to the plastic pins on the side. If you don't get it just right, it will get stuck, and it will be a big pain to get it free again - especially because of all the short wires.

The trick is to look at the handle end, and slide the long pin into the 4th groove. See the photo:

You should hold the pack parallel to the housing, get the position just right, and with a very little push it should click right in. If you need to force it, you do it wrong.

Fixing the button

If you accidentally 'broke off' the button - chances are, you did not really break it off, just took it apart. You can either put back the original pieces if they are undamaged and present, or take them off from a confirmed dead/deacticated BMS.

• The 'remains' of the button should look as on the photo, and should be operational if pushed from the top
• The plastic piece should bend downwards
• The top metal bracket's indent should be away from the edge of the board

The metal bracket can be popped off with a sharp metal plier leveraged on the IC next tot he button.

If the plastic on the button is broken, as on the photo, the metal bracket cannot hold. Then the whole button need to be desoldered and another put on. For desoldering, use air on 5, and 385 degC displayed. It will damage the plastic of the switch a bit. If it is needed for reuse, use maximum 370 degC, but it will take forever to get it off.

The button itself is 3.5mm x 4.5mm big. It is called an edge mount right angle tactile microswitch. Exactly this:

https://no.mouser.com/ProductDetail/?qs=wr8lucFkNMXz9UbduBxtIQ%3D%3D

Recell

The cell arrangement should be different than the original - makes the welding much easier! However, the assembly will require special care to not pinch the wires.

Connector pinout

Waking up from deep discharge without disassembly

• Use a desktop power supply with a Bosch connector
• Set up 28V and 5A
• Plug in, the light on the battery will come on, and it will 'let through' a current pulse
• Switch current off, wait for light to go off, switch current back on..
• Repeat this 5-6 times, until it keeps charging

Tested with cells at 1.3V, worked.