Changing batteries


(Barry) #61

Excellent, I hope you open source this or make the battery pack available to other Twizy owners on this forum :grinning:

(DaniJ) #62

Another few road tests done. This time mostly at higher speeds. Took the twizy for an endurance test and got 90km on motorway at 80-85kmh + 10km at 50kmh.
The conditions was at a temperature of 5 degrees Celsius and light wind on mostly flat roads.

Then charged the battery from empty to full, and the energy meter showed 12.7kWh was used to charge the new battery. I dont know the use/loose of the standard charger incl. 12V charger, so I guess roughly 10-11kWh was put in to the battery which is roughly as expected. :slight_smile:

The heating up of the motor is a huge issue when driving continous speeds above 60kmh in my experience.
After the motorway the motor temperature displayed on powerbox was up to 116 degrees Celsius, despite the outside airtemperature being 0-5 Celsius.
Definately some modification to cool the motor is needed if driving at such continous speeds.
Any experience on effecient cooling for the twizy motor?

(pisoiu) #63

Hi DaniJ,
Congratulations for your project.
Can you share some of its details? I am interested to know what chemistry did you used (LiIon or LiFePo), what termination voltage (per cell) and what type of balancing?
Thank you.

(DaniJ) #64

Reusing Gs yuasa lev50 cells from a wrecked ev. 14s5p makes about 200Ah as the 50Ah cells are at about 80% SoH. This setup gives same voltages as oem twizy battery and offered a fitting design of cells placement.
The bms is tricky. I followed an advice of the PowerBox guru :slight_smile: as I’m only skilled in AC power stuff, not programming. :slight_smile: So its an orion jr bms as actual balancing and a virtual bms to communicate CAN protocol with the rest of the system, as far as I understand.

(DaniJ) #65

Fully charged


Setting up the bms for this type of cell.

The custom made box. Sticks down 1cm below the buttom. Oranges pieces as vibration-pads between the box and seat fixing.

Front. Utilizing the space between the steel bars for the seat fixing. This is where the bms is located.

Rear. Keys importance is to know exactly where the space is and where the steel bars and bolts are located. All HV components are compacted in the tigny hatch along with all the HV connector.
The charging cable is the cable to the right. Unlike oem pack which has charging socket/ cable in front.

(DaniJ) #66

On a test run I drow 100km.
A fun goal was to drive to a tesla supercharger and take a picture. :slight_smile:

Done! :slight_smile:

Then I wanted to drive back on the motorway and empty the battery as test.

But even on the way to the SuC (tesla supercharger) I noticed the motortemperature surging to 110°C.
So I continued at 70kmh for a bit, but the temperature stayed high and barely reducing, despite airtemp. being 2-3°C. So I drow off the motorway as the motortemp. reached 116°C not to burn off it or the wires insulation.

I gave it a 15min break and it dropped to 95°C and drow a total of 100km on a charge mostly motorway at 80kmh.
Not bad.


Fascinating stuff DaniJ, just goes to show what can be done! Just out of interest is the battery capacity the same as before (6.1kWh?) or larger or just increased density?