Error Code P0A90-604

Hello Prius fellows,

I'm seeking your expertise ...

I just made my own PHEV-addon (with Tesla-style 18650 cells, and the same style packs) for a Prius 2004 (second gen).
When i drive Prius without my battery connected (via a contactor) i don't get any error codes, the car runs fine.
When i turn my battery on (lithium battery gets connected to the nickel battery, they are coupled in parallel) the car after having driven for about 5 to 10 kilometers gets an error code: P0A90-604.
I checked that code on the Internet and it says:

DTC Detection Condition: MG2 power balance malfunction (small power balance)
Trouble Area: - Battery current sensor - or - Hybrid vehicle motor

My lithium battery is connected to the main relays of the prius battery (and is on the battery side, so when the car is off, i still get high voltage on the harness that comes out of the nickel battery and goes into the lithium battery)

My suspicion is that since the lithium battery is connected before the current sensor on the nickel battery, what happens is, that the generator (MG2) say outputs 100A, but the nickel battery (according the the current sensor) only receives a small fraction of that, while the majority of the amps gets utilized in the lithium battery (6kWh).

What do you think, if i put my lithium battery connectors behind the current sensor (or in other words connect the lithium's positive and negative poles directly to the corresponding poles of the nickel battery), should this help resolving the 604 error ?

Thank you very much in advance!
Kind regards,
Denis

 

nothing else besides the battery. (but the battery itself has also a bms, a charger and a switching box full of relays)
The car works just as fine as long i do not activate my battery, but even then, when my battery is turned on, the error message comes on only after 5 to 10 km of driven distance.

 

Thanks, I thought so too. I will reconnect my battery during this weekend and see what happens.
My goal with the extra battery is to drive electric to and from work (25 km each way, 50 in total). Theoretically i should get 50 km or so in electric mode (6kWh).

 

Most of the retro kits have / or had a dc-dc converter. Mine doesn't. With out a converter it is cheaper and more safe.
I also have the plug-in part, i charge it using an Elcon Chrger 2.5kW

 

Correct, it will be connected this way in a couple of days Thanks for the reply, i was having similar thoughts

 

Thanks! I will post pics and detailed video of the kit.

 

Thanks!

 

I've got 58s21p. The cells are Samsung INR18650-13L, chemistry NMC. The pack get charged up to 243,6 Volt.
It is still in development, theoretically it should be good for 50-60 km of pure electric distance.

 

still in development ...

 

Nope. As long as the voltages of the packs do match, and the packs themselves are kept actively balanced, you can mix as many chemistries as you want (of course within the reason).
Luckily for as (garage tinkers), the prius ECUs and softwares do not trace the chemistry of the batteries as long as thermal, potential (aka voltage), resistance and other parameters are kept within the predefined range in the prius' operational algorithms.

I was also having an idea of building myself a hydrogen fuel cell and couple it to the prius battery. Yes, i know, it is ridiculously useless and unnecessary, but so cool!