High Voltage Battery Charge Too Low - Vehicle Cannot Start

[alchemistjazz]

Did you check the cars history for write off insurance issues eg vehicle check etc?

Yes no insurance write off

[Marco1979]

So before the 12v battery was drained completely the car drove normally. After the drain it does not recognize IMA. Might that be due to a complete reset in which the versions / part numbers are checked (and do not match the original setup)? Maybe the software needs to be made aware of a new engine?

[Lord Voltermore]

I'm reminded of the joke  "  How many computer programmers does it take to change a light bulb?  Cant be done. Its a hardware problem". 

My very basic understanding is  when you power up the car it does a series of computer  systems checks, which only takes milliseconds.If f these checks are correct  the car throws a heavy duty switch to connect the HV battery to the car.   If the software checks fail the HV battery remains isolated from the car circuits and presumably shows nil bars.  . Also i think the HV battery will be isolated from the car as a safety precaution in the event of a trauma such as a crash,  and possibly certain electrical  work being carried out. Such as replacing an engine  ,batteries etc.   Its quite possible the HV battery is fine, just isolated.      But i dont know.  Even the Honda technicians dont yet seem to know from experience  without £1500 of checks. (Not that long in the workshop I suppose at main dealer rates)   

I'd start with the basics. When the powertrain/IMA was removed and replaced outside the Honda network   was all the wiring replaced correctly with sound  electrical contacts. Or the 12v and HV battery changes.  If you are very lucky correcting a loose  connection this might solve all the gremlins.   But I suspect there will also be some sort of software reset required.  If you are very unlucky you might get electrocuted, or brickingfry some might brick the car, or get electrocuted.     

Such  problems will become more frequent when warranties have expired, rather than just those refused due to unauthorised work.   Hopefully by then there will be more experienced HV  /EV  mechanics working independently at more realistic rates.   Learning those skills could be lucrative. Or get you electrocuted, or brick expensive electronics, or start a  fire.   

[alchemistjazz]

So before the 12v battery was drained completely the car drove normally. After the drain it does not recognize IMA. Might that be due to a complete reset in which the versions / part numbers are checked (and do not match the original setup)? Maybe the software needs to be made aware of a new engine?

Will take another look in the HDS if I can see any options related to the engine change.
With the new HV battery it showed 7 bars which discharged in minutes so I assume the IMA fault existed and is shorting somewhere, hence I can not access the IMA menu.

Just need to work out the fuses it could be before checking the engine grounds.

[alchemistjazz]

So before the 12v battery was drained completely the car drove normally. After the drain it does not recognize IMA. Might that be due to a complete reset in which the versions / part numbers are checked (and do not match the original setup)? Maybe the software needs to be made aware of a new engine?

Will take another look in the HDS if I can see any options related to the engine change.
With the new HV battery it showed 7 bars which discharged in minutes so I assume the IMA fault existed and is shorting somewhere, hence I can not access the IMA menu.

Just need to work out the fuses it could be before checking the engine grounds.

Or am I getting the IMA no communication error because the HV battery has discharged too much?

[Lincolnshire Rambler]

I agree with LVs comments - assuming all the electrical connections have been correctly assembled you can see it’s a software bit of programming needed . Given some parts like LED light units need the correct coding for the Canbus system to reconfigure to operate the new part then it’s going to be the same for an engine swap - all the engine sensors may need to be reset to be accepted into the donor car ? Hence the Honda dealers £1500 quote to sort things out? You can imagine the complexity of controlling the petrol engine from the PCM unit . I think a real underestimate of the task involved in resolving maybe ?

[alchemistjazz]

Would the car have started if the new engine needs to be re-coded/re-learn? though only the electric started.

[Lincolnshire Rambler]

I don’t see that the cars electronics would be self contained enough to allow an engine swap out or any work on the HV battery . I can imagine the car would need plugging into Hondas diagnostics to enable a “step through “procedure to be run . This would ensure everything is checked and then allows the systems to work and hence the car to fully function . As others have mentioned the HV battery is fully isolated until the HV circuits have been checked prior to allowing its use to start the car or power up.