How Test a Hybrid Pack which had been unused for almost a year

Yeah you would need some way to apply voltage to the battery pack and see if it rises see if it holds voltage like 211 which is what the system runs on The car is not going to be any help to do this It's dead as a doornail not running parts could be missing off of it I don't know. But you would need like my Venice hybrid charger set on step two and connected to the battery before you even turn it on test the battery with your test meter and see if you have any voltage at all 12 14 90 whatever it is. Then apply the charger and the way I understand it with the charger is you connect the charger it's on setting two in my case It's putting out 309 volts I think to the battery pack and you watch the meter and when it gets to the point where it makes no changes to the voltage on the meter for 5 minutes you turn the charger off That's what the charger builder said to do and then you can test the battery after you disconnect the charger wait a couple hours and go out and check it again that sort of thing Make sure it's holding voltage and all that If you wanted to get more carried away and hook up a halogen light you could run the battery down and then charge it back up and that sort of thing I guess you could mess around with the car if you wanted to put a 12 volt in it but I'm not sure your car is complete enough to make that even worthwhile.

 

Yes. But not an easy way.

If you intend to drive it again, get a good charged 12 V battery, then try to start it
and let the car tell you if the HV battery is still good or not.

You might be pleasantly surprised.

 

Some modules will self-discharge faster than others after sitting for a year which may lead to warning lights and hybrid system shut down... This is easily addressed by doing a full charge and balance using a high voltage trickle charger like the ones sold by hybrid automotive and maxx volts. Or you can save a huge amount of money and build your own charger: Build Hybrid Battery Maintenance Gear For Under $100 | PriusChat

 

A healthy pack may have the symptoms of an unhealthy pack after a year... You can just go for it and see what happens. Sometimes it's not an issue. But if it were me, I'd test it thoroughly and build a spread sheet for future reference. First by charge and balance, then after a few days or more of sitting I'd get the voltage readings of each of the 28 modules to see if any self-discharge issues are apparent. Then I'd do load testing to connect each 8v module to a halogen headlight bulb 12v/50w for two minutes to measure how much the voltage drops in each module to ensure they're all within the 0.3v to 0.4v load test voltage loss at the 2min mark. There's other tests I'd do beyond that, but that's just me... If you got a hobby charger capable of charging 8v NiMH batteries you could charge up all the modules a couple times, which would be similar to charge and balance, but less effective/thorough.