I checked the voltmeter and lo and behold, it had a common ground. So effectively I was connecting the negative terminal of the IMA system to ground.
It did not like that.
Neither did the voltmeter which now only displays a strange reading without much reference to the input, even when fully isolated.
I ripped the meter out and tested all connections for further shorts. None of that, everything should be fine.
With the harness reinstalled, ex voltmeter, it was time to test the waters again.
First, test the harness without batteries again. No problem whatsoever.
Hooked the Fluke up to the current bearing connector terminals and they show 107.5 Volt; about average.
Switch off, hook up the batteries. I can now test the system voltage through the charger connectors on the batteries. 126.0 Volt, the batteries hold 42 Volt each, being charged to capacity.
The moment of truth. Flip the switch!
The voltage races down to 109.5 Volt and stays there for a second or ten. Then I hear the dreaded Ping on the dash:
Check IMA system!
The voltage is back up to about 122 Volt. The IMA system disconnected the terminals and the battery shows what its resting voltage is at 99.9% SOC.
Switch off. Contact off and on again. Reset the IMA codes.
What if the engine were running?
I start up, walk to the back, flip that switch again and see the voltage race back down to 109 Volt. And it stays there, no codes.
Success!
Time to put it on the road for a few laps around the block.
It runs fine, but as the engine is still cold there is not much happening IMA wise. The blue light goes off, still nothing much.
Fuel consumption is normal for running around the block with a lukewarm engine. The parallel pack seems to have little effect. When I decelerate it recharges mildly. When I accelerate it uses some boost but not much.
Then all of a sudden it jumps into full EV mode while accelerating mildly.
Ha, at last some effect from the pack!
PING.
Check IMA system. Dang.
The engine revs up to 1700 RPM and will go no lower.
I pull up my driveway and do the ritual:
Switch off. Contact off and on again. Reset the IMA codes. Check the voltage. Start again. Switch the pack on. Get moving again.
PING
Check oil level.
Oh Honda you funny *******, you know the oil is good. This is just bullying.
Key off-on, warning is gone.
Now for some more speed, as the crawl around the block does not exercise the system enough. But 1 km into the trip, another
Check IMA system.
Park. Switch pack off. Contact off and on again. Reset the IMA codes. Check the voltage. Start again. Switch the pack on. Get moving again.
Okay, this was still in suburbia. I'm now close to a 40 mph road.
Then at last it can run free. And it does. Until the Check oil level appears again. I hide it with the Mode controls on the steering wheel.
Fuel consumption is still around normal. Hm.
I play with the gas pedal to provoke EV mode. It happily complies. Gently I start accelerating. The boost needle swings up. It works...
PING
Check IMA system.
Ritual. Get going again.
Gently acceleration is the key. One 50 mph road, doing fine. Traffic lights, wait. Engine keeps running (no auto stop) Hm. No error though.
On to the highway. The engine RPM climbs mildly while the boost swings high.
It pulls quite well now for those low revs!
But
you guessed it. Again. Luckily, once at speed on the highway the IMA system is not really necessary.
Leaving the highway at my home town, I park and reset the code yet again.
For the remainder I get spared from further codes, until I hit the speed bump area - another IMA fault code to rub it in on the home stretch.
The resting voltage on the batteries is still at around 120 Volt.
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So I have to let this sink in.
The voltage on a fully charged 36 cell LiFePO4 pack seems to be too high for the IMA system to handle with ease.
The batteries themselves hold up well. They stayed at ambient temperature, just like the cables and control box.
The voltage hardly sags; I expected it to drop to around 117 Volt unladen, but even after a 15 mile trip wit at least some extra support, so it has delivered power, yet the voltage hardly goes down.
The relays do not cause problems after all. It was the dodgy voltmeter that caused the spikes I saw.
I could reduce the discharge rate by lining up a couple of lamps. Maybe that keeps the errors away. And I can make a switch to operate the relays from my drivers position instead of in the boot, maybe even a voltmeter (though that obviously cannot be fed by the 12V system).
I will check out on those ODBII fault codes, but first some sleep now. To dream of sheep jumping an electric fence, probably
