Yeah, from what I gather, turning the car on while it's charging confuses the battery because it gets two conflicting signals, one from the car's computer, another from the grid charger, and that breaks a bunch of stuff. These cars aren't originally designed to be grid charged, so the system is more delicate than an actual plug-in hybrid vehicle.

 

Hi,
I just bought HCH 2007 only 53k miles driven and last serviced from honda at 50k miles. Everything is good so far. It gave me 53.6mpg (uk) on highway. Auto stop and battery looks perfect. The only issue I’m facing is that the fan runs constantly on high speed. Starts when I switch on and goes off after few seconds of switching off the engine. I have no idea about the grid chargers on anything. I don’t even know the history of the car related to grid charging. Hybrid batteries work looks OK to me. Did anybody find the solution of this problem?

TIA
Saad

 

On the HCH I shorting the PWM control line to ground would do that. Assuming the HCH II is similar one of these may be the case:

1. In the cable that line is shorted to ground.
2. The controller is broken and holding that line low.

More complex failure modes are possible. For instance, the controller may think your battery is very hot and so has cranked the fan all the way up to cool it.

If it were my car I would try to get a probe onto the PWM wire to see what is happening. If while the car is off there is no resistance from the PWM wire to ground then it is probably a short. If you are lucky it will be in the little stub of cable that plugs in the fan. Otherwise it is in a longer cable and I don't know where that one goes in your car.

 

Your initial assumption is correct.

 

So, sorry to somewhat necro this post, but it's the top result in a google search and I am having the exact same issue with a new maxxvolts charger.

I reached out to them via their website, and did not receive a response - they claim that I typed my email address incorrectly. Since I hadn't heard, I opened a refund-request through ebay to either get the charger returned, or hopefully to finally find a fix to this fan issue.

From maxx-volts:
This is the 4th reply from them with roughly the same content, each time they've been asked if they have a fix for this particular problem. They've been linked to this thread and still claim there's nothing in their charger that could possibly cause this, even though it's clearly related to this particular device.

 

I know this is an old thread, but have the same issue after installing (and fully removing) a Maxx Volts charger. Did you ever resolve the issue?

I've fully removed the balance charger and installed a new hybrid battery—still the same... fan runs at full speed any time the car is running.

 

I never got it resolved. I just ignore the noise now.

I got multiple extremely rude responses from MaxxVolts basically calling me a liar, and saying that everyone from this thread is lying about this as well, and that nothing in their unit could have possibly caused this... which everyone here knows is total bullshit. He also said "it's because your **** car is 15 years old and the batteries are overheating", which is hilarious, as it's a brand new pack I just had warranty-swapped from GreenTec. I bought the grid charger in anticipation of extending their life, not in expectation of causing more problems.

Recommendation: don't ever do business with Maxx Volts.

 

Sorry to hear this. I've not heard of this with other products. I would suggest you contact MV, but I doubt you'll get any satisfaction. It seems that anything that goes wrong with their units is clearly the user's fault.

If the install/removal process ever results in grounding the PWM signal line, you will get this behavior. I can't say if something in the equipment or installation could somehow result in this being a permanent condition, but that's what it seems like. If you're in a climate that get's pretty hot, the only risk is burning out your fan motor - which is way cheaper than a new battery. Even in cold weather, it helps to warm the battery to a more favorable operating temperature.

Also, since you've been back there, NEVER operate the vehicle with the IPU lid open except for short test drives. When the cover is off, battery and component cooling is disabled.

If I ever own another HCH2 here in Phoenix AZ, I may incorporate this "feature" into my fan. Honestly, I'm likely to do it on my HCH1 as I've already been through a couple reconditioned batteries (of my own build from crap laying around with minimal effort to make a long term repair), in the last 5K miles or so.

 

This is actually a feature of most Prius Hybrid apps like Dr. Prius and Hybrid Assistant, the ability to turn on the fan high and at lower temperatures to extend battery life at least in theory. I like it. If you are anywhere from middle USA southward I would definitely say its beneficial to have the fan running.

 

Except those things accomplish it without breaking the system. I can definitely see a downside when the interior of the car is 140°F, and the battery is 25°F cooler. Not a lot of advantage to ramming 140°F air through it to heat it up. Delaying it 5 minutes to get the interior cooled down would be great. This is the primary reason I haven't done it on the HCH1.