Controlling the HCH II IPU Fan
 

I'm planning to build a grid charger and I'd like to be able to use it without removing the battery from the car, so I'll need to be able to externally power the IPU fan.

I've found some info for the HCH-I (200hz PWM) but not much on the HCH-II fan; might be the same but inverted PWM signal.

I see from HybridAutomotive's older install instructions that the fan harness has 4 wires. Does anyone know which wires are relevant? Is it like 12v, gnd, pwm, something else? Or is it like 12v pwm, gnd, something1, something2?

Anyone know what connector that is?

Re: Controlling the HCH II IPU Fan
 

(+), tach, pwm, (-)


Get a high power 10A/12V PSU and short PWM to (-) and drive fan at full speed.

Re: Controlling the HCH II IPU Fan
 

Oh perfect! I can just put a 12v SPDT relay and a diode* in my harness... When the external 12v is present, short PWM to (-). When the external 12v is not present, connect PWM to the car's PWM generator.

*2 diodes if the relay needs an external flyback diode.

Re: Controlling the HCH II IPU Fan
 

If I am understanding this correctly, it can be accomplished with the relay you mention and Zener diode 1N4742. any chance you could confirm or explain a little more?

Re: Controlling the HCH II IPU Fan
 

​​​​​​​is there any way to force the fan to operate at full speed during normal car operation as well?

Re: Controlling the HCH II IPU Fan
 

At least a couple of folks on here have experienced this after installing a Maxx Volts grid charger harness, and to my knowledge, it was never resolved or explained.


I suspect the same is true - short the PWM to ground, and you have full speed fan all the time.

Re: Controlling the HCH II IPU Fan
 

I know this is old, but has anyone figured out the Maxx Volts issue? Installed one and now have the fan running at full speed all the time- even with the harness removed.

Re: Controlling the HCH II IPU Fan
 

If the harness is removed from the car it has nothing to do with the charger. Sounds like you fubared something trying to mess with the car. PS, Why are you bumping 4 year old threads in multiple forums? Respect the forum by not posting the same crap in multiple threads.

Re: Controlling the HCH II IPU Fan
 

I’m assuming this previous post is from Maxx Volts, as it’s come minutes after a quite rude exchange on eBay after I requested a refund. All I want, and I’m sure the other users with the same problem want, is a solution for how to get the fan back to normal operation.
if the fan operation was normal prior to installation and operation of the balance charger following the instructions exactly, and the issue with the fan accursed immediately after using the balance charger, and still occurs after removing it, it sounds like an issue the balance charger manufacturer would be interested in knowing and helping to resolve.

Re: Controlling the HCH II IPU Fan
 

There are people that have never even used a grid charger with their fan running on high. It has nothing to do with grid charging. One common thing I have seen is fans running on high speed on replacement, rebuilt and aftermarket batteries. Not sure if they are the same battery ID as the original ones being replaced but I know there is a code on the pack itself for some reason which is specific maybe to PTC strips, resistor bypass or whatnot.

Was this an original or rebuilt or aftermarket battery in your car?