I have 2004 (DD) and a 2005 (project) HCH1 and a Maxxvolts EV-1 grid charger. I have successfully grid-charged the batteries of both cars multiple times both in and outside the vehicle. When inside the cars the charger powers the IPU fan without issue... until recently.

The last time I tried to grid charge, everything started correctly and the fan was running (seemingly at full speed as expected). I went to check on it about 1.5 hours later and the fan was no longer running at all. I immediately terminated the charge. It was a February day in Michigan so I'm hopeful the battery did not get hot enough to be damaged. Now I am trying to figure out what went wrong and what I might be able to do to fix it.

I am aware of other users' issues with the IPU running constantly after grid charger use (stemming apparently from the MV unit cooking the BCM). I have not had this problem. While my current problem could have a similar cause, it is not the same issue.

Other possibly relevant information:
- The 12V battery was not installed in the car during charging or later testing. I know this doesn't affect IMA battery charging but don't know what effect it may have on fan control.
- Out of necessity, the charger was plugged into the equivalent of a 100' outdoor extension cord. Some forum research suggests that this may have contributed to the problem due to the added resistance but I would like to understand better why and how.

Things I have checked and corresponding results:

- Confirmed that all connections from grid charger to vehicle were correct, still had continuity where expected and no continuity where not expected.
- Confirmed that IPU fan still works by applying 12V battery voltage across blue wire and black wire at connector adjacent to fan.
- Checked voltages supplied by grid charger to various pins. The charger harness has five wires. I measured their outputs (using an inexpensive DMM) with the charger plugged into the 100' extension cord (first voltage listed) and later with it plugged directly into a household outlet (2nd voltage listed). Here are the results:

Wire ---------------------V(100' cord)-------- V(no ext. cord)
Red (IMA+) -------------->260V-------------------- >260V
Black (IMA-) ----------------0V ----------------------- 0V
Green (Ground) ----------- 0V ---------------------- 0V
White(to fan red) ---------12.1V -------------------12.1V
Orange(to fan blue) ------7.4V* ------------------- 9.2V*
* If this is actually a PWN signal it may not represent a voltage but rather a combination of voltage and % of time pulse is "on". I would like to understand this better.

Questions/Things I would like to understand better:
1) The IPU fan has a four wire connector (yellow, blue, red, black). I know that the fan is PWM controlled but I don't know the specific role of each of those wires in modulating the pulse width. (For this reason I can't tell if the voltages my charger currently supplies to the fan wires are problematic.) Any help in understanding this control system would be very useful.

2) Would anyone who has a Maxxvolts charger know, or be willing to measure, what the expected voltages would be at the various wires/pins while running (but not connected to the vehicle)? It is really only the voltage to the orange wire (pin 5, the center pin in the 3x3 grid) and the white wire (pin 7, the one that is the only occupied pin in its row) that and I need to compare to my own readings.

3) Does anyone know if any of those wires from the charger supply a PWM signal or if they are just constant voltage? (On one hand, since it seems to be running the fan constantly at full power, I would have expected just a straight 12v supplied to the fan and a return path to ground. However, since the MV charger does not use the ground (black wire to the fan connector) this does not seem to be the case. Also, when I supply 12V across the two wires that the charger does access (blue & red) the fan does nothing. But when I apply 12V across blue and black, the fan fires right up at apparently full speed.)

My theory is that the voltage supplied to one or both of the fan control wires is incorrect either because of A) the added resistance in the long extension cord or B) because something inside the charger failed (or B caused by A). I'm hoping that the info & insight provided by other forum members can help me either confirm or correct that understanding. Thanks in advance for anything you can contribute.

 

There is another thread on this issue. It appears the Maxx Volts charger damages the fan control circuit on the MCM. I would be interested to know if you still have the vehicle if the fan works normally when the charger is unplugged.

Here is the link to the other thread: https://electricvehicleforums.com/fo...-install-31066
Reply over at that thread if you can so we can keep this issue in one spot.