I apparently have a dead HV battery on a 2006 with 151k miles. Don't have the code right now but it corresponded to unbalanced hv battery pack, had the red triangle, check engine light, etc. I pulled the service plug and the cover off of the hv pack and measured voltage. I was under the impression that when the plug is pulled that there will be no voltage across the battery side leads, but I measured 177 volts. The car side was 0 volts. I then put the service plug back in and measured voltage again and it was 216 volts (battery side) and 0 volts on the car side. Does this sound fishy? Why would I measure something above 0 volts with the service plug removed? I thought its purpose was to isolate anything on the outside of pack from high voltage? Is there a clue here that maybe something other than the hv battery is not working? Thanks
That is a clue that the traction battery has a high voltage ground fault. Probably at least one module has an electrolyte leak to the battery case, which results in your being able to measure voltage even when the orange safety interlock is removed.
Okay, that's something to look for. If the orange interlock is removed, does the potential for high current to flow exist in this situation?
Hi cgates30, Pulling out the service plug merely separate the pack into 2 portions: High voltages are still present depending on where you take the measurements. I assume your car side refers to (B) and battery side refers to (A). Your measurement of 177V is not a valid value since the other end is not grounded. If you measure (A) to the service plug connector, you should get about 216/14 * 5 = 77V. If there are leakages to the ground on any of the 5 blocks, 10 ~ 14, you should get some voltage lower than 77V, not 177V. To isolate anything on the outside of pack from high voltage is the job of SMR (System Main Relay). Until you removed 1 side of the busbar, be sure to wear high voltage insulation gloves at all time when working on the HV system. Vincent
I've measured cell voltage on all 28 cells (1-28, 1 being closed to the ECU/service safety plug): 7.51 * 7.64 7.67 7.66 7.67 7.69 7.66 7.66 6.79 ** 7.67 7.66 7.67 7.67 7.65 7.67 7.67 7.68 7.67 7.66 7.67 7.67 7.67 7.66 7.67 7.66 7.68 6.38 ** 7.58 * Obviously numbers 9 and 27 have strayed from the flock. It looks like 1 and 28 are falling, but should they recover if I discharge/charge cycle 3 times? Regarding a previous post, when I pull the service plug and measure voltage on the terminals I am still seeing 166 V on the battery side of the contactor. (between the green circles in the photo below, sorry I borrowed this photo from someone else). I may be misunderstanding, but I was under the impression the service plug interrupts this circuit. I have not measured from either post (green circles) to the service plug.
The problem with using most digital volt meters is that the draw so little current any leakage "particularly on high voltages" will give readings. A 10k ohm resistor between the measuring probes will give a more realistic measurement. Or measure with a old style analog meter. John (Britprius)
I put a 10K (brown, black, orange, gold) resistor between one lead of the meter and one post on the contactor and connected directly from meter to the other post. I'm still getting a high voltage (144V. originally it was 177, then 166, now 144...). Meter is an HP E2378A multimeter. I guess it is a little old, but has compared well to other meters in the past.
Sorry I did not make it clearer in my post. The resistor does not go in series with the meter but across or between the two meter probes in parallel with the meter. This act as a very small load on the voltage being measured. John (Britprius)
High voltage ready at the contactor sub. Same here! The instructions are confusing. The reading was takin between the two main number 4 size wires.Before or on the battery side of the double contactor. With the contacts open Zero Volts on the other/fender well side. Now. Unplug the orange pluge/then the reading from the Same place will be half what it was. But mine NOW? AND HIS /HAS NO CHANGE! STILL HIGH/AS IF THE SERVICE PLUG IS STILL INPLACE CLOSED. THE INSTRUCTION MAD NO SENCE TO ME. A LEAKING CELL///THAT MAKES SINCE. SOME TIMES IVE CLEARED MY OBD 2 CODES. STARTS RIGHT UP/FOR 2 MILES. TODAY I COULD HEAR////FRYING BACON? NOT GOOD. THATS WHEN I FOUND THE 235VOLTS BETWEEN THE TWO LEGS/BAYTERY SIDE OF THE C O N T ACTS.LIKE THIS GUY. EVEN WITH THE PLUG PULLED? AND IS THIS CONNECTED? MY KEY FOB IS NO LONGER WORKING? YES NEW EVERYWHERE BATTIRES. IVE LOOKED INSIDE THE BOX CONNECTED TO POSITIVE POST TO CHEK THE FUSE I MAY HAVE DONE SomeTHING
You have at least two battery modules with electrically conductive paths to a common point, such as the case. At least one module on each side of the service plug. Hence, with the service plug removed, there is still an electrically conductive path around it. The car will have given the P0AA6 trouble code to report this problem. That'll be the code you were clearing so you could keep driving the car. As you have discovered already, with a P0AA6 code you cannot assume pulling the orange plug makes the battery safe. Some people around here will skip the high-voltage gloves sometimes and work a little carelessly inside the battery. A lot of the time you can get away with that because of the protections, like the orange plug, that are built in. When a battery has a P0AA6 code, that is not the time to skip your gloves or be careless. Whatever you do in this battery should be done very, very carefully.
