Photos - P3030 - Burnt Wiring Harness

Not sure why they would say it in that way, because I charge until I do not see the voltage increase, and then charge for a further 4 - 6 hours. While this can be around 24 hours, it can be less and it can be more. I have been going for as long as 40 hours on a top balance.

This what I do. I use my phone (even better if you can use a spare phone) with an app called Gorillacam Pro (worth the few dollars it costs). I set it up on a tripod and take one photo every 5 minutes. It was available for Apple and Android. I say was as it looks like it has been withdrawn, from the Apple app store at least. That is a shame, because I looked at a lot of time lapse apps before finding Gorillacam Pro. In particular it allowed intervals greater than 1 frame per minute and the option of saving the images as single images to the camera roll rather than as frames in a video.

It is worth doing this, as it makes monitoring and data collection so easy and you get more reliable data with which to work.

I guess you'll be doing what I did a few years ago to find an app the fit the bill.

 

Yes the charge length is rather nebulous. My voltage topped out quite early in about 15 hours at 239 volts but listening to advice here I let it go for about 30 hours. Voltage did not change on the Prolong meter from the 15 hours to 30 hours . I like the Prolong as it’s current limited to .339 which is very very low charging current so takes forever but very little heat is generated with that low current. That is the proper way to do this imho. Takes patience but won’t hurt the pack.
My battery is a little weird in that I did the first discharge improperly or at least much differently than prolong suggests. I did the first discharge down to 87 volts then stopped. Discharged no further. Then did a 15 hour charge. Very mild first discharge. It worked great the battery was like new after that for almost a year then started to decay so I did a 30 hour charge and it’s been like new for the last 4 months. But after that first mild discharge the top voltage which was ususlly 241 volts is Now 239 and never higher.

135000 miles on the car bought it new in 2007.

 

It is a mystery although I suspect metal whiskers (I am not closed-minded and it is probably many different failure modes). A sudden polarity reversal could result in a higher voltage; perhaps even drawing two metal whiskers 'together', starting an arc, or allowing a spark to jump from a whisker and starting the short between terminals.

The two big caps next to the connector connect directly to the 'usual suspect' pin (11 or 22 IIRC). The pin that goes bad seems to have a special function as opposed to all the others. I think it is the HV leak detection circuit; I haven't mapped out the battery ECU in enough detail but I continue to research!

I would recommend, as preventative maintenance, inspecting the inside part of the battery ECU connector maybe once a year (I am going to do once every 3 months). This should detect corrosion. It won't detect invisible whiskers like those in my avatar - I can't see that with anything except my USB microscope and having the light in a certain direction - it is that thin!.

 

That orange connector that's burnt is connector B12 a 22 pin connector that monitors all battery modules via Bussbar 1 and Bussbar 2.
All the pins on that orange connector are directly connected to the battery's for monitoring.

The other smaller white connector monitors 4 ptc's for heat monitoring and 3 connections to the main final output current sensor. That circuit is fine.

The big white connector is battery blower-can buss-inverter comm-Board B+- ignition B+-com to HVCE.

All pins on the burnt orange connector are labeled VBB with the exception of the last pin 22 which is labeled GBBO that seems to be the pin that is seeing the initial damage the one on the end.

Pins 19 to 22 are burnt. We see that exact burnt connector all the time same pins 19-22 so something really bad is happening to the battery modules they connect to. Only thing that's really bad is voltage reversal. The grand failure here makes sense as it is seems to only happen on failing battery's that have there ground fault nag cleared and are continued to drive. Which makes sense since Toyota is making that ground fault a fatal failure code but when over ridden by a 12 volt battery reset and continued use fails spectacularly.

Imho I don't think there's any design problem with this battery ecu circuit. They last years and years with no issues but only fail when used out of design parameters and driven with a fatal code.

 

I agree that the battery ECU was well designed, according to the best industrial protocols etc. As a European, I am guilty for 'RoHS'. Actually I am not, because some of RoHS was nonsense - such as banning ultra-thin lead plating of components, while allowing lead-acid batteries to still exist in cars. The banning of lead-based paint was intelligent, the banning of lead in solder was stupid, and massively contributed to the e-waste phenomenon, and actually caused more environmental damage (in my considered opinion). When I was away from the UK for 5 years, I stored my powerful x86 computer in my bedroom. It didn't get damp. It was made in the early days of RoHS and was covered in 'fur' (tin whiskers to the extent that all the external connectors (RS232 etc) looked 'misty'.

All that said, all electronics since RoHS has to be lead free (except aeroplanes, which is partially reassuring since I once saw body bags in fields and plane parts on the streets everywhere after a 747 crashed - due to a terrorist bomb, but today's fly-by-wire airplane ECUs are fortunately made with lead solder, which is a good thing safety wise). There should be an allowance for car ECU manufacturers to use lead plating but unfortunately this is not the case.

My Prius battery failure happened out of the blue; it happened after I bought a Nissan Leaf and started leaving the Prius 2 weeks between using it. I had the classic pin 11/22 short, but also a short at the other side of the connector which has no corrosion anywhere. My car never had any kind of HV fault prior to this (and, in fact, I have just reassembled it after a minor refurbishment; I also cleaned the car inside to a 'valet' standard - hot work in summer (New Zealand) - the car engine was powered up so the battery cycled repeatedly. The battery is now perfectly balanced (and has a 'new' secondhand ECU without plasma burns).

Despite finding metal whiskers throughout all three battery ECUs I currently have, I can't blame Toyota. All electronics have the same problem, and it is beyond Toyota's control. That said, I will be doing some tests soon re: resistance of the battery ECU, and will either be able to make modified looms which can NEVER overheat (best case scenario), or will be able to make modified looms which, combined with a modified ECU (surface-mount component modifiations), could never overheat.

Voltage reversal still confuses me, since the cells usually can't reverse polarity and then go back to normal. However, when my ECU burnt a few connectors, the 'open' voltage sensors (those that were burnt through and electrically isolated) tended to jump back and forth between positive and negative voltages. While reassembling my car just now, I forgot to put the safety plug into the HV battery - interestingly, one of the cells (I think it was cell 10 or 11) was alternating between positive and negative - but no other error codes (no triangle of death). Once the safety plug was reinstalled, everything worked fine.

All this said:

Please make sure your battery looks good inside, replace the voltage sense harness, replace the ECU. I recommend keeping the dead ECU as they are hard to come by, and are likely to become repairable soon!

 

Cross threading is even better then loc-tite, right?

 

Still looks like there is corrosion in your lead and voltage sensing wires. Notice the nice green stuff in your second photo? You could see how much a new set if wires is. Might be worth it if you really want things clean.

 

Very nice writeup and a good job!

About the voltage sense wires - I would order one now and keep it ready for the rebuild. Also, please inspect the battery computer voltage sense wires (at the computer connector end) periodically for corrosion. Also, the parked up hybrids - please disconnect the orange connector on each one. My Prius was fine until I left it parked (and not obviously damp) for 2-3 weeks and used my Leaf for my commute. That was a false economy, but also it was interesting that the battery decided to do the burnt connector thing when the car was sitting unused as opposed to daily or near daily use.

 

I am incorrect about this. I was just rummaging around through my parts supply. The sensor harness does not come with the long cable(-) or short cable(+). Those are packaged and sold separately.