HV Battery Almost fire and replacement :'(

On the bright side, the orange plastic is not melted. Gen 1 modules had an electrolyte leakage issue, so Toyota had a procedure to fix it by adding the nastiest sealant in the universe to the module terminals to try to stop the leaks. You have one battery that has the 'fix' performed and one that doesn't.

 

Not all Prius generations have put #1 at the same end ... that's probably why you've seen both ways mentioned. Have to be careful which things you read are for which generation.

 

Generally any rechargeable battery that goes to/near zero volts is toast. You might recover it some, but capacity and reliability will be poor. IF you can salvage the battery ecu and source a harness for it, then you could consider finding a set of Gen2 modules and making that into a functional pack.

Posted via the PriusChat mobile app.

 

Based on all the signs of overheating, I'd say none of modules are salvageable, especially if they're the original Gen1 modules.

A single bad cell in one of the modules will prevent the banks from having an even voltage and set the dreaded 3006 engine code. When this happened on my '01, I could still drive it, but the unbalanced battery caused excessive current and heat. I could hear the cooling fan running at high speed if I drove the car even a short distance. I tried swapping out the bad modules, but this was only a temporary fix which lasted a few months before another cell failed.

If all the other parts are good, old OEM battery packs are still quite valuable as a core exchange for a new Toyota battery. Normally this is done at the dealership, since a certified hybrid mechanic needs to take the ECM and relays out of the old battery and put them in the new pack, but some dealers will sell the battery to the end user if you're able to do this kind of work yourself.

Another option is to use the old pack as a core exchange for an after market battery pack which comes with all the parts, but not likely to last as long as a new Toyota battery.

You could also buy a complete set of gen2 modules off Ebay and install them, but there's no guarantee they will last.

 

I have a pack that came out of a gen 3. All of them leak electrolyte out the negative post (gen 2 too). Add some condensation/humidity, it leaks accross bus bar and down the sense wires. I've found it in the main GND cable as well. (The battery with the main GND is #1.) Eventually the electrolyte gets to the orange connector and starts to short the pins together. There is no current limiting on the sense wires, so burn baby burn. In the ECU there are 1k resistors in series to the sense wires, lot of good they do there. Could be the vents get stuck and cannot release the pressure, so the batt-post seals over-pressure and begin to leak. So we have the green mess and fires. Thanks panasonic...

 

Your theory is that electrolyte experiences capillary action along the stranded wires and causes corrosion at the ecu?

 

If you plan to keep the car rather than just drive it for a year or two, or you plan to sell it, I highly recommend you spend the cash to get a brand new battery from Toyota. You need the old one as a core, the new one doesn't come with the sense wires or the ecu or anything,
so you need a good one for that. Unforunately for us all, but good for some,with stolen cats an epidemic for the prius, you can buy cars really cheap that have good batteries these days. Still a brand new one will last 100k miles, not 1k miles..

 

Yes, I cut off the terminal and stripped the sense wires back to where there was clean copper. It seeped a good distance into the wire. Even the ground wire was heavily oxidized(black) along the length. Would not be a stretch for the electrolyte to travel outside the sense wire jacket into the harness with any condensation that may develop.

The 24S active balancer arrived yesterday. The balance wires are only 1' long. I'm still waiting on the silicone wire I ordered to extend these wires and also make a new sense wire harness with new pins in the orange connector. I keep getting a full green bar display randomly dropping to one violet bar. I've already replaced the ground ref pin in the connector thinking if it was intermittent, that would show a single bar if it went open. That did not correct the issue and I get the same thing with my spare ECU. I'm sure this is not good for the pack if the car thinks a near full battery is low and proceeds to recharge...the fight continues. Thankfully the weather is warming up here.