HV Battery repair gone wrong

REWARD if you can help solve my problem please.

Well I guess I’ll just jump right in.
My 2006 Prius Hv battery pack was throwing codes. I tore it down and tested all modules and found one bad 6v module. I order 1 gen2 module from a reputable source, and installed it. I didn’t have any issues with removal of hv battery or repair thanks to this wonderful forum of amazing people. I installed the hv pack and only made it a few miles before it gave me the red triangle and other engine codes. So I took it apart and sanded all the copper plates on the bus bar and torqued them down to spec. It lasted 22 miles before just the red triangle came on with no other engine lights/codes. I couldn’t get any scanner to find any codes. All my modules still tested good, the car drove fine, and the system appeared to still work and charge. After more researching I decided to see if balancing the pack would help. I had all modules right at 7.8s and tried to run them parallel to “balance”. Instead of taking the time to completely dessemble the pack and flip the modules the same direction, I stupidly built my own wire harness to connect all negatives to negatives, and positives to positives. With both bus bars completely disconnected from all modules. I hooked all negatives together, and began carefully hooking up positives. As I was finishing the first side I noticed that my harness was heating up. I began rapidly disconnecting the homemade harness and bumped into multiple surfaces creating very small sparks but it didn’t seem too alarming. I tested all my modules to see if the harness problem may have harmed them. They all tested great and almost exactly identical. I decided to just hook the bus bar back on and give it a go. I tried to start the car but my dash instantly lit up with all symbols including triangle and wouldn’t even try to start. I disconnected the 12v battery (which is brand new) to try and reset the codes. No help. I checked the service disconnect making sure it was installed correctly and tested the 125amp fuse inside the handle and its all good. The weird thing is, I can’t seem to get 220v on either side of the main line. When I try to start the car I pick up 40v then drops to 25v on the battery side of the main line. All modules test 7.8 and I’ve visual inspected every aspect of the battery pack wire harness and don’t see any problems. The display still showed 3/4 charge on the pack, so I know there is signal from the battery. I’m completely lost at this point. I’m not sure what to test next or what questions to ask. I’d like to order a nice scanner to help if anyone has a suggestion for a Prius friendly one. Thanks to anyone that can help explain, and thanks for all the help I’ve received from PriusChat as an outsider up to this point!

 

You’re absolutely right, I’ve read 10 years of info but unfortunately started at the beginning. I’ve learned now that a lot of the methods I was learning are no longer practiced. Like “battery balancing” by running parallel. I have however tested load on my modules and couldn’t find any problems with any but one. I know it’s better to replace in pairs, but I wasn’t aware of that until after I ordered only one. I was thinking about ordering another one to pair with my new one, or just do a pack shuffle. Now though I’m nervous I’ve damaged something other than the modules. Like the computer, or relays, or something. The only thing that keeps me from assuming the worst, is that I have no power from the pack. Is it possible to lose all voltage just from a small sense wire? Thanks for your reply jc9! I’ve been reading your post like gospel for about a week, and I appreciate all the work you do for this forum! Sam goes for Hv Battery Hero and a few others.

 

Haha, well the code reading problem wasn’t my main concern after I lost all power from the battery. Originally I could get Orielys scanner to pick up the codes I needed, but after I attempted to fix the original problem, the car wasn’t giving me any codes, just the triangle. I tried three different scanners to no avail. Now I’m sure there are a million codes that I could pick up, but I’m not sure how accurate anything would be since I can’t even get the car to power on.

 

Oh yeah? That’s pretty interesting considering I work with voltage as high or higher than 220 on a weekly basis. I was worried that contacting the body of the car with my harness connecting to the small amount of modules I had hooked up could possibly short circuit something. I think you’re just mad because you have no idea lol.

As for me posting on multiple threads, thanks for the advice. It’s hard to use this website on my phone so I was having trouble at the beginning. You seem like a man who thinks he knows a lot.

 

Thanks, I’ve already ordered one someone suggested so hopefully it helps with all my problems. Have you ever seen an hv battery only put out 40v, but have a charge?

 

Also, thank you for the motivation to rebuild this battery no matter what. When I’m done with this one, If you’re interested in learning you can hold the light and hand me screwdrivers on the next one.

 

Well Brad seems like an a**hole. Even if he knew how to help (which he obviously doesn’t) I wouldn’t listen to a word he said.

You seem down to earth though, so thank you for your reply and advice.

I’ve tested everything and it all checks out. The only thing I think it could possibly be is the sense wire is broken inside of the insulated part of the wire. I’ve order a new wire harness, scanner, and a couple modules just in case. Hopefully I will have everything by Monday and will be able to figure it out. I just cant believe a small 16g wire could be causing me to loose that much voltage.

 

Oh and I typically work with AC. I’ve handle 600 amp junctions without a hitch dozens of times. So in no way am I nervous about handling 220v.

 

You didn’t misunderstand anything. What you’re explaining makes perfect sense, and is kind of what I assumed to be close to the problem. I haven’t messed with the car since first posting, but I plan to go back over everything I could have missed. Thanks for the help. I’ll fill you in when I get everything I need Monday.

 

I came to this forum with the upmost appreciation for the help you guys give to people for free. I even wanted to pay for the help because that’s how much I appreciated it. I never pretended be an expert about these cars or this forum. Regardless, I’ve seen multiple “experts” like brad act like know-it-all a**holes to people just looking for help. I don’t need to belong to a forum for seven years to see that.

 

That’s exactly what I wanted to hear!

 

Being concerned for someone’s safety is one thing, being a jerk is another. It’s very easy to decipher the deference.

I obviously offended him from “hijacking” someone’s thread, but in my defense at first it was the only place this forum would seem to let me post.

I’m not seeing any danger in my first post other than building my own harness and it heating up. (The info to run parallel came from this forum and people like you to begin with). However before I was even done connecting them I realized my points were heating up. When I say heating up, I literally mean just getting warm. I’m familiar with electricity, so I understood very quickly that if I continued connecting them and left it alone, the small amount of heat could become dangerous. So while disconnecting them I touched the car with the harness and created a small arc. I was worried it could have shorted something. (Hints me writing on this forum.)

How else but headlong would you jump into a project? This is not rocket science, despite how hard you guys might like patting yourself on the back.

I have respect for this job and electricity, direct or alternating. I’m literally rewiring an entire church as we speak. I do not need some keyboard warriors to tell me how to respect electricity. Obviously there are things about this battery I don’t know, which is why I’m here... so what exactly are you referring to when you say

“and the possibility that there could yet be some stuff you had never thought worth spending the time to learn, that really might be”

Am I not here on this forum trying to learn?
If I assumed there was nothing to learn, why would I even ask questions?