4x4 EVC
Well-known member
- Joined
- Jul 29, 2024
- Member Number
- 7987
- Messages
- 105
I thought it might be interesting to see how EV conversions aren't the end all and be all of everything perfect in the world - far from it.
They break, things you build don't always work out, stuff on the trail brakes things, etc., etc., etc. - all normal.
Sometimes it's just a bad design or temp-fix - exactly like every other DIY fix on your rig - but, because it's EV, you might be interested in how things break, what happens next, how to spot it and most importantly, how to fix it, even on the road.
So, I'll kick it off - FAILED HV (AC side) WIRING
First, gotta' show you how I charge - I use a standard J1772 plug and socket that is the most standard plug in the world for all EVs (including Tesla with an adapter). For me, I ran that from my gas fill pipe location (for obvious reasons) then run all the way to the front to the OBC (On Board Charger). Here's how it runs:
Once it reaches the OBC, it looks like this under the hood:
So, now the FAIL.
I was charging up the Jeep after a long day of driving, down to just 5% (that's bad, I know, I know...), which requires it to charge for about 6 hours. When I went out to check on it, I asked my son if he smelled anything, like the smell of a burning wire or rubber or something like that.
He did but it wasn't coming from under the hood, it was coming from under the rear passenger side wheel well. Here:
Ugh!!!
Here's where it was if looking from the side:
(NOTE: this is a picture AFTER I fixed it, showing the path only here)
While charging, it uses AC to pump juice into the OBC which is basically an inverter to convert AC to DC.
The fail is in the wiring - when I made this harness, it was too short to run from the back to the front of the Jeep. So, I used a solder slug heat shrink but joint. Those things work great EXCEPT if you use coper wire and join it to tinned wire.
For reasons I don't need to go into here, the solder slugs are NOT super useful with tinned wire. The just don't work well at all.
This cause resistance and as we all know in ecteronic and personal relationships, resistance causes heat and heat causes (divorce, break-up, throwing toasters) failures.
Here's the fail, showing it here after I pulled the harness out:
Failed design: NEVER, NEVER, NEVER EVER have two joints on the same line unless an emergency. I had two joints within 6" of each other. FAIL - how stupid. Each time you have a joint, regardless of how good it is, it will causes resistance.
So, with a long charge, it must have heated up one or both of the joints and due to the way I ran the wires around the frame rail, it happened to put the joints on a bend and when it got hot, it remelted the solder joint and started to bend, this caused the wire to heat up even more as the AC juice tried to 'jump' the bend.
Once I saw it, stupidly, I reached my stupid finger in there to see if what I saw was indeed a break - so stupid. Of course it was. When I touched it, it arched to the frame.
Here's what happened next:
After I jumped back about 2 feet from where I was standing, I disconnected the J1775 connector and stared at it in disbelief. I wasn't shocked but I was surprised.
Afterwards:
In fact, it now charges faster - due of course, to the lower resistance of the harnesses joints. Not like double fast but still, noticeably faster.
Lessons - at least for me:
Notes: even though I fried this harness, the Jeep could drive because the charge harness isn't part of the drive circuit. It could drive with that entire circuit / harness removed. Just not charge until I fixed it. So, if I was on the trail and I was charging using a generator or at the camp site that had either a genny or a plug, I would still be able to drive out on my own, if I had enough charge. When I noticed the smell of burning plastic, I had about 67% charge, so about 65 miles or range. Plenty to get out or home or back to humanity if necessary.
Done, fixed, back to 100%.
- Patrick
They break, things you build don't always work out, stuff on the trail brakes things, etc., etc., etc. - all normal.
Sometimes it's just a bad design or temp-fix - exactly like every other DIY fix on your rig - but, because it's EV, you might be interested in how things break, what happens next, how to spot it and most importantly, how to fix it, even on the road.
So, I'll kick it off - FAILED HV (AC side) WIRING
First, gotta' show you how I charge - I use a standard J1772 plug and socket that is the most standard plug in the world for all EVs (including Tesla with an adapter). For me, I ran that from my gas fill pipe location (for obvious reasons) then run all the way to the front to the OBC (On Board Charger). Here's how it runs:
Once it reaches the OBC, it looks like this under the hood:
So, now the FAIL.
I was charging up the Jeep after a long day of driving, down to just 5% (that's bad, I know, I know...), which requires it to charge for about 6 hours. When I went out to check on it, I asked my son if he smelled anything, like the smell of a burning wire or rubber or something like that.
He did but it wasn't coming from under the hood, it was coming from under the rear passenger side wheel well. Here:
Ugh!!!
Here's where it was if looking from the side:
(NOTE: this is a picture AFTER I fixed it, showing the path only here)
While charging, it uses AC to pump juice into the OBC which is basically an inverter to convert AC to DC.
The fail is in the wiring - when I made this harness, it was too short to run from the back to the front of the Jeep. So, I used a solder slug heat shrink but joint. Those things work great EXCEPT if you use coper wire and join it to tinned wire.
For reasons I don't need to go into here, the solder slugs are NOT super useful with tinned wire. The just don't work well at all.
This cause resistance and as we all know in ecteronic and personal relationships, resistance causes heat and heat causes (divorce, break-up, throwing toasters) failures.
Here's the fail, showing it here after I pulled the harness out:
Failed design: NEVER, NEVER, NEVER EVER have two joints on the same line unless an emergency. I had two joints within 6" of each other. FAIL - how stupid. Each time you have a joint, regardless of how good it is, it will causes resistance.
So, with a long charge, it must have heated up one or both of the joints and due to the way I ran the wires around the frame rail, it happened to put the joints on a bend and when it got hot, it remelted the solder joint and started to bend, this caused the wire to heat up even more as the AC juice tried to 'jump' the bend.
Once I saw it, stupidly, I reached my stupid finger in there to see if what I saw was indeed a break - so stupid. Of course it was. When I touched it, it arched to the frame.
Here's what happened next:
- The BMS instantly kicked a isolation fault
- The EV public charger sees a fault.
- BOTH decoupled the 'handshake' instantly - NO electricity flowed from charger to Jeep, exactly like a GFI.
After I jumped back about 2 feet from where I was standing, I disconnected the J1775 connector and stared at it in disbelief. I wasn't shocked but I was surprised.
Afterwards:
- NO damage to any of the Jeep's EV components, all the built in safeties worked - thank god, the OBC costs about $1,800!
- After I got over the panic, I figured it out, there was a small bad weld on the shock tower mount on the frame. It wasn't the sole problem but it did provide a rub point that could have added to the problem. STRAP everything down!
- I had extra wire in that harness so I decided to pull the harness out as a whole, unplugging it from the OBC and cutting the rest of the zip-ties and taking it out the back of the gas fill point.
- Once out, I cut out the failed joints (SOOOOO stupid!), used new solder slug butt joints - one per wire only, electrical taped and placed the new loom around it. Then I snaked the harness back in and around the frame. It's still a bit too exposed in the wheel well area but I can re-run this later.
- Plugged it all back together, tested it and it all worked.
In fact, it now charges faster - due of course, to the lower resistance of the harnesses joints. Not like double fast but still, noticeably faster.
Lessons - at least for me:
- Pay more attention to full harness design
- NEVER skimp on all the safety features in the BMS and all your components
- DON'T touch stuff that looks like it's burnt or otherwise screwed up unless you are wearing HV gloves and everything is off.
- YOU can fix almost everything on the road / trail, don't panic.
Notes: even though I fried this harness, the Jeep could drive because the charge harness isn't part of the drive circuit. It could drive with that entire circuit / harness removed. Just not charge until I fixed it. So, if I was on the trail and I was charging using a generator or at the camp site that had either a genny or a plug, I would still be able to drive out on my own, if I had enough charge. When I noticed the smell of burning plastic, I had about 67% charge, so about 65 miles or range. Plenty to get out or home or back to humanity if necessary.
Done, fixed, back to 100%.
- Patrick
