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Front Collision TESLA P85. Repair and Troubleshooting Help Needed.

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#81
I've heard that Teslas really suck back the juice from the 12V battery, so my guess would be that the DC-DC converter isn't doing it's job, could be several reasons, either it's not connected properly/working at all, or it's simply not getting the message that it's needed.

I suppose to test the theory, put a volt meter on the cables heading from the DC-DC converter to the battery and watch for a while (possibly a long while as it may be intermittent) if you're reading less than 12v you're not charging, if you're in the 13.5-14.5 range you're charging, and if you're much higher than that something's definitely wrong and not good for batteries.
 
#82
jaguar36 said:
It sounds like they didn't just remotely brick CJS2's salvage car or anything. However as a condition of doing the inspection they did requrie him to give them permission to kill the car if they felt it was warranted. Without that they wouldn't let the car supercharge, or use 3G, which does make sense.

I certainly think that Tesla has to do a better job dealing with salvage cars, as it will start to effect insurance rates.
Click to expand...

It will affect more than that...it will affect EPS, buyers confidence and most likely it will result in litigation...and if these actions that Tesla are taking arent expressly written in the Ts and Cs, I cant imagine how they could act on them without someone seeking damages.
 
#83
Just a little update. So i left my 12v battery connected to the car for around 24hrs, and when I came to check it out, it was almost dead. My multimeter showed 6.7V on the battery terminals. I understand that my DC-DC can be faulty or something, however it was removed from the car that was wrecked on the drivers side, and was not damaged. Are there any ideas on what to check and how to get it fixed?
 
#84
Yauheni said:
Just a little update. So i left my 12v battery connected to the car for around 24hrs, and when I came to check it out, it was almost dead. My multimeter showed 6.7V on the battery terminals. I understand that my DC-DC can be faulty or something, however it was removed from the car that was wrecked on the drivers side, and was not damaged. Are there any ideas on what to check and how to get it fixed?
Click to expand...
Put a voltmeter on the terminals behind the nosecone while the battery contactors are open(use a fresh battery), then open the door(you should hear two clicks from the battery contactors closing). The voltage should jump a into the 14V range. What firmware is the car on?
 
#87
I dont know what you exactly mean. But my car software has v5.8 release. I just checked the new battery, connected it to the car, and the voltage on terminals on the nosecone was pretty much like on the battery even when i opened the door. I started to check the fuses because this was the first thing that came up to my mind and i found that 225AMP fuse is blown. Im not sure what this fuse for, because my car was driving fine even with blown fuse, hopefully when i replace it the car will start charging. Now , even when i connect fully charged battery i get message that 12v battery is low and car may shut down unexpectedly.
96e008de262bca7e7b8beb01f6909685.jpg
 
#88
I don't have the diagram in front of me, but I'm 99.9% sure that is the fuse for the DC-DC converter's output to the 12V bus.

You were able to drive basically the same as you would be able to drive an ICE car with a bad alternator..... until the 12V battery dies.

Unfortunately, I personally would be more concerned as to why the 225A fuse blew, especially if none of the others are blown.
 
#89
That 225 Amp fuse is the fuse from the battery to the DC-DC. Just like wk057 says. The question is "why did it blow?"
Either the DC-DC had a fault, or maybe the accident shorted that terminal to chassis ground on or near the DC-DC. Since you mentioned that the connector on the DC-DC was damaged it might have been the latter, but you'll need to inspect it all carefully yourself.

If you measure the voltage on both sides of the fuse while the car is turned on, then I would expect the battery side to be at battery voltage and the DC-DC side to be at charging voltage of about 13.8 to 15.5V. If this is true then I would probably try replacing the fuse (with everything shut off of course). If the DC-DC side doesn't show charging voltage then I'd try bypassing the fuse with a light bulb and see if the situation changes. I think you want to avoid replacing the fuse if the DC-DC converter output is shorted to chassis ground.
 
#94
Update. I just connected the battery and checked voltage without fuse. The battery is has about 11.9V while battery has around 12.4V. The other side in fact, has about 0.4V, which is close to 0. I dont know why I have almost No Voltage from DC-DC LV Positive cable to the fuse box.

Need your advice!
 
#95
Yauheni said:
Update. I just connected the battery and checked voltage without fuse. The battery is has about 11.9V while battery has around 12.4V. The other side in fact, has about 0.4V, which is close to 0. I dont know why I have almost No Voltage from DC-DC LV Positive cable to the fuse box.

Need your advice!
Click to expand...

It's possible the DC-DC won't engage if it doesn't detect 12V. Also, 11.9V is pretty low. A fully charged 12V lead acid battery is around 14.5V and settles in the upper 13V area (~13.7-ish)
 
#96
Yauheni said:
Update. I just connected the battery and checked voltage without fuse. The battery is has about 11.9V while battery has around 12.4V. The other side in fact, has about 0.4V, which is close to 0. I dont know why I have almost No Voltage from DC-DC LV Positive cable to the fuse box.

Need your advice!
Click to expand...

The main contactors need to be on for the DC-DC to wake up. Was the car "awake" and ready to drive? Did you hear the main contactors turn on?

It may be that the DC-DC needs to see voltage to turn on. For that I would try clipping a light bulb across the (missing) fuse terminals. The light will provide battery voltage to the DC-DC, but will prevent any fault currents from flowing in case the DC-DC has internal damage.

Please let us know what you learn, even if it works since it will help us all understand how it works in the future.

btw, wk057, I also use Digikey since they usually provide reliable links to the manufacturer's data sheets.
 
#97
The car was awake but it didnt want to drive because of the low battery message.

Otmar, you are saying just to get a regular 110v light bulb and connect it instead of fuse,
Then connect 12v battery and see whats gonna happen? Is this correct?
 
#98
Yauheni said:
Otmar, you are saying just to get a regular 110v light bulb and connect it instead of fuse,
Then connect 12v battery and see whats gonna happen? Is this correct?
Click to expand...

I'd suggest a 12V light bulb, like a regular (incandescent) brake light bulb in a socket with wires. I keep one around taped up with clip leads to use as a current limiting link. The advantage is that if the load across the bulb is high, then the bulb lights up. A 110V incandescent bulb could could also work, but won't light much (just a dim glow) if there is a load, plus it can be hard to find old school 110V bulbs anymore. :)
 
Last edited:
#99
Keep in mind the light bulb will burn out (like a fuse) under substantially less current than the DC-DC is capable of, potentially even under the current it would see under normal use to charge the 12V battery. So, this may be futile... but would be my first test as well.

But, again, if you're seeing 11.9V on the 12V battery I would suggest charging that with an external charger 100% first, probably to ~14.5V.
 
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