Always on lighter/12v port - Charging battery banks

[Don]

I'm still leaning to the front connection....I guess at 20A since your reasoning makes sense, but wouldn't the 15A breaker trip from a load on that rear end before the wire melts?

Yes, fuses protect the wiring - If you run a wire from a positive source at the front of a car (maybe directly to the battery) and your panel has a 15 amp breaker at the rear of the car, what happens if your newly installed wire rubs against a sharp edge somewhere along the line and shorts to the chassis?? The answer is . . . . you have a FIRE!

Fuses should be placed as close as possible to where the power originates . . . . to protect the wiring. Additional fuses or breakers may be placed to protect the circuitry the wire is powering, but you still need a fuse of the appropriate size for the wire as close as possible to the power source

Don

 

[bradleydavidgood777]

totally makes sense thanks!

 

[yannd]

Would be nice to have all the installation photos, specially for the ones that connect directly to the 12V Contactor on the battery pack...I think @Aerowhatt has this type of setup...anyone else ? I'm looking to plug a 48V 3kWh battery bank to as 12V-48V 10A boost converter to trickle charge from the main traction battery.
Thanks !

 

[yannd]

I had the need for 12 Volt on all the time also, mine for a 300 watt sine wave inverter. I picked up the ground behind the panel that you show your set up mounted into. The always hot positive is available at the front side of the On Board Charger under the rear deck. I just removed one of the child seat restraint attachment points and ran the positive through a plastic grommet through the bolt hole left behind. Sealed and supported on each side by a good dollop of 50 year silicone caulk, #10 wire and a 30 amp wet location inline fuse very close to the positive post on the OBC. It's worked very well for 3 years now and was easy to remove and re-run for a warranty trip to the dealer. Never know any of it was there unless the cover is popped and the inverter behind it is in use.

Aerowhatt

Do you think a 50A fuse would be ok ? Any similar users in Canada that did this type of 12V connection ? (I'm in Montreal)
https://addison-electronique.com/en...current-connector-with-eye-terminal-fuse-50a/

Also, do you think a switch would be needed to avoid having the 50A being pulled at same time as when the car is on (I guess the 12V aux battery at least takes 30A?)

Thanks,

 

[JoeS]

yannd, I have a similar system, using the 48v LiFePO4 pack to run a sine-wave inverter which powers my refrigerator and induction cooktop when the grid goes down. In my case, I have a fused Anderson connecter hooked up directly to the 12v battery, so it's primarily a static system. I can envision, if I needed to use this setup while driving, (e.g., while on my way to help someone out), I could run an external wire from under the hood and around through a window to the pack sitting in the back.

Edit: we just cross-posted. Is that 12v@10A or 48v@10A? In my case, I'm slowly trickle-charging the 48v bank and not trying to supplement the power draw on it.

I sure miss Aerowhatt, as he passed away late last year. He had a great technical bent and did a lot of experimentation which he shared with us.

 

[Don]

Do you think a 50A fuse would be ok ? Any similar users in Canada that did this type of 12V connection ? (I'm in Montreal)
https://addison-electronique.com/en...current-connector-with-eye-terminal-fuse-50a/

Also, do you think a switch would be needed to avoid having the 50A being pulled at same time as when the car is on (I guess the 12V aux battery at least takes 30A?)

The little 12 volt battery wouldn't provide 30 amps for very long (in only 15 or 20 minutes, the battery would probably be pulled down to 10 volts) and 50 amps would last even less time, so the car would need to be in 'Ready' mode so that the power is actually coming from the traction battery, via the DC to DC converter. The converter is rated for 75 amps, but I doubt it would be very happy if you were pulling 50 amps continuously - It would get pretty hot pretty quickly and if you start burning up components on the car, things will get expensive. If you're going to run an 8 gauge wire, a 50 amp fuse is fine. If you want to use 10 gauge, just swap out the fuse for a 30 amp

Don

 

[Herbie]

I had the need for 12 Volt on all the time also, mine for a 300 watt sine wave inverter. I picked up the ground behind the panel that you show your set up mounted into. The always hot positive is available at the front side of the On Board Charger under the rear deck. I just removed one of the child seat restraint attachment points and ran the positive through a plastic grommet through the bolt hole left behind. Sealed and supported on each side by a good dollop of 50 year silicone caulk, #10 wire and a 30 amp wet location inline fuse very close to the positive post on the OBC. It's worked very well for 3 years now and was easy to remove and re-run for a warranty trip to the dealer. Never know any of it was there unless the cover is popped and the inverter behind it is in use.

Aerowhatt

Reviving an old thread......:
I'like to mount an inverter and/or make connection for infrared heating in the same way/on the same spot as (late) Aerowhatt did. Can anyone point me in to the right spot to tap into the 12V system in the engine bay?
Some pictures would be great!