12V outlet in truck bed

[andy3888]

I want to put a portable frIdge in the truck bed. Is there a way to get 12V DC without using the 110V to 12V converter? We get 120V AC by using an inverter from the 48V lithium battery. There is energy loss during the conversion. There will be another energy loss to change it to 12V.

I have 2 approaches and not sure it will work.
1. Tap into the 48V lithium and step down to 12V
2. Connect to the 12V battery in the front. I think if the car battery is low, it will re-charge from the 48V lithium battery.

Any comment or other suggestion?

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[billybob]

I'm for efficiency but in your scenario I'd get a "portable fridge" or "plug in cooler" that goes directly to 120V. If you want 12V the 120V to 12V adapters are about $20 and are ~90%+ efficiency. I have been looking at the plug in coolers to leave in the box of my truck and almost all of them have the adapter included for 12V or 120V.

I'd bet the factory 48V to 120V is a decent design in the 92-96% range.

1. You could tap directly onto the inverter connectors and get 48V to 12V but most reasonably priced off the shelf components are still going to be around 90%. For the 4-8% savings in efficiency most likely not worth the components, cables, and risk with cutting into the factory 48V.

2. I don't know for sure but I doubt it would be setup this way. I recall there was a dual alternator scenario so I'm guessing for reliability and isolation they are completely separate systems.

I'm buying a koolatron cooler that has both a 12V and 120V. Going to use the 120 in bed and backseat. Using it this way the factory battery management system should work as expected and start the engine as needed. The battery management system may throw faults when you draw power from the 48V pack directly but there is nothing going out of the inverter.

 

[mdmeints]

Another option would be to somehow use the trailer battery charger from the 7 pin trailer plug. Not sure if that is switched but could be an option.

 

[andy3888]

I'm for efficiency but in your scenario I'd get a "portable fridge" or "plug in cooler" that goes directly to 120V. If you want 12V the 120V to 12V adapters are about $20 and are ~90%+ efficiency. I have been looking at the plug in coolers to leave in the box of my truck and almost all of them have the adapter included for 12V or 120V.

I'd bet the factory 48V to 120V is a decent design in the 92-96% range.

1. You could tap directly onto the inverter connectors and get 48V to 12V but most reasonably priced off the shelf components are still going to be around 90%. For the 4-8% savings in efficiency most likely not worth the components, cables, and risk with cutting into the factory 48V.

2. I don't know for sure but I doubt it would be setup this way. I recall there was a dual alternator scenario so I'm guessing for reliability and isolation they are completely separate systems.

I'm buying a koolatron cooler that has both a 12V and 120V. Going to use the 120 in bed and backseat. Using it this way the factory battery management system should work as expected and start the engine as needed. The battery management system may throw faults when you draw power from the 48V pack directly but there is nothing going out of the inverter.

I think you made very good point. Can you confirm the 120V is available all time? Even the truck is locked and alarmed.

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