3rd battery
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Tuned
Joined: Mar 2020
Posts: 325
Likes: 106
From: SoCal
3rd battery
Hey all!
I am considering putting a 3rd battery on the frame rail of my truck for running accessories like a 12 volt fridge in the bed and anything else I can think of. Today I am running my fridge off upfitter switch number 5 (set to always hot) but while camping I am worried about putting stress on the truck batteries. Plus let's be honest these batteries are for starting the truck...
I currently have two schools of thought and am curious who might have done this and general input on my project.
-Install a DC to DC battery charger and just run it off my Upfitter number 5. This allows to charge the 3rd battery while the truck is on or off. These chargers typically have battery rundown protection and support multiple inputs (maybe I do solar as well). One challenge is few of these are weatherproof so it should be installed in a box or the cab which means running wires in and out of the cab.
-Install a battery isolater and connect the 3rd battery so it is always charging off the alternator and not worry about it.
Thoughts, comments, recommendations?
I am considering putting a 3rd battery on the frame rail of my truck for running accessories like a 12 volt fridge in the bed and anything else I can think of. Today I am running my fridge off upfitter switch number 5 (set to always hot) but while camping I am worried about putting stress on the truck batteries. Plus let's be honest these batteries are for starting the truck...
I currently have two schools of thought and am curious who might have done this and general input on my project.
-Install a DC to DC battery charger and just run it off my Upfitter number 5. This allows to charge the 3rd battery while the truck is on or off. These chargers typically have battery rundown protection and support multiple inputs (maybe I do solar as well). One challenge is few of these are weatherproof so it should be installed in a box or the cab which means running wires in and out of the cab.
-Install a battery isolater and connect the 3rd battery so it is always charging off the alternator and not worry about it.
Thoughts, comments, recommendations?
Mountain Pass
Joined: May 2020
Posts: 243
Likes: 94
Most DC-DC chargers are usually set so that they only charge the house battery when the vehicle voltage is at about 13.5 or higher (usually adjustable), so it's only charging when the alternator is charging.
There are different types of isolators: split diode and solenoid. The split diode type are generally not very good as they'll have a 1 volt voltage drop. The solenoids have a few disadvantages, but I do like them for some applications.
The dual battery setup will run your typical 50qt ARB fridge for a couple days without much of a drop in battery voltage. I do this a lot.
It really depends on how complicated you're willing to make your setup and various conditions, such as draw, how you use it, and sun availability (for solar).
You could just run it off your main batteries and use a 100 watt solar panel to charge them.
The needs on my next truck (2022 F450) will be a little different, and so that setup will definitely be on the complicated side of things.
There are different types of isolators: split diode and solenoid. The split diode type are generally not very good as they'll have a 1 volt voltage drop. The solenoids have a few disadvantages, but I do like them for some applications.
The dual battery setup will run your typical 50qt ARB fridge for a couple days without much of a drop in battery voltage. I do this a lot.
It really depends on how complicated you're willing to make your setup and various conditions, such as draw, how you use it, and sun availability (for solar).
You could just run it off your main batteries and use a 100 watt solar panel to charge them.
The needs on my next truck (2022 F450) will be a little different, and so that setup will definitely be on the complicated side of things.
More Turbo
Joined: Mar 2021
Posts: 507
Likes: 233
I am using a Bluetti EB70 to keep my fridge running in the backseat. I have the fridge plugged into the Bluetti's 12v port and the Bluetti charing off the 12v port in the truck. I can put 20% to 40% charge back into the Bluetti with just 2 hours of driving. I have tested the Bluetti and it can power the fridge for about 60 hours in the house. Will be a lot less in hot weather though. But since I drive every day most of the time, I should be able to put more charge back into the Bluetti than I use over night.
Thread Starter
|
Tuned
Joined: Mar 2020
Posts: 325
Likes: 106
From: SoCal
Most DC-DC chargers are usually set so that they only charge the house battery when the vehicle voltage is at about 13.5 or higher (usually adjustable), so it's only charging when the alternator is charging.
There are different types of isolators: split diode and solenoid. The split diode type are generally not very good as they'll have a 1 volt voltage drop. The solenoids have a few disadvantages, but I do like them for some applications.
The dual battery setup will run your typical 50qt ARB fridge for a couple days without much of a drop in battery voltage. I do this a lot.
It really depends on how complicated you're willing to make your setup and various conditions, such as draw, how you use it, and sun availability (for solar).
You could just run it off your main batteries and use a 100 watt solar panel to charge them.
The needs on my next truck (2022 F450) will be a little different, and so that setup will definitely be on the complicated side of things.
There are different types of isolators: split diode and solenoid. The split diode type are generally not very good as they'll have a 1 volt voltage drop. The solenoids have a few disadvantages, but I do like them for some applications.
The dual battery setup will run your typical 50qt ARB fridge for a couple days without much of a drop in battery voltage. I do this a lot.
It really depends on how complicated you're willing to make your setup and various conditions, such as draw, how you use it, and sun availability (for solar).
You could just run it off your main batteries and use a 100 watt solar panel to charge them.
The needs on my next truck (2022 F450) will be a little different, and so that setup will definitely be on the complicated side of things.
Considering Solar for when I camping. Might even find one that can go on my bed cover
Thread Starter
|
Tuned
Joined: Mar 2020
Posts: 325
Likes: 106
From: SoCal
I am using a Bluetti EB70 to keep my fridge running in the backseat. I have the fridge plugged into the Bluetti's 12v port and the Bluetti charing off the 12v port in the truck. I can put 20% to 40% charge back into the Bluetti with just 2 hours of driving. I have tested the Bluetti and it can power the fridge for about 60 hours in the house. Will be a lot less in hot weather though. But since I drive every day most of the time, I should be able to put more charge back into the Bluetti than I use over night.
Fleet Mechanic
Joined: Oct 2012
Posts: 1,830
Likes: 253
From: NorCal
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Mountain Pass
Joined: May 2020
Posts: 243
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Lots of good suggestions so far. My preference is for some form of isolation. If the third battery is going to be lead acid, then an isolator is probably the least expensive solution. If the battery is higher end, like LiFePO4, then a DC-DC charger - that has the proper LiFePO4 charge profile - is the only way I would go. However, LiFePO4 has issues with temperatures below 32° F and I wouldn't expose the battery and BMS to the elements.
I recently saw a post on another forum where a Bluetti was the cause of a fire that destroyed a house. Will Prowse on YouTube has mixed reviews of the Bluetti units over the past year. I could build a milk crate solar generator with equivalent capacity for less, but it wouldn't look as nice. There are plenty of DIY systems that have caused fires, but a lot of them have numerous design and implementation mistakes.
I recently saw a post on another forum where a Bluetti was the cause of a fire that destroyed a house. Will Prowse on YouTube has mixed reviews of the Bluetti units over the past year. I could build a milk crate solar generator with equivalent capacity for less, but it wouldn't look as nice. There are plenty of DIY systems that have caused fires, but a lot of them have numerous design and implementation mistakes.
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