Adding a second battery to a 2021 F150 Hybrid

[cvretis]

I want to add a second AMG battery to my 2021 Power Wagon. Since the normal stuff that runs even when the engine is off, there are not enough amps to run my small 12V cooler. My thought is to have 4G wire from the main battery to the new AMG mounted in a battery box in the covered pickup bed.
Connect both batteries with 4 AWG wire.
Install a Blue Sea Systems 7635 m-LVD Low Voltage Disconnect from the primary battery to the backup battery.

Any ideas on this? Changes?

Thanks

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[labjr1]

It should not create any problems. I haven't done it with my truck, but I have will all of my Jeeps to support the additional power requirements for winches and for field welding / repairs on the trail. Since you have the Prius F-150 (like me) you already have 2 batteries, so this would be adding a 3rd but as long as they stay in parallel they are just additive. I would recommend using a battery isolator if you want to keep power in reserve in the event the main system is drained.

 

[My 2ND Ford]

If you are mounting the battery in the bed, your wire size is too small. You would be better with 2 awg or 1 awg, with 1 gauge being my choice. Yes to the battery isolator.

 

[JoeRedFly]

I'd upgrade the ancillary battery under the backseat to a lithium battery instead.

 

[Gros Ventre]

Well... Is your purpose to run 12VDC things engine and generator off? If so you might consider two things. 1st is a battery disconnect that separates the engine off stuff from the rest of the truck 12VDC system when the engine is shut down (& I don't mean a low volts disconnect). GM made one of these for their trucks like the Suburban (I had this on mine). Second, given what you speak of for usage you should put in a deep cycle battery. I had one of these as a second battery on my Suburban and ran separate wiring for the things I ran engine off, like a cooler. While they make deep cycle AGM batteries, what you will really need is a regular flooded cell deep cycle battery since it'll have greater capacity. Having a low volts disconnect on the deep cycle battery, in addition to the engine off disconnect, is a good idea. If you really deep cycle that battery you can reverse a cell and when that happens the battery is gone.

 

[Diligenthunter]

Definitely recommend just upgrading the battery under the rear passenger seat, the non power boost have two battery’s here so there’s plenty of room for a bigger one.

 

[PaulGrun]

I'd upgrade the ancillary battery under the backseat to a lithium battery instead.

Is it a good idea to mix an AGM battery (the main battery in the engine compartment) with a lithium battery? The two battery types have very different charcteistics and require much different charging profiles. I don't think the two are fungible.

 

[JoeRedFly]

The lifepo4 batteries built for cars have built in battery management circuitry. A few peeps on this forum have done it. Although I would question the need to do it for something like a dometic electric cooler, not much power draw there.

 

[Popplemer]

If you're running a cooler another solution is to buy a power station and plug your cooler into that. If you plug the power station into the trucks 12v power port the power station will charge when you're driving and provide power to the cooler after the ignition is off. Cheaper and more effective if you ask me. My $.02

 

[Handle]

In this thread the incompatibility seemed to be an issue

https://www.f150gen14.com/forum/threads/testing-an-aux-batt-solution.17547/#post-363281

 

[Karl]

For my boat, I was also concerned about charging current, or a battery going bad. I found this smart charger that can isolate the batteries on Amazon:
Renogy 12V 20A DC to DC On-Board Battery Charger for Flooded, Gel, AGM, and Lithium, Using Multi-Stage Charging
Renology 12 V 20amp

 

[ReverendQ]

Definitely recommend just upgrading the battery under the rear passenger seat, the non power boost have two battery’s here so there’s plenty of room for a bigger one.

I was wondering if adding a second OEM battery into the tray and in parallel to the first would provide additional Ah to mitigate the issues of not being able to start and/or run 12VDC electronics/ports longer. Any thoughts?

 

[Diligenthunter]

I was wondering if adding a second OEM battery into the tray and in parallel to the first would provide additional Ah to mitigate the issues of not being able to start and/or run 12VDC electronics/ports longer. Any thoughts?

You’d be able to double your AH. I was leaning towards replacing mine with a larger one at some point.

Battery dimensions I took when I had the cover off.

Dimensions are if the battery was standing up not laying on it’s side.

H
4.75 could go 1.5 inch taller before hitting the noise suppression thing.

D
2 7/8

Width
5 1/4

 

[HammaMan]

This battery, that's not currently available, will fit in the box if you cut up its internals. I have this battery for testing

https://www.amazon.com/gp/product/B0C3CZQCKP/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

Here's the BMS's logic in operation. This was back in april or may. Key on, key fob in-vehicle, hvac blower setting 5, this is what the truck's BMS does (above batt connected, keep in mind below 13.4v it's consuming the LFP for all vehicle loads ~50a)...

Mods to box to fit batt

lid

Results, fits with lid closed

Even this 'tiny' LFP is comperable to a 60ah lead acid battery in terms of usable energy it can deliver. This like installing an 8x larger aux batt vs the 7ah AGM.

 

[rockfish]

If you're running a cooler another solution is to buy a power station and plug your cooler into that. If you plug the power station into the trucks 12v power port the power station will charge when you're driving and provide power to the cooler after the ignition is off. Cheaper and more effective if you ask me. My $.02

I agree and have an Anker Solix C8000 power station that I bought direct from them for $629. It can run my 12v cooler for 3 or more days and I can charge it in about an hour in generator mode while I drive. I also replaced the Motorcraft AGM battery with an H7 AGM from X2 Power which I think is very high quality. I have the original Motorcraft AGM under the rear seat as a spare and use it to run the fridge as well and charge it from a Noco 10 AMP from the Pro Power 7.2 kw generator. I go on long trips out west and want to have a spare and this is a good use for it.

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