Hidden 12v Gel Cell Deep Cycle Battery

[Porpoise Hork]

Stumbled across this video where he goes into great detail about the hidden battery on the F150 PB. He also goes into testing procedures and a lot of of other details about it. For those who didn't know about it this a really informative short video on this system.

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[Otterdiver]

So am I right in assuming this could be a very convenient place to power an amplifier from?

 

[Porpoise Hork]

So am I right in assuming this could be a very convenient place to power an amplifier from?

With the PB it very well could be.

 

[Gros Ventre]

I believe the second, small, battery is a "Keep Alive" battery for certain circuits such as the main computer memory. As such it is not simply in parallel. Rather the isolator mentioned is designed to allow it to charge without draining power back into the main system. It then is hooked into limited circuits that Ford wants to protect from power loss.

 

[HammaMan]

So am I right in assuming this could be a very convenient place to power an amplifier from?

This battery powers the ECU and other electronics during startup. I personally wouldn't use it for any high-current tapping. Given the wire size, with a sustained draw you could prevent the battery from charging. While your device may be happy eating 12 or 13v for operation, the battery isn't getting any charge from such voltage.

The isolator opens when the vehicle is started thus transferring most of the truck's 12v powered components over to that little battery while one of the 12v starters are engaged, which occurs when the vehicle is in park. While in drive, the ICE is started via the hybrid motor engaging the clutch behind the flywheel.

The belt-driven 12v starter generator is used when sufficient main battery voltage is present. When your starting battery has lower voltage, you'll hear the traditional flywheel starter engage. You can also feel the starter generator start the truck as it will quickly spin up the ICE and rock the truck -- it's a beast providing 280a of 12v juice when the ice is running. Additionally, the DC-DC converter provides 220a of 12v juice for a total 12v generating capacity of 500a of 12v power, an amount that makes twin HD alternator trucks jealous.

Given the 125a fuse protecting this circuit, as a rule of thumb you don't want an intermittent device to exceed 80% fuse capacity of the 125a (100a).

For a continual load, I wouldn't go above a device fused above 45a. Anything outside of that will cause the voltage at the battery to go below minimum charging voltage.

 

[travisN000]

I used it to add an manually switched USB / 12v power strip..

https://www.f150gen14.com/forum/thr...er-for-my-fridge-and-other-accessories.12825/

 

[towpro]

The auxiliary battery provides
support for transient electrical
loads that occur during a crank
event when the main engine
compartment battery is isolated
from the rest of the vehicle and
unable to provide transient
support.

Page 6

 

[Gros Ventre]

In other words, as has long been the practice with internal combustion tyoe engines, when starting the engine the main battery, along with a few circuits needed for starting, are disconnected from the rest of the electrical system. The computer memory and some other things are then kept "alive," and at 12v nominal, by this smaller 12v battery. Normally, the 12v system voltage drops by as much as 4 volts when starting because of the large current draw by the starter motor. In wintertime this reduction is notaby large (both current draw and battery temperature effects) as reflected by batteries that operated fine all summer and failed as winter temperatures came on.

 

[JerryLZ]

Thats roughly about where I had my other battery stashed in my 09 when I had everything amplified. I fit it in one of the cubbys under the rear seat. Didn't have a jack but I had boom boom

 

[Samson16]

The belt-driven 12v starter generator is used when sufficient main battery voltage is present. When your starting battery has lower voltage, you'll hear the traditional flywheel starter engage.

Does main battery = starting battery? If so, are you referring to the large AGM in the engine bay? If the large AGM and small AGM are connected in parallel, how does the system know the voltage level of each, or is it a 12VDC bus voltage that's monitored? The traditional flywheel starter uses less current than the starter/generator to start the ICE?

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