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Is it possible to have bigger 12v in the lightning?

Kansan

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Wayne
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Wondering if anybody ever tried the H4 upsize. I've been watching my Flash H3 with OBDLink and it will occasionally (but not always) drop from 95% SOC to 82% SOC in a few hours of being parked. A module, or modules, are doing something. The system would benefit from a bigger battery.

I also have a ICE 2023 F150 5.0 with what looks to be a similar 12V BMS. The battery that Ford provides in the 5.0 is an H6, which is far too small and many people (including me) have had problems with the H6 draining down while parked, especially in cold weather, resulting in the truck shutting down systems due to low voltage. Changing the charge level in ForSCAN made no difference - the BMS wouldn't push the battery to 90% charge. I swapped the H6 for an H8 and monitored the 12V system with an Ancel monitor and OBDLink. After installing the H8 and resetting the BMS the system went through a day of what looked to be a learning process during which it charged at very high rates - I presume it is a routine that the BMS uses to determine the size of a newly installed battery. After the learning process was over the BMS manages the larger battery very well and it resolved my low voltage issues (my driving habits did not change). The BMS charges the bigger battery at higher charge rates, so short drives recharge the battery more quickly. The extra reserve capacity comes in handy to power the modules during the lengthy active period after shutting off my truck. I did not have to change any settings in the BMS in order to achieve this result.

Watching the H3 in my Flash with OBDLink I see a noticeable difference between it and my H8. The Flash recharges the H3 at a higher amps and sustains the higher rate for much longer. I've seen my H3 battery achieve 98% charge during long drives. The BMS in my 5.0 very obviously throttles charge amperage and won't let the battery get over 93% SOC. This might be due to the fact that the BMS on my 5.0 is trying to act like a mini hybrid system - when the battery is at 89% SOC or higher, the BMS will draw from the battery during acceleration (to unload the alternator) and it will send extra charging amps to the battery during braking - in significant amounts (all to try to boost gas mileage by an infinitesimal amount.)

It's entirely possible that the 12v BMS in the Flash doesn't have the same capability (as the BMS in my 5.0) to adapt to different size batteries. So, wondering if anybody has been successful at upgrading the battery in their Lightning.
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Replacing the stock battery may be a non starter. The bms is pretty complex. What I did was add a 50ah lithium and a dc-dc charger. Charger top up the lithium when the vehicle is in “run state”, bms sees the charge current as just normal draw and tops up the agm battery normally. The lithium is mounted to the frame rail under the bed.
Do you have a model number of your DC to DC Charger? thanks
 

HI Zeus

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I'm planning to take a different approach, for different reasons (winch). Because I'm fairly clueless about electrical mods, and don't want to F anything up, I'm going to install a 12V deep cycle battery in the frunk "cooler" area (don't really seeing using the cooler as such), and have it hooked up to a trickle charger that is plugged into one of the 120 outlets. That way I'll always have a good strong winch battery as well as backup to the OEM 12V if ever needed. So, I'll basically have a closed system for the winch electrical system. I think this would be excessive for the OPs application though.
 

K6CCC

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Here's what I am planning on doing. I will have an aux battery plant that will consist of two deep cycle batteries in parallel. The two batteries will be mounted in the bed just forward of the wheel wells. Because of the shorter bed than my previous truck that means the battery boxes will be mounted to a frame holding them mostly above the front of the wheel well. That will put the top of the battery boxes just below the top of the bed. All the aux loads will come off that battery plant - 2 way radios, some lights, and several cameras. To charge the aux battery system will be two things. First is a 15 amp charger that will source power from the rear seat 120V outlet. The second will be a DC to DC converter that as far as the "normal" vehicle electrical system is concerned will simply be about a 15 amp load. Both of those charging sources will normally only be charging when the vehicle is ON, although there are times I manually have the ProPower stay on after vehicle shutdown - in which case the AC powered charger will stay on longer.
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