"Newer" Ford trucks don't charge house batt's?

I have a question:

If I have 2 x 100ah LiFeO4 house batteries with a charge rate spec of "1C" sitting at 20% after a rainy few days in the forest, how long does it take to charge these batteries via the truck engine when I start up and drive away, using the "7-way" connection?

I figure a 40amp DC-DC charger recharges them fully in 4 to 4-1/2 hours.

My flooded Bosch battery come with 96 months warranty.
I snatched it like 3 years ago before those warranties got nulled and now all you can get is 3 years.
When $50 battery goes dead after 3 years - you don't think twice about replacing it, but when you have $250 AGM battery who dies 2 months past its warranty, you scratch your head.

Yes, the VMAX battery has the same float voltage recommendation. Unfortunately, that’s not adjustable on the Redarc. Same float voltage regardless of the charging profile, except for Lithium which is 13.6. But, since I’m actively using the battery while we’re driving, the Redarc isn’t what’s controlling the float voltage of the camper battery most of the time. The Progressive Dynamics PD4645 handles that when the camper is at home in my garage.

But.......(there’s always a “but”) the PD4645 float voltage is 13.2, and it’s not adjustable either. It’s 15 minute 14.4 volt equalizing mode every 21 hours apparently isn’t enough to keep the battery 100%, so the Trimetric shows some capacity loss over several weeks. I have the Trimetric configured to remind me to push the “boost” button on the PD4645 every 3-4 weeks.

I’ll let everyone know how long this VMAX battery lasts for me because I don’t think there are many here who have one. It meets my needs, it’s a few months over five years old, and if it were to go casters up tomorrow I’d buy another one. Trojan group 31 deep cycle batteries weren’t cheap, and I had to pay more attention to them.

If I were going to spend any more money improving my camper battery’s charging system, it would be to replace the PD4645 with something that’s adjustable. I’m not sure what that would be right now, because there are some size constraints I have to consider.

:):)

the quality of flooded lead acid batteries has gotten really bad ever since the gov't cracked down on lead in the US. Most are not made here anymore.
I've been in the desert for 28 years, if a flooded battery in a car makes it past 3 years I consider it a gift and replace them. I've given up on them, agm will go 5 or more.

I doubt it's your ford's fault. Buy a $10 elm and download forscan so you have some empirical data on your alternator, testing with a dvm on startup doesn't tell you everything.

Kayteg1 wrote:

NRALIFR wrote:

I believed the exact same thing until I bought my current truck. All of a sudden, even though I did the same thing to the charging system that I had done on two previous trucks, using higher gauge wires than I used on either of the two, it couldn’t keep up with the draw from running the fridge in AC mode while driving, and we were arriving at our destination with a severely depleted battery. That just won’t work for us.
:):)

You are not giving specifics, so hard to figure out what you are talking about.
I had undercharged batteries with my 2017 F350 as well, even truck had dual alternators. Even I did not used power for fridge, the deeply discharged batteries did not recharge in 3-4hr drive like they used in the past. I figured out the new truck has more sensitive circuit breaker on charging circuit, who was trickling with more time off, than on and that did not give enough charge. Had the same phenomena with 40 amp converter who would not charge much in 3 hr of generator running.
So do you have lead-acid batteries and use B2B charger for them? What voltage you set?
When I am not electrician, my experience is that any charging voltage over 14V will shorten battery life.

Kayteg, go read what you wrote. You’re firmly contradicting yourself and contradicting known facts to try to prove I’m not sure what. Other than arguing against a DC/DC Charger while confirming that your truck does a poor job of charging house batteries on its own!

NRALIFR wrote:
The camper battery is a VMAX SLR125, which is actually one of their batteries marketed for solar use, but they work fine in RV deep-cycle as well. According to the specs, they should be charged at 14.4-14.9 volts, and the DC-DC charger provides 14.6 volts in bulk/boost mode, 13.3 in float.
:):)

This is led-acid battery and rated for 13.5-13.8V float.
Meaning your B2B charger keeps it undercharged.
And again, from my experience when voltage above 14V makes quick charge, it shortens battery life.
For decades driving Fords and Mercedes - batteries in Mercedes last up to 13 years, where charging system doesn't exceed 14V, when in Fords charging at 14.5V AGAIN this year, I had to replace batteries who just passed 3 years.

StirCrazy wrote:
I think that for sure you would need to change the factory charge wire to a larger guage. I was thinking in the 2/0 range back to my batteries in the camper. the only thing I kinda like about the dc to dc idea is you can limit the charge draw where if I just do a nice new charging line it will ramp the alt up to full output if nessasary which makes them run hot.

Steve

Large wire is great if you are satisfied with alternator system voltage.
The DC-DC will get 14.6 volts 20 amps on the house battery in all conditions. And drop to float if the battery becomes fully charged. Will go more than 20 but you would need to pull wire.

The camper battery is a VMAX SLR125, which is actually one of their batteries marketed for solar use, but they work fine in RV deep-cycle as well. According to the specs, they should be charged at 14.4-14.9 volts, and the DC-DC charger provides 14.6 volts in bulk/boost mode, 13.3 in float. The battery is five years old.

The specifics are that the 2016 charging system couldn’t keep up with the usage from the camper battery while we were driving, despite having installing 4 AWG wires from the truck batteries to the camper plug in the truck bed. The wires in the camper umbilical cord were 8 AWG from Lance, and were upgraded to 4 gauge when I installed the DC-DC charger.

Upgrading the wires in the two previous trucks that hauled this same camper had worked fine before. I could count on having a camper battery that was showing about 90% on the Trimetric monitor when we would stop for the night. With the 2016 truck, it would always be under 70% until I installed the Redarc. It was dependent on what the fridge thermostat setting was and where in a cooling cycle it was when we stopped, and sometimes it was much lower than 70%. Know what is now? It’s always very close to 100% when we stop.

Don’t start in on me about the Trimetric either. :W I know what it’s limitations are and I don’t take it’s indication 100% literally. I can tell when the battery is low from the way the fans and water pump sounds as well. Going to bed with a furnace fan that sounds like a low battery doesn’t make for a good nights sleep. Makes me wonder if I’m going to be able to take a shower in the morning, or get the generator started if I want to nuke my sausage mcmuffin. Hmm, sounds like a good reason to cary around one of those lithium jump starter gizmos, doesn’t it? Nah, you don’t want to mess around with that. You’ll shoot your eye out. :W:W <= (inside joke for one special member)

I’m afraid I don’t keep logs, charts and graphs on anything anymore. Too much like work. Actually, I never did much of that on my own time even when I was still working. I just used the excuse then of “I’m too busy”. Now, I’m too retired.

:):)

NRALIFR wrote:

I believed the exact same thing until I bought my current truck. All of a sudden, even though I did the same thing to the charging system that I had done on two previous trucks, using higher gauge wires than I used on either of the two, it couldn’t keep up with the draw from running the fridge in AC mode while driving, and we were arriving at our destination with a severely depleted battery. That just won’t work for us.
:):)

You are not giving specifics, so hard to figure out what you are talking about.
I had undercharged batteries with my 2017 F350 as well, even truck had dual alternators. Even I did not used power for fridge, the deeply discharged batteries did not recharge in 3-4hr drive like they used in the past. I figured out the new truck has more sensitive circuit breaker on charging circuit, who was trickling with more time off, than on and that did not give enough charge. Had the same phenomena with 40 amp converter who would not charge much in 3 hr of generator running.
So do you have lead-acid batteries and use B2B charger for them? What voltage you set?
When I am not electrician, my experience is that any charging voltage over 14V will shorten battery life.

time2roll wrote:

StirCrazy wrote:
Just a question, I understand how the smart alts in the new fords work, just had to diagnose my system to find a broen monitering wire , but just trying to wrap my head around this, if you have your charging system in tact and you have your camper pluged in and the batteries are down that would put a load on the trucks batteries and then the PCM would raise the voltage output from the altanator to charge the batteries untill that load is not detected any more, meaning the batteries are fully charged. the system doesnt say it takes 800 watts to start the truck so thats all I am putting back in. the new fords use a two wire feed back and command loop to controle the altanatore output depending on the Voltage read directly from the battery. so if you conect your batteries in the camper to the truck batteries then the overall voltage will be inbetween them and if thats the case then the system will ramp up the charge untill all the batteries are charged.

now if there is an isolater in there that could change things, and a DC_DC charger is starting to sound like it is a more efficient way to go but the responce from the altanatore should be the same either way , unless I am missing somthing like an isolator or somthing but that wouldmt make sence to have that thee when it is designed as a system to charge the camper batteries or such

Steve

Yes you have it right. The alternator does not know anything. Not the charge level in the start battery, not the accessory load. The alternator just produces the amps required to maintain the voltage set point directed by the vehicle computer.

The newest vehicles have tuned this voltage to optimize fuel economy vs just providing tons of voltage to make sure the battery is topped off quickly. So your RV battery may not receive the proper voltage at the end of a long #14 wire for any type of fast charging. The DC-DC charger will resolve this issue for the RV battery.

Diode isolator (motorhome) could drop another half volt, relay isolator (Ford truck, some MHs) will pass through full voltage.

I think that for sure you would need to change the factory charge wire to a larger guage. I was thinking in the 2/0 range back to my batteries in the camper. the only thing I kinda like about the dc to dc idea is you can limit the charge draw where if I just do a nice new charging line it will ramp the alt up to full output if nessasary which makes them run hot.

Steve