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

S Davis wrote:
My 2019 chev puts out 14.4 volts all day long, that is one of the reasons I went with a DC to DC charger, I can drive up to six hours a day for work and didn’t want to cook the batteries. With the 50 amp charger I have not had to plug in to charge, In fact I don’t have any other charger hooked up yet.

I run a compressor refrigerator and a 300 watt psw inverter in the cab as well as battery charging for my work tools. I am adding two more Trojan T-105 batteries for a total of six and another Redarc 50 amp charger for 100amps of charging.


Inverter/ charger box

So your basically new truck does not lower the voltage or output once it’s batteries are fully charged? I don’t believe that. So why would camper batteries be at greater risk of over charging compared to the truck batteries?

Not that the charger doesn’t do a faster/ better job of charging, but I’d bet $ that the truck won’t over charge your camper batteries.

Siletzspey wrote:

BFL13 wrote:

noteven wrote:
... how long will the standard 7 way pin system take to recharge Li batteries?

Same time as "ordinary" batteries. ...

FLA batteries start to accept a charge and pull amps at 12.6V, but LFP batteries start that process at 13.6V, a whole volt higher. Depending on your alternator's voltage output and the voltage drop in your wiring, LFP could charge SLOWER than FLA, and FLP charging could fail to reach 100% SOC where-as FLA could.

With my 45A Progressive Dynamics Inc charger running in FLA mode, my old ~200Ah of FLA would pull 18A over 10ga wiring. Still running in FLA mode, my 200Ah of BB LFP at 30% SOC only pulls 4A over shorter and bigger 8ga wiring. Putting the charger into boost/LFP mode (boost the voltage) increases the pull to 39A. Point being, same charger, the LiFePO4 charge rate is 1/4th the flooded-acid rate.

Sterling (make of DC-to-DC alternator chargers) has some nice videos on YouTube where they wire LFP direct to an alternator with ~4ga wire, and the charging rate is pathetic. Then they insert a DC-to-DC charger in the line and the charge rate jumps substantially, because the charger can re-boost the voltage.

All in all, current is pulled based on volts being delivered. For 7-pin systems, the Achilles heel is voltage. Solve the voltage problem, and then you can start to worry about current problems.

--tg

Good info , thanks! Yes, the current amount depends on the "spread" between the charger's voltage and the battery's voltage. You see that when amps taper when the battery's voltage rises during a recharge, while the charger's voltage is constant.

Another thing working the other way for current is the lower resistance of an Li. makes comparisons more complex to test, an Li has a flatter voltage until nearly full and a low R too.

An alternator is not like a normal converter/charger with a current limit and a voltage set-point, so that's another thing. You don't dare try for the the alternator's current rating (very high) and its voltage is sort of variable as programmed or by what the engine battery is doing compared with the house batts and what the temperature is up by the alternator. Anyway--

On Sterling and DC-DC we had a thread (garbled on my part!) that could have used your input when it came up later in the thread. You can still add something useful to this thread--be very much appreciated by the tech issues crowd for sure!

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30157504/srt/pa/pging/1/page/4.cfm

BFL13 wrote:

noteven wrote:
... how long will the standard 7 way pin system take to recharge Li batteries?

Same time as "ordinary" batteries. ...

FLA batteries start to accept a charge and pull amps at 12.6V, but LFP batteries start that process at 13.6V, a whole volt higher. Depending on your alternator's voltage output and the voltage drop in your wiring, LFP could charge SLOWER than FLA, and FLP charging could fail to reach 100% SOC where-as FLA could.

With my 45A Progressive Dynamics Inc charger running in FLA mode, my old ~200Ah of FLA would pull 18A over 10ga wiring. Still running in FLA mode, my 200Ah of BB LFP at 30% SOC only pulls 4A over shorter and bigger 8ga wiring. Putting the charger into boost/LFP mode (boost the voltage) increases the pull to 39A. Point being, same charger, the LiFePO4 charge rate is 1/4th the flooded-acid rate.

Sterling (make of DC-to-DC alternator chargers) has some nice videos on YouTube where they wire LFP direct to an alternator with ~4ga wire, and the charging rate is pathetic. Then they insert a DC-to-DC charger in the line and the charge rate jumps substantially, because the charger can re-boost the voltage.

All in all, current is pulled based on volts being delivered. For 7-pin systems, the Achilles heel is voltage. Solve the voltage problem, and then you can start to worry about current problems.

--tg

Seasons Greetings theoldwizard1!

One more quick question - just curious why you noted we would not need to use extra heavy duty wire.

Also, what do you recommend for the design of the dc to dc setup in a Ford F-350 with dual alternators and dual starting batteries?

Can just one battery be connected or is it recommended to use both batteries and what gauge wire would you recommend be used? (As we presumed the original factory charging wire would be too small.)

Thanks again!

theoldwizard1 wrote:


A DC to DC charger is the only way to fully recharge a RV house battery bank. And they do not need extra heavy duty wire !

NRALIFR wrote:
Twenty year old camper, that’s how big the battery box is. It will only hold one battery, and a group 31 is the biggest that will fit. It is an AGM, so I don’t have to pay much attention to it. It would take some major remodeling to install a bigger box.

I’ve had an idea rolling around in my head for years of redesigning the step up into the overcab bed to include a a second big AGM battery there. That’s pretty doable for me, as we need the step anyway. But you know. $$$, time, effort, blah blah. :W

Oh, and if I were to do that, the battery I’d put there probably wouldn’t be THAT much less than $450. Might even be more, and I’d still need a good way to charge it while driving. I might not need 30 amps though, having more depth with two batteries.

:):)

I have a 29 year old, and the battery comprtment in that would barly hold a small car battery. I managed to fit two 6V deep cycles in the other compartment that accesses all the plumbing and storage. bad part is I lost some storage, good part is I have 220AH and everything I take fits in the old battery compartment or inside the camper.

Steve

noteven wrote:

time2roll wrote:

noteven wrote:
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.

Only trouble is most 7-pin connectors have OEM #14 wire and a 40 amp fuse. Good chance that 40 amp DC-DC will pull 50/60 amps and open the fuse resulting in no charge. I recommend 20 amp DC-DC if using the OEM 7-pin connection.

I didn't word that right - how long will the standard 7 way pin system take to recharge Li batteries?

Same time as "ordinary" batteries. Say you get 10 amps from the 7-pin (mine will do more like 6 amps after the first few minutes at 15 to 10 ) then your "ordinary" batteries will accept that many amps easy, so no different from Li batts.

Li batts have a higher amps acceptance rate, but that doesn't count when they are not being offered that many.

NRALIFR wrote:
Twenty year old camper, that’s how big the battery box is. It will only hold one battery, and a group 31 is the biggest that will fit. It is an AGM, so I don’t have to pay much attention to it. It would take some major remodeling to install a bigger box.

I’ve had an idea rolling around in my head for years of redesigning the step up into the overcab bed to include a a second big AGM battery there. That’s pretty doable for me, as we need the step anyway. But you know. $$$, time, effort, blah blah. :W

Oh, and if I were to do that, the battery I’d put there probably wouldn’t be THAT much less than $450. Might even be more, and I’d still need a good way to charge it while driving. I might not need 30 amps though, having more depth with two batteries.

:):)

Got it.

What about 2nd battery in bed of truck? I have seen folks do this.

In any case, lot’s of options for power. Sounds like you found your best option. Merry Christmas.

My 2019 chev puts out 14.4 volts all day long, that is one of the reasons I went with a DC to DC charger, I can drive up to six hours a day for work and didn’t want to cook the batteries. With the 50 amp charger I have not had to plug in to charge, In fact I don’t have any other charger hooked up yet.

I run a compressor refrigerator and a 300 watt psw inverter in the cab as well as battery charging for my work tools. I am adding two more Trojan T-105 batteries for a total of six and another Redarc 50 amp charger for 100amps of charging.


Inverter/ charger box

noteven wrote:

time2roll wrote:

noteven wrote:
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.

Only trouble is most 7-pin connectors have OEM #14 wire and a 40 amp fuse. Good chance that 40 amp DC-DC will pull 50/60 amps and open the fuse resulting in no charge. I recommend 20 amp DC-DC if using the OEM 7-pin connection.

I didn't word that right - how long will the standard 7 way pin system take to recharge Li batteries?

There is no definitive answer because of equipment and usage variability.
Few to no trip reports that I have read. Unless your truck alternator continuously produces 14.6 volts the lithium battery may never fully charge.

Would be wonderful to read a report with and without a DC-DC charger.

NRALIFR wrote:
These are the cable size recommendations for installing the 25 and 40 amp Redarc chargers.



Just to get 4 AWG wires from the truck starting batteries, through a CB and ignition controlled solenoid, then under the crew cab and to the front wall of the pickup bed, I ordered 25 ft each of red and black fine stranded welding cable from TemCo. You’d be surprised how little of that cable was left over. The circuit length was just over 20 ft just to the plug at the front of the bed.

I had to order a little more cable to upgrade the wires in the camper umbilical cord to the battery. The total circuit length by the time I finished was just under 30 ft.

I don’t think you’ll be happy with the performance if you try to use the OEM circuit through the 7-way plug. You’ll either be blowing fuses or having an auto-reset CB constantly clicking off and on because it’s heating up.

:):)

I didn't word my post correctly. I meant how long to charge Li batteries with the standard 7 pin wiring?


I understand how a DC-DC charger is installed.