Inverter charging the camper from the trucks batteries.

[work2much]

Has anyone installed an inverter in their truck that they use to charge the camper?

My thought is that converting to 120v and connecting to the campers 120v system would allow a more stable charging source using the campers charger rather than the trucks alternator and all the DC line loss/heavy cable and possibly inconsistent voltages.

I would install a battery isolator that is switched by the ignition circuit as well as an in cab switch. Most of the time we don't need any more than what our solar provides but it could be handy to add charging while we drive when we get multiple cloudy days.

The inverter mounted in the truck would also give us a 120v power source when we don't have the camper with us. Our campers inverter/charger is adjustable for charging amperage so we could keep the amperage at a level that the trucks alternator could handle.

Potential issues could be engine compartment heat and protection from the elements. Maybe the inverter could be mounted in the cab.

Another negative could be the loss of efficiency converting 12v to 120v and back to 12v. Given that the trucks engine has unlimited power for this application though I think that may be a moot point?

Thoughts?

[NRALIFR]

work2much wrote:
Can you give me an example of a unit that can charge at 100Ah and is programable for specific bulk, absorption and float voltages for my LFP? , Serious question I am interested. Also looking at a voltage drop calculator I would need 4/0 cable to stay under 3% line loss with such low voltage and high amperage. That is heavy and expensive. Weight isn't my friend..

*************
Edit: Sorry Greg, I didn’t realize until after I posted this that the CTEK charger referenced below does NOT support lithium batteries. Kinda surprising considering it’s price.

I’ll leave the info in case someone finds it useful.
*************

Have you looked at CTEK DC-DC chargers? Specifically, this bundle?

CTEK 140A Off Grid Bundle

I remember looking at the CTEK brand when I was looking for a DC-DC charger for my TC. You and I are at opposite ends of the spectrum in terms of charging capacity needs. I very quickly ruled this bundle out because I don’t need 140 amps of charging for one group 31 AGM battery, and the price was way out of my budget anyway (to say the least).

CTEK is also pretty much across the board more expensive than every other brand. I got the impression they are considered top notch, though. The Redarc 25 amp charger was a little cheaper than the CTEK 20 amp, and they seem to have a very good reputation as well, so I went with the Redarc.

I took a quick look through the manual for this CTEK bundle, specifically looking for the recommended wire sizes. There are several wires associated with these two units, and depending on which one your talking about and how long it is determines the wire size. Worst case though, at lengths out to 30’ I see no recommendation for wire any bigger than 1AWG.

Just thought I’d make sure you knew about this. I totally forgot about the potential to combine these two units and get 140 amps output.

:):)

[S_Davis]

NRALIFR wrote:

S Davis wrote:
When you did your setup did you have a single alternator or dual alternators, with the 4 gauge you should have been able to pull 80 amps. What kind of amps where you seeing, was lack of alternator capacity the problem?

I’ve unfortunately never had a truck with dual alternators, but I don’t think alternator capacity has ever been a problem. My 2016 F450 has a single 200 amp alternator. I’ve upgraded the charge wires on three previous trucks ( ‘84 F250, ‘95 F350, and 2010 F450) and had satisfactory performance, though each one performed slightly better than the previous truck because I made some changes each time.

I increased the wire gauge on each truck, starting with 10 AWG on the ‘84, and ending with 4 Awg on my current truck. All the previous trucks had the typical charging system: two starting batteries and an alternator with an internal voltage regulator. I connected the upgraded camper charge wire directly to the alternator.

This worked well on the three previous trucks, with the alternator almost keeping up with the draw of the fridge running in AC mode from an inverter while we were driving (about 33 DC amps). I say almost because I could see that the camper battery would lose a little ground while the AC heater was on, then it would charge a little when the heater was off. As long as the fridge tstat wasn’t set so low that the cooling unit ran all the time, the camper battery stayed above 90% (on the Trimetric).

On my 2016 F450, I found that the charging system had changed quite a bit. The starting batteries and the alternator are all connected to this component, which I could never find any information on.





I suspect it’s for the ECM to monitor and control the voltage output of the alternator(s). Because of this, I was very apprehensive about connecting a load directly to the alternator. So, I connected to the starting batteries instead. The charging performance wasn’t even as good as the 2010 F450, despite using larger wires. We were ending the day with a camper battery around 70%. I had to find another way to improve the charging performance from the alternator.

:):)

Ok thanks for the info, I am hoping for decent charging, my 2013 2500HD has a second 120amp alternator to the aux battery with studs to connect at the 120amp factory fuse. With 1/0 DLO to the batteries I am hoping for a 100amp charging rate.

[NRALIFR]

S Davis wrote:
When you did your setup did you have a single alternator or dual alternators, with the 4 gauge you should have been able to pull 80 amps. What kind of amps where you seeing, was lack of alternator capacity the problem?

I’ve unfortunately never had a truck with dual alternators, but I don’t think alternator capacity has ever been a problem. My 2016 F450 has a single 200 amp alternator. I’ve upgraded the charge wires on three previous trucks (‘84 F250, ‘95 F350, and 2010 F450) and had satisfactory performance, though each one performed slightly better than the previous truck because I made some changes each time.

I increased the wire gauge on each truck, starting with 10 AWG on the ‘84, and ending with 4 Awg on my current truck. All the previous trucks had the typical charging system: two starting batteries and an alternator with an internal voltage regulator. I connected the upgraded camper charge wire directly to the alternator.

This worked well on the three previous trucks, with the alternator almost keeping up with the draw of the fridge running in AC mode from an inverter while we were driving (about 33 DC amps). I say almost because I could see that the camper battery would lose a little ground while the AC heater was on, then it would charge a little when the heater was off. As long as the fridge tstat wasn’t set so low that the cooling unit ran all the time, the camper battery stayed above 90% (on the Trimetric).

On my 2016 F450, I found that the charging system had changed quite a bit. The starting batteries, starter, and the alternator are all connected to this component, which I could never find any information on. There’s an unused lug that I believe a second alternator would connect to as well.





I suspect it’s for the ECM to monitor and control the voltage output of the alternator(s). Because of this, I was very apprehensive about connecting a load directly to the alternator. So, I connected to the starting batteries instead. The charging performance wasn’t even as good as the 2010 F450, despite using larger wires. We were ending the day with a camper battery around 70%. I had to find another way to improve the charging performance from the alternator.

:):)

[crawfdp1]

Yes, have built two systems. One was truck mounted with batteries and inverter beneath, on a 2008 F450, second was a supplemental charging system using truck engine on a 2016 F350. Look for 'supplemental charging system' article at truckcamperadventure website.

duncan

[S_Davis]

NRALIFR wrote:
Well, I’ll be interested to hear about the details of your install. I considered doing the same thing myself when it became clear that upgrading the 12v charge wires alone wasn’t cutting it. The technical aspects of installing an inverter were proving to be more challenging than a DC-DC charger. The 4 gauge wires were already in place on the truck at that point.

Because of the people, pets, and gear we haul in the cab, there wasn’t really a good place to install an inverter there. I also couldn’t come up with a place under the hood to mount one, and an inverter that can survive that invironment is going to be more $$$’s. I was considering a much smaller inverter than you will need, I’m sure. You may want to add alternator temperature monitoring to the features you need on the inverter. I recall seeing some marine units that would do that, and automatically drop out if the alternator gets too hot.

Good luck, and keep us posted. I’ve never seen a TC with that many solar panels on the roof. Our campers are pretty close to the same size, but due to the stuff that’s already up there, AC, vents and such, I’d have trouble fitting two panels.

:):)

When you did your setup did you have a single alternator or dual alternators, with the 4 gauge you should have been able to pull 80 amps. What kind of amps where you seeing, was lack of alternator capacity the problem?

[JD5150]

work2much wrote:

time2roll wrote:

work2much wrote:

NRALIFR wrote:
If you want better alternator charging, consider a DC-DC charger instead of an inverter.

:):)

Can you give me an example of a unit that can charge at 100Ah and is programable for specific bulk, absorption and float voltages for my LFP? , Serious question I am interested.

Something like this:

https://www.redarc.com.au/smart-start-bcdc

Only 20 Amp charge.

I don't know if these will work for you. You can charge from 85 amps up to 200 amps from a 12 volt alternator.
yandina.com/

[NRALIFR]

Well, I’ll be interested to hear about the details of your install. I considered doing the same thing myself when it became clear that upgrading the 12v charge wires alone wasn’t cutting it. The technical aspects of installing an inverter were proving to be more challenging than a DC-DC charger. The 4 gauge wires were already in place on the truck at that point.

Because of the people, pets, and gear we haul in the cab, there wasn’t really a good place to install an inverter there. I also couldn’t come up with a place under the hood to mount one, and an inverter that can survive that invironment is going to be more $$$’s. I was considering a much smaller inverter than you will need, I’m sure. You may want to add alternator temperature monitoring to the features you need on the inverter. I recall seeing some marine units that would do that, and automatically drop out if the alternator gets too hot.

Good luck, and keep us posted. I’ve never seen a TC with that many solar panels on the roof. Our campers are pretty close to the same size, but due to the stuff that’s already up there, AC, vents and such, I’d have trouble fitting two panels.

:):)

[work2much]

time2roll wrote:

work2much wrote:

NRALIFR wrote:
If you want better alternator charging, consider a DC-DC charger instead of an inverter.

:):)

Can you give me an example of a unit that can charge at 100Ah and is programable for specific bulk, absorption and float voltages for my LFP? , Serious question I am interested.

Something like this:

https://www.redarc.com.au/smart-start-bcdc

Only 20 Amp charge.

[time2roll]

work2much wrote:

NRALIFR wrote:
If you want better alternator charging, consider a DC-DC charger instead of an inverter.

:):)

Can you give me an example of a unit that can charge at 100Ah and is programable for specific bulk, absorption and float voltages for my LFP? , Serious question I am interested.

Something like this:

https://www.redarc.com.au/smart-start-bcdc

[S_Davis]

work2much wrote:
On this truck we have a single 220AH alternator. Our next truck will have dual 220AH alternators I think. 2019-2020 ordering info not online yet for Ram 5500. They may also have an uplift option for heavy duty amperage draws as well.

How much we could draw for an inverter on current truck will have to be determined but the inverter charger can be set for almost any charging amperage so I am aware that currently 100+ AH draw may be too much. Not sure what the alternator reserve capacity is at normal engine RPM's

I think I will need to start playing with an inverter and see how it goes before mounting and permanent wiring.

I think the trucks with dual alternators are set up figuring you are going to be using it for accessories and don't use funky charging logic. My truck starts charging at 14.7 when started and within a couple minutes goes down to 14.4 and sits there all day long.

[NRALIFR]

S Davis wrote:
:):)

BTDT on my current truck, and was disappointed with the results. The starting batteries do cause some issues, but the “smart” charging systems on the newer trucks cause problems as well. That’s why DC-DC chargers are becoming more popular for RV’s. Connect the charger to the starting batteries, and the truck alternator and ECM don’t know it’s there.


:):)

Does your truck have dual alternators?

No, mine has a single “Extra Heavy Duty” alternator. I believe it’s 200 amp.

:):)

[work2much]

On this truck we have a single 220AH alternator. Our next truck will have dual 220AH alternators I think. 2019-2020 ordering info not online yet for Ram 5500. They may also have an uplift option for heavy duty amperage draws as well.

How much we could draw for an inverter on current truck will have to be determined but the inverter charger can be set for almost any charging amperage so I am aware that currently 100+ AH draw may be too much. Not sure what the alternator reserve capacity is at normal engine RPM's

I think I will need to start playing with an inverter and see how it goes before mounting and permanent wiring.

[S_Davis]

:):)

BTDT on my current truck, and was disappointed with the results. The starting batteries do cause some issues, but the “smart” charging systems on the newer trucks cause problems as well. That’s why DC-DC chargers are becoming more popular for RV’s. Connect the charger to the starting batteries, and the truck alternator and ECM don’t know it’s there.


:):)

Does your truck have dual alternators?

[NRALIFR]

work2much wrote:

NRALIFR wrote:
If you want better alternator charging, consider a DC-DC charger instead of an inverter.

:):)

Can you give me an example of a unit that can charge at 100Ah and is programable for specific bulk, absorption and float voltages for my LFP? , Serious question I am interested. Also looking at a voltage drop calculator I would need 4/0 cable to stay under 3% line loss with such low voltage and high amperage. That is heavy and expensive. Weight isn't my friend.

You’d probably have to look at a marine type DC-DC charger for one like that. The RV models I’m familiar with typically max out at about 40 amps.

ProMariner has models up to 130 amps. That model spec’s 1 AWG wire for up to 25’, and 0 AWG up to 30’. I’m not sure if it supports lithium batteries though. I’d be surprised if the marine market didn’t have exactly what you’re looking for (for a small fee 😛 )

Just for wire size comparison, I’ve got a Redarc BCDC1225 installed in my camper. The total circuit length from the truck batteries, through a CB and isolation solenoid, down along the frame rail, into the camper umbilical at the front of the truck bed, and to the Redarc unit installed next to the battery box is about 25 ft. I’m using 4 AWG welding cable, and I see full rated output from the Redarc (25 amps) all the time. The wire doesn’t even get warm. Redarc actually spec’d 6 AWG wire for my circuit length. Redarc DOES support lithium, and they have a 40 amp model.

work2much wrote:
For those who have upgraded their cable sizes what amperage are you seeing the alternator delivering? I wonder if the starter batteries close proximity to the alternator may cause them to see have higher voltage than the camper batteries thus slowing down the alternators current rate to the batteries farther away, even with massive cabling.

BTDT on my current truck, and was disappointed with the results. The starting batteries do cause some issues, but the “smart” charging systems on the newer trucks cause problems as well. That’s why DC-DC chargers are becoming more popular for RV’s. Connect the charger to the starting batteries, and the truck alternator and ECM don’t know it’s there.


:):)