12v alternator -> 120v inverter -> 24v battery charger?

[BillyGoat]

I've searched and am unsure if I'm missing something here. I aim to charge from my F350 dual alternator diesel truck to my truck camper 24v lithium setup (100ah but planning to double this). I have a Victron Orion currently that gets hot and only puts out 10 or so amps and also an eg4 40 amp battery charger for shore power.
My question is:
Could I wire up a 2000w inverter into the cab of my truck with a switch that could turn the inverter on when I'm going for a drive, then run an extension cord to the bed of the truck where I will:

1) be able to have inverter power for random daily tasks
2) plug into the camper 40 amp battery charger to charge the lithium 4x faster than the Orion.

This seems like a bit of a hack way to do it but I don't have space for 4-5 orions which I don't feel is a great product anyway. Would this somehow mess up the alternator? Is there a better solution for high-output alternator charging?

 

[Andrewr05]

You need to be sure that your inverter load doesn't go over the limit of the alternator.

What does the alternator put out?

2000W inverter size ÷ .85 (inverter loss calculation) ÷ 13.8 is about 170A at that inverters max draw.

 

[Dooug]

What model Orion and what size wiring to it?

The eg4 charger should pull just under a 1000 watts depending on efficiency. So a decent 2000 watt inverter should run that easy enough while driving. Your not crazy for heading this direction, it's a pain to charge DC at high current.

I had considered swapping one alternator out for a 24 volt but so far I think my over the road charging will be adequate at 10-15 amps.

 

[BillyGoat]

What model Orion and what size wiring to it?

The eg4 charger should pull just under a 1000 watts depending on efficiency. So a decent 2000 watt inverter should run that easy enough while driving. Your not crazy for heading this direction, it's a pain to charge DC at high current.

I had considered swapping one alternator out for a 24 volt but so far I think my over the road charging will be adequate at 10-15 amps.

I have the 12|24-15 not-so-smart version. I posted before and it seems to be the case with everyone that they derate pretty quickly when they get hot. I've considered the 24v alternator as well, but if I could get 40 or so amps @ 24v with the charger I already have, that would be more than enough for driving and charging.

I just wasn't sure if there was something I was missing with the DC-AC-DC charging besides some efficiency loss.

Edit: 4awg wire run back to the truck camper. I will probably remove the orion and just go with the inverter and run a extension cord back to the bed

 

[TacomaJoe]

40A at 24V would be 80A at 12V from the alternator. Factor in conversions and you're looking at closer to 100A from the alternator.

 

[DIYrich]

Unless you have another use for the inverter/charger, I would add a 2nd TR12/24-15. They can be stacked.

 

[Dooug]

I have the 12|24-15 not-so-smart version. I posted before and it seems to be the case with everyone that they derate pretty quickly when they get hot. I've considered the 24v alternator as well, but if I could get 40 or so amps @ 24v with the charger I already have, that would be more than enough for driving and charging.

I just wasn't sure if there was something I was missing with the DC-AC-DC charging besides some efficiency loss.

Edit: 4awg wire run back to the truck camper. I will probably remove the orion and just go with the inverter and run a extension cord back to the bed

There is in inefficiency of going DC/AC/DC but there's also plenty of inefficiencies try to move 80+ amps of 12v DC to try and match the EG4 charger output.

4 gauge should be plenty for teu conversion. There is a little fan mount for the oriona on Etsy, the heat really does knock them back.

 

[Zwy]

I've searched and am unsure if I'm missing something here. I aim to charge from my F350 dual alternator diesel truck to my truck camper 24v lithium setup (100ah but planning to double this). I have a Victron Orion currently that gets hot and only puts out 10 or so amps and also an eg4 40 amp battery charger for shore power.
My question is:
Could I wire up a 2000w inverter into the cab of my truck with a switch that could turn the inverter on when I'm going for a drive, then run an extension cord to the bed of the truck where I will:

1) be able to have inverter power for random daily tasks
2) plug into the camper 40 amp battery charger to charge the lithium 4x faster than the Orion.

This seems like a bit of a hack way to do it but I don't have space for 4-5 orions which I don't feel is a great product anyway. Would this somehow mess up the alternator? Is there a better solution for high-output alternator charging?

I've been doing it for some time as my Growatt is 24V but rarely need it. https://diysolarforum.com/threads/flat-mount-panel-vs-tilt-mount-in-winter.69599/post-880024 It works quite well and also provides me a backup source of power should I need it. I hard wired the inverter with 2/0 battery cable to the back seat area, cables come up thru the floor. I was planning on a video showing it in the future.

 

[BillyGoat]

40A at 24V would be 80A at 12V from the alternator. Factor in conversions and you're looking at closer to 100A from the alternator.

Yeah I think my dual alternators put out ~410 amps so should be well in the clear

 

[BillyGoat]

There is in inefficiency of going DC/AC/DC but there's also plenty of inefficiencies try to move 80+ amps of 12v DC to try and match the EG4 charger output.

4 gauge should be plenty for teu conversion. There is a little fan mount for the oriona on Etsy, the heat really does knock them back.

I 3d printed the little computer fan holster for the Orion and it barely helped with the derating from the heat. As long as there isn't some 'gotcha' that will blow up my alternator I'm going to give the inverter setup a try.

 

[BillyGoat]

I've been doing it for some time as my Growatt is 24V but rarely need it. https://diysolarforum.com/threads/flat-mount-panel-vs-tilt-mount-in-winter.69599/post-880024 It works quite well and also provides me a backup source of power should I need it. I hard wired the inverter with 2/0 battery cable to the back seat area, cables come up thru the floor. I was planning on a video showing it in the future.

Yep, this is exactly what I was thinking as well. I know you haven't used it much, but do you have any input on what amps you are getting at idle? It would be nice to run idle the truck for an hour or 2 and fully charge the battery in the winter without having to bring an extra little generator

 

[Zwy]

Yep, this is exactly what I was thinking as well. I know you haven't used it much, but do you have any input on what amps you are getting at idle? It would be nice to run idle the truck for an hour or 2 and fully charge the battery in the winter without having to bring an extra little generator

I go by watts. 60A at 24V = 1440W which would be 120A at 12V.

The factory alternator was 105A and I figure it easily handled running the truck. The second alternator is 3000W or 250A and 1440W or 120A would be about 1/2 the peak watts/amps at higher rpm. Reality is I set the Growatt to charge at 30A so I'm only pulling 60A from the alternator. 720W is about my PV size on the camper, I currently have 600W but will have 800W when I get the roof air off. Installing a mini split now.

You could use a 500A shunt for determining the draw at idle and compare to the alternator output curve. I just figure if I don't get greedy with the watts it won't be a problem. If I went to 1440W plus 800W from PV minus inefficiencies, I would still be able to fully charge the 280Ah battery in about 2 hours. I really don't need to charge that fast.

If you really want to know, you can use a clamp on DC ammeter along with a thermal camera or temp gun and see how much you can load it down at idle while watching alternator temps.

 

[12vDC]

Yep, this is exactly what I was thinking as well. I know you haven't used it much, but do you have any input on what amps you are getting at idle? It would be nice to run idle the truck for an hour or 2 and fully charge the battery in the winter without having to bring an extra little generator

I just installed a Victron BMS (its an 80A current limiter) for alternator charging.
I have the BMS operating from a dash switch and did not install it to run full time, only at idle. I have the Orion30 for full time duty.

I was finally able to test it last weekend having the bank SOC go down to 55%.
At idle, between the Orion30 and the BMS, I was only getting 64A at the beginning of the test (out of a theoretical 110A total capability).
I have a standard Nations 280 drop-in replacement, and for my brief test (I didnt leave it extended idle) it seems this alternator does not produce a lot of juice at idle. Now that I think about it I should have monitored at a higher idle. I will do that next time.

I do believe however, as the inefficiency of the Orion30 begins to throttle with heat loss, the additional current available from the alternator (no longer being drawn from the Orion) should flow through the BMS (I will continue to get ~64A regardless of the Orion throttling). I will monitor for this as well on the next test. I have to deduce the power flow because the Victron BMS module is not bluetooth and is not available in the Victron Connect app. I subtract the Orion current from the total current flowing through the shunt to derive the BMS current supply.

I might have to install a remote start with high idle.
I can make such a decision after the next higher idle test.

 

[BillyGoat]

go by watts. 60A at 24V = 1440W which

I go by watts. 60A at 24V = 1440W which would be 120A at 12V.

The factory alternator was 105A and I figure it easily handled running the truck. The second alternator is 3000W or 250A and 1440W or 120A would be about 1/2 the peak watts/amps at higher rpm. Reality is I set the Growatt to charge at 30A so I'm only pulling 60A from the alternator. 720W is about my PV size on the camper, I currently have 600W but will have 800W when I get the roof air off. Installing a mini split now.

You could use a 500A shunt for determining the draw at idle and compare to the alternator output curve. I just figure if I don't get greedy with the watts it won't be a problem. If I went to 1440W plus 800W from PV minus inefficiencies, I would still be able to fully charge the 280Ah battery in about 2 hours. I really don't need to charge that fast.

If you really want to know, you can use a clamp on DC ammeter along with a thermal camera or temp gun and see how much you can load it down at idle while watching alternator temps.

Thanks for the info! I'm with you on being conservative with the draw to not blow out the alternator. I think the shunt and a thermal camera might be the answer to make sure I'm not overdrawing. It sounds like the Growatt is a nice setup where you can limit the AC draw and dial it in. My charger is all or nothing but 80A (~1000w max) from the alternator theoretically should be fine for the truck.

 

[BillyGoat]

I just installed a Victron BMS (its an 80A current limiter) for alternator charging.
I have the BMS operating from a dash switch and did not install it to run full time, only at idle. I have the Orion30 for full time duty.

I was finally able to test it last weekend having the bank SOC go down to 55%.
At idle, between the Orion30 and the BMS, I was only getting 64A at the beginning of the test (out of a theoretical 110A total capability).
I have a standard Nations 280 drop-in replacement, and for my brief test (I didnt leave it extended idle) it seems this alternator does not produce a lot of juice at idle. Now that I think about it I should have monitored at a higher idle. I will do that next time.

I do believe however, as the inefficiency of the Orion30 begins to throttle with heat loss, the additional current available from the alternator (no longer being drawn from the Orion) should flow through the BMS (I will continue to get ~64A regardless of the Orion throttling). I will monitor for this as well on the next test. I have to deduce the power flow because the Victron BMS module is not bluetooth and is not available in the Victron Connect app. I subtract the Orion current from the total current flowing through the shunt to derive the BMS current supply.

I might have to install a remote start with high idle.
I can make such a decision after the next higher idle test.

Great info, I think I will test this out with another victron smart shunt in between the battery and inverter so I can keep an eye on the draw from the alternator. A tuner with a high idle switch would probably be a good idea to get the alternator to pump out some more juice, i just worry about it overheating

 

[Dooug]

There are a couple switch kits for high idle, tuner not required. Can also use an upfitter switch and resistor wired into the factory harness for high idle. There's a chart to pick resistor ohms for "X" rpm.

Set the shunt to DC meter if hooking up to a cerbo. If I see a good deal I'll grab a second one for just this.