Planning stage for unusual RV conversion

[chevymike]

Hi all,

Been following Will's YouTube stuff for a few months now, trying to learn what I can for my project. It is a little unusual. I am converting a CUCV M1010 ambulance to a camper. These ran dual alternators standard. Mine has been converted over to 12 volts and has two large frame 160amp, self exciting alts. Here's the planned layout. Alt #1 will run the starting batteries/truck cab systems. Alt #2 will be isolated to run only the camper battery system. I need a little help in designing the camper system.

I picked up two 24 volt, 150 watt panels cheap (but high quality ones). I am looking to have 100-200ah LiPo4 battery system. I have been looking at some charging setups (Renogy DC/DC charger w/ MPPT, RedArc Manager 30 and similar). It seems none of these will take the 24 volt panels for the solar input side. Also it seems all of them give priority charging to the starting battery and then camper. In my system, there is no "starting" battery in the camper side but does have Alt #2 as a stand alone alt.

What charging system can do like the Renogy or RedArc that will handle the 24 volt panels and a direct alternator power without any "starter" battery hooked to it? Ideally something fairly simple but very reliable. I would like to not need 10 different parts to make up what the others can do with one or two pieces.

Open to ideas and thoughts. Thanks!

Here's a pic of the rig.

 

[chevymike]

@Will Prowse or anyone else. Gotta any ideas?

 

[Ped]

Theres only 1 combined unit and it only accepts 25a on each side that i know of. If theres others theure priced beyond what i would ever look at. Otherwise it can be done in 3 pieces for high amp charging. Inverter wired to alternator powering a 75a+ converter and a regular charge controller.

 

[WoodsieLord]

I think an alternator without a battery has a very unstable voltage (heavily depends on the engine's RPM). I'm very new to solar and I'm not familiar to anything other than my cheap PWM controller and lead acid batteries. With my limited knowledge on the subject, if I were you, I would install a switch that would let me select the power source exclusively: Select Alternator or select solar. I would have to read a lot but perhaps I would venture placing a super capacitor between the alternator and the selector. So that it will smooth out the charging voltage.

Also, I take it the alternator is 24V, right? If you're planning to use an MPPT, I think you will require a higher voltage for a decent efficiency. Better wait for more wise people to answer

regards!

 

[mberding]

I've installed a couple of the Renogy 50-amp DC-DC converters, and they're working well. They are in traditional setups though, where the alternator is charging a starter battery.

If it were me, I'd go ahead and hook up a DC-DC directly to the alternator. Worst case scenario, it doesn't work, but hey, it's quick, cheap, and easy! If it doesn't work, then I'd add a small lead-acid battery under the hood, hook it up the second alternator, then hook up the DC-DC charger to that small battery. That's pretty much a guaranteed-to-work situation.

With regards to your solar panels, you've got two choices: either get a separate solar charge controller to handle them, or sell them and get some 12v panels.

 

[Ped]

I think an alternator without a battery has a very unstable voltage (heavily depends on the engine's RPM). I'm very new to solar and I'm not familiar to anything other than my cheap PWM controller and lead acid batteries. With my limited knowledge on the subject, if I were you, I would install a switch that would let me select the power source exclusively: Select Alternator or select solar. I would have to read a lot but perhaps I would venture placing a super capacitor between the alternator and the selector. So that it will smooth out the charging voltage.

Also, I take it the alternator is 24V, right? If you're planning to use an MPPT, I think you will require a higher voltage for a decent efficiency. Better wait for more wise people to answer

regards!

It should have a voltage regulator.

 

[chevymike]

Also, I take it the alternator is 24V, right?

As my original post said, both alternators are 12 volt units. The solar panels I picked up are 24 volt.

 

[chevymike]

I've installed a couple of the Renogy 50-amp DC-DC converters, and they're working well. They are in traditional setups though, where the alternator is charging a starter battery.

If it were me, I'd go ahead and hook up a DC-DC directly to the alternator. Worst case scenario, it doesn't work, but hey, it's quick, cheap, and easy! If it doesn't work, then I'd add a small lead-acid battery under the hood, hook it up the second alternator, then hook up the DC-DC charger to that small battery. That's pretty much a guaranteed-to-work situation.

With regards to your solar panels, you've got two choices: either get a separate solar charge controller to handle them, or sell them and get some 12v panels.

Yeah, I was wondering if that Renogy unit would allow direct alternator hookup without having a starter battery. Be nice if it does. Really can't do another battery since I already have two under the hood for starting the diesel engine.

 

[Geriakt]

Consider the Victron Orion TR Smart DC to DC charger and a separate MPPT.

 

[chevymike]

Consider the Victron Orion TR Smart DC to DC charger and a separate MPPT.

Looking that over, it seems to say the following "For use in dual battery systems in vehicles or on boats where the (smart) alternator and the start battery are used to charge the service battery "

I will not have a start battery on this circuit, only a direct alternator output (which is regulated at 13.8-14 volt). What throws me off with most things I have read is, the using the alternator AND start battery. I need something that will work directly with the alternator ONLY. That seems to be where things get muddy.

 

[chevymike]

Well to add a little more info into this build, my best friend just got me 8 Winston 100Ah which will be setup as a 12 volt 200Ah bank.

So, this is what I have for current equipment and need to figure out how to make this all play together that will be very reliable and as small of a footprint as can be done.

2) Siemens 24volt, 150w solar panels
1) Alternator, 160 amp max, regulated to a max 14 volts
8) Winston 3.2v, 10Ah cells

I guess one of the things I am struggling with is, if I have a separate DC to DC charger (for Alt charging) and MPPT charger (solar), do both of these output connections go directly to the battery bank? I am not wrapping my head around two different charge outputs connecting to the battery bank and what prevents overcharging? I really wish there was a Renogy DC to DC Charger w/ MPPT (that Will reviewed) that would take 24v panel input.

 

[nibs]

Just use the 24 volt panels to charge 12 volt house system, put it through a controller and it will be fine. I use a 36v panel through a low cost controller to charge my 24 volt converted garden tractor, no problems after 1 1/2 years.
Stay with 12 v for the house and house batts because almost all rv stuff is 12 volt.
My motor coach had one 24V alternator so rather than dance with reducing 24v to 12 v I mounted a second 12 v alternator in 2001, and never regretted it.

 

[mberding]

I guess one of the things I am struggling with is, if I have a separate DC to DC charger (for Alt charging) and MPPT charger (solar), do both of these output connections go directly to the battery bank? I am not wrapping my head around two different charge outputs connecting to the battery bank and what prevents overcharging? I really wish there was a Renogy DC to DC Charger w/ MPPT (that Will reviewed) that would take 24v panel input.

Yes, both connect to the battery bank. Each system (the DC/DC and the MPPT) are both smart enough to not overcharge. If, for example, your MPPT has already charged up your batteries and they're full, the DC/DC just won't do anything. It'll see that the battery is already full.

 

[nibs]

Why do you want a DC to DC charger?

 

[Geriakt]

Looking that over, it seems to say the following "For use in dual battery systems in vehicles or on boats where the (smart) alternator and the start battery are used to charge the service battery "

I will not have a start battery on this circuit, only a direct alternator output (which is regulated at 13.8-14 volt). What throws me off with most things I have read is, the using the alternator AND start battery. I need something that will work directly with the alternator ONLY. That seems to be where things get muddy.

So just hook it up through the main cab battery alt system if you need DC to DC charging or simply add a 12 volt battery to the secondary alt to act as a voltage regulator.
If you are interested in the Victron Orion TR Smart you should post you question on the Victron Support Fourm. I think you can connect it directly to the Alt without a battery.

 

[Supervstech]

I don’t think you will need anything to work this... your charge controller mppt for the solar can regulate the panels... your alternator voltage regulator can handle the surplus charging duties...
The reason for the dc to dc victron is to protect a starting system... you don’t need that.
You could setup a normal mppt CC and hook the alternator to a generator input...

 

[nibs]

Why are you trying to make the house battery do service for the truck? Or do I mis understand you?
The "truck" battery is a very different animal to the "house battery"
Truck needs to deliver very high amperage for a very short time, house battery needs to deliver less amps but over a much longer time. You need heavy wiring to the starter and lighter wiring to the house.
By eliminating the truck battery you are giving up a safeguard. House batt can be discharged and the truck will still start.
Your rig has two alternators which is the best of alternatives, one for the completely separate house, and one for the truck. Any accidental surge voltage in the house will not damage the truck if they are completely separate.
Having lived full time in a sailboat and a motor coach for a total of 20 years I ask why you are trying to reinvent the wheel. $100 will get you a truck batt and the wiring is already in place.

 

[chevymike]

Wouldn't the DC/DC charger be needed so it can have a correct charge profile and prevent over/under charging from the alternator?

 

[grizzzman]

Wouldn't the DC/DC charger be needed so it can have a correct charge profile and prevent over/under charging from the alternator?

Yes but..... Renolgy says no to going straight to the alt. If your battery disconnects during heavy charging bye-bye Alt. diodes.

 

[chevymike]

Yes but..... Renolgy says no to going straight to the alt. If your battery disconnects during heavy charging bye-bye Alt. diodes.

Ah, that is something I would not have thought of. Humm.....