Multi input charge controller

The problem is that you have widely varying input power sources... Some like solar panels can be turned on and off without damage. Others, like directly connecting a car alternator, will be damaged (or cause damage) if you use a "series controller" (like a solar charge controller) and just turn their output on/off.

And AC to DC power sources can have wildly differing output voltage/current/designs/requirements.

Can you tell us a bit more about what you are trying to do? The loads you want to drive (i.e., large or small power requirements), cost vs weight (use large heavy lead acid batteries or light weight/expensive LiFePO4 type), etc. We have had quite a few questions from people that want to run CPAP machines or other medical devices.

In general, the loads are very important--Because conservation of energy usage is almost always a better investment than using less efficient loads and designing a large off grid power system.

Will all of the power sources be brought with you and/or consistent interface (i.e., using a 10 amp 12 VDC lighter plug on car with the car running or stopped)?

How big/what voltage/what type of battery bank? How large of solar array (and voltage/panels you want to use)?

Just a ton of questions.

-Bill

If you plan on weekend use--Then you can get away with 5 amp (5%) rate of charge. However, if this is a daily use system, then I would suggest ~10 amp (10%) rate of charge.

If you have a 10 amp simple AC battery charger and 200 Watts of Vmp~18 volts at 11 amps total--Then you could use a simple PWM solar charge controller (DC from utility charger, or DC from solar panels) to regulate the average charging current to the AGM battery.

The truck lighter charging is a question... Typically, a 12 volt automotive type alternator charges around 13.8 to 14.2 volts. AGM batteries should not see more than 14.4 volts (typical) maximum charging voltage.

If the truck/car is not running, then you have ~12.0 to 13.0 volts (12.7 nominal) voltage and this will not recharge your battery bank.

For charging when the engine is not running, you would need a "boost" type battery charger to raise the votlage from 12.x volts to 14.x volts charge the AGM battery. Or, you can look for a buck/boost charger so that it can take any "reasonable" charging voltage from your vehicle to recharge the AGM battery (you could also probably move the AC to DC power source to this buck/boost charger).

Anyway, you have very different types of charging sources with a wide range of voltage/current profiles. It is difficult to give a generic answer--Each charging source needs to be defined and designed to meet those requirements.

Unless you want to make an electrics DIY project out of this--I would suggest that you may end up with 2-3 separate chargers connected to your one battery bank. It will be less complicated.

-Bill

Welcome to the forum Peetree.

Yes, it is possible to to use solar panels to charge batteries on a car... A few cars even offer solar panels built into the roof. Presently about 10 car models in the USA have "solar roofs":

https://carbuzz.com/10-high-tech-cars-equipped-with-solar-panels/

There are multiple reasons why a mfg may not choose to build a solar roof into a car... I will try to quickly list a few reasons:

1. Solar panels are not that "efficient or capable" of gathering solar energy.... Just a quick back of the envelope math: An electric car draws around 250 to 300 Watt*Hours per mile of driving. A 1 meter * 2 meter solar panel * 1,000 W/sqmeter * 0.15 solar panel eff * 0.77 panel & charging eff * 5 hours of "good sun" per day = 1,155 WH per sunny day from a 3.3 ft * 6.6 ft roof panel... 1,155 WH per day / 300 WH per mile = 3.85 Miles per day of driving from solar).
2. A fair amount of electronics are required to connect a solar panel to a high voltage car battery bank... A typical solar panel outputs 0.5 volts per cell, or around 18-40 volts typical per panel... The vehicle motive battery bank is typically around 300-400 VDC... So need the electronics and charge controller to boost the 40 VDC from solar panel to 400 VDC to charge the battery bank. Is not difficult to do--But adds cost/weight/etc.
3. Vehicle needs to be parked under the sun "all day"... If there is any shade (trees, buildings, power lines, parking structure, etc.), the amount of solar power harvested can quickly drop to zero WH harvested. In real life, a stormy day can be 1 hour per day to >7 hours per day in in "perfect" conditions... 3 hours per day is "not bad" for winter for most places--And easily 1-2 hours per day in poor average winter day. Plus for "optimum" harvest that panel should be tilted towards the sun. "Flat" mounted solar arrays (car roof) harvest much less energy.
4. Solar is only available when harvested and used. Obviously, limits on access to sun, and amount of storage available (EV's do have a lot of storage available--But a full charged battery cannot store "more free solar"--Battery must be somewhat discharged and/or vehicle using power driving/AC/lights/etc.).
5. Energy Taxes... In most locations, there are no road taxes yet for electricity for electric vehicles. When EVs "few", the government was willing to forgo road taxes (fuel vehicles can have $1 to several $ per gallon of fuel taxes. But the government was going hammer and tongs against people using "untaxed" vegetable oil or "agricultural diesel" in their cars. And now there are multiple agencies (in USA) pushing for using GPS to charge ~$0.50+ per mile road taxes and/or adding $300+ per EV and even hybrid Vehicles per year license renewal taxes). And we have seen/used cameras and transponders/fast passes for for tolls/road taxes.

How much is a person willing to pay for 4 Miles per day of "free solar energy" that lives outside of (for example) the sunny South/West USA?

Here is an example of a person that added 9 solar panels to the top of his Tesla Model Y for 40 miles per day:

https://carbuzz.com/news/tesla-model-y-owner-makes-own-solar-roof-that-adds-20-miles-daily/

Things can be done... Should they be done? Will they be done?

-Bill