Foretravel Owners' Forum

I think in a lot of solar systems, the solar gets disconnected when on shore power.

I think in a lot of solar systems, the solar gets disconnected when on shore power.  If this can be used to offset shore power usage for 12 volt loads that is pretty cool.  If this is a grid tie inverter and can offset ac loads, that is amazing.  That's the kind of system I'd be after because we're often on metered shore power and that would get the system to pay for itself in a reasonable time.

Once we have our Victron inverter and solar system installed, I envision turning off the invertor charger during daylight hours when we pay for electric separately, and when on 30 amp shore power (to cut amps used).  Doing do should let all 12 volt loads be supported by solar and batteries versus converting 110 volt to 12 volt.

Edit: Perhaps setting voltage charging  limits higher on solar system than the inverter charger, it would occur automatically?

The invertor circuits however, would continue to come from shore power, correct? (unless we kill incoming shore power).

Between residential fridge, convection microwave, washer dryer, air con, AH on electric element, etc we would likely leave shore power connected at all times, and only turn off the battery charger on the inverter.

Most of the solar charging is done at 13.4 or 13.8 somewhere in there.  So 600 watts of solar is about 45 amps into the batteries. 

It appears on my Victron system that if we have driven for a few hours and things are charged up and then we are plugged in then the charger and solar are adding just a bit. Start batteries come back up to float quickly.  If I turn off the inverter and charger then solar goes up.  My second battery bank runs inverter only circuits that are on all the time. (Refrig and electronics) this bank gets charged by a smart charger and solar.  Solar alone, no landline connection, can almost always keep up with the normal day time loads and add enough to get through the night for several days without any generator support. 

If frequently see no charger input even if it is on when the batteries are charged and just a bit from solar that is what is getting pulled from the batteries and thw inverer/charger overhead.  Very nice.

Pierce,

Unless there is very little voltage difference in the battery banks, I would be concerned about using the cigarette lighters as the "combine" point.

Lots of places in back where connection points connected to the two banks are close together and linked with large-gauge wires.

The "trickle charger" i'm speaking of is a $24 2 amp Harbor Freight charger. I just have it plugged into the outlet next to the bus where my solar connects to the engine and house batteries. Photos make it clearer. I bought several for the cars and tractor. They work really well. They keep float/maintenance voltage a little above 13V.
 
So, if we go out of town without the coach, I don't keep 110v on the coach, I just pull the small charger's plug and plug an extension cord into it and connect the jumper up front. If the coach is plugged in, the OEM controller/charger works on the house batteries, the small charger works on the engine batteries. Makes things simple. I don't like to have power to the coach if we are away for any length of time.

Pierce

The "trickle charger" i'm speaking of is a $24 2 amp Harbor Freight charger. I just have it plugged into the outlet next to the bus where my solar connects to the engine and house batteries. Photos make it clearer. I bought several for the cars and tractor. They work really well. They keep float/maintenance voltage a little above 13V.

Pierce

Roger, how do you split the solar charge to your two battery banks?

My first design was going to put solar power into the alt post on the Sterling ProSplitR.  This is a smart zero voltage drop isolator that distributes charge based on voltage level of each of the three battery banks, Start,  House 1 and House 2 and in that order.  When the start batteries reach a set level then it moves to the House 1 bank until they reach a set voltage and then on to the House 2 bank.  It checks the Start batteries periodically and if they are below a set point it returns focus to them.  Once all are up to a set level then they get an equal share of the charge current whether it is from the alternator or solar. 

We ran into an issue with power to the Sterling to turn it on.  This is usually an ignition source.  When only on solar it needs to come from the solar charger but that was a bit complicated because we didn't want to feed power back into the ignition circuit and the Sterling Start post is connected to the Alt post by default unless it isolates it while in use.  That needs some diodes and switching to make that happen and I ran out of time. There is a solution, I just need to figure out an elegant one

So I used a Victron ArgoFET isolator, zero voltage drop.  Solar goes into the input side.  Three outputs feed the Start, House 1 and House 2 banks.  The solar charger senses an average voltage across all banks to determine its output.  That output is divided proportionally between the three banks, the lower voltage gets more amps. 

It is pretty easy to change this.  I may remove the start battery connection and jumper the start and House 1 banks.  I am still learning how the two house banks use power.  The House 1 bank (refrigerator and electronics) is a pretty steady load over time.  The House 2 bank (all other 12 v loads and inverter output if it is on) has a much wider load range.