Interaction between Inverter/charger and Charge Controller

System

I've been trying to determine how these two systems might co-exist in my RV. The inverter/charger will maintain the coach batteries whenever shore or generator power is present. When operating the motorhome motor, the double alternator supplies up to 70 amp to the coach batteries (unless someone has changed the wiring on this). Since I usually travel with the generator running, I don't know if the alternator actually feeds the coach batteries or not.

So my question is, Will the charge controller create a conflict with the inverter/charger and or the alternator? or can I ignore them?

I've seen information on only one charge controller that suggests they both cannot be on at the same time.

mike95490

Re: Interaction between Inverter/charger and Charge Controller

Brands / Models ?

Often, an engine alternator, will not have quite enough voltage to completly top off Deep Cycle batteries.
Alternator regulaters often peak at 13.8V, to keep from boiling the engine battery, they don't have the 3 or 4 stage charging schedule - just a simple voltage regulator.

While on the road, why not run off the dual alternators, and just fire up the gennie when needed. Do you have solar at all ?

What sort of loads are you running, when: traveling / parked

crewzer

Re: Interaction between Inverter/charger and Charge Controller

I've seen information on only one charge controller that suggests they both cannot be on at the same time.

Which one?

System2

Re: Interaction between Inverter/charger and Charge Controller

I don't remember which controller had the off-switch.

The standard RV dual engine-driven alternator won't top off the coach batteries. I have heard of a charging controller for the engine alternator that operates the alternator as a 3-stage system to keep the coach and chassis batteries really topped off. But I've never found one (but haven't really looked either).  Now that I've looked, here is one: http://www.amplepower.com/products/sarv3/index.html

The running loads (down the highway) are the refrigerator and frequently the coach air conditioner. The gen set has more than enough power (6.5 Kw) to run everything on the coach all at once. The dual engine alternator will easily run the refrigerator if that's all we need to power.

During the summer, we dry-camp at exhibitions where I and my wife have to be in our sales booth during the day. We need to keep a large vent fan running to keep the dog cool enough (she stays in the coach). During the evenings, we are not allowed to run a generator because of noise. So the coach batteries need to supply lighting, the vent fan again and the occasional running of the microwave (coffee & popcorn) plus a little power through the inverter for the laptop or television.

During the winter, we need to replenish the coach batteries during the day after running the forced-air furnace during the night. We also run everything except the vent fan when dry-camping in the winter.

Current Coach batteries (220 VA) aren't large enough to go for more than a day if we run the furnace. Hence the desire to find a solar solution.

mike95490

Re: Interaction between Inverter/charger and Charge Controller

mrehmus wrote:

http://www.amplepower.com/products/sarv3/index.html

I'd look toward a 24V solution, instead of 12V Loads you describe, draw lots of amps, and have losses in 12V system 24V has half the loss.

Current Coach batteries (220 VA) aren't large enough to go for more than a day if we run the furnace. Hence the desire to find a solar solution.

Is the furnace fan 12V or 120VAC

VA aren't often used - it's not a standard. 220VA @ 12V = ???
Convert everything to Watts, and then you can see how many Amp Hours you need to store
How many batteries can you carry in the compartments ? 2 group 24 ? 4 group 24 ?
You need to find the Voltage, and Amps for each load, and if it is 120V (microwave, TV) or 12V LED cabin lights.

System2

Re: Interaction between Inverter/charger and Charge Controller


Furnace and every thing else in the coach except the AC, refrigerator (3-way power capability so Propane works for dry-camping) and microwave is 12VDC. 24 VDC would be a major conversion expense and several appliances cannot be obtained for use with 24 VDC.

I should have said 220 ampere-hours on the battery set. But one gets to pull only around 50% of that if battery life is to be reasonably normal. By experience, the coach, with the furnace set on 60 degrees and an outside temp of 30 degrees, uses about 60 ampere-hours per night with lights, minimum microwave operation and normal water pump use.

Anyway, the system is adequate and I know how to figure consumption.

The original question is whether my Inverter/Charger, when powered by the gen set or by shore power, will seriously conflict with an independent solar power kit and should one be switched off when the other is in operation?

crewzer

Re: Interaction between Inverter/charger and Charge Controller

The original question is whether my Inverter/Charger, when powered by the gen set or by shore power, will seriously conflict with an independent solar power kit and should one be switched off when the other is in operation?

There's typically no serious conflict when the outputs of multiple charging sources are "similar" voltages and they're all connected to the same battery bank. Whether the PV controller's output will rise above the other charger's voltage limit is another issue. You can try running both, but, once the batteries reach the inverter/charger's voltage limit, you may find that you'll need to disconnect the inverter/charger and let the PV controller finish charging the batteries.

Depending on your needs and interest, you might want to consider replacing the inverter/charger with one that offers a programmable battery charger, and, even better, one that includes temperature compensation. Take a looks at units from Magnum, Outback and Xantrex. Examples include:

http://www.magnumenergy.com/Mobilepower.htm
http://www.outbackpower.com/Mobile&Marine.htm
http://www.xantrex.com/web/id/41/p/1/pt/7/product.asp

Another possibility might be a multi-stage regulator for the second alternator.

See: http://www.xantrex.com/web/id/107/p/1/pt/7/product.asp
and: http://www.balmar.net/page14-Regulatorsmain.html

HTH,
Jim/crewzer

mike95490

Re: Interaction between Inverter/charger and Charge Controller

furnace set on 60 degrees and an outside temp of 30 degrees, uses about 60 ampere-hours per night with lights, minimum microwave operation and normal water pump use.

60AH @ 12.5V = 750 Watt hours

Suppose you just mount panels flat on roof, no tilt options (saves peeling them off at a low bridge, or 60MPH driving)
I'd guess you will get about 50% of their rated output. Figure a good useable 4 hours of sun per day, you'd need about 400W of panels, to get 800Wh out of them (in the good 4 hour sun time)
Or a fancy mounting system, to get more efficiency from them, needs less panels, but you have to tilt & un-tilt them.
What sort of roof space do you have to mount panels ?
Panels may also shade roof, reducing air conditioning demand. Panels need air circulation to keep them cool, at hot temps, their output drops off.