Solar Upgrade - No need for multistage converter?

[pteck]

I'm in the process of doing a modest power systems upgrade on my 27FB. Key to the upgrade is adding a small ~200W solar system, along with new 2x grp 27 batteries.

A key upgrade that many do seem to be the upgrade of the stock Parallax 7355 55amp converter to a multi-stage PD 4655. This is to maximize battery life by having a proper float mode when plugged in for an extended time.

That said, I'm not sure I really need the converter upgrade, especially with solar. I store my AS in the open. Which means I will rarely have it plugged in for extended lengths of time, and the solar charger will keep the batts topped off. Only time I may be plugged in will be for active vacations or running A/C with a generator.

Is my thinking correct on this?

[uncle_bob]

Hi

What sort of conditions will you be operating under? When the batteries get hot (120F) or cold (40F) the "magic voltages" for float or bulk charge change significantly from what they are at 70F. To the degree that dropping from a "bulk charge" voltage down to about a half volt lower "float charge" voltage is important. The > half volt change in the voltages is equally important.

As you shop, at least *consider* one of the (many) systems that will let you put a temperature sensor on the batteries. Yes, you *will* have to get a wire to the sensor. No pain, no gain ....

Bob

[pteck]

I'm in the desert, SW region of the continental US. So will generally be in warm sunny weather areas.

While I'm an engineer with elitist thoughts, cost is a design parameter too, where practical 90% solutions generally represent the best value.

I'll have to do some researching on solar controllers, and at least look into temp sensor controllers.

[uncle_bob]

Hi

There are a number of places on the web where you can find the voltage vs temperature curves for various battery types. There's not a lot of deep dark secrets involved. It's mainly something that was pretty tough to do decades ago and now is much easier.

Bob

[alano]

I didn't think it was worth upgrading my converter since my solar charger is properly maintaining the batteries.

When you're connected to shore power just leave your Use/Store switch in the Store position.

[uncle_bob]

Hi

Depending on the model and year of your AS, the "store" switch may or may not take the battery out of the loop on shore power ....

Bob

[NWRVR]

I had 120W factory Zamp solar on my 2014 International Serenity and always had the battery switch in "store" from March to November when outside. Batteries were always full according to the controller. When I stored her in the garage for winter I left it in "store" and put an external float charger on the batteries. Sometimes it is the basic solution that makes the most sense. I guarantee that you have more sunshine where you are.

[pteck]

That's the confirmation I'm looking for. I can always chase better but in practice, it's just not necessary sometimes.

I'll leave in the stock converter charger for now and focus on a solar upgrade this time around. And inverter...

[alano]

Originally Posted by uncle_bob

Hi

Depending on the model and year of your AS, the "store" switch may or may not take the battery out of the loop on shore power ....

Bob

Very true. Do you know the cutoff date when AS changed to isolate the batteries while on shore power?

[uncle_bob]

Originally Posted by alano

Very true. Do you know the cutoff date when AS changed to isolate the batteries while on shore power?

Hi

What they do still depends a bit on the model. The 2018's disconnect to a greater extent than the 2017 model year trailers. The 2018's still have stuff like the propane detector on the battery when it's in "disconnect".

Bob