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Solar and Charger into one?

ajriding
Explorer II
Explorer II
I am modifying my cargo trailer to be more like a camper, and dug up some old stuff for it.

I have a modern MPPT solar controller for the 100 watt (soon to be 200w).
Two golf cart batteries.
I have an old 12.7 volt, 15 amp DC power source of a 1972 Winnabago, attached to a 115 circuit breaker box complete with shoreline/generator switch.

I am sure there is no monitor on the DC charger/power source.

The solar I know how to set up no problem, no questions.
The power source no problems either.

What I want to do is have the shoreline DC power source be "smart". I do not want to just send 15 amps to the battery everytime I plug in or want to use the DC power source instead of the batteries. I will be running a Danfoss chest fridge, and just minimal lights and minimal charging, min fan etc.

I do not want to buy a $500 controller that controls both power sources (solar and charger) electronically, but can spend under $50 for something to make it all work together.

The breaker box does have a breaker for the charger if it comes to that so I can still plug in and have shore power for AC or electric heat without charging (overcharging) the battery.
I would rather have something monitor the battery automatically, so looking for a thing maybe to go between charger and the battery to control the charge while the solar works in the daytime but not at night.

Keeping the battery in float while running the fridge and outlets off the charger/converter is the most preferred solution.

Anyone tackled this?
26 REPLIES 26

ajriding
Explorer II
Explorer II
Hard to believe how long it took to build the electrical system.


The batteries are two 6-golf in a box. The box is self contained and vented, varnished and will be painted one day.
I used two bolts to get the power through the box.


The metal bracket that is almost painted yellow spanning the styrofoam is the spare tire bracket for the outside (no structure on the nose so made this)


I turned box around to show how the vent works, but this


is the vent system, is a sink drain piece with a lip and a radiator hose section that fits perfectly over. The thin stained piece of wood has a hole cut in it the exact diameter as the black pipe. I used 4 screws and held it to the box (mount not pictured)

Still need to add water pump and plumbing, but most electrical is done.
I am waiting for parts to put the 100w panels on the roof, so still have to run solar wire to a controller to the batteries.

I have a 20w panel to a controller to that small exit sign battery just for the brakes (it was there before the conversion, so I decided good to keep it in case I remove camper batteries for some reason).

Breaker box has Gen/City power select and breakers for Air Con, outlets, converter and spare.
Fused DC block.

Alternator goes through a DC breaker (100 amps) so I can choose to turn it off on a sunny day. I will add another breaker between battery and converter soon.

I think, since the converter does not send power to the battery, that I can just use a fused circuit and send power to battery if I want to charge it that way. I do not think this would cause any issues. This will connect the converter power to the battery, as is the converter only powers the camper as mentioned above post.
That's no biggie, but when I switch back to battery there will be power going to the converter switch (switched to BATT) and power going out to fuse block which would be connected to the battery, or the battery connected to it sending power to the switch too. I think, electrically, either is the same - just power going from batt to the switchโ€ฆ Or am I missing something critical?

ajriding
Explorer II
Explorer II
I tested the DC power source. It puts out just over 13.8 volts on "converter", none when switched to "battery".
So, all this time I thought it was a chargerโ€ฆ
I think I will need to wire it to put charge into battery.

It has two 12+ outs and one ground.
One 12+ goes to "lights"
The other 12+ goes to (really comes from) "battery" +.

When switched to converter the lights wire has power, but none on battery. When switch to battery the lights goes dead and if I had a battery there would be battery voltage from the battery wire and on the lights wire from the battery presumably.

When I switch to "battery" the "lights" and "battery" 12+ wire get connected, when I switch to "converter" there is no connection between batt and converter wires.
So, both the battery and the converter feed into the "lights" output to power the camper, and there is a select switch to choose which one, but I can't tell that any power goes back to the battery.
So< i should be able to add a switch to run power to the battery from the "lights" output 12+ wire and give battery 13.8v charge.

So, anyway, I think 13.8 is good charge voltage given the solar is the primary power source, so I will keep this power source.

And, likely I had a birdsnest of wiring and the "lights" got connected in the nest to a 12+ from the battery which would have fed back into the battery to do some charging, so I guess it did work. This is off my first camper, and I have refined my skills quite a bit since then.

Also, In 20 years I have stayed at one campground and that was because we were at a specific event and was the only place to park, and it was literally 19 yrs ago. I'm sure not eyeing those restrictive retirement campgrounds, but thanks for heads upโ€ฆ

I always have triangles, never used them, but have changed flats a few times on the interstate. Don't park on the left to change a left tire, park on the right with your rear end out in traffic so you get hit, at least cops won't give you a ticket for having a flat.

btw, this is something everyone needs to know about:
Wago connector

ebay has 60 for $13

Dtank
Explorer
Explorer
ajriding wrote:
I am modifying my cargo trailer to be more like a camper, and dug up some old stuff for it.

The solar I know how to set up no problem, no questions.
The power source no problems either.



Problems....:W

There are campgrounds that will *not* accept your cargo trailer home-made RV (no matter how nice it looks). It's a liability issue.

My BIL ran into that with his race car trailer (kinda like a home-built toy hauler). Race tracks = OK. Campgrounds on the way to distant events = maybe yes, maybe no.

Maybe westernparkowner (hope I got his ID correct) will chime in.

Of course, if you're boondocking - no problema!

.

markchengr
Explorer II
Explorer II
I never go on the road without triangles AND flares and I don't even tow. Have used them a few times for other folks in trouble. -Mark.

ajriding
Explorer II
Explorer II
Thanks, but that was just for fun. I owned this in my first motorhome and used it onboard that for 15 years. no complaints.
I have a very expensive camper in the drive, so this cargo trailer project is not going to be the end-all of technology. I want it to work well.

Back then, about 2001, I had a 12x14 solar panel that was only 5 watts. I wired it straight into the battery, all 18 volts, and it did a great job keeping the battery alive while in storage. I never had to charge it. Today I have a 12x14 inch 20 watt solar panel to keep my cargo trailer brake battery alive but have graduated to an MPPT controller. It also powers a few LED lights and the exhaust fan. It being the battery. I think I will leave that solar/battery system in place just for the brake battery and introduce the RV batteries for everything else. That makes no sense to not use the camper batteries, but I have no other use for a small solar panel and exit battery.

Did you know that in most states you need to carry either flares or reflective triangles when towing a trailer? I have the triangles, and they take up space.

BFL13
Explorer II
Explorer II
I have had no luck finding the manual for that. This guy has some info on the wires in his question, which might help.

http://www.airforums.com/forums/f449/confused-about-converter-in-60-overlander-58613.html
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

time2roll
Nomad
Nomad
That 1972 converter is a door stop. Do yourself and your battery a favor and get a modern multistage converter. Although skip on the WFCO brand.

ajriding
Explorer II
Explorer II
So, for fun the 1972 model is a Phillips Power Converter model PC 151-M-2
115 volts, 2.7 amps, and 60 (watts I assume but the sticker is torn).
12.7 volts DC Current, 15 (amps I assume but sticker is torn).

The wiring diagram on the inside of the cover says one wire goes to/from battery, the other wire to the "motor". I assume "motor" refers to any DC item and that's how I used it.

Through the vents I can see one giant transformer and one blue bean-sized something, maybe a diode.

There is a "Batt/Conv"switch to select battery only or converter. I am not sure if when switched to Conv if it just powers the "motor" or also sends volts to the battery at the same time. When the Conv is selected the lights were always brighter than the battery was ever able to make them.
I think how I wired it was I ran the battery positive into the converter and then the converter had one output for 12+ and that powered the "motor" and everything DC in camper.

If I remember correctly, when AC power is to this it still hums, so maybe is charging, or on, but I will have to wire it up and test it to know. Its been 4-5 yearsโ€ฆThe converter was on its own circuit breaker so I used that as the on/off switch.

BFL13
Explorer II
Explorer II
Some googling says the 1972 Winnies had this, which has an Optional charger that could be 15a if label is "L" model.

You have a choice to be on battery or converter for 12v with either an automatic or a manual switch for that. It warns about checking the battery water weekly if you have the charger. ๐Ÿ™‚

https://www.progressivedyn.com/wp-content/uploads/2017/04/731q-738q-user-manual.pdf

The RV has all the latest elegance it says here

https://winnebagoind.com/resources/brochure/1972/72-Brave-bro.pdf
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

pianotuna
Nomad III
Nomad III
The proper place for the existing converter is a dust bin--or recycling center.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

BFL13
Explorer II
Explorer II
All charging goes to the loads first, then the batteries get anything left over. If the loads take it all and want even more, that has to now come from the battery.

That is why RV converters are set to 13.6v as "normal" for while camping, and only go to 13.2v "storage" for battery maintenance when not camping and there are no other 12v loads.

The OP's 1972 converter needs to be checked for actual voltage no load and then when under the expected 12v loads, to see if it can hold the loaded voltage up enough so the battery does not have any draw on it.

The loads should be connected on the other side of the battery from that old converter so the battery will act as a filter for any "dirty 12v" that could ruin the fridge controls and any other circuit boards in the various 12v loads.

BTW, did we discover whether that "15 amps" is its 120v rating for the AC breaker panel or indeed for its DC output rating?
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

time2roll
Nomad
Nomad
Yes the battery voltage will sag if the load exceeds the solar charging capacity. Then voltage will recover when the load is reduced and the solar gets back to charging. A good converter will hold the battery very steady at about 13.6 volts. That old converter might help you out if plugged in but if you expect a fast charge on generator power you will need a new modern multistage converter.

BFL13
Explorer II
Explorer II
If you have been running the load for a time, the voltage will only bounce back to 12.4, not 12.5. Amp Hours. Don't forget the hours.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

red31
Explorer
Explorer
A load tester apples a large load to a battery and hopefully the voltage does not drop below 9v. Turn it off and the voltage returns to near where it started.