Charge splitter with solar, dual batteries problem

[SimonSolar2C]

Hi,
Couldnt find an answer about this, so posting here.
I have a sunraider style toyota RV
It has the original charge splitter going from generator system to the car and leisure batteries.
Ive added a Solarix 2010 MPPT charge controller and 200watt panel
Everything is within spec and correctly wired, and most of the time it works well, charging the leisure batteries under solar power by 11am
Sometimes, when the van is left idle, the controller displays an unknown status light, and battery voltage 'drops' to 8.4volts. Nothing is turned on as far as I can tell, but even if it was, the battery should be charging.
So :
1. Is it okay to have the original charge splitter installed with the solar system?
2. If thats not the problem, any ideas why is it getting into this weird state?

I think it corrects itself when we start the engine and it charges up under engine alternator, then it will work flawlessly for some months until for some reason it messes up

[Alex Adams]

Just a guess. It looks like you have your fridge wired directly to the solar controller. On every solar controller I have looked at, it says to use that output for small stuff like lights and such. I suspect that the fridge may be causing your error. You could try wiring it directly to the battery. It would help to say what type of fridge (make, model) and what the info light does during this problem. If you look in the manual there are different patterns meaning different things based on that light.

[Franswa]

it's complicated enough to "marry" a solar system to an RV's charger/converter system....you wanting to add an engine generator to the system just makes my head hurt...LOL


if it was me the first thing I'd do is add a switch on the positive wire between the splitter and your batteries so you can turn that off and see how the system performs without it....(with you adding 180W of solar on the roof I can't think of when you would ever need engine generator charging anyway)


your two 12V batteries wired in parrallel are of different sizes....that's not recommended and could "confuse" your charge controller


a lot of charge controllers have a "load" connection for use with lights that can be timed, entry gates, etc. Myself and a lot of people ignore those load terminals altogether and source all power needs from the batteries. You could try that and see if it was the problem


I'm at the other end of the scale....my system does not have a converter anymore and through manual switches I can switch from charger (plugged in to shore power) to solar.....both can be turned on or off as needed/wanted...(makes evaluating performance/use quite easy)


good luck

[redbarron55]

If that fridge is a three way or two way with LP gas and you have it on electric the draw will pull the batteries down pretty quickly.

[SimonSolar2C]

Thank for all the feedback folks.
To answer all your questions, yes the fridge is an older style Electrolux 3 way fridge - they are terrible on 12volts and draw about 10 amps but I usually dont run it unless Im driving, and I flick it off when I stop ans use LPG.
I put the fridge on the controller output, which is rated for 20amps, because I wanted to ensure the fridge doesnt over discharge the batteries. That output turns off at ~11volts. The lights and other stuff is unlikely to over discharge the batteries, therefore I run that directly off the batteries.
Interesting point about the batteries being different sizes, but they are connected in parallel, so wouldnt the solar charger just 'see' one bigger battery? The two batteries would equalise between eachother.

[SimonSolar2C]

PS @Alex, the manual doesn't include a description of the lights its displaying - Ive written to them 5 days ago

[Alex Adams]

Ask and ye shall receive! The internet is your friend:



I downloaded the manual from:

https://www.steca.com/index.php?Stec...roductdownload

In addition, the tech specs on the website say that the controller output for load is only 10 amps. The charge output is 20 amps.

[Franswa]

Looks like I was wrong on that one....it should not be a drawback after all (file that in the "salesman talk" category)...except that two new batteries of the same size will store more power that two mismatched batteries of different ages


it was a good idea to wire the fridge to the "output" terminals of the controller to make sure batt. voltage did not drop below a certain level....
but how did the voltage drop to 8V (extreme low!) then...(????)

[Byron Kinnaman]

Things are a lot more simple than you're being lead to believe. First you didn't say how much or big your solar panel is. (in order to run the fridge and charge the battery at the same time you'd need in excess of 200Watts of solar). From looking at your pencil diagram I would say simply disconnect the Fridge for the output of the charge controller and NOT try to run the fridge on battery. Without the fridge running on battery everything will work just fine.

[Franswa]

his diagram shows 180W of solar panels....which I thought was HUGE.....and his fridge is a three-way....not a full time electric like some all electric trailers have around here...,.

[Byron Kinnaman]

Originally Posted by Franswa

his diagram shows 180W of solar panels....which I thought was HUGE.....and his fridge is a three-way....not a full time electric like some all electric trailers have around here...,.

9 amps indicate running on 12 VDC.

[Byron Kinnaman]

[QUOTE=SimonSolar2C;736898]Hi,

1. Is it okay to have the original charge splitter installed with the solar system?
2. If thats not the problem, any ideas why is it getting into this weird state?

/QUOTE]


1. Yes it's OK as long as you're not trying to run something more than the charge controller can handle. (FYI there's no need to connect the "Load" terminals to anything)
2. The "weird" state is caused by running the battery down with the fridge.

[Byron Kinnaman]

Originally Posted by Franswa

his diagram shows 180W of solar panels....which I thought was HUGE.....and his fridge is a three-way....not a full time electric like some all electric trailers have around here...,.

Without knowing what the open circuit voltage out of the solar panel or if it's in direct sun light or not it's kind of difficult to say if 180 Watt is enough. According to my calculations and assumptions I come up with 10 amps in direct sunlight maximum out of the 180 watt solar. Anything less than direct sunlight the output drops. Even in direct sunlight he's marginal at best.

[Franswa]

yeah, Byron, 9 amps is probably what fridge uses on DC....but he says he only selects that when he's driving.....maybe the fridge stays on....but you'd think he'd notice that (cold fridge after days in storage)


one of my 40W panels is supposed to put out 2.7 - 3A Max....so yeah, at high noon on a sunny day 180 should run the fridge on DC and then some
(but that's at "high noon")

[mszabo]

Disconnect load to refrigerator.
Power to refrigerator should be a fuse circuit from battery.

[Franswa]

another piece of the puzzle is he said his battery (poor thing) went down to EIGHT volts !!! so with the fridge connected to load terminals on controller (that has 11 volt cut off).....his problem is somewhere else (ain't the fridge)


good puzzle...small phantom load somewhere in the rig???...small enough to not be a problem overnight/regular use....big enough to draw the battery down WAY too low in storage??? gonna have to find that before buying new batteries...because that is in his future (drawing them down to 8 volts)


if it can't be found a house battery cut-off switch would be an easy fix (for when in storage)

[John in Santa Cruz]

so what is this charge splitter you speak of, and how is it wired in?

odds are very good the vehicle alternator at idle can NOT supply enough current through the wiring harness of both the tow vehicle and trailer for the fridge, so the fridge is sucking current out of the trailer battery and dragging the whole thing down.

with my Casita 16 and 2008 Tacoma, the fridge on DC would drag the battery down even when I was driving, so I left it on propane. 2 hours into a road trip and my battery was down to 11.6V.

I've never even tried the jumbo fridge in my Escape 21 on DC, only on AC or propane. In theory the F250 diesel should easily run it but again, wire gauge is an issue.

[redbarron55]

If the battery was discharged to 8 volts it is already damaged and perhaps was previously.
As to the 11 volt protection by the charge controller that is too low as well for battery health.
I would have the batteries tested.
Most refrigerators do not use the thermostat on 12 volts as the current is pretty high to cycle on and off and the 12 volt is not very efficient.
Electric compressor refrigerators are much much more efficient drawing about 40 watts running with about a 50% or less duty cycle.
The absorption DC draws about 140 watts continuously instead of an average of less than 20 watts

[Roger M. Sonora]

Hi, Here are a couple that can probably answer every question you could come up with about Solar and a Toyota Sunrader.
Enjoy their video and check out their page for contact info.
Good Luck and Happy Travels, Roger

https://youtu.be/R8ILMYQvnk0?t=13

[Mike_L]

A 12 volt fridge is a massive draw on a battery. I found that out the hard way. When the tug was running, no problem. Only, I would park and forget to put the fridge on propane and in no time at all the house battery would die.
I wired the fridge directly to the tug through a solenoid so power was cut when the tug wasn't running so as not to kill the tug battery.