[El Guapo]

Two Renogy 100W panels, one Renogy 200ah battery, Renogy Adventurer charge controller.

I think I'm having an issue with my battery or charge controller or something is actually draining my battery very quickly. My battery has been hooked up for a few weeks and I've been using a few LED's for light while working on it in the evening with not much noticeable change in the % battery charge.

Yesterday we hooked up the solar panels and took the van out for a few days. I'm having huge swings in my %battey and volts according to the charge controller readout. The only load I'm running continuously is a Truckfridge 130. We've run the water pump in the last 24 hours a total of only about two minutes at about 10-15 seconds at a time.

I've gone from nearly 100% to about 50% in about 30 minutes today with nothing running but the fridge. Does this seem right? That's about 100ah drained in 30 minutes from just the fridge. Below are a few notes in readings from today. Any idea if I'm having some kind of a problem?

%charge-volt reading on charge controller-volt reading on Blue Sea voltmeter-time

%-Vr-Vs-Time
22-12.8-12.78-0700
36-13.0-13.00-0900
68-13.9-13.73-12:00
95-14.0-13.94-1400
60-13.6-13.50-1430
57-13.5-13.46-1435
67-14.4-14.28-1445
81-13.9-13.81-1500

 

[keeponvaning]

Do you have the controller set correctly? With those loads it should basically just chug along on the solar forever.

 

[El Guapo]

I set it according to the manual, which only showed a few parameters to set - power generation rested to zero, select battery type and choose temperature readout in degrees C or F. I couldn't get the battery type selection to come up. Would that cause the big swings? Supposedly this fridge averages only 2 amps per hour over and it's not hot where we are.

 

[RDinNHandAZ]

Perhaps, but your battery voltage varying from 12.8 to 14.4 is not an indicator the the batteries are 50% drained. When the fridge is on, the full battery will read about 12.8 under a 2-3 amp load. When fridge is off it will quickly rise to 14.3 or so. It may be fine. Voltage is not a good indicator of state of charge (SOC) The fridge is a significant load over r24 hours the pump is insignificant as are a few LED lights.
If you see 12.2 volts or below the batteries are in a low SOC.
Get a Watt meter if you want to know what you have used or a SOC meter for how much is left:
https://www.amazon.com/uniquegoods-...1497910414&sr=8-1&keywords=12+volt+watt+meter
https://www.amazon.com/Midnite-Sola...sr=8-9&keywords=Battery+state+of+charge+meter

 

[MsNomer]

I'm going out on a limb and suggest an erratic wire that's throwing off the meter. I had similar erratic readings when our solar was hooked up and traced it to one tiny strand that had escaped the screw on the back of the meter. One of the very, very few electrical issues I have ever diagnosed (with help from the vendor) and fixed myself, given that I am an ignoramus with electrical stuff.

 

[Winston]

We concur with RD that voltage does not accurately correspond to battery State of Charge. Case in point, your 22% SOC at 12.78 volts cannot be correct. As we recall, our AGM Lead Acid battery when 'resting' (i.e. when neither under charge nor current drain) was at 50% charge at approximately 12.5 volts.

We find an ammeter to be indispensable in trying to 'understand' electrical "whats-going-on" situations. We'd recommend installing a shunt to run both the ammeter and a more accurate State of Charge measuring indicator.

One thing you might try, see what happens midday while running just the solar panels and frig. Most frig's draw between 4 and 5 amps while "on". At 12.5 volts, 5 amps corresponds to 50 watts. Your 200 watts of solar, midday at your latitude should supply over 100 watts (without clouds or shade, of course). Under this 'test' condition your battery voltage should remain constant but probably will slowly increase.

 

[keeponvaning]

Doesn't your charge controller have a light that indicates when the batteries are at full charge? My Renogy mppt has a green LED that flashes when the batteries are fully charged (supposedly anyhow). I've never had a battery that went dead or gave me any problems with the Renogy/Tracer 30 amp charge controller and 300 watts of solar.

 

[El Guapo]

Thanks for the advice. I'll check on everything suggested. If I can't find it I'll call Renogy when I get home. No I haven't seen any kind of light when it's at 100%.

Something else very odd it did was last night. At around an hour to dusk it said 37% charge. By then the panels were producing virtually no elec. I checked it about an hour later at dusk and it was saying 85% charge and continued to rise, in the dark. That didn't make any sense.

 

[keeponvaning]

You may need a new controller. Renogy replaced mine for me under warrantee when it was acting strangely.

 

[El Guapo]

I called Renogy tech support. They said the %charge/SoC displayed on the charge controller is not showing what % the battery is charged or how much capacity is left. They said that a load can cause that number to change very quickly and that the volt current at the post is a better indicator of capacity used/remaining, but that can sometimes be thrown off also if a load kicks on.

My 200ah Renogy gel battery supposedly is at 50% SoC when at 12.1v and at 100% when at about 14v. I wish I had recorded the conversation because I think he also said something about zero charging or load for 30 minutes for the readout to be accurate.

 

[RDinNHandAZ]

What he was probably saying is a battery which has rested for about that long gives a more accurate voltage than when a load is on or a charge is coming in. Your reading of 12.1 to 12.8 when resting is about 50% to 100%