Calling all Battery Gurus

Piddlin

Member
Joined
Apr 15, 2019
Messages
15
Location
NC
Last year I bought a Renogy 100ah Pure Gel (discontinued this year). I also purchased a Genius G7200 charger (also discontinued this year) and hard mounted it inside the camper and wired it so anytime I'm connected to shore power, it's maintaining the battery. The description claims charger / maintainer.

I know the next part is going to get dissected pretty well, but I did not buy the Victron monitor. Instead I bought a cheaper version from Amazon. I couldn't swing the additional money to go with the batt and charger.

Alright, now the issue. The camper stays attached to my truck and in the garage, connected to shore power. When camping I mostly use LEDs and the fridge a little and normally don't have a problem. We went to a cooler camp spot a few weeks ago and ran the diesel heater overnight. The heater pulls ~1 amp after start up. I also ran the fridge constantly. When we woke up after the first night, the battery monitor was flashing showing 0%. I ran the generator a few hours and got it back to 80%. It was warm enough the 2nd night not to run heat. When we got home, I read over the monitor instructions again and remembered there is an optional setting for min voltage and I had set it to 12 (2 volts per cell = dead). So I changed it to 11 volts, charged fully, set to 100% and figured problem solved.

Just got back from an overnight trip and again woke up to 0%. This time the only thing that had ran was the heater at ~1 amp. The voltage on the monitor was 10.2 volts. The heater will code if it receives under voltage and it had not. I turned off the heater and the voltage rebounded to 12.2.

My questions are- Have I ruined the battery by leaving it connected to the charger constantly, even though it's supposed to have a maintenance mode? It's concerning that the charger and battery were both discontinued this year. Is it just the result of a cheaper monitor and I need to turn the min voltage off and just consider 50-40% dead? Victron is currently not an option.

Sorry for the long post, but thanks for reading.
 
I'm no battery Guru, and I also have a Noco 7200. I think the Noco may have killed your gel battery prematurely. I don't see where that unit has a specific GEL mode. https://media3.webcollage.net/3619744553eaf7183edc446279362fdef6533782?response-content-type=application%2Fpdf&AWSAccessKeyId=AKIAIIE5CHZ4PRWSLYKQ&Expires=1893468497&Signature=oLuZZTsoQr9HpBC8D230GHPe6CE%3D

And GEL batteries seem to want a lower charging voltage than AGM batteries
http://www.bblbatteries.co.uk/docs/hints_tips/Battery%20Charging.pdf

SO, your monitor may be fine, and the batteries... toast. Just sayin.
 
Thanks for the reply Vic. Reading over your links and looking at the Amazon reviews, it seems the Pure Gels were not the best design. Most of the bad reviews are from this year and the positive reviews were prior. So, longevity seems to be the problem.

As I look to buy new batteries, the 7200 is ok to leave connected to regular AGMs when not in use?
 
I have a Noco 7200 also and have never had an issue with over charging with lead acid or AGM batteries, so I have a couple questions for you: When the Noco is connected and in maintenance mode what voltage are you seeing on the monitor? Does this match what the battery manufacturer recommends? If the answer is no, then you need to get a different charger, or switch to AGM batteries. It is also possible you have a defective battery. Warranty???
 
I have the Noco Genius 7200, also. It has been replaced in the Noco line by the Genius10 at a similar price but has 10 amps instead of 7 amps. I consider that a good thing.

Paul
 
Thanks for the replies. I believe Vic was right. When I researched batteries last year, it seemed gel was superior to AGM. Looking now at the reviews, it seems different. I have another AGM I charged with the G7200 and currently operating the heater to test. After 6 hours, It’s at 94 ah, which is where I would think it would be. Anyone want a slightly used pure gel battery? I think I’ve bought my last.
 
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