Questions about Group 31 starting batteries getting run down overnight by fridge and also solar.

onanysunday

onanysunday

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So I have a 99 National Tradewinds with the Cat 3126. The two engine starting batteries are group 31 in size. Just got back from an 8 day trip and every night I would charge them up to 12.7-13. Overnight and in the morning the two batteries would be discharged to 11.7-11.9 volts. Drove home yesterday and parked it. After letting the coach sit a few hours the batteries were showing 12.7. This morning they are checking at 12.4 along with the (4) 6 volt house batteries also checking at 12.4. National is running the fridge off of the two starting batteries. That is the only thing I turned off last night so the fridge is the main draw pulling it down. It is running on propane but obviously it has a 12 volt draw as well. (Looks like 2.7 amps).  It is a Norcold fridge and here is the tag. I don't remember it drawing the batteries down this fast but maybe I was running the big gennie more often. I believe it charges at 40 amps. 

So I need to do some kind of solar. Don't want to spend a fortune on a system. I will say I like to play the stereo in camp and the Fosgate amp will draw the 4 house batteries down as well. What about this Renogy 100 watt portable panel?  https://www.amazon.com/Renogy-Watts-Monocrystalline-Foldable-Suitcase/dp/B00LXG4AXS?th=1

Seems reasonable in price and I don't have to wire the whole coach. How fast would this charge the two group 31 batts and then the 4 6 volt batts? I would just extend the wires if needed and connect with alligator clips. Don't want a controller if not necessary.  On a nice sunny day would the 100 watt panel charge the group 31s in lets say half a day and I could switch over the the house batteries and give them a charge as well?

I do have a pro series DSR145 which I run off of the 2000 little gennie. Intermittent 40 amp charge that will bring them back up in an hour. But a PITA to do every day. https://www.schumacherelectric.com/products/dsr145-6v-12v-125a-proseries-battery-charger-engine-starter/

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Your fridge is running off your starting batteries? Never heard of such a thing. That would bug the crap out of me. 

 
Dockmaster said:
Your fridge is running off your starting batteries? Never heard of such a thing. That would bug the crap out of me. 
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Correct. That is how National did it. Sounds like the older propane refrigerators did not draw much battery power. This fridge was replaced before I bought the motorhome. I guess the newer ones draw more from reading in the RV forum. I do really like the fridge.

 
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I have a 150w panel flat on my roof. Highest it gets is 8a at noon. Its not much we always need supplemental genny and even that sucks because it doesnt fully charge. Your rig might be the same. Will explain below. 

Its possible you have a mixture of problems. 

1. Batteries are not new. 

2. I bet glamis was pretty cold during your trip?

3. The batteries might not be getting fully charged. Which will cause their lifespan to suffer. You said the starting batteries get up to 13v. Is that resting? Or charging voltage? Because they need to be up in the 14v range to be absorbing their bulk charge. The charger inside my trailer does not go into 14.4v mode. Which means my batteries never get fully charged. You could start the genny and measure the voltage. Give the battery time to get up to 14.4v if its low. But make sure it gets there. Its kinda messed up because your 6v batteries are actually supposed to get 14.7v. So if your RV charger is doing both 6v and starting, youre limited to being safe and staying down at 14.4v to keep the starting batteries happy. But.....this is all around 70f. On a cold glamis night the batteries are supposed to be charged even higher. Thats getting a little picky though. But if you end up investing in a good solar controller it will have a temp probe that you place near the battery and it will auto adjust charging voltage. (i dont have that feature on my older GoPower 30a PWM that came on the trailer)

4. Could look up equalization charge for the 6v. Your charger might very well have that feature. Do Not charge the starting batteries this high. But its good for the 6v to get charged up to 8v. Which seems nuts. Because that means your 12v system is charging up at 16v. You kinda dont want to have 12v things running at that high of a voltage. Say like an unregulated LED light that would get way too hot and could be dangerous. I disconnect the batteries from the trailer when i do an equalization charge. There is a ghetto way to do it. I bet you have a 5a battery tender? Its a 12v tender that will supply about 4.8a to your 6v battery. You can do this outdoors and dont breath the fumes. Check voltage until it gets to 2.7v per cell which is 8.1v for a single 6v battery. You would do this individually. I do it to my 6v when im being lazy. A smart charger of some sort will allow you to adjust charge voltage and do it much safer. Because it can hold the 8.1v for a longer period of time. Where the battery tender is going to try to keep pumping 5a until it sees 12v. Thats no bueno since youre charging a 6v battery. You would obviously disconnect the charger when the batteries get up to 8.1v if its around 70F outside. 

5. I have this saved on my laptop. Helps to remember 6v charge specs. https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

 
Should add if anyone does an equalization charge make sure water level is above the plates, but do not top them off. 

The water level will rise and they will bubble like a mammer jammer. Make sure to loosen the top caps so the battery can vent easier. 

Keep baking soda water around. I have a 32oz gaterade bottle of baking soda water with my glamis/offroad chemicals. Lives next to spray bottles of soapy water and another with simple green. They come in handy all the time.

 
Wopa, My 4 house batteries are 6v with caps to check the water. But the two group 31 batts to start the coach and what the fridge is running off of are sealed batteries.

 
Forgot about this old solar panel I have laying around. This thing is at least 15-20 years old. Threw it on the group 31 batts and within a couple of hours it brought them from under 12.4 to a little over 12.7.

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Oh wait .... Date on that panel is 2000 so 21 years old. lol. 

 
From the owners manual:

DC amp draws (at nominal 12 Vdc) Automatic ignition------------------------------------------------------------------------------------------------------------------ 0.50 A Moisture reduction heater and divider heater------------------------------------------------------------------------------- 0.70 A Fresh food compartment lamp ------------------------------------------------------------------------------------------------- 0.46 A Gas valve ---------------------------------------------------------------------------------------------------------------------------0.146 A Fans (2) ------------------------------------------------------------------------------------------------------------------ 0.30 A (per fan)
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 Hard to believe it pulls it down that far. Certainly a bad design coming off the starting batts and not the house batts.  Will it be as easy as just moving the wires to the other bank of batteries?

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Can you post pics of the batteries? Maybe someone accidentally hooked up the fridge to the wrong bank. 

Be curious to see if the fridge 12v wires could even reach the 6v battery bank. Or if the connectors would even fit onto the 6v lugs.  

I think i was mistaken above. Your 12v starting batteries are probably only charged by the alternator. 

Next time the genny is started i would monitor the 6v battery bank. Make sure its getting up to 14.4-14.7v. I realize that is a whole different subject than your starting batteries running low. 

 
Batteries

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My guess is the fridge wires run to the controller. Back of fridge. 12V appears to be the white and black wires below the yellow sticker. 

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Found the power wire for the fridge. Gray wire where the 15 amp fuse is removed.  Controller has 4 sections. Right now the wire goes to the Coach switched section.

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Then there are 3 other sections.  Ignition switched, Chassis Batt, and Coach Batt. I have an open port at P-5/F-2 and guessing that is where I need power.

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I remembered this company had taken over the Custom RV Products controllers. I actually bought a new one from them in 2018 for $389.00

Thank You
Chris Bayus


M&M RV Electronics
205 N Main St.|Ohio City, OH 45874
(419) 965-2662|(419) 965-3014
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I have each bank of batteries on a big master switch. It is weird on the controller because if you throw the switch for one bank at a time it will have power to both sides of the controller. There seem to be solenoids that have time delays built in.  But in the right sequence I can get P5 to work with a 15 amp fuse in F2. And it is powered only by the (4) 6 volt batteries. I am going to call Chris on Monday to make sure it won't do anything weird to pull power from here. I will now have the issue of the 4 batts getting drawn down on nights it is cold with the heater and the fridge all on the same circuit. Still happy to put it all on that bank of batteries. I left my 21 year old solar panel on all day and this evening voltage was at 12.5. Still wouldn't mind having a newer panel or some kind of solar setup. Just being a cheap bastard because I need to order a new radiator for the Funco. Among other things. lol. 

 
If that gray wire is your refer power line, it looks like it is on the coach side, not the chassis side. Are you sure it is your fridge that’s drawing down your chassis batteries? 

 
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