Fridge on 12v drains battery overnight???

**tonygoncalves** · 10-24-2021, 02:45 PM

As per testing from Battleborn using AGM lead acid batteries and their own lithium batteries, when the temps dropped to freezing, they were only able to get 42 amps at a 30 amp discharge rate out of a 210Ah AGM battery bank, so only 1/5 of rated capacity.
https://battlebornbatteries.com/lead...study/?afmc=1x

It's just something most people forget about, especially at shoulder season when the temps are colder, how much battery capacity is lost when the batteries themselves get cold.
So for OP, if the weather drops to 60F overnight and if he only has a single 100A lead acid battery, he might only have 30Ah of capacity at that temperature. If he has a 3A draw, then his battery is dead within 10 hours.

**Redapple63** · 10-24-2021, 03:14 PM

Originally Posted by tonygoncalves

As per testing from Battleborn using AGM lead acid batteries and their own lithium batteries, when the temps dropped to freezing, they were only able to get 42 amps at a 30 amp discharge rate out of a 210Ah AGM battery bank, so only 1/5 of rated capacity.
https://battlebornbatteries.com/lead...study/?afmc=1x

It's just something most people forget about, especially at shoulder season when the temps are colder, how much battery capacity is lost when the batteries themselves get cold.
So for OP, if the weather drops to 60F overnight and if he only has a single 100A lead acid battery, he might only have 30Ah of capacity at that temperature. If he has a 3A draw, then his battery is dead within 10 hours.

I think you may have hit the nail on the head on this one. Are we sure that a two way fridge is using 2-3 ah on propane? I would factor in maybe 60% duty cycle equates to 45 ah in a 24 hour time or 22.5 ah in 12. 60% duty cycle takes that to say 1.875.

With a 30 ah capacity for a single 12v battery and based on other usage during the day, water pump, lights etc. Yep, I could see it.

To the OP, please provide your battery setup. Would definitely help narrow down possibilities.

Bill

**DECelt** · 10-25-2021, 06:41 AM

Originally Posted by Redapple63

I think you may have hit the nail on the head on this one. Are we sure that a two way fridge is using 2-3 ah on propane? I would factor in maybe 60% duty cycle equates to 45 ah in a 24 hour time or 22.5 ah in 12. 60% duty cycle takes that to say 1.875.

With a 30 ah capacity for a single 12v battery and based on other usage during the day, water pump, lights etc. Yep, I could see it.

To the OP, please provide your battery setup. Would definitely help narrow down possibilities.

Bill

Hi all. So it's a standard marine battery...group 27. One battery only. It's coastal Delaware, so nighttime in the 60's this time of year. I think the issue is the 2118 fridge itself...nothing wrong, but it's running a 12 volt perimeter heater and door flapper heater 24/7....and the control module. Add in the usual suspects for parasitic draw and I think it's just too much for one group 27 battery. These ain't your grand dad's RV fridges anymore I guess. The 20 watt solar should be my ore than sufficient bro keep my battery topped, but I don't expect it to run the trailer. Just a trickle charger.
I'm going to measure the drawdown today if I can stop being lazy. [emoji57] I have the ability to use the storage facility 15 amp power for short term....so I think that's the best solution for letting the fridge to temp before a trip.

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**DECelt** · 10-25-2021, 08:23 AM

Originally Posted by DECelt

Hi all. So it's a standard marine battery...group 27. One battery only. It's coastal Delaware, so nighttime in the 60's this time of year. I think the issue is the 2118 fridge itself...nothing wrong, but it's running a 12 volt perimeter heater and door flapper heater 24/7....and the control module. Add in the usual suspects for parasitic draw and I think it's just too much for one group 27 battery. These ain't your grand dad's RV fridges anymore I guess. The 20 watt solar should be my ore than sufficient bro keep my battery topped, but I don't expect it to run the trailer. Just a trickle charger.
I'm going to measure the drawdown today if I can stop being lazy. [emoji57] I have the ability to use the storage facility 15 amp power for short term....so I think that's the best solution for letting the fridge to temp before a trip.

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Ok...I got off my butt. I'm not particularly electrical, but here is what I got with a multimeter;

Battery voltage when power on and charging (just connected) is 13.65 volts.

Battery at rest with no power and completely disconnected (ground removed) is 13.03 volts.

Battery across terminals with fridge on at 12.87 volts.

That doesn't look like a huge draw. The most recent incident was fridge on and 19 hours between fridge on and finding it dead. I guess that's just too much for a single battery.

The batteries is a Precision marine group 27 rated for 660 cca. I can not find any other specs on the battery.

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**Hoopy Frood** · 10-25-2021, 09:04 AM

Those numbers help a little, but you really need to know the amount of amperage draw to determine how long that battery will last.

**tonygoncalves** · 10-25-2021, 10:35 AM

Marine 27 batteries usually only have 80-100ah of capacity, and that is at a low amp draw. Due to the nature of lead acid, with their internal resistance, the higher the draw the lower the capacity. Especially since yours is designed as a starting battery with 600 cold cranking amps, instead of a house battery with the AH listed. Basically, you have a battery designed as a 100m sprinter, but you need a battery designed as a marathon runner.

I think your issue is a combination of the following:
-single 27 size lead acid battery, 80-100ah capacity of which only half is usable if you don't want to damage the battery
-cold weather overnight draining the capacity even lower
-20w trickle charger isn't enough to charge the battery to full absorption during the day, especially with shorter fall hours
-and last but definitely not least, the the 12v perimeter and door flapper heaters. I don't know exactly what those are, but as soon as you say you have electrical heaters on, you know you're going to have a much higher than usual amp draw.

Solutions would be either, in order of estimated cost:
-plug in to shore power when you want to run your fridge overnight before a trip, otherwise leave everything off
-add another 27 marine battery of the same kind, wire them correctly, and you now have double the capacity. but, depends on the age of the current battery you have, you don't want them to be older than a year apart, otherwise the younger one is going to be doing all the work.
-plug in or install a much bigger solar panel, 100W or higher. may not solve your issue if your current battery won't last the night, but will help if you double up your batteries
-buy a proper battery monitor, like the Victron ones I mentioned earlier. the only way to know exactly what power you have and how much you're using, especially with lithiums
-switch to a single lithium battery. they're rated for 100ah, 100% draw. but you'll need to upgrade your charging equipment like the converter and solar charge controller, etc. the factory charge controller won't fully charge a lithium battery or keep it charged, even when plugged into shore power

**tonygoncalves** · 10-25-2021, 10:40 AM

Originally Posted by Hoopy Frood

Howard and Peggy
2019 Momentum 351M
His: 1999 Honda Interceptor
Hers: 2013 Spyder ST-S

Ok, now I'm really interested in how you tow a 5th wheel behind your motorbikes. Do you have some sort of parallel shared hitch, like with a dual horse drawn wagon?

**Hoopy Frood** · 10-25-2021, 11:14 AM

LOL I never thought about putting the truck on there. It's been in front of quite a few pop-ups, and fifth wheels. It's a 2001 Dodge Cummins dually w/six speed manual. Fairly low mileage for a 20 year old truck 121,000 miles. I almost sold it this spring when prices were stupid, not that they still aren't. I had offers for what I paid for it 20 years ago.

But it does the job, and saves me money to travel with. Win, win.

**DECelt** · 10-26-2021, 06:15 AM

Originally Posted by tonygoncalves

Marine 27 batteries usually only have 80-100ah of capacity, and that is at a low amp draw. Due to the nature of lead acid, with their internal resistance, the higher the draw the lower the capacity. Especially since yours is designed as a starting battery with 600 cold cranking amps, instead of a house battery with the AH listed. Basically, you have a battery designed as a 100m sprinter, but you need a battery designed as a marathon runner.

I think your issue is a combination of the following:
-single 27 size lead acid battery, 80-100ah capacity of which only half is usable if you don't want to damage the battery
-cold weather overnight draining the capacity even lower
-20w trickle charger isn't enough to charge the battery to full absorption during the day, especially with shorter fall hours
-and last but definitely not least, the the 12v perimeter and door flapper heaters. I don't know exactly what those are, but as soon as you say you have electrical heaters on, you know you're going to have a much higher than usual amp draw.

Solutions would be either, in order of estimated cost:
-plug in to shore power when you want to run your fridge overnight before a trip, otherwise leave everything off
-add another 27 marine battery of the same kind, wire them correctly, and you now have double the capacity. but, depends on the age of the current battery you have, you don't want them to be older than a year apart, otherwise the younger one is going to be doing all the work.
-plug in or install a much bigger solar panel, 100W or higher. may not solve your issue if your current battery won't last the night, but will help if you double up your batteries
-buy a proper battery monitor, like the Victron ones I mentioned earlier. the only way to know exactly what power you have and how much you're using, especially with lithiums
-switch to a single lithium battery. they're rated for 100ah, 100% draw. but you'll need to upgrade your charging equipment like the converter and solar charge controller, etc. the factory charge controller won't fully charge a lithium battery or keep it charged, even when plugged into shore power

Thanks for the detailed reply. I've never had a trailer with just one battery and guess that I was a bit spoiled [emoji2]. Since we don't boondock I think I'll just accept the limitations at this point.

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