Fridge Causes Voltage Drop?

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Desert Scruff

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Jul 31, 2016
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I have a CR85 Isotherm refrigerator in a 2016 Fleet and recently have had the voltage drop to 10.5 volts on three occasions. The drop occurred after the fridge had been running almost continuously for 10 hours, using about 25 Ah each session.
I have two AGM batteries less than two years old and all the tests I've done on the batteries show they are in excellent shape. I was scheduled to have a final test done, a stress test, but have to drive 250 miles round trip to the shop.
When the voltage is at 10.5 and I turn the fridge off, the voltage immediately jumps to 12.5. In doing online research I discovered it is not uncommon for the voltage to drop when the fridge compressor runs. I also know this can be caused by the wiring to the fridge being too small.
But assuming FWC did not use too small a gauge wire, does anyone have an idea what is causing the voltage drop and what to do about it?
I have also had to make numerous manual adjustments to the thermostat to keep the fridge from either freezing food or becoming too warm. On another post I saw where a fan inside the fridge will solve that problem.
Thanks for any help you have to offer (and I would rather be talking about a trip than complaining about a problem).
 
I took delivery of a Hawk in March of 2017 also with the CR85. This April I experienced the exact same thing. I removed the two batteries (Exide) and had them load tested and both failed. I called the phone number on the battery for the warranty and they replaced both of them with no questions asked. I ended up installing two 6 volt batteries and changed out my Zamp charge controller to a Victron. I'm thinking the Zamp overcharged the batteries also setting off the propane alarm regularly. I noticed the alarm would only go off when the batteries were being bulk charged at 14.4 volts. Everything has been working fine since l made those changes.

Carl
 
Desert,
Did an auto repair shop test the batteries? or did you?

Our AGM model Inimidator by East Penn Mfg. is tested every 6 months by my regular mechanic. Battery is over two years old now (guarantee 2 years). In March it was tested = still over 80% good. Roof solar panel keeps it topped off to 100%. Works well under a load.
 
Thanks, Carl, for the input. I get the battery stress test done in a couple of days. It sounds like we are/were dealing with the same thing. I hadn't thought about the Zamp controller overcharging but I have wondered if the converter's "smart" charger was a culprit. If the batteries fail the load test I will take the same path you did to solve the problem. Did you add the fan inside the fridge box? Which Victron controller did you change to? I already have added the Victron battery monitor to track the Ah going out of the batteries.

I would go to 6 volt batteries but one corner of the Fleet battery box has an adjoining cabinet projecting into it a few inches at the top and that is enough to prevent accommodating the additional height of one of the two 6 volt batteries.

Jim, thanks, and you can see I'm heading for the final battery test.
 
The amp draw as measured at the fridge compressor is what when this happens?
 
Desert Scruff, I very seldom used the converter so I ruled that out. I did add a fan inside the fridge and monitor the temps with the AcuRite wireless fridge thermometer. I'm satisfied with the results of the fan. I went with the SmartSolar MPPT 100/30.

Ardvark, In my case I was looking at the app on my phone checking the battery stats when all of a sudden the volts started dropping very fast. It took about 30 seconds to go from 12.7 down to 10.5. The amp draw at the time was the normal 3.8 with the fridge running. The amp draw never changed while the volts dropped off. This was at night so no solar and the camper was not plugged into shore power. I got lucky with the timing to witness this.
 
With two 6 volt batteries I would get about 200 usable Ah versus 85 usable Ah with the two 12 volt batteries. That's the way I understand it.

I should correct myself in the first post in talking about the drop in voltage possibly being caused by too small a gauge wire. Again as I understand it, that voltage drop would be at the fridge and not the battery. The voltage drop to 10.5 I was seeing was at the battery.
 
Amp hours of two 6s in series or two 12s in parallel is roughly the same: http://www.batteriesnorthwest.com/batteryschool.cfm?TID=20#ANC20 Historically the advantage of 6s over 12s has been plate thickness although it has been argued more recently that with quality batteries the difference in charging cycles is not greatly different.

With an atypical rapid discharge, voltage only tells you something is happening, but not what. In the case of the fridge, how much amperage should it be drawing versus how much is it actually drawing? If everything is good there, then you are looking at maybe batteries that can't handle the load or something else.
 
FWC says the amp draw of the fridge averages 2.7 and my monitoring shows that is the range I'm in even at 10.5 volts.

On 6 volt batteries I meant to say, I would gain 15 Ah available over the 12 volt batteries, going from 170 Ah total 12 volt to 200 Ah 6 volt.
No wonder I need help.
 
I have a crude understand of parallel VS series battery configuration so going to two 6 volts in series to gain perhaps 15 amp/hrs is counter intuitive to me because if one battery in series craps out you lose the circuit but in parallel there is a "work around' [literally]...

Does the external charging via 110 or solar factor into using 6 volt or 12 volt batteries?

I have the OEM FWC set-up in our '16 Hawk with a CR110 and so far no battery issues...we have Zamp full roof and portable solar array [240 w] and IQ4.
 
Wallowa said:
I have a crude understand of parallel VS series battery configuration so going to two 6 volts in series to gain perhaps 15 amp/hrs is counter intuitive to me because if one battery in series craps out you lose the circuit but in parallel there is a "work around' [literally]...

Does the external charging via 110 or solar factor into using 6 volt or 12 volt batteries?
Click to expand...
There are three big reasons to go with 6 volt deep cycle golf cart batteries:
  1. They are (relatively) inexpensive. < $1 per amphour for FLA, about twice that for AGM.
  2. They are easy to find, any town with a golf course will have a battery source near by (some golf course maintenance shops will sell you batteries if you ask nice). True deep cycle 12V batteries are harder to find.
  3. Lead is heavy. It is easier to muscle 60 lbs twice than 120 lbs once. And batteries are usually sited in an inconvenient place for lifting.
A 6 volt battery is three 2.1V cells connected in series, a 12V battery is six 2.1V cells in series. If hooked up right the charging source won't know the difference.

jim
 
There are three big reasons to go with 6 volt deep cycle golf cart batteries:
  1. They are (relatively) inexpensive. < &#36;1 per amphour for FLA, about twice that for AGM.
  3. They are easy to find, any town with a golf course will have a battery source near by (some golf course maintenance shops will sell you batteries if you ask nice). True deep cycle 12V batteries are harder to find.
  5. Lead is heavy. It is easier to muscle 60 lbs twice than 120 lbs once. And batteries are usually sited in an inconvenient place for lifting.
A 6 volt battery is three 2.1V cells connected in series, a 12V battery is six 2.1V cells in series. If hooked up right the charging source won't know the difference.

jim


OK help me understand if you will; I really don't know the answer....what is inherently deficient in using two 12v AGM batteries that are NOT deep cycle batteries if the charge is correctly maintained via a solar, AC or the alternator on the vehicle?

As for weight, my 12v AGMs are no where near that weight you mentioned and my battery box in the Hawk is easily accessed [side dinette]....

My way of approaching this is if it works...stick with it...and KISS...but hey I could and may be wrong!

Phil

Ps...

Just read this:

"You can use two 12-volt 24 group batteries wired in parallel that provides 140 to 170 AH. Parallel wiring increases amp hours but not voltage.
If you have the room, you can do what a lot of RVers do and switch from the standard 12-volt batteries to two of the larger 6-volt golf cart batteries. These pairs of 6-volt batteries need to be wired in series to produce the required 12-volts and they will provide 180 to 220 AH. Series wiring increases voltage but not amp hours."

http://rvservices.koa.com/rvinformation/rvmaintenance/what-you-need-to-know-about-your-rv-batteries.asp
 
Wallowa said:
OK help me understand if you will; I really don't know the answer....what is inherently deficient in using two 12v AGM batteries that are NOT deep cycle batteries if the charge is correctly maintained via a solar, AC or the alternator on the vehicle?

As for weight, my 12v AGMs are no where near that weight you mentioned and my battery box in the Hawk is easily accessed [side dinette]....

My way of approaching this is if it works...stick with it...and KISS...but hey I could and may be wrong!
Click to expand...
Deep cycle batteries should last longer than non deep cycle batteries. It depends on how the batteries are used, how well controlled the charge cycle is, how often and how long they are left undercharged (less than 100%), . . .

As to weight, deep cycle batteries have thick plates with lots of lead; thats what makes them heavy. About 65 lbs per 12V, 100AH of battery(s). A lot of 12V marine batteries are mislabeled 'deep cycle'. At 69 Y.O. I struggle with lifting my golf cart batteries into their nest in the front corner of the camper (under the bed).

Lots of guys use non deep cycle 12V batteries in their campers with no problems, you will just have to replace them sooner. No wrong answer, just tradeoffs.

You are correct: two 12V, 100AH batteries in parallel = two 6V, 200AH batteries in series.

jim
 
JaSAn said:
Deep cycle batteries should last longer than non deep cycle batteries. It depends on how the batteries are used, how well controlled the charge cycle is, how often and how long they are left undercharged (less than 100%), . . .

As to weight, deep cycle batteries have thick plates with lots of lead; thats what makes them heavy. About 65 lbs per 12V, 100AH of battery(s). A lot of 12V marine batteries are mislabeled 'deep cycle'. At 69 Y.O. I struggle with lifting my golf cart batteries into their nest in the front corner of the camper (under the bed).

Lots of guys use non deep cycle 12V batteries in their campers with no problems, you will just have to replace them sooner. No wrong answer, just tradeoffs.

You are correct: two 12V, 100AH batteries in parallel = two 6V, 200AH batteries in series.

jim
Click to expand...

Thanks...understood.

Phil
 
I got the batteries load tested today and both failed--after less than two years. They are being replaced under warranty. One battery failed quicker than the other, 4 minutes versus 13 minutes. The battery guy thought most likely one battery was weak at the start and pulled the other battery down.
 
Vic Harder said:
hmmm ... that's the second time I have heard this story recently. ZAMP controller in both cases.
Click to expand...

I will bite...how does having a Zamp controller kill a battery or batteries?

Phil
 
Check out Handy Bob Solar. All controllers are not equal nor are all wires sized properly. It's quite a read but also an education. Happy camping, Bigfoot Dave
 
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