Fridge / Battery Experiment

[ILH]

I've been trying to leave my fridge running between two-week trips, so that I don't have empty the contents. Recently I added a second battery and removed the fuses to items that draw current (such as gas detector, TV booster, etc.). I was able to last two weeks without a problem.

Since I hadn't pulled the fuses until the second week, it seemed to I might be able to make three weeks if I pulled the fuses on the first day.

Today I parked the RV after returning from the long weekend - and pulled the fuses. My next trip is in tree weeks to the NY rally in Verona. Let's see if the fridge will make it!!!!

 

[pegmikef]

I wonder how far down the batteries going . . . I think I have read on this forum that anything below 50% can damage the batteries.

 

[ILH]

I found the following description regarding deep cycle batteries:

Deep Cycle Batteries

Marine applications, golf buggies, fork lift trucks and electric vehicles use deep cycle batteries which are designed to be completely discharged before recharging. Because charging causes excessive heat which can warp the plates, thicker and stronger or solid plate grids are used for deep cycling applications. Normal automotive batteries are not designed for repeated deep cycling and use thinner plates with a greater surface area to achieve high current carrying capacity.

Automotive batteries will generally fail after 30-150 deep cycles if deep cycled, while they may last for thousands of cycles in normal starting use (2-5% discharge).

If batteries designed for deep cycling are used for automotive applications they must be "oversized" by about 20% to compensate for their lower current carrying capacity.

 

[alwayslooking]

What type of refrigerator do you have? What were the temperatures during your experiment? Do you have 2 or now 3 batteries? What type of battery are you using? Are all batteries the same type, age and make?

 

[fredwrichardson]

I wonder how far down the batteries going . . . I think I have read on this forum that anything below 50% can damage the batteries.

I would look into adding a supplemental solar system so you do not have to pull the fuses. With the solar system you could charge a 50Ah battery from 50% to fully charged in 1.5 hours (depends on sunlight availability). At 33.3 percent duty cycle on the refrigerator (1/3 on and 2/3 off) you could run the refrigerator for about 3 hours. As long as you have sun for 12 hours the system could run the refrigerator all day without battery loss. If you added an additional panel you would have surplus power The solar system is $324.99 plus free shipping (prime) from amazon, Here is the link . You would be able to go way beyond the three weeks you are aiming for.

 

[jimtoo]

What would be wrong with something like this, solar chargers for maintaining a battery while parked for a couple of weeks or more while using fridge. I know my son has a couple on gates with 12v batteries. The farmers, ranchers been using these for years. I know my son has replaced one battery in about 3 years. The batteries he uses are just 12v auto batteries like most of have in the trailers.

Jim M

 

[ILH]

What type of refrigerator do you have? What were the temperatures during your experiment? Do you have 2 or now 3 batteries? What type of battery are you using? Are all batteries the same type, age and make?

I'm not sure what the inside RV temps are, but outside will be very mild this week (mid 70s). Both batteries are new this year and matched.

- - - Updated - - -

What would be wrong with something like this, solar chargers for maintaining a battery while parked for a couple of weeks or more while using fridge. I know my son has a couple on gates with 12v batteries. The farmers, ranchers been using these for years. I know my son has replaced one battery in about 3 years. The batteries he uses are just 12v auto batteries like most of have in the trailers.

Jim M

I'd love to add a solar system to my trailer - but finding a reasonably priced one here in Canada has been impossible. I'll be looking when I'm in NY in a few weeks.

 

[scottyb]

I found the following description regarding deep cycle batteries:

Deep Cycle Batteries

Marine applications, golf buggies, fork lift trucks and electric vehicles use deep cycle batteries which are designed to be completely discharged before recharging. Because charging causes excessive heat which can warp the plates, thicker and stronger or solid plate grids are used for deep cycling applications. Normal automotive batteries are not designed for repeated deep cycling and use thinner plates with a greater surface area to achieve high current carrying capacity.

Automotive batteries will generally fail after 30-150 deep cycles if deep cycled, while they may last for thousands of cycles in normal starting use (2-5% discharge).

If batteries designed for deep cycling are used for automotive applications they must be "oversized" by about 20% to compensate for their lower current carrying capacity.

You might want to do a little more research about the level of discharge. The commonly used benchmark is 50%. If you constantly go below that you will shorten your batteries life drastically. This applies to both high-end flooded lead acid batteries like Trojans and AGM's. Lithium ions may be the exception but who can afford them? Most 12V marine batteries are not true deep cycle batteries. They are hybrid starting batteries and they will not last long at all if you discharge them below 50%. There is a lot of good info here The 12V Side of Life

 

[Jesstruckn/Jesstalkn]

I agree solar is your best solution. Drwaing the 12V batteries down over and over will kill the life of them really fast. Solar will keep them fully charged and you will have no issues for a long time. Also you will not have to pull fuses.
You could probably get by with a cheap Harbor Frieght or Northern Tool Solar charger.

 

[Jim.Allison]

Battery life suffers exponentially based on the discharge. Deeper discharges dramatically lowers battery life. But shallow discharges exponentially raise battery life. The manufacturers of Deep cycle batts have determined that 50% is the most efficient number for life vs $$.

You will not ruin your batts discharging to 20% here and there, but if you are constantly discharging beyond 50% then you want to add some capacity somewhere in your panels or your batts, or both.

 

[caissiel]

I am in New Brunswick Canada and 3 years ago I added 200 watts and MPPT controler for $400. Have 3 batteries and it paid for itself by saving my batteries. 2 batteries use to need replacement every 2 years. So far I have never seen my battery condition under 12 volts.
Before with power plant the batteries were never able to be maintained and were constantly under 12 volts.
Believe me good deepcells are damaged fast with improper charging and depletion.
I bought my setup from Solar Power Canada in Montreal. On ebay they are priced at $241 for 100 watts. Best option on my RV. Still cannot understand why anyone would not have any Solar panels as its the best for batteries. The modern converters kill our RV batteries because they are not designed to save batteries for boondocking application. With the previous unit under same conditions my batteries lasted up to 6 years.

 

[Jim.Allison]

Many batteries are ruined by unregulated solar maintainers that charge hot batts. A regulated solar charger should have a temperature sensor.

- - - Updated - - -

I'm not sure what the inside RV temps are, but outside will be very mild this week (mid 70s). Both batteries are new this year and matched.

- - - Updated - - -



I'd love to add a solar system to my trailer - but finding a reasonably priced one here in Canada has been impossible. I'll be looking when I'm in NY in a few weeks.

http://www.amazon.com/Unisolar-Flexible-Solar-Panel-Laminate/dp/B006EP6MCU

Probably one of the best panels for the money.

 

[ILH]

OK - taking everybody's advice, I added a 40 watt solar panel with a charge controller into the mix.

However, what I'm finding is that the LED battery status lights just don't give enough information. My son (the mechanic) wants to swap out the fuel gauge on the control panel with a high definition volt meter. My only issue is I'm not sure if the gauge is 2 inch or 2 1/16 inch. Does anybody know?

 

[avvidclif]

I would rather know what the gas level is than the voltage is. There are other ways to monitor the voltage to the battery. A $10 voltage current/monitor from the auction place will show battery voltage and current. And current either going in or coming out (negative).

 

[ILH]

I would rather know what the gas level is than the voltage is. There are other ways to monitor the voltage to the battery. A $10 voltage current/monitor from the auction place will show battery voltage and current. And current either going in or coming out (negative).

I should have explained better... I don't use my aux fuel tank and pump. I plan to return the fuel gauge before I sell the RV. So in the meantime, it seems like a good place to have the volt meter.

 

[Oregon_Camper]

I would rather know what the gas level is than the voltage is. There are other ways to monitor the voltage to the battery. A $10 voltage current/monitor from the auction place will show battery voltage and current. And current either going in or coming out (negative).

That is exactly what I did...works great. (yea...I know the level is low in the picture. )

 

[avvidclif]

How did you cut the hole to mount it in? I have 2 I want to mount to monitor the voltage and current on both 120v lines.

 

[Oregon_Camper]

How did you cut the hole to mount it in? I have 2 I want to mount to monitor the voltage and current on both 120v lines.

First step was to remove the control panel to get a clear view of the area where I wanted to attach the monitor. Then I simply measured the diameter of the rectangle I needed and cut out the opening. I then tapped into the 12v power at the control panel. For you're config, you'll just need to find a 110v line, which should be easy to find, once panel is removed...see picture. Question....why monitor the 110v line?

 

[avvidclif]

First step was to remove the control panel to get a clear view of the area where I wanted to attach the monitor. Then I simply measured the diameter of the rectangle I needed and cut out the opening. I then tapped into the 12v power at the control panel. For you're config, you'll just need to find a 110v line, which should be easy to find, once panel is removed...see picture. Question....why monitor the 110v line?

View attachment 39235

What did you cut the hole with? I'm not a carpenter.

I have 50A service to the RV. I want to be able to monitor the voltage and current draw on each 120v line. At first to check the balance between the sides and then once noted will allow rapid troubleshooting if there is a problem on either side.

 

[boatto5er]

What did you cut the hole with? I'm not a carpenter.

I have 50A service to the RV. I want to be able to monitor the voltage and current draw on each 120v line. At first to check the balance between the sides and then once noted will allow rapid troubleshooting if there is a problem on either side.

If you install a Progressives Industries internal EMS with remote display, you'll be able to see both.