Help with battery and/or fridge

[TexGX]

It seems something is going on with my fridge or battery. With my Weaco set on the middle cut off setting, the fridge will run for a moment then the error light comes on. If I move it to the low setting, it seems to run fine, but I am worried about running the battery down. I had the battery (Die Hard Plat) checked at sears and the machine said it was a good battery. I pulled the ARB from the trailer and it did not seem to want to kick on either. The volt meter showed 12.34v's with the key off and 13.85 with the key on. I am trying to figure out the issue. It has been working fine up until this point. Anyone have any sugestions?

TexGX

 

[TexGX]

A little added information. I tested the voltage at the battery (12.11) and at the plug in the back (11.9). This has me thinking it is my battery again. Any other ideas?

TexGX

 

[wrcsixeight]

It's not your battery but the length of too thin wire leading to the rear plug. Too much voltage drop! Especially once the fridge asks the wires to transfer some amps. They warm up and cause even more voltage drop to the point where there is not enough to run or turn on the compressor.

The easiest remedy it to run a new length of 2 wire 10 awg wire from the battery to the rear plug. Fuse it at the battery.

12.11 volts at the battery terminals is the sign of an undercharged battery, or a sign the battery is on it's way out, so It can contribute to your fridge issues. Try putting it on a 10 amp automatic charger overnight, or a 10 amp manual charger for upto 10 hours. 6 hours after you remove the charger, if the battery reads under 12.5, replace it, and shoehorn in the largest dual purpose battery you can inside.

Starting batteries will protest when asked to repeatedly power a fridge overnight

 

[trump]

:iagree:

Been running into a little of that myself from time to time with my Waeco. I've been meaning to move a couple gauges larger in wire size, but have been a bit lazy. BTW I'm running a brand new DieHard Platinum as well.

 

[TexGX]

wrcsixeight,

Thanks. It looks like I used 12 gage not 10. I will replace that soon. I had the guys at Sears look at the battery again today. It showed 12.1 volts today without running the fridge. They told me that I needed a special charger for Platinum batteries. They said my current chargers would not give the Platinum a full charge. Is that correct? If so, I will also need to buy a different charger as well to top off the battery. I asked why was the truck not charging the battery completly and they said it would not. I think I will be looking into a dual battery set up soon.

TexGX

 

[wrcsixeight]

You do not need a special charger for AGM batteries. While it is true they should not go much over 14.5 or 14.8 volts, most chargers will not do that anyway.

Most people vastly overestimate their alternators contribution to recharging the battery. From a jumpstart, 8 hours of driving should have your battery in the 85% range. This varies by vehicle, but the best case would be 4 hours.


Battery load testers need to be used on a fully charged battery, and might not even be accurate then.

If they performed a test on your 12.1 volt battery, it is unlikely it passed, or that they even tested it.

The 12 gauge should have sufficient unless the circuit length is really long.

I'd try temporarily hooking the fridge much closer to the battery and see what happens to battery voltage when the fridge's compressor kicks on.

Most modern Battery chargers have a flooded/agm setting.

Mine does. The biggest difference is the float voltage. 13.2 for flooded. 13.6 for AGM. Get one capable of at least 12 amps, and use it before and after an outing.

 

[TexGX]

wrcsixeight,

The cable to my plug runs from the drivers side front to the passager rear. I will change it out to 10g. The charger I have only goes to 6. I might look into a new charger as well. The long term solution will be a dual battery set up with a solar charging system. Thanks for all the great info.

TexGX

 

[wrcsixeight]

Throw the 6 amp charger on overnight.

Check voltages again in morning on rear plug and battery terminals.

Did you fuse at the battery on your 12 awg? What size fuse?

You are fusing to protect the wire, not the fridge. The fridge plug will have it's own fuse. Use a 25 amp fuse at the battery. Less resistance.

 

[theksmith]

i agree with what's been said so far

- 12.1 volts is too low, battery sounds like it's own the way out, battery should be at 12.6 to 12.8 at rest (after a normal driving for several hours, without huge loads, and then vehicle turned off for a couple hours)

- with your vehicle running and no real load, you may get 13.6 to 14.5 volts depending on the manufacturer, all will charge your battery, but lower voltages will take longer. at 1000 RPM, i would expect closer to 14 volts (often idle conditions don't really put out the full alternator potential)

- you have a fair voltage drop at your receptacle, definitely check all connections and replace with appropriate gauge wire. remember you can just run to a GOOD frame ground rather than use a ground wire back to the source, but make sure the connection is good by checking the resistance between your proposed grounding location and the battery negative terminal. should be close to 1 ohm.

refer to a table like this for correct wire size, but always go one size up when in doubt is my personal rule of thumb: http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html

- sears employees come in all IQ levels, the ones telling you that you need a special charger in your car are full of guano, furthermore telling you that 12.1v resting state is "full charge" also qualifies as dung shoveling.

- also keep in mind that if you've been only doing a lot of short trips and running your fridge, you may have not given your battery proper time to charge. every start is hard on the battery and takes a little time to recover, then if you run a fridge or other accessories a lot without doing longer trips that allow time to charge the battery fully, you might get the results you have mentioned. i would have sears or someone put the battery on an overnight charge to get it back to proper level, fix your fridge connection low voltage issues, then monitor your driving habits and how the battery goes - if you're not being hard on it and it ends up at 12.1 resting voltage again after a few days, replace it.

 

[TexGX]

Thanks for all the great info. It seems to me that the main problem is not letting the battery get full charged. I will hook up the charger and see what happens then. I do have a fuse on the wire to the plug, but I think it is near the plug. I will check it all out tomorrow when I have time to replace the wire.

theksmith,

Thanks for the chart. I will go with 10 gage.

 

[Mike S]

It is quite possible that your battery has a dead cell or has overheated during charging and expelled some gas leaving it below spec. I have found that when you start to have this type of problem with a battery it is not worth the aggravation of chasing down the problem.

Replace the battery. Run wire that is at least one size greater than is required for the amperage draw of your fridge. Make sure you have a solid ground.

 

[TexGX]

Following the advise here, I have changed out the 12g for 10g. I did have 10g on the ground, but 12 on the other. The only issue I had was finding a 10g fuse to wire in. I found a 30a fuse and made my own so I could have all 10g and not 12 at the battery and 10 passed the fuse. I will see how it works. I am going to put battery on the charger all night again. It showed 12.6 this morning after the charge. I will do it again tonight. I think I am just not able to keep up with the usage. Will look into the dual set up soon.

Thanks for all your help.

TexGX

 

[TexGX]

The battery charged up nice. I am reading 12.58v, but I am only getting 12.40 at the plug. It is only about 15 feet of wire. I changed out the 30amp fuse for a 20amp fuse and that did not seem to make much difference. I am running 10awg from battery to fuse to plug. The fuse is 4 inches from the battery. I have 10awg from plug to ground in engine compartment. This wire does have one connection of 10 to 10. Is this normal or am I missing something?

Thanks for your continued help.

TexGX

 

[dwh]

The battery charged up nice. I am reading 12.58v, but I am only getting 12.40 at the plug. It is only about 15 feet of wire.

#10 over a 15' run (30' round trip) will normally have a 1%-1.5% voltage drop. Depends on the load. Here, scroll to the bottom and play with the voltage drop calculator (you would enter 15 for the one-way circuit length):

http://www.powerstream.com/Wire_Size.htm

I changed out the 30amp fuse for a 20amp fuse and that did not seem to make much difference.

It shouldn't make any difference - they should both have the same resistance.

I am running 10awg from battery to fuse to plug. The fuse is 4 inches from the battery. I have 10awg from plug to ground in engine compartment. This wire does have one connection of 10 to 10. Is this normal or am I missing something?

Not sure what that means...one connection of 10 to 10?

 

[TexGX]

dwh,

Thanks for the calculator. It is reading almost a 1.5% drop so I guess that is normal for this length of wire. The last part just means that I spliced the wire to the ground, but both peices are 10awg. I am planning on doing a short trip this weekend. I will see how it works out. I put the battery on my mantainer last night to full charge it before I head out and I will put it back on when I get back.

TexGX