36 replies to this topic

[Ethergore]

Good Afternoon,

 

I felt like posting for a few reasons after some difficult experiences with my new 2 way fridge and solar panels.

 

My current system contains:

-2001 toyota tundra with a 100 amp alternator

-2009 Hawk

-75 amp hour Die Hard AGM with dual terminals

-Sure 1314a separator

-100 watt Renogy flexible solar panel remotely mounted (ie not mount to the roof)

-30 amp charge controller with LCD display

 

This system needs to power:

-Water pump

-Norcold fridge with Danfoss compressor (3 amp draw) rated to run 50% at 80 degrees

-LED lights

-Misc 12 volt stuff (negligible)

 

So my problem happened in the following scenario.

-Left home fully charged and fridge pre cooled (measured 12.8 volts after sitting 2 hours)

-Drove from 12 pm to 6 pm and parked

-I woke up the next morning at 6 am with 12 volts (ie less than 50% charge)

-Drove from 7 am until 5 pm doing mostly off roading with the AC on

-Arrived at destination with 12.2% (IE 50% charged)

 

 

Obviously my battery would be damaged if I left my refrigerator running on a 50% charged battery overnight so I turned my truck on and let it idle. What I noticed is that my separator was turning off and on. I checked with my multimeter and the separator was doing what it was supposed to (turning on at 13.2 and off at 12.8 v).

 

The lesson I learned was that my deeply discharged battery is unable to be charged with the separator in line because the voltage will drop low enough to let the separator turn off.

 

What I ended up doing is bypassing the separator so that both batteries were combined and let the truck idle for 4 hours to get to a charge of 12.7v. The next day when I woke up the battery was down to 12.2v so after starting the truck I again bypassed the separator and drove most of the day off road. This time when I arrived at my destination my battery was at about 12.7 with a surface charge.

 

 

So from what I have read, this is not abnormal behavior. I have noticed people with similar setups but I am assuming that maybe they don't have a problem because they are not driving as much and their system is fully charged when the sun sets.

 

I know some may recommend I get more storage (battery) but if my system is fully charged when the sun sets I am able to start the day with a battery that is less than 50% discharged.

 

So it seems like there are a few solutions I can think of to my situation.

 

1) Get a DC to DC charger to charge my aux battery with the correct voltage

 

2) Permanently mount my solar panel so I am always getting a charge at the correct voltage (except without sun)

 

3) Use a solenoid to connect batteries at startup

 

 

 

Number 1 seems like it will work if I am driving all day but what if Im in town and stop to eat and sight see regularly. I still need to power my fridge and cant put out portable solar as it may get stolen.

 

Number 3 seems like it should work and is basically what I did to get through my last trip but knowing the voltage is that low should I be concerned about low voltage problems within my vehicle? Also, I still have the problem of not driving enough during the day.

 

Number 2 seems like the best option since I will always have charge during the day and hopefully always have a fully charged system when night comes (assuming there is good to moderate sun). The only problem is if I stay parked stationary in the shade. But I guess I can at least buy another panel for this situation which is still cheaper than a dc to dc charger.

 

What does everyone think and what is everyone's experience with this? Am I understanding everything correctly or am I missing something?

 

Thanks?

[dsrtrat]

It could be the truck battery is weak and not taking a full charge causing the separator to cycle more than normal.

The fridge may also be using more amps than the manufactures rating, you will need a logging amp meter to check your current draw over time.

Mount the solar panel on the roof for a while, and see how much difference you have in your recharge.

 

Dsrtrat  

[Beach]

If your charge line to the house battery is to small a wire size it will cause a voltage drop which will affect charging. With the truck running check to see what the voltage is at the house battery. You might want to consider a larger battery bank, if you get into rainy weather or heavy cloud cover sometime with no sun for 2 or 3 days you will need it..  

[ntsqd]

Sounds like you need to know what your demands on the house battery truly are. I can recommend the Bogart Engineering Tri-Metric. It is not the least expensive option. Others will likely recommend the "Watts Up" meter sourced form Amazon. Either way you'll be able to see what the demands on the battery are, and by pulling fuses and turning things on and off  you'll be able to determine what each load really is.

 

What I'm hearing makes me think that you may have a load that you don't know about, though if the house battery has been treated this way for too long it may be weak and need to be replaced.

 

With all LED lights and rarely running out 3-way off the batteries (except when driving) the roof-mounted 100W panel & 15A PWM controller that I added have had no trouble keeping the camper batteries up. I really don't expect that a 2-way fridge (I'm really, really tired of the 3-way's unpredictability) will tax the system.

[Ethergore]

It could be the truck battery is weak and not taking a full charge causing the separator to cycle more than normal.
The fridge may also be using more amps than the manufactures rating, you will need a logging amp meter to check your current draw over time.
Mount the solar panel on the roof for a while, and see how much difference you have in your recharge.
 
Dsrtrat

I thought about the starting battery being low. It tests between 12.5 and 12.6 after sitting all night. From what I read that's normal for a wet battery unless I don't understand correctly. I thought about maybe getting an AGM starting battery but it seems like an expensive attempt at a dilution.

[Ethergore]

If your charge line to the house battery is to small a wire size it will cause a voltage drop which will affect charging. With the truck running check to see what the voltage is at the house battery. You might want to consider a larger battery bank, if you get into rainy weather or heavy cloud cover sometime with no sun for 2 or 3 days you will need it..

I thought about this too. I checked the voltage from the starting battery all the way back to the aux battery at each point. They all read the same voltage which was 13.5 at the time. No drop down to the 0.1.

I do plan on getting more storage but I'm waiting until I have enough money to get two 6 volts and rebuild my cabinets to fit them. With that said, that won't fix my recharging problem if I do run then down to 50% like I do now.

For now I drive most of the time on trips and if my alt would charge me up I would be OK if there was rain or cloud.

[Ethergore]

Sounds like you need to know what your demands on the house battery truly are. I can recommend the Bogart Engineering Tri-Metric. It is not the least expensive option. Others will likely recommend the "Watts Up" meter sourced form Amazon. Either way you'll be able to see what the demands on the battery are, and by pulling fuses and turning things on and off  you'll be able to determine what each load really is.
 
What I'm hearing makes me think that you may have a load that you don't know about, though if the house battery has been treated this way for too long it may be weak and need to be replaced.
 
With all LED lights and rarely running out 3-way off the batteries (except when driving) the roof-mounted 100W panel & 15A PWM controller that I added have had no trouble keeping the camper batteries up. I really don't expect that a 2-way fridge (I'm really, really tired of the 3-way's unpredictability) will tax the system.

I would love to get one but can't afford it at the moment. Despite not knowing my exact draw, I do know I draw less than 50% over a long night in 90 degree weather. I tested it out in my driveway from full charge. So basically, my capacity should be sufficient if I can have my system fully charged when night falls.

I plan to achieve this with my solar for now but from the replies I'm getting from everybody maybe what I'm experiencing is not normal.

From reading other forums many people say they don't get more than an 80-85% charge on their aux battery from their alternator. Is anyone else running a 2 way fridge on just their alternator and their aux battery without problems?

I feel my problem is that I can't get my battery fully charged before night and then I wake up with less than 50% charge and the alternator can't recover. Anyone agree or disagree? Any more ideas to try?

[Ethergore]

Ntsqd- also I made sure I don't have a random draw by hitting the kill switch and checking the voltage then turning it back on with everything turned off. I got no change in voltage even with out being able to turn off my co detector.

Edited by Ethergore, 28 July 2014 - 02:14 AM.

[camelracer]

I don't understand why your battery separator is cycling. Your alternator should be putting out enough power to maintain the minimum lock in voltage. I would check the alternator output or a large cyclic load under the hood.

[Ethergore]

I don't understand why your battery separator is cycling. Your alternator should be putting out enough power to maintain the minimum lock in voltage. I would check the alternator output or a large cyclic load under the hood.

 

I was afraid I would hear this. I'll look into diagnosing the alt then. The only thing I tried so far was to see if the voltage to the aux battery or starting battery increased when held at 2500 RPM. It didn't, so maybe thats my problem. Its funny because I've been working on my own cars for years and have never had to diagnose an alt problem. Guess there is always a first.

 

Now that you said this is not normal behavior, I am also wondering if my separator is my problem. I have also had my Hawk on a 2004 Dodge diesel and the separator would cycle pretty often but would still eventually charge my battery. Only, back then, I didn't have the fridge. I guess I will try bypassing the separator and checking voltage as well.

 

Thanks for the lead!