Nova Cool, battery, & solar problems

Hi and thanks for looking at my question:

I have a Lance 815 truck camper, Nova cool 12v electric refrigerator, 2 100W solar panels (I tested them awhile back), 1 Renogy solar charge controller, 2 costco interstate deep cycle marine batteries with 600cca.  I load tested the batteries with a legit tester and they both had  way more cca than 600.  I called Novacool and they suggested removing the resistor so that it operates with less electricity.  I did that.  They also suggested using a multi-meter and comparing the two batterie's voltage but I was a little confused with what they are saying, how much it would really matter and I'm good with using the tool.  The main problem is that my camper will rarely get above 3/4 bars of battery life even though the refrigerator in not on and it is in storage.  When camping:  it always is down to 1/4 or 2/4 by the evening or less, then when it gets that low the controller has a red light which means battery is over-discharged and it will have trouble getting past the error. 

The Nova Cool refrigerator is awesome but something is going wrong.  I do not believe on a semi-sunny day that this system should have issues.  Please let me know if you have a suggestion.

You might try an amp meter to see what the refrigerator is pulling. But, if you never teach a full charge even with it off, the problem is in your solar system. Use the amp meter to measure the output form the panels. And then from the controller.

Hi jberend, and welcome to the forum.

I'm not a specialist by any means, but I think you're measuring your batteries the wrong way. For an RV application, it doesn't matter how many CCAs (Cold Cranking Amps) they have; this is for applications where they are to provide a lot of current (hundreds of amps) over a very short period (a few seconds) like when starting an engine.

For an RV application, what matters is their AH (Amp Hours) capacity, ie how much Amps over how many hours they will be able to supply. If your batteries are indeed deep cycle, they should state that capacity prominently somewhere (and if they are 12V each -- connected in parallel -- they should be around 100AH each, giving you a total of about 200AH, of which approx. 100 AH is usable (as you shouldn't discharge these batteries more than 50%).

That said, after you determine exactly your batteries' AH capacity, I second halfwright's suggestion of using your multimeter's amp meter to determine how much current your Novacool is actually drawing, and ditto for your solar system power output. Just make sure your multimeter is actually able to measure DC amps.

Good luck, and please keep us posted.

Cheers,
--
  Vall.

While you don't have true "deep cycle" batteries what you have should work reasonably well.  Note, a true deep cycle battery will not have CCA anywhere on the battery. 

If you are spending much time dry camping/boondocking you are missing an item you must have.  That is a real battery monitor, such as a Trimetric: http://www.bogartengineering.com/products/trimetrics/

The monitor you have, i.e. number of bars showing the charge level is worthless.

A real battery monitor shows the actual percentage of the state of charge (SOC), the number of amps going in and out of the battery at any point in time, the number of amp hours (AH) used, and you can see exactly how many AH's you have put back in the batteries when charging, you can also see the battery voltage at any point in time. 

Without knowing exactly how many AH's you have used and replaced, you are flying blind. 

jberend said:

Hi and thanks for looking at my question:

I have a Lance 815 truck camper, Nova cool 12v electric refrigerator, 2 100W solar panels (I tested them awhile back), 1 Renogy solar charge controller, 2 costco interstate deep cycle marine batteries with 600cca.  I load tested the batteries with a legit tester and they both had  way more cca than 600.  I called Novacool and they suggested removing the resistor so that it operates with less electricity.  I did that.  They also suggested using a multi-meter and comparing the two batterie's voltage but I was a little confused with what they are saying, how much it would really matter and I'm good with using the tool.  The main problem is that my camper will rarely get above 3/4 bars of battery life even though the refrigerator in not on and it is in storage.  When camping:  it always is down to 1/4 or 2/4 by the evening or less, then when it gets that low the controller has a red light which means battery is over-discharged and it will have trouble getting past the error. 

The Nova Cool refrigerator is awesome but something is going wrong.  I do not believe on a semi-sunny day that this system should have issues.  Please let me know if you have a suggestion.

Click to expand...

With your camper in storage and therefore your batteries should be fully charged, what is the battery voltage? 

Since they are being charged with the solar controller, I would expect to see a voltage of around 13.4V, which is a float charge from the controller.

Disconnect or turn off the solar controller (and not connected to shore power).  Turn on 2-3 incandescent light bulbs, or if all lights are LED, turn them all on.  You want about 3-5 amps draw on the batteries.  After about 15-30 minutes the 13.4V surface charge should have dissipated and your true battery voltage of 12.6V for a fully charged battery should be seen on your volt meter. 

If the voltage is not about 12.6, or quickly drops to 12.4V to 12.2V you have a bad battery.  I suppose it could be a bad or loose cable connections as well. You could also have something pulling 5-15 amps you are not aware of.  However in a truck camper that would be unusual.

Going back to having a real battery monitor.  All the above would be available at a glance any time you are at the camper. 

How old are the batteries? Have the plates always been covered with electrolyte? If they have not been cycled often or not been fully charged they could be losing capacity. It is common for some solar systems to not top the batteries off completely. Check the Specific Gravity and possibly equalize. The deep/marine batteries are good but they wont stand up to 50% discharges as well as true deep cycle batteries. Number one is checking SG.

It appears that there are roughly two amperage that your Nova kool may be pulling, 2.2 or 4.4 for larger models or models with freezers. If it has a 50% on time you are averaging 1.1 around the clock plus a little more for your house loads such as monitor, stereo etc so call it 1.5 amps x 24 hr = 36 amp hours. An average 100 watt panel should give 30 ah per day in good sun so you should be ok with 200 watts. If you add in lights, water pump, laptops, phones etc you may experience some days of not getting a full charge. I would also consider what your controllers max voltage capability is.

Some controllers also have an automatic equalize feature every 30 days or so. In order to equalize the battery has to be fully charged first so before the equalize charge starts you may need to do supplemental charging with a generator etc to first have the battery fully charged. Temperature compensation is also good to have. What model is your Renogy?

Thanks for all of your replies.  I ordered a DC amp meter and will get it next week.  I used a multimeter yesterday on a hot sunny day and the panels read 14.4v  and the output of the controller was 12.4.  Do you think I might need a new controller?  I saw a chart that said a batterie's full charge is at 12.74v but mine would never get there with my controller.  If you think I need a new controller then please suggest a quality one. 

Both batteries read 12.4.  The batteries are only one year old and I've never had to add liquid to them.  However, they have been over-discharged many times.  I've done more research and I'm thinking I should invest in two quality 6v batteries (Crown or Trojan).  I tested them with a Midtronics power sensor micro 5000.  Do you think that tester tests the batteries enough or do I need something better?

My refrigerator is an R4500 (4.3 cu. ft.) according to the manual is drawing 2.2 amps.  I probably have two lights on for 2 hours at night and run the water pump a total of 5 minutes per day.  Charge 2 phones at night and that is it for consumption.  It is a small camper and we are in it only at night.

If I bought a Trimetric battery monitor would it be an easy installation of just connecting it to the main system or would I need to plug each panel and each battery to it individually?

Thanks again for your replies

The Trimetric is a battery monitor. it uses a device called a shunt which is placed between the negative battery cable and the negative battery post and measures amps going out and amps going in.

Bogart Engineering (Trimetric) also makes a solar controller which can stand alone and do basic solar charging or it can be linked with the Trimetric to perform full function solar charging including equalize and high voltage finish charging. I wouldn't worry about a Trimetric now as basic battery monitoring can be done with a digital voltmeter. The Trimetric or any amp counter would show amps going out or in with the Trimetric but your Renogy cant be plugged into the Trimetric to control the setting in the Renogy.

It would seem that each of your panels when positioned directly at the sun should probably produce about 17 volts or so. This is checked by removing the panel wires and placing the voltmeter on the panel wires. If both panels check out ok you then connect the in parallel to the solar controller assuming it's a PWM model. If you have good voltage from the panels going into the controller and you then check your battery voltage you could see a wide variation in voltage DEPENDING on the battery state of charge. Just say your battery voltage is down to 12 volts and you have both panels in full sun, you could see 12. 2 or 12.3 or 12.4 or whatever until the battery charge rises. As the battery charges the amps will fall and the volts will rise.

If the solar is actually topping your batteries off each day you should see your digital voltmeter drop from 14.x down to a float voltage of about 13.2 to 13.4 and at that point you should see a HIGH specific gravity. If you have weak sun at times day after day and are not able to actually charge the battery fully, you will see a drop in the SG at which time you may need to do supplemental charging which can take many hours or depending on charging sources even DAYS. If the SG is left in a low state for long periods of time the battery will be damaged.

Group batteries are more susceptible to getting somewhat lazy compared to true deep cycles and will need a high top voltage or equalize charge to drive them back up.


The first thing to do is get a hydrometer at a auto parts store and check the battery specific gravity. You may need to put a 120 volt powered battery charger on them to get the charge/SG back up.

Check the SG and tell us what it is.
What model is your Renogy controller?
We need to look at your controller adjustments and shoot for a top voltage setting of 14.6 minimum up to 14.8 or even 14.9. Some of this may also depend o voltage drop between your controller and batteries. you could see 14.8 at your controller and 14 at your battery.

What size wire do you have from panels to controller and from controller to battery? 
How long are your wire runs?

Also. If you check battery voltage with nothing connected to them you will get an actual at rest voltage reading indicating true battery state of charge. If you are charging at  about 14.x volts and you were to remove all the cables from the battery and place a voltmeter on it you will see that the voltage slowly drops as the surface charge is lost. After sitting a couple hours or so you would get a true state of charge reading which should be 12.7 to maybe 12.6.

The reverse of that also happens when the battery is under load. If I check my voltage when my furnace, frig and other things are running I may see a voltage sag to about 12.4 yet when everything shuts off the battery voltage will recover to 12.5 or possibly 12.6. 

You have received excellent advice from QZ.

About the installation of the Trimetric. 

if/when you order the Trimetric you need to order the 500amp shunt as well. 

To install the shunt you remove any cable(s) attached to the negative post of your battery pack that go to the RV.  These cable(s) are then attached to the RV side of the shunt.  You then need to build or have built a short cable with the same wire size of the cable you removed from the battery (probably around #2 wire size) and connect that cable from the negative battery post to the shunt.  Next you find a place to mount the Trimetric inside the RV in a place easily viewed and run the small (4 wire if I remember correctly) cable to  the shunt.  More details and installation instructions can be found here: http://www.bogartengineering.com/products/trimetrics/.

If you are handy with tools, it is not overly difficult or complicated.  The worst part is running the cable from the monitor to the shunt and building the short cable that goes from the shunt to the battery. 

As source for the cable is to go to Amazon.com and do a search for "# 2 battery cable".  You can find cables there in varying lengths. 

The battery monitor is indispensable for anyone dry camping or boondocking more than 2-4 days between connecting to shore power.