High Heat and Camper Batteries

[RC Pilot Jim]

Heat affects on camper AGM batteries.

Yesterday we returned from a 2 week - 5 state road trip to visit the western slope of Colorado (Montrose, Ridgeway, Ouray, Silverton, Durango, Mesa Verde). I will do a report for the travel section. Battery was running the Engel fridge - charging off the alternator and solar panel when stopped. Day temps every where we went were 95* - 111*. We averaged 250 miles per day.

On the return section we visited our daughter in Phoenix Friday to Sunday with a Monday departure. Weekend temp range 95*-108*. Driving 250 miles a day easily kept our battery charged between 81% - 91%. We camped in Ouray and Durango plugged into electricity which ran the fridge, fan, lights, while maintaining the battery at 100%.

Phoenix was another experience.
Our Eagle air conditioning is a "Best Western" or "Comfort Inn" when the temps are over 90*. We camped at "Comfort Inn" and truck sat outside in the sun all weekend, charging on the solar panel only running the fridge, as we visited with her riding around in daughters vehicle.

Monitoring (Trimetric TM-2030-RV) the battery condition Saturday morning low percentage of full 71%. late morning fridge was drawing 2.5 amps leaving 2.5 amps to charge . Checking it again in early evening battery had dropped to 61% full. Panicked we shut off the Engel and transferred the food to the electric fridge in the room. Monday morning battery was back up to 85% so I did no apparent damage to it. Turned on fridge to get it cold. 30 minutes later replaced the food. We departed for drive home. Arriving after 6.5 hours running fridge and charging battery. Percentage of full was 90%.

I asked her significant other if heat affects batteries and he said yes. They experienced their car battery dying in a shorter time since moving there. I've included a link for you to research "high heat affecting battery performance" click on the blue link.

I added this info to my main post as I use it as a history record.

I'm NOT a battery expert. Asking the experts to comment. Thanks.

 

[rando]

The Trimetric doesn't know anything about your battery loosing capacity in the heat - only how many amps going in and going out. In fact the Trimetric is one of the few battery monitors NOT to have temperature compensation available.

So what this is telling you is that your fridge was drawing more power than your solar panels were producing, pulling your battery down, which makes sense given the temperatures. I would guess your fridge was running 100% of the time.

 

[ckent323]

I share Rando's thoughts.

What size solar panel are you using? What brand and model of battery do you have?

How big are the wires between your truck and the camper house battery bank?

The compressor in Engel portable refrigerator/freezers allegedly draw between 2.5 A and 2.8 A when running. That is around 60 Ah to 66 Ah in 24 hours if it is running all of the time.

 

[smlobx]

Another potential cause that I have read about here is that if the side that your fridge is on is exposed directly to the sun it could exacerbate the continual cooling need

 

[craig333]

From the trimetric website. Optional Temperature compensation if temperature sensor is used.

 

[rando]

Pretty sure that temperature compensation is only for the Bogart charge controller, not the battery monitor. Bogart has a lengthy document explaining why ignoring temperature or Peukert coefficients is somehow better. This is part of the reason I am so down on Bogart - it appears they are trying to whitewash a limitation in their system with some marketing dressed up as engineering.

 

[RC Pilot Jim]

Thanks All.

Answering Kents questions.
1. 150 watt Renogy Ridgid
2. Exide AGM 80 amp hour 2.5 years old. . Warranty 2 years. My mechanic checked it before the trip and it was functioning at 88% of new.
3. Checking the terminals there was yellow powder on the negative post/
4. wire stock 12 gauge ) I know 10 or 8 is better, however don't want to rewire)
5. running it well ventilated in the dark with roof vent open and side window open. Still it was very, very hot inside...close to 120*.

Phoenix Arizona in July is the only time I have ever had a problem though in October we will again be at Ocotillo Wells and temps could be well over 100* this year

 

[JaSAn]

The Trimetric doesn't know anything about your battery loosing capacity in the heat - only how many amps going in and going out . . .

Please explain. I thought normal chemical reactions speed up or slow down with temperature, not change character (capacity). This implies that a LA battery looses AH when hot, that less electrons are available. Something is not making sense to me and I am not finding anything online to explain what's happening.

jim

 

[rando]

I actually think battery capacity increases slightly at higher temperatures, but the cycle life decreases. Capacity is fairly drastically decreased at low temperatures. But the Trimetric doesn't know that the capacity has changed, all it knows is the battery size that was programmed into it when it was set up, not the capacity at any later point in time.

For example, say you have a nominal 100ah battery (at 20C) - and then you pull 50 Ah out of it. All the Trimetric knows is that you pulled 50ah out and that the batteries original capacity was 100ah, so it displays 50% SOC. Now lets assume the same situation but you are now at a temperature of -10C, the battery capacity is now only 75 Ah. But the Trimetric doesn't know that, so after pulling 50Ah out, it is still displaying 50% (50Ah/100Ah), but in reality you have used 66% (50Ah/75Ah), leaving your true SOC at 33%.

 

[ckent323]

RC Pilot Jim,

It seems to me that if your fridge was running continuously it was probably pulling your battery down to about 23 % to 25% of capacity.

It is not clear to me if it is a starting battery, a hybrid battery or a true deep cycle battery. If not true deep cycle you may be severely impacting the life of the battery if you are actually running it down to only 25% of full charge.

I cannot help but wonder if the small 12 ga wire is the reason recharging takes so long when driving.

Looking at the Renology specs for a 150 watt panel (no idea if it is the same as yours) reveals that its optimum production is 8.38A. So at best you get 8.4 A/hour but that is probably only true for a few hours a day when the sun is the highest in the sky assuming no shade and you are on flat ground not parked on an incline.

On average my guess is your panel produces about 6.5 A between say 9 AM and 6 PM in summer. Therefore suspect that it is only producing around 60 Ah - 70 AH a day and maybe less. So it seems to me your solar panel could not even keep up with your fridge when it was running flat out around the clock and that is assuming nothing else was drawing a load - (i.e. all other devices were off).

Others with more knowledge and experience may have a better perspective on what happened.

It appears to me that you have very little reserve capacity built into your solar system/Battery system and it may be appropriate to reevaluate your power needs/use relative to your battery capacity and solar system production capability relative to your typical camping scenarios.

For example consider that even partial cloud cover can dramatically reduce the power production from your solar system. How often might you be camping in reduced sunlight situations with partial or full cloud cover or even smoke or tree shade?

In the cases of reduced solar production your recharge capability will be limited and because of the small wire size from your truck generator you would need to run it for many hours to recharge the battery. Mitigation measures might be to use shore power or to carry a small gas powered generator or add more solar and battery capacity or maybe just monitor the battery charge and manage use carefully.

But if you decide to live with the current system I think the risk of having to shut off the refrigerator and get everything perishable into an ice chest of something would remain.

Regards,

Craig

 

[Vic Harder]

Good evaluation Kent. More solar is a good start... that or camping in cooler temperatures!

 

[PackRat]

Far be it for me to disagree with the facts/figures stated above but in layman's terms, I think this is what the guys said:
1) with it hotter than HELL where the 'fridge is located, it runs constantly
2) since it runs constantly it is drawing perhaps more energy FASTER than the solar system can replace
3) anything that impedes maximum exposure to the sun to insure maximum daily production from that solar panel also puts the truck and the Engle also in the maximum solar HEAT for up to maybe 12 hours per day.
4) using wire of a lesser gauge than is best for the system means the system is not charging at its potential.
5) as noted above, if the Engle is next to the sunny side of the camper or is otherwise exposed to the heat buildup it and the associated electronics are suffering and unable to maximize the solar charging output
6) a check of the temp during the mid-afternoon where the AGM and the electronic are located would tell you if they are being cooked
7) if they are accessible to the inside of the camper, check the mid-afternoon temp in there as well.
8) anything you can do to LOWER the temp of the location of the battery and electronics seems to be helpful from the guys have written. Maybe even keeping a vent open during that time of the day to let the heat escape from wherever you have the battery and the electronics

Finally, I think I agree with Kent and Vic....when under maximum power usage you just are not making enough with that solar panel you have and that might alleviate the problem....beyond that....it's all in the electronics I think!

 

[RC Pilot Jim]

Thanks, Craig, Vic and Pack Rat.

What I got out of all that is if I'm not going to change the wire diameter or the panel size and be crazy enough to visit the daughter in July in 110* plus Phoenix heat. I should plan on moving any food in the Engel to the fridge in the motel room and shut off the Engel for the duration of my stay.

Since we are now doing one road trip per year we are going to try to travel in May or September when its cooler. Next year we are checking out Idaho so Won't go through Phoenix on the way home.

 

[ckent323]

RC Pilot Jim,

Beware of hot days as well as cloudy days. ;-)


Best,

Craig

 

[Old Crow]

-snip-

3. Checking the terminals there was yellow powder on the negative post/

-snip-

Your post made me curious about terminal corrosion colors.

This 'How To Deal With That White And Blue Crap On Your Car's Battery Terminals' article suggests the yellow powder may be evidence of sulfation due to undercharging. And there's probably a small leak around the negative battery post.

(Neither of which is a reason to replace the battery right away. Also- I don't think I've seen that idea of white/gray/yellow corrosion on the negative terminal = undercharging before and so far haven't found corroboration of it. I'm wondering if you're just seeing evidence of the sulfation in every battery and it's only visible because of a small amount of acid or acid fumes escaping the battery case past the post. And of course we're not even sure that's what the yellow powder is.)

.

 

[RC Pilot Jim]

"Old" interesting comment.

When the first battery (Exide) died at 3.5 years there also was yellow powder and a small hole around the negative post.

I will ask my mechanic if he saw any powder when he last checked it. Four Wheel was installing that make battery in new campers in 2012. with a two year factory warranty plus an additional one year from Four Wheel.

We drive about 70 miles of bad (awful) washboard road twice a year. The Trimetric shunt is connected to the negative post. Battery box is tied down, however the battery in the box is not. I wonder if the shunt puts additional load on the post causing it to fail over time.

I read "Old Crow's" link , "How to...." and saw this this statement:

"The corrosion around the negative terminal is most likely going to be white/grey/slightly yellowish, and is the result of undercharging the battery, causing sulfation.

Trimetric displayed 91-100% full for most of the trip. the only day it was undercharged was Saturday - 61% . Could sulfation happen in one day? I suppose it could if I have a small hole in the case next to the post. I will check that and report back.

 

[pvstoy]

As I read everything above and what was not mentioned was with that high heat tempature the battery and such being heat soaked. The actual wire becomes less efficient and has more loss of amps passing through to the battery.

Agree that the refegrator was in a placement that it was being heatsoaked and was causing it to run continually while the solar could not keep up with the amp draw and loss in the wires.

 

[Bigfoot Dave]

I would be suspect of the battery given the mechanics test # and the corrosion. Is the vehicle charging the battery or is it only the solar? Ventilation is critical for the fridge and anything impeding airflow will cause problems.
The settings on the charge controller could be causing undercharging too. If the battery was subject to undercharging for 2 1/2 years it's an old problem that has been growing. I have the Trimetric RV2030 and the SC 2030 solar controller with temp compensation and it works great after rewiring the camper to minimize voltage drop. Up in northern Minnesota our big challenge is trees shading the panels.
Enjoy the summer, Bigfoot Dave

 

[RC Pilot Jim]

Thanks PVStoy and Big foot for your "high heat" comments.

We have a friend that works for San Diego Gas and Electric. She said, " As the temp increases over 100 degrees the panel(s) has difficulty dumping the heat which can cause up to a 30% drop in efficiency". "Further wire gauge (size) also affects performance. The larger the gauge the more efficient the system works". 10-8 gauge would be more efficient.

I'm assuming the factory uses 12 gauge because the top moves up and down. Over time the wire would break at the fold points much easier with the thicker wire. Hard side campers don't have that issue.

We've been home 10 days now. Daily temperature still very Palm Springs like 95* - 103* plus every day and we are less than 8 miles from the ocean with mid-west humidity.

Camper/truck back in the carport. Battery came back up to 90% July 30th after 6.5 hours on the alternator. As of this writing its no load condition is 100% with NO powder residue on neg terminal.