batteries and weight

[Patricia D.]

In order to keep the weight of my small trailer down and to keep it balanced from side to side, I have decided that I only want to carry one battery. I am going to have it inside the trailer on the curb side just back of centre to help offset the weight of my cooler and tall cupboard on the driver's side.
I intend to get a 150 -160 watt solar panel.
I have been reading the thread currently running on 2 6v or 12 v batteries and the assumption there is that 2 batteries are needed. It seems that the more the better is the order of the day.
So, my question is if there is whether 1 deep cell AGM battery will do the trick or do I have to find a way to increase the number of batteries.
I know this is a complex issue based on power needs (basically LED lights, 12v cooler, ipad, computer, fan, 12v radio), location etc. but I am just looking for some suggestions on the type of battery and perhaps some examples of batteries that might work, especially those available in Canada.

[John in Michigan]

The sizing of solar panel and battery really depend on your power needs. Based on the accessories you listed, it appears the 12v cooler would be the highest power draw. Do you know the voltage/wattage/amperage of your 12v cooler? To determine your total needs in amp hours, you must determine the amperage of each accessory running at 12vdc, then multiply that by the number of hours used per day.

IF you find that the total amp hours used per day is less than 50, then a 12 volt 100 amp hour battery would work assuming the solar panel(s) produce enough power (in amp hours) to recharge the battery. And yes there are 100 amp hour AGM batteries available.

A 150 watt solar panel will produce about 7 amps per hour in full sun...

[Franswa]

daily power consumption, battery bank capacity and size/power of solar panel....

increase/decrease any of the three to acheive your goal (s)

that's the puzzle...have fun

[Raspy]

Patricia,

I found that a 12volt cooler was a huge energy hog and wasn't very effective. If you run short of power, getting rid of that could make the difference. If you have propane, why not have a propane fridge? I also suspect you'd be happier with two batteries if you could find a place for them. Some days are cloudy and some nights you might want more power for something. Remember too, you can only run the batteries down to about 50% charge or they won't last. Your starting point of 150 watts of solar is good. This will allow you to see how fast the batteries come up and get a feel for how much you have stored to match your loads. You can try to live within those means and watch the voltage, then adjust as needed.

I was able to get by pretty well with a propane fridge, two 50 watt collectors and one group 27 deep cycle flooded battery, in a previous camper I had.

[Glenn Baglo]

Best read the instruction manual for that 12V cooler.
My recollection is that they are only good to chill 34 degrees below the ambient temp. So, if it is 80F outside, the food in the cooler will be at 46F which is not safe.

[Raspy]

Originally Posted by Glenn Baglo

Best read the instruction manual for that 12V cooler.
My recollection is that they are only good to chill 34 degrees below the ambient temp. So, if it is 80F outside, the food in the cooler will be at 46F which is not safe.

That would assume there was no loss from the box. Mine would not get that big of a temperature spread. While trying, it constantly drew power. And the outside temp could easily be higher than 80 degrees which makes matters worse. I got rid of it after one disappointing trip.

[John in Santa Cruz]

note there are also 12V *refrigerators* which used a motorized compressor like a household fridge, these use far less power than the more common 'peltier' style coolers.

my son uses one of these in his vanagon camper, https://www.amazon.com/dp/B00T36NUYA powered off a separate 'house' battery (12V 100AH group 27). he's running about 160 watts of solar on his roof, and he can keep a weeks worth of food cold in summer desert conditions. it draws like 7A at 12V (84 watts) but its only on about 1/2 to 1/3 the time as long as everything is already cold.

[Patricia D.]

Thanks for all the input. I am looking at a Dometic cooler that is around 3-6 amps. Pricey but not as much as a fridge.
If you have 2 batteries, do they actually have to be right together?

[redbarron55]

When I rebuilt my Scamp I put the battery behind the driver's side wheel well and installed a vent line for the caps through the side wall. I also left a space over the tool box space for a second battery if necessary.
If I put in the second battery when the present group 29 dies I will take in that space for a second six volt battery.
I just installed a 100 watt solar panel and will be testing the system over the next few weeks, especially going to the Hiawassee rally the 18th.
My intent is to have the solar panel keep the battery up while the Compressor refrigerator is running and the Scamp is parked or traveling.
You can put vented batteries almost anywhere if the have the proper lines for the purpose.
Mine is under a bunk and so far I have had no problems with the installation

[Defenestrator]

The batteries don't necessarily have to be right next to each other, but the wire connecting them has to be quite large so it's usually easier to keep them very close to each other. Plus, it makes it easier to seal+vent just one compartment.

One (100Ah?) battery is enough to keep that cooler running continuously for about 8 hours at the most. If temperatures are low, like 60F, that's probably good enough since it'll only have to run a small percentage of the time. The solar will increase that as well, so as long as it's cool but sunny it'll probably do.

Of course, that doesn't leave much/any power for the rest of the stuff. So, I'd say that setup would be borderline at best.

Other possibilities:
1. Get Lithium batteries ($$) and more like 300W of solar (if there's enough roof space.. may need some freestanding as well). Lead batteries lose life if left below 50% regularly, and can't be fast-charged above 80%. Lithiums can run more like 20-95%, so you get around 2-3x as much real-world capacity. Plus they're smaller and lighter.

2. Run a generator. This tends to make neighbors cranky, especially if you have to do it overnight, but as long as you keep gas in it you'll have plenty of power even with a small one.

3. Get a propane fridge. Then one battery plus 150W of solar will be enough without a lot of stretching.

[Patricia D.]

Thanks for your responses.
I am still not decided about what to do but do know that I do not want to put out money on a generator. I would be willing to put in 2- 6v batteries and more solar but I have been concerned about the weight distribution.
I have read renovation posts that have talked about having weight balanced from side to side. On one side of trailer at the wheel well will be the tall cupboard with the cooler which weighs about 45 lbs empty and the battery or batteries would be on the opposite side. 2 batteries as redbarron55 suggests, would be about 130 lbs.
I suppose if I used the tall cupboard for the cooler, food and cookware, it might come close to balancing the weight of the batteries on the opposite side.
Or am I just overthinking the weight issue? If I am aware of the issue and endeavour to keep the most weight near or between the wheel wells, is that sufficient from a safety standpoint?

[Franswa]

bad weight distribution side to side will affect how the trailer reacts in an emergency (hard stop or swerve)....just when you need it to handle really well...since you are starting with a blank slate might as well try to get it right...

my trailer came out of the factory heavy on the left side....not great but that's the way it is....so now ANYTHING that gets put in that trailer finds its "home" depending on how much it weighs...light goes left, heavy goes right....I've been gaining but I'm not fully there yet