Coleman Stirling Power Coolers

[witzgall]

Yeah, the battery is the weak link. Get a real one - at least a small car battery.

What is the battery voltage in the morning - that will tell you something. If it is close to 12v or lower, you have found your problem.

Chris

[witzgall]

Do you have a charge controller? If not, you may be boiling that battery when you leave these hooked up without a load on the battery. You would be putting ~2.5 amps into a 12 ah cell - that is too much for trickle charging without a controller. If you have done this much, you no longer have a 12ah battery!

Chris

[ericb]

It works fine on a sunny day. It can run for about 30-36 hrs on battery alone if the ambient's not too high, say 20 degrees C.
And yes, I do use a charge controller. It even cuts the load when the voltage drops under 11,5V.
With regard to the controller: when the battery is full, it stops the panel from overloading the battery. What happens, however, is that if the solar panel delivers about 1.5A,and the battery is full , the charge goes from 1.5 to 0 to 1.5 to 0 etc etc. I'm not entirely sure if that is trickle-charging ?? Could that affect battery life?

Eric.

[tvengineer]

Originally Posted by ericb

Tv-engineer, i've also got one set up with a solar panel/battery. I've noticed that 40W of panel and 15Ah battery is not enough to keep it running continuously. Could you provide some details of your set-up?

Regards, Eric.

Sure... Mine is QUITE a bit bigger than yours

Seriously.. THe Fridge one (I have two colemans) is running on 2 80 watt panels ... Morningstar 10amp solar charge controller into 2 golf cart type batteries in series. THe panels are probably a bit oversized.. but they are located in an area that only gets full sun for a few hours a day.

The second attempt.. (on the second coleman) I wanted enough power to run it FULL BOAR 24/7... so I designed for 50watts of power 24 hours a day on the worst day of the year...
I have two 205 watt solar panels... 30amp morningstar solar controller and 4 golf cart battereis in series parallel.

I can probably get way more out of this system once I get the panels properly mounted on the roof (they are just on top of a shed right now)..
and I need to upgrade to bigger batteries..

Then.. I would likely run both colemans on that bigger 410watt system.. and free up the two 80watt panels for something else.. like night watchman type yard lighting...


OH.. I wish I could just buy 20 more panels and be done with the power company all together.

OH ..OH... check out Solar Panels : Solar Panels Direct $2.18 per watt they have a great price right now on their SUN130 130 watts for $257.40
I am sure that ONE of those .. and a couple golf cart batteries would be more than enough to run your coleman on COOL3 or FREEZE 1 99percent of the time.

My colemans are in an unairconditioned shed.. and they do draw more power on HOT days... I monitor my batterys closely.. and only ONCE this summer have I had to switch down to COOL 2 (vs COOL 3) to conserve a bit to let the batteries build back up on cloudy days.

[tvengineer]

Darn.. I typed a long reply.. only to have the server eat it...

Oh. well.. I see now that you want it for camping...
So a system like mine is way overkill..

Your big advantage is that you can point your panels at the sun periodically thru the day.. that will help alot..

Your battery is way too small... If you can aford the weight you should try a sealed AGM battery.. like the OPTIMA Blue Top...

Your panels are small and EXPENSIVE!!! and they don't have a charge controller.. If it is not too big.. check out Solar Panels : Solar Panels Direct $2.18 per watt they have a 130 watt for like $260... not much more than you paid for the 20 watt ones!
I use the morningstar solar controller.. there is a 6amp one on ebay right now for less than $50....

Like I said.. your ability to keep your panels pointed at the sun all day long will give you alot more power than mine that are fixed.. mine only get to point directly at the sun for a few minutes a day.. that is the only time they make their full power.. all the other time they make a bunch less..

Again.. your battery is the weak point right now.. My coleman on a cool day.. running at COOL3 draws about 1 amp at 12v... Your battery is rated at 15amp hours probably at a 20hr rate.. so really it can only make 750milliamps for 20 hours.. asking it for more reduces its capacity.

Not having a gell battery on a charge controller has certainly done damage to it by now..

[Badsanta]

I was always told that 12 volts is a dead battery and a cut out at 11.5 would be more so.

[ericb]

Thanks TV. I almost see myself tying a trailer to the trailer to haul all the solar panels and batteries to the camp site.

But seriously, you have given me a lot to think about if i want to keep it running all day.
Unfortunately, i'm in the Netherlands, far away beyond that big pond they call the Atlantic Ocean. Shipping rates from the US for this kind of products are NOT NICE, several hundred dollars. I've tried...
I am looking around to get a good deal locally, but first I needed to get a better idea about sizing. I'm always struggling with battery capacity. 24h, 1.5A means 36Ah per day (or 432 Wh), means 100Ah battery for about three days, right? But somewhere I read that if you want 100Ah, you need a 200Ah battery because the battery can only be discharged to 50%
And if I want to charge that battery again after a few cloudy days in mid-winter, while running the cooler of course, the panel should indeed be 200 Watts or so.. right?

Does anyone know about an accurate online solar calculator????

[ericb]

Originally Posted by Badsanta

I was always told that 12 volts is a dead battery and a cut out at 11.5 would be more so.

Well, i'm not sure, since I don't have a V-meter attached,but these are the values the documentation of the charge controller gave me... I looked it up, it even says 10.5 V

[tvengineer]

EricB..

First let me apologize for being a stereotypical American ass.. and assuming everyone on the internet if from here

Just about everything you ever needed to know about batteries is here..

Deep Cycle Battery FAQ

I try to not let mine get below 80 percent on a daily basis.. that is because I want them to last a long long time..

In your camping application, it would not be terrible to let them go down lower every once and a while.
Again.. I would suggest you look for a sealed AGM type battery.. they must have something like that in your part of the world.. the little gell cell battery's are not meant for this large an application.

You wouldn't need to put another trailer behind a trailer to lugg it all around..
the battery would be the size of a small car battery.. and the 130watt solar panel that I put in that last link is around 5 feet by 2 1/2 feet..
Could be rigged on the top of the car.. or on the top of a covered trailer.

Now finding one at a reasonable price where you are.. I understand that is another story.

Take a look at the battery info though... you should get a lot out of that.

Louis

[Captain Bill]

Maybe I'm misreading something here. If I understand it correctly you are proposing to camp outdoors at about 50 degrees N. in the winter. My experience would suggest that if you open the top you won't need any power for refrigeration, or are you camping in warmer areas than north central Europe?

[tvengineer]

Thinking about his battery needs...

My Coleman draws about an amp to keep thing really nice and cold..
Sometimes more.. if the outside temperature is HOT...

Also.. this is to KEEP things cold.. One of the really neat things about the COleman is that the minute you put something warm inside, you can almost instantly see the current ramp up to increase the cooling output of the stirling.. (you can hear this as the unit gets a little louder)..

So.. back to the battery problem.. Lets say you want to run the unit at 1.5 amps 24hrs a day from a battery. Deep cycle batteries are rated at their 20 hour rate.. so to provide 1.5amps for 20 hours you would need a 30 amp hour battery.. But that is to ZERO DEAD... on the battery after only 20 hours of opperation. You should not let your battery go dead ever... The least amount you cycle your battery ... the better.

I said I don't like mine to go below 80 percent on a regular basis..
For your camping application you could get by with letting it go down a lot further once and a while... so to keep round numbers lets say 50 percent..
1.5 amps for 20 hours to 50 percent means you need a 60 amp our battery. Multiply that out for 24 hours (not 20) and you need 72 amp hours. Really not that big a battery for a deep cycle.. any marine deep cycle from the auto parts store would fit this criteria.

Now.. we have a system where you can run your cooler for a whole day on battery power alone...
The other 1/2 of the equation is charging...

You have 40watts of panels... now here is where some of the dirty little secrets about solar come into play.. that 40 Watts is calculated at the maximum amperage the panel can supply.. and at a certain volatage.. usually around 17volts.. This is called the "maximum power point"

To keep it simple... lest say 17volts at 40 watts.. about 2.3 amps...
If you could get ALL the electricity from your 40 watt panel to go into the battery (leaving out efficiency etc.).. the most you can hope for, with the panel pointed directly at the sun is 2.3amps.
So..you are charging your 1/4 dead battery at 2.3 amps... for at best.. maybe 4 or 5 hours a day...
2.3 amps times 5 hours a day.. = 11.5 amp hours a day....
Remember.. up above.. we calculated that you used 30 amp hours for one day..
Your putting less than 1/2 of what you took out each day...

or.. another way to look at it.. your 40 watt panels added 1/3 of a day to the battery..
If you didnt mind running the battery down to dead.. you could camp for 48 hrs with not solar input... with the solar input you can camp almost a whole extra day get more solar panels.. any your there.

Sorry for the long reply.. it's kinda fun to think this stuff through.

[ericb]

Originally Posted by Captain Bill

Maybe I'm misreading something here. If I understand it correctly you are proposing to camp outdoors at about 50 degrees N. in the winter. My experience would suggest that if you open the top you won't need any power for refrigeration, or are you camping in warmer areas than north central Europe?

Well, Captain, I'm actually living at 52.325681,5.607973. Not really very far north, I think. I can assure you that I need power for refrigeration (in summer). Yesterday it was about 20 C (68F). Mid-august,we've had 29C (84F) for a couple of days in a row on an island in the north of Holland. Inland temperatures were up to 35 C locally. And when I go to France or Italy...

[ericb]

Wow,Louis, thanks. That gave me lots to think about.

I'll have to look in to a better panel, battery AND charger, I guess... <looking at bottom of wallet >
To give u an idea, the cheapest 135Wp panel I could find in NL webshops is €489,= . Translate to $679,=.............. Not sure if I want to spend that on a camping rig. Oh well, I could always use that to keep the beer cold all year long

I'll have to give it some thought, though.
What happens now is that the charger cuts the load, the cooler slowly warms up while the panel charges the battery again to over its cut-in voltage, and the cooler cools again. During the weeks of camping, it probably never gets to 100% again. So yes, I might have killed the battery already. At the moment it sits in my garage, panel connected,cooler disconnected. The only load is the charger itself. The charger says it's full, then pretty soon it goes charging again. It did'n do that so fast when i bought the battery.

[ericb]

BTW, Captain,
I'm not going camping in winter. It would be nice, however, to be able to use the cooler in the garage to keep some cold beer in

[tvengineer]

Originally Posted by ericb

Not sure if I want to spend that on a camping rig. Oh well, I could always use that to keep the beer cold all year long

I never said that what I was doing was sane!
I guess I have about 2,000 us dollars in it already.. and no end in sight

I lived thru Katrina.... and saw where it took almost a Year for electric service to be restored.. Last year during Gustav.. my power was out for 5 days...
but I had a coleman.. and a battery.. and I had COLD...
After that I found another coleman. bought 2 40 watt panels..
Thinking, just like you, .. each coleman draws 20 or so watts.. 2 colemans = 40 watts.. it is daylight 1/2 the time... 40 x 2 = 80 watts..

Then I started to learn...
and I found the 2x 80 watt panels on ebay and got them..
I rapidly found out that they could NOT run both colemans.. but they did pretty well at running one..
But I wanted more.... and I wanted FROZEN... the best deal on solar I could find at the time was the 205 watt ones... so I sprung for 2 of those.

It is a sickness... mine probably brought on by trauma from the hurricanes..
but with the colemans... it is relatively easy to have refrigeration completely self sufficient from the electric company or a steady supply of gasoline...
and once you can't get either of those.. the ability to fend for yourself is important..

Louis