Edgestar vs. Engel Freezers

[Russ]

run their Freezers on 24v but it would be very advantageous if the unit is further from the power source due to less voltage drop with the same size cables and also as there would be less amps it would mean the delivery voltage of the battery would be higher for longer.
It would just be a bit difficult to manage using the batteries for the fridge on 24v and lighting/starting etc on 12v especially if one gets drawn down it could also complicate it for charging but nothing that couldn't be fixed.

The Edgestar uses about half as much amperage at 24v. There is a big advantage to run it on 24v. If I could figure out how to charge the two 12v batteries from a 12v solar panel and simultaneously combine them to 24v to run the fridge it would be ideal.

--Russ

[Hamin' X]

Your power usage (watts) remains the same, so the only advantage would be smaller wire for a given distance.

~Rich

[Russ]

Your power usage (watts) remains the same, so the only advantage would be smaller wire for a given distance.

~Rich

I don't understand the watts thing because watts are relative to volts as I understand it. But amps is amps regardless of volts I always thought.
So when the fridge advertises 4 amps at 12v and 2 amps at 24, I assume that's pulling less juice and more efficient at 24v, no?

[Obelix]

Russ,

The relationship between Watt, Volt and Amperes in DC current is simple.
Volts times Amps = Watts (4 A at 12 V = 48 W or 2 A at 24 V = 48 W)
Both cases talk about the exact same energy

Obelix

[Hamin' X]

Let's try and explain it this way: Say you have two 12v batteries, both 100 amp hr capacity. If you put them in parallel, positive to positive, negative to negative, you will have 12v and 200 amp hr capacity. If you wire them in series, positive to negative and take your power off the free ends of both batteries, a positive and a negative, you will have 24v, but only 100 amp hr of capacity. So, if you are running an appliance at 24v, even though it only draws half the amps of 12v, you will only have half as much reserve in the batteries. Watts is a unit of power and voltage * amps = watts. So, if your appliance draws 10 amps at 12volts; 12v * 10amps = 120 watts. If it only draws 5 amps on 24v; 24v * 5amps = 120 watts. The power consumption is the same. The pertinent value is the watts.

However, voltage drop in a wire run is relative to amps. The more amperage drawn, the more the voltage will sag. So, higher voltage is more advantageous for longer runs of wire. That is why (in a simplified manner, because it is AC) the long distance power transmission lines run at a much higher voltage than your normal 120v house voltage. Long distance transmission line voltage runs into the 100's of thousands of volts, to reduce losses.

~Rich

[DaveB]

Rich,
For others that want to use 6 volt golf cart batteries the same as you mention also applies to get 12 volts.
Dave

Let's try and explain it this way: Say you have two 12v batteries, both 100 amp hr capacity. If you put them in parallel, positive to positive, negative to negative, you will have 12v and 200 amp hr capacity. If you wire them in series, positive to negative and take your power off the free ends of both batteries, a positive and a negative, you will have 24v, but only 100 amp hr of capacity. So, if you are running an appliance at 24v, even though it only draws half the amps of 12v, you will only have half as much reserve in the batteries. Watts is a unit of power and voltage * amps = watts. So, if your appliance draws 10 amps at 12volts; 12v * 10amps = 120 watts. If it only draws 5 amps on 24v; 24v * 5amps = 120 watts. The power consumption is the same. The pertinent value is the watts.

However, voltage drop in a wire run is relative to amps. The more amperage drawn, the more the voltage will sag. So, higher voltage is more advantageous for longer runs of wire. That is why (in a simplified manner, because it is AC) the long distance power transmission lines run at a much higher voltage than your normal 120v house voltage. Long distance transmission line voltage runs into the 100's of thousands of volts, to reduce losses.

~Rich

[Divecoz]

What the conscience on using 3 new AGM 12 Volts batteries? Series two for the 24 volts and center tap off those for the general lighting??
I am even considering ???
3 - 12 AGMs for house and fridge and a much smaller Motorcycle 12 V. for a starter battery.. Its tempting.. Lots of Big Road Bikes ( 130 CU.IN.)
Run a smaller battery than we dedicate for our motors.... I guess I just need to look up the amp draw on a Merc 50 HP EFI BF.. and then maybe pull the Battery from my bike and see if.... and how well .....it works?

Has anyone found a comparison of AGM Batteries? There must be a bad one and a best one and the group in the middle???...

[Sumner]

What the conscience on using 3 new AGM 12 Volts batteries? Series two for the 24 volts and center tap off those for the general lighting??
I am even considering ??? .....

As has been mentioned the only reason to go 24 volts to the frig would be to use a smaller wire size. The run is going to be so short this isn't a problem, so why complicate things.

Also you are now going to have a confusing system to try and charge with the above. I don't see an easy way to charge two 12 volt batteries in series. The MPPT solar charge controller we use for the solar array does have a separate charging circuit for a 12 volt starter battery if needed. We don't use it and have the 2 12 volt batteries in parallel so that they charge off either the solar charge controller, the outboard or the gen-set or all of the above at the same time.

We decided against a separate starter battery since we can pull start our 9.8 HP if needed. I looked into possibly using a motorcycle battery also, but some of the smaller ones have a limited amp output, so check on that real careful before going down that road. Also by the time I found one with a large enough output capability is wasn't really any cheaper, so gave up on that.

Good luck,

Sum

Our Trips to Utah, Idaho, Canada, Florida

Our MacGregor S Pages

Mac-Venture Links

[Divecoz]

Sum.. What do you have for solar ? I looked on your site and I did not find it..
Waeco has a built in -2.3 cu.ft. with a danfos 35 compressor for about $700
she draws 40 watts , and at 86 degrees it will run 40% of the time..

[Sumner]

Sum.. What do you have for solar ? I looked on your site and I did not find it..
Waeco has a built in -2.3 cu.ft. with a danfos 35 compressor for about $700
she draws 40 watts , and at 86 degrees it will run 40% of the time..

Here is a link to the 40 watt we started with...

http://purplesagetradingpost.com/sumner ... de-22.html

and one to the 180 watts total we have now...

http://purplesagetradingpost.com/sumner ... de-33.html

If that Waeco is an upright don't forget that everytime you open it most of the air in it will spill out. A chest type won't do that. It looks like our 63 quart...

http://purplesagetradingpost.com/sumner ... de-22.html

..... is about 2.1 cu. ft.. In the specs I see they claim the edgestar is 6+ amps at 12 volts. I don't know how they got that, but it isn't right. I have an amp meter accurate to .1 amp and I see about 3.5 amps when it is running.

The boat right now is 82 deg inside and has been between mid 70's to mid 80's for the past 4-5 days. Last night the frig ran for about 4 hours to cool a full box down from 44 to 38. It was off all night and was 44 when we turned it on this morning. It then ran again for about 4 hours and went back down to 38 and cycled off. It is now 4:15 about 4-5 hours after it went off and is still 39 inside (temp gauge is on the side). It might not run again until tomorrow morning at this point.

It is very effecient and has a 'true' compressor type system just like the waeco and engel. We used it for 25 days in the fall and a week now on this trip, so I don't have a long time report, but would definitely buy another if it keeps running like it is. I had considered the other two, but they were a lot more for the same size.

We got this on sale about a year ago at Christmas for $435 freight paid. Now it is...

http://www.compactappliance.com/FP630-S ... el_Coolers

$499 frieght paid. Still a great deal in my mind.

I think an 80 watt panel might carry it on long trips with longer summer days if you are a place that gets sun. It is really hard to get full rated watts out of a panel on a boat and under all weather. I'd figure about 1/2 the rated output over about 6-8 hours sun in the spring through fall to be safe. We have the gen-set to back things up and might have to use it for an hour or so before we get our replacement panel Monday.

Solarblvd...

http://www.solarblvd.com/Solar-Panels-& ... _info.html

...has a great price of $159 on the 80 watt they are sending me. Only problem is that it is about 8 inches longer than the one I broke so will stick out even further . I'll for sure now dock on the port side. I was expecting to pay over $300 for the replacement panel.

As I mentioned we went with a more expensive MPPT controller.....

http://www.solarblvd.com/Charge-Control ... _info.html

...to maximize the output of the panels as we can't add any more. So far we are real happy with the controller and the panels we got from them.

Good luck,

Sum

[Divecoz]

OK 1 more question? Koolatron? Plate Technology? I take it not knowing much....that Plate is crap/cheap / junk.... Not Worth it????

*SUM: without a doubt Chest coolers dont spill the cold out and that is very important ...!! THANKS.. for the reminder!!

[Sumner]

OK 1 more question? Koolatron? Plate Technology? I take it not knowing much....that Plate is crap/cheap / junk.... Not Worth it????..[/i]

I have a frig....



..... in my teardrop...

http://purplesagetradingpost.com/sumner ... index.html

.... that I think uses that technology.



It only cools about 20 degrees cooler than the ambient temp and will run a battery down in 6-8 hours. I use ice in that frig now.

Don't waste your money on one in my opinion,

Sum

Our Trips to Utah, Idaho, Canada, Florida

Our MacGregor S Pages

Mac-Venture Links

[Russ]

I have a frig....



..... in my teardrop...

http://purplesagetradingpost.com/sumner ... index.html

.... that I think uses that technology.

That thermoelectric technology is cute, but it doesn't work. It sucks so much power and delivers so little cooling. No place on a boat with limited battery capacity. In fact, I had one running on A/C in my house. Barely kept stuff cold and ran all the time making all kinds of noise. Cheap is cheap.
The only solution is a real compressor fridge.

[Divecoz]

Thanks Russ:
It goes with the old adage : Too good to be true ? Because it is , Too Good To Be True!!!!
""That thermoelectric technology is cute, but it doesn't work. It sucks so much power and delivers so little cooling. No place on a boat with limited battery capacity. In fact, I had one running on A/C in my house. Barely kept stuff cold and ran all the time making all kinds of noise. Cheap is cheap.
The only solution is a real compressor fridge.
RussMT ""