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06-15-2020, 09:25 AM
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#21
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Senior Member
Name: zack
Trailer: scamp 13
California
Posts: 347
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Thanks.
Quote:
Originally Posted by floyd
Remove group 24 battery, install group 27 battery.
If battery box is too small... get larger battery box, available at WalMart for +- $7.
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Thanks. Sounds easy. I ordered a group 27 box
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06-15-2020, 09:34 AM
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#22
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Senior Member
Name: zack
Trailer: scamp 13
California
Posts: 347
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Does anyone know the 12 volt battery charging rates (in amps) for a 2015 Scamp 13 plugged into shore power? Does that depend on time and 12 v battery state of charge? I am particularly wondering how fast the charge rate is when the battery is around 50% or 25% depleted. Thanks a lot.
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06-15-2020, 02:03 PM
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#23
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Senior Member
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 5,155
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Quote:
Originally Posted by zack sc
... has anyone made the switch? What Li-ion batteries did they use?
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see:
Lithium Battery project
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06-15-2020, 02:22 PM
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#24
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Senior Member
Name: Larry
Trailer: Trillium
Arizona
Posts: 440
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Trojan?
Hi Zack,
My favorite group 30 battery is a Trojan SCS225 wet cell. My first one
lasted 10 years with careful maintenance. I have a 150W solar
charger that never failed to keep up with demand as long as
the sun was shining. Not Cheap = about $230 with core exchange.
Although inexpensive, I am not a fan of Walmart or most batteries that
people seem to prefer to save money... Seems like false economy.
I only replaced the battery after 10 years cause I wanted to ensure
that I would have to deal with the inconvenience of a failure out
camping and have to buy a crappy battery in an emergency. I might
have been able to squeeze a couple of more seasons out of the battery.
As far as charge rate goes.... Most wet cell deep cycle battery literature
recommends to charge at a capacity/10 rate based on the 20
hour discharge rate with a maximum C/5. So the SCS 225 with
130 Amp Hour rating should charge at about 13 Amps ideally
with a maximum of 26 Amps. Most onboard converters put
out more current so they are not ideally suited for such charging.
My 150W system charges the battery at about 7-8 Amps and does OK.
At home I use a little 10W solar panel into the solar controller for
trickle/maintenance charge... Does the job.
For 12V education please check out:
https://www.solar-electric.com/learn...-and-charging/
Take Care, Uncle Larry
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06-15-2020, 03:36 PM
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#25
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Senior Member
Name: zack
Trailer: scamp 13
California
Posts: 347
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27TMX
Quote:
Originally Posted by Larry C Hanson
Hi Zack,
My favorite group 30 battery is a Trojan SCS225 wet cell. My first one
lasted 10 years with careful maintenance. I have a 150W solar
charger that never failed to keep up with demand as long as
the sun was shining. Not Cheap = about $230 with core exchange.
Although inexpensive, I am not a fan of Walmart or most batteries that
people seem to prefer to save money... Seems like false economy.
I only replaced the battery after 10 years cause I wanted to ensure
that I would have to deal with the inconvenience of a failure out
camping and have to buy a crappy battery in an emergency. I might
have been able to squeeze a couple of more seasons out of the battery.
As far as charge rate goes.... Most wet cell deep cycle battery literature
recommends to charge at a capacity/10 rate based on the 20
hour discharge rate with a maximum C/5. So the SCS 225 with
130 Amp Hour rating should charge at about 13 Amps ideally
with a maximum of 26 Amps. Most onboard converters put
out more current so they are not ideally suited for such charging.
My 150W system charges the battery at about 7-8 Amps and does OK.
At home I use a little 10W solar panel into the solar controller for
trickle/maintenance charge... Does the job.
For 12V education please check out:
https://www.solar-electric.com/learn...-and-charging/
Take Care, Uncle Larry
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Thanks a lot Uncle Larry. What do you think of the Trojan 27TMX. ??
So basically C/10 to C/5 is the correct charging range? I am thinking that for the 27TMX that would mean about 10 amps (C/10) up to 20 amps (C/5). I am guessing that the Scamp on board charger is somewhere in that range, but I don't really know (And neither did the guy at Scamp I spoke to).
But I am betting someone here knows the answer, and maybe it involves a little calculation using internal resistance rather than a fixed current?
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06-15-2020, 05:07 PM
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#26
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Senior Member
Name: Mike
Trailer: Escape 21 & Jeep GC 5.7 (Previous 2012 Casita FD17 & 2010 Audi Q5)
Puget Sound, WA
Posts: 1,775
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Quote:
Originally Posted by zack sc
The fridge requires about 80 watts to operate whether it is on 110 volt, 12 volt or propane.
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80 watts sounds high for control board power. When the refrigerator is run on 12 volts, it takes additional current to operate the heating element for the absorption cycle. This heating element does not provide the same energy as the propane and 120VAC modes, but it's still much more current than running the control board. So, it doesn't provide the same cooling capacity. From the Dometic manual for the RM2454 and others:
Quote:
Note: The DC mode is a holding mode not a full cooling mode. DC should be used once the unit is cooled down and constant supply of DC available (driving down the road).
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Dometic's DC heating elements run from about 150 to 250 watts for the models in this manual. The AC elements run from 175 to 325.
Quote:
DOMETIC DIAGNOSTIC SERVICE MANUAL
AMERICANA & AMERICANA PLUS
RM 2351, RM 2354, RM 2451, RM 2454
RM 2551, RM 2554, RM 2652, RM 2662
RM 2663, RM2852, RM2862 & NDR1062
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The 2454 is the refrigerator we had in our Casita, so I had the manual handy. The Scamp probably has a smaller fridge, but the principles apply.
__________________
~ “It’s absurd to divide people into good and bad. People are either charming or tedious.” Oscar Wilde ~
~ “What the human being is best at doing is interpreting all new information so that their prior conclusions remain intact.” Warren Buffett ~
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06-15-2020, 05:29 PM
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#27
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Senior Member
Name: Jon
Trailer: Escape 21C
New York
Posts: 2,387
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Quote:
Originally Posted by zack sc
Thanks a lot Uncle Larry. What do you think of the Trojan 27TMX. ??
So basically C/10 to C/5 is the correct charging range? I am thinking that for the 27TMX that would mean about 10 amps (C/10) up to 20 amps (C/5). I am guessing that the Scamp on board charger is somewhere in that range, but I don't really know (And neither did the guy at Scamp I spoke to).
But I am betting someone here knows the answer, and maybe it involves a little calculation using internal resistance rather than a fixed current?
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The problem is you cannot charge a lead acid battery at C/5 or even C/10 all the way to full. From 50% to about 80% the converter or solar controller will go into the bulk mode, putting as much current into the battery as possible. As the battery reaches 80%, the converter switches to the absorption mode, which limits the charging current in order to prevent off gassing. If it didn't limit the current the battery would overheat, boil the electrolyte, and produce excessive hydrogen gas. That limited current prolongs the charging time until full.
Fully topping off a lead acid battery takes as much as 4 - 6 hours of absorption time. While you can stop charging at 80%, and many do to save gas and shut down their generator, obviously you are not using the full capacity of the battery.
One advantage of lithium batteries is they can be safely charged at C/2, or even C if you are willing to go below 3000 cycles, until they hit around 98% - 99%, at which point the charging current slows down.
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06-15-2020, 05:52 PM
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#28
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Senior Member
Name: Jon
Trailer: Escape 21C
New York
Posts: 2,387
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Quote:
Originally Posted by zack sc
People say the 3-way Dometic is inefficient with 12 volt, but I don't really agree with that. The fridge requires about 80 watts to operate whether it is on 110 volt, 12 volt or propane. And that is, in a sense, very inefficient compared to a big home fridge that uses just about 20% more power to cool a much larger volume. The dometic 3-way is equally inefficient on all its power sources, the issue with 12 volt is that 12 volt batteries tend to contain very little total energy (compared to a propane tank). However, when you run out of propane, having a great battery that can save your food by keeping it cold for 8 hours is a pretty nice thing to have. The keys thing is probably to make sure you charge the 12 volt back up after that and don't count on just the tow vehicle alternator, cause I think they charge pretty slow. (Which reminds me, does anyone know roughly the charging amps on shore power for a Scamp 13???)
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You didn't list the model refrigerator in your Scamp 13, however I find it hard to believe it draws 80 watts running on propane. For example, the control board for all the refrigerators listed above is fused at 3 amps, or a maximum of 36 watts. I bet the actual current is far less than that. My 6 cu ft DM2663 draws under 1 amp on propane, which includes the control board & gas valve. The 12V heater element is 275 watts, or 23 amps, the 120V element is 375 watts, or 3.1 amps.
The smallest DC heater is 150 watts or around 12.5 amps, while an average would draw closer to 17 amps. When on 12V, the heater element has a 100% duty cycle, or on all the time.
Aa to the converter output, check the model number. The last 2 digits are often the maximum current rating, but Google the model number to be sure. I didn't find any information on the 2015 Scamp 13, but the current model has a 30 amp Progressive Dynamics PD 9130 converter.
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06-15-2020, 06:37 PM
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#29
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Senior Member
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 5,155
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I like my fridge because when on propane it uses 0.0 watts of DC power. And it has a freezer section!
Dometic RM-2410
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06-15-2020, 07:10 PM
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#30
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Senior Member
Name: Jon
Trailer: Escape 21C
New York
Posts: 2,387
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Quote:
Originally Posted by gordon2
I like my fridge because when on propane it uses 0.0 watts of DC power. And it has a freezer section!
Dometic RM-2410
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I had one in my Escape 17 and also liked it except I had to replace the thermostat 3 times. A PIA since you had to pull the refrigerator (although after I switched to a 21 I saw a YouTube on how to do it without pulling the refrigerator).
Also don't damage the door gasket. You can'r replace it - must do the entire door at a couple hundred bucks. Still, having a gas valve that was held open by electricity generated by the flame was great for dry camping!
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06-15-2020, 11:51 PM
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#31
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Senior Member
Name: zack
Trailer: scamp 13
California
Posts: 347
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energy
Quote:
Originally Posted by Jon Vermilye
You didn't list the model refrigerator in your Scamp 13, however I find it hard to believe it draws 80 watts running on propane. For example, the control board for all the refrigerators listed above is fused at 3 amps, or a maximum of 36 watts. I bet the actual current is far less than that. My 6 cu ft DM2663 draws under 1 amp on propane, which includes the control board & gas valve. The 12V heater element is 275 watts, or 23 amps, the 120V element is 375 watts, or 3.1 amps.
The smallest DC heater is 150 watts or around 12.5 amps, while an average would draw closer to 17 amps. When on 12V, the heater element has a 100% duty cycle, or on all the time.
Aa to the converter output, check the model number. The last 2 digits are often the maximum current rating, but Google the model number to be sure. I didn't find any information on the 2015 Scamp 13, but the current model has a 30 amp Progressive Dynamics PD 9130 converter.
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Sorry, I was really unclear. I was referring to the energy used to drive the cooling process, which I thought was about 80 Joules per second (aka Watts). It draws zero current on propane; but I was thinking that burning propane is producing about 80 joules/second of heat energy.
The second point is, I may have remembered the number wrong. It may be more like around 120 Watts. Have to recheck my manual and notes.
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06-16-2020, 01:24 PM
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#32
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Senior Member
Name: Larry
Trailer: Trillium
Arizona
Posts: 440
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Trojan 27TMX ?
Hello,
The Trojan 27TMX is a good choice... However, I prefer to have a
bigger one as it will probably last longer as the depth of discharge
will not be a great.
The rule of thumb for cycling deep cycle batteries is to never draw
them down more than 50% of their capacity. Doing so shortens
the battery's life substantially. Also, the battery should be completely
recharged every day/night If the battery is only discharged 20-30%
of its capacity it will last longer.
Uncle Larry
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06-16-2020, 01:29 PM
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#33
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Senior Member
Trailer: Escape 17 ft
Posts: 8,317
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A bigger battery is more lead is more weight. You must pay attention to where you place that weight and what it does to tongue weight.
__________________
What happens to the hole when the cheese is gone?
- Bertolt Brecht
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06-17-2020, 07:51 AM
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#34
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Senior Member
Name: Larry
Trailer: Trillium
Arizona
Posts: 440
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Weight
Hello,
The Trojan 27TMX weighs about 55 pounds. The SCS225
I use weighs about 66 pounds.... the extra 11 pounds seems
worth the extra capacity.
Let's see, 20% more weight for 24% greater capacity....
There is always a trade off.....
Uncle Larry
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06-20-2020, 11:02 AM
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#35
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Junior Member
Name: Chuck
Trailer: Scamp 16' Deluxe
Utah
Posts: 5
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A larger 12 volt or 2-6v wired in series deep cycle batteries. The 13' Scamp frig will not do well on gas when traveling. So it must run on 12 volt during travel. When boon docking run on gas. When you have shore power run on 110v.
Biggest problem I had on my 2012 13' was the little spiders plugging up the gas orifice with cobwebs I guess. Or a condensation of moisture and corrosion plugging the orifice. What ever caused it the only way to clean it was disassembly and usually use a wire from a small tig wire brush to open the hole in the orifice.
My 2 cents, Chuck
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06-20-2020, 11:12 AM
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#36
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Senior Member
Name: Kenneth
Trailer: Scamp
Wisconsin
Posts: 1,867
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Gas refrigerator on the road
Quote:
Originally Posted by utahwv
A larger 12 volt or 2-6v wired in series deep cycle batteries. The 13' Scamp frig will not do well on gas when traveling. So it must run on 12 volt during travel. When boon docking run on gas. When you have shore power run on 110v.
My 2 cents, Chuck
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Many of us do not have 12 VDC refrigerators. I have run gas for thousands of miles with out a problem, but mine is located on curb side. After watching this group for some time, it looks like the people that have it on street side can not keep it lit. I think Scamp says not to use gas on the road just so they do not need to deal with the issue. NOTE: Always stop away from the gas pumps and turn off the refrigerator ( I turn the gas tank off) before driving up to the pumps to fill.
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06-20-2020, 11:26 AM
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#37
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Senior Member
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 5,155
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Quote:
Originally Posted by utahwv
...What ever caused it the only way to clean it was disassembly and usually use a wire from a small tig wire brush to open the hole in the orifice.
My 2 cents, Chuck
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Please dont do that. See middle of 19th paragraph here:
The RV Doctor: Cleaning & Servicing the RV Absorption Refrigerator
And the entire article is good to read for anyone else who has an absorption refrigerator in a recreation vehicle that is not working as it should.
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06-20-2020, 06:08 PM
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#38
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Senior Member
Name: David
Trailer: 2013 Scamp 13 S1 BB
IL
Posts: 281
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At least in the rm2193 the office is just metal, no ruby, and a tig brush was the only thing that was able to fix mine. I have no problem running on propane when driving, but I do partially block the lower refrigerator vent around the burner.
As to power use in rm2193 it's 120 watts on dc or ac, that's almost 10 amps assuming 12.5v. that's 80 amp hours for 8 hours, that means you would need at least 160 amp hours just to run the fridge
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06-28-2020, 07:28 PM
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#39
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Senior Member
Name: zack
Trailer: scamp 13
California
Posts: 347
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2193
Quote:
Originally Posted by Jon Vermilye
You didn't list the model refrigerator in your Scamp 13, however I find it hard to believe it draws 80 watts running on propane. For example, the control board for all the refrigerators listed above is fused at 3 amps, or a maximum of 36 watts. I bet the actual current is far less than that. My 6 cu ft DM2663 draws under 1 amp on propane, which includes the control board & gas valve. The 12V heater element is 275 watts, or 23 amps, the 120V element is 375 watts, or 3.1 amps.
The smallest DC heater is 150 watts or around 12.5 amps, while an average would draw closer to 17 amps. When on 12V, the heater element has a 100% duty cycle, or on all the time.
Aa to the converter output, check the model number. The last 2 digits are often the maximum current rating, but Google the model number to be sure. I didn't find any information on the 2015 Scamp 13, but the current model has a 30 amp Progressive Dynamics PD 9130 converter.
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Thanks Jon. I appreciate the good info and analysis. Sorry for the long delay in responding; I was boon docking for a while and then resting up.
My Dometic is a 2193 (3-way). I believe that on 12 volts in draws about 10.5 amps, so about 130 watts. I am guessing that on 110 volts it must draw more than that on high (it is adjustable on 110 v), probably 170 watts?, so about 1.5 amps perhaps.) What I was trying to say before was that it is not efficiency that is the problem on 12 volts, it is the lack of total energy in a 12 volt battery. In either case it is using the battery, I believe, to heat a resistor, which is really efficient, just not very effective in the 12 volt case because the battery drains fairly quickly. Then with propane, it is a completely different source of heat energy and works well because a tank of propane contains a lot if energy; maybe about 50 or even 100 times more than a group 27 12 volt battery. It is no big deal, just my 2 cents.
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07-01-2020, 09:52 AM
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#40
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Senior Member
Name: zack
Trailer: scamp 13
California
Posts: 347
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on board charger specs for Scamp 13
Does anyone know the specs for the onboard charger that Scamp sells with the Scamp 13? For a 12 v battery between about 50% and 80% charged, what charging current would the onboard charger supply?
PS. Or does that depend substantially on the internal resistance of the battery?
PPS. I know the last 20% or so is more complex. I am interested in the charging rate for the easy part.
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