Installing 12V Tank Heaters, Need Advice

Turtleknits · 10-02-2019, 11:45 AM

Hello, I'm a newbie on the forum. After our first winter trip last year, we discovered why tank heaters are needed. I got a quote from a highly-recommended shop.
I need advice before I go ahead with the job. I have a 2018 17B.

1. Do we need a second 12V battery? We'll be running the heaters while we're driving or plugged into shore power. The mechanic says we need the extra battery for when we stop along the road. Couldn't we just turn off the heaters for 15 or 20 minutes, or leave the truck running ?

Also, why does he recommend adding a 2nd 12V battery instead of switching to 2 6V batteries? Is it for the cost (since we already have 1 12V battery) or is there a technical reason?

2. He says we need to add a second converter for the tank heaters, since they take 36 Amps . Our current converter is 40A. Do we need this 2nd converter (plus the new 12V DC distribution system)? We have 30A now. I understand that with 30A service you can have > 30A of equipment since everything isn't turned on at once, but with the tank heating pads will we have to change to 50A?

Any advice or thoughts will be appreciated!

cpaharley2008 · 10-02-2019, 01:05 PM

I had the factory 12v tank heaters on my first E19. They are thermostatically operated, on at 30 and off at 40 and operate off 12v. That is a problem in that they pull a lot of battery juice, thus you will need to be plugged into electricity as the dual six volts can not keep up with the draw at night with the pads and heater and there is no solar then. I did not get the heat pads again on my next 3 Escapes. With the foam spray underneath and heat inside the trailer, my tanks never freeze.

cpaharley2008 · 10-02-2019, 01:06 PM

A second converter is not needed as the factory one will handle 2 12v or 6 volt batteries. Sounds like you maybe getting the tourist estimate....

padlin · 10-02-2019, 01:28 PM

Quote:

Originally Posted by Turtleknits

Hello, I'm a newbie on the forum. After our first winter trip last year, we discovered why tank heaters are needed. I got a quote from a highly-recommended shop.
I need advice before I go ahead with the job. I have a 2018 17B.

1. Do we need a second 12V battery? We'll be running the heaters while we're driving or plugged into shore power. The mechanic says we need the extra battery for when we stop along the road. Couldn't we just turn off the heaters for 15 or 20 minutes, or leave the truck running ?

Also, why does he recommend adding a 2nd 12V battery instead of switching to 2 6V batteries? Is it for the cost (since we already have 1 12V battery) or is there a technical reason?

2. He says we need to add a second converter for the tank heaters, since they take 36 Amps . Our current converter is 40A. Do we need this 2nd converter (plus the new 12V DC distribution system)? We have 30A now. I understand that with 30A service you can have > 30A of equipment since everything isn't turned on at once, but with the tank heating pads will we have to change to 50A?

Any advice or thoughts will be appreciated!

Who are you using for the install?

If you want to try and remember to always turn off the pads when you turn off the truck or leave it running then it sounds like it'd be okay, personally I'd not trust myself to never forget.

There are a couple reasons why they may have recommended 12v batteries, cost being one as you have a close to new one now. With 2 12v batteries, if one were to die you'd still have 12 volts. Although I've yet to hear of it happening, if one 6v batteries die, you better go look for a quick replacement. In general 2 6v batteries have more power then 2 12's. The 12's I've had in the past were about 85 amps each, so 170 combined. My 6 volt batteries have 230 amps. Pound for pound a battery is a battery.

I've never heard of having a 2nd converter but there are others hear who know electrical much better then I. Taking a quick look on line here
https://www.ultraheat.com/ultraheat-rv-tank-heaters
I see 13.5vdc 25 gallon tank pads with a 4.1A draw as opposed to the 12A draw that you are looking at, big difference. They how their 75 gallon pads at about 12 amps.

steve dunham · 10-02-2019, 01:34 PM

Most vehicles cannot provide enough charge current to run the refrigerator on 12 VDC and you end up arriving at your destination with a drained battery
Your refrigerator draws far less than the tank heaters so I doubt the system you describe would work even with two batteries
We have the factory tank heaters and only run them when hooked to shore power
When traveling / camping in the winter we leave our fresh water system winterized and haul water in jugs .
Even with the factory tank heaters , I don’t consider my Escape to be a four season trailer .
We have traveled in temps in the 20 below F range

padlin · 10-02-2019, 01:51 PM

Steve has a point, no way can the TV provide 36 amps, even 12 is doubtful.

Brian B-P · 10-03-2019, 12:30 PM

Quote:

Originally Posted by Turtleknits

We have 30A now. I understand that with 30A service you can have > 30A of equipment since everything isn't turned on at once, but with the tank heating pads will we have to change to 50A?

It looks like you are confusing current in the 12-volt system with current in the 120-volt system. The trailer has 30 amp 120 volt AC service, like most RVs (other than the largest). The converter can produce 55 amps of 12 volt DC power, and only needs about 6 amps of 120 volt AC power to do it. This AC power requirement by the converter, or even a second converter, is a small part of the trailer's 30 amp AC power capacity.

When comparing current in circuits of different voltages, it helps to understand that power = current x voltage, so the same power at a higher voltage is less current. If the tank heaters use 36 amps at 12 volts, that's 432 watts. For the converter to put out that much power it only needs to take in a little more... less than 500 watts. 500 watts at 120 volts is only 4.2 amps. Since 120 volts is conveniently 10 times 12 volts, for rough comparisons (ignoring the slight inefficiency of the converter, and variations in actual voltages), you just move the decimal point to compare: 36 amps to the 12 volt tank heaters needs about 3.6 amps from the 120 volt shore power, via the converter.

Brian B-P · 10-03-2019, 12:34 PM

Quote:

Originally Posted by Turtleknits

Also, why does he recommend adding a 2nd 12V battery instead of switching to 2 6V batteries? Is it for the cost (since we already have 1 12V battery) or is there a technical reason?

There's no way for us to know what he is thinking, but a guess might be that you already have one 12 V battery, so it would be cheaper to just add a battery than to replace it with two new batteries.

There's no technical reason to prefer two 12 V batteries if they are always going to be connected together, and there are technical reasons to use two 6V batteries... but either way works. If using two batteries of either voltage, it is advisable for them to be matched (same capacity, type, condition), so adding one and still using the existing battery doesn't seem like a good idea to me.

jxoco · 10-03-2019, 12:43 PM

Quote:

Originally Posted by Turtleknits

. I got a quote from a highly-recommended shop.
I need advice before I go ahead with the job. I have a 2018 17B.

!

Did you contact Escape and find out what they install?
We have the tank heaters factory installed in a 17B, but we have never used them.
(there is supposed to be two 12v pads down there.)
We have the sprayed-on foam.

Any winter camping we have done was on the way to somewhere warm and so we traveled completely dry.

Turtleknits · 10-04-2019, 02:18 PM

Thank you Brian for the 120V vs 12V refresher. Makes perfect sense, and I've used that info in another context but forgot to apply it to the converter.

I have been talking to Dustin at Escape about the heating pads themselves, but I'll call him again and ask him about the converter, thx for the idea. At this point, I think we're going to skip the expensive complex system.

Turtleknits · 10-05-2019, 10:34 AM

Thank you, all. I'm going to DIY it with my son's help!

Does anyone on this thread know the tank dimensions so I can order the pads? My trailer isn't at home. I can call ESI on Monday, but I'd rather order the pads this weekend.

20 gal Fresh
28 gal Grey
19 gallon Black

(I do know that I only need 2 out of the 3, but not sure if it's grey or black I need to do.)

padlin · 10-05-2019, 11:08 AM

The black in inside.

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