dumb question about volt meter

[David Tilston]

Originally Posted by Bob Miller

"Lighter Sockets" and "12 Volt Accessory Sockets" should be two different birds to the point that many vehicles with both, label the accessory sockets "Not for cigarette lighter use". I think that the accessory sockets are designed to hold the plugs better as well as be designed for constant use.

That said, I have no idea how to tell them apart, but if it sez "Lighter Socket" on the package I keep looking.

I would think that the ones that say "Not for cigarette lighter use" are simply not fused high enough, and/or don't have a sufficiently large wire to carry the current that a lighter would require. I assume that if it is specified for a cigarette lighter, it is of higher quality.

Several 12 VDC devices take quite a bit of power. I have a 12 VDC resistive heater that uses 125 W. That would be in the 10 A range. I wonder how much a lighter takes.

[Carol H]

Originally Posted by VicCT

I will head over tonight to check, but I think I would have noticed if it was there. Couldn't I add a regular outlet to run on 12v, instead of the socket? Forgive me if that is a newbie question! This is all a bit overwhelming.

If you mean by a regular outlet a 110 wall type outlet like the one found in your home? I haven't ever seen one that works off of 12v. The problem with the regular wall outlet is it will only work when plugged into electrical power and has no connection with your battery. That will not help you with your original question as to how to easily monitor your battery levels - for that you need a 12v receptacle . They are pretty cheap to buy and simple to install and hook up.

[Bob Miller]

Lighter sockets on a CRV and a Blazer are fused the same as the accessory sockets, 15a. Another difference may be that the lighter socket is better designed for the heat generated. I think that the "Rule of Thumb" for accessory outlets is 10a. hence the 15 amp fuse?

[VicCT]

Thanks all! You are a fantastic source of info for us newbies. I just checked - - no 12v socket. I will ask the trailer company installing the hitch if they can install one. It may be simple, but I don't do electric.

[Bob Miller]

Sounds like a good plan, but get them to install two outlets at the same time. it's will only add a few dollars to the bill now and you will need them as soon as you start using your trailer.

BTW: If you have separate fuses in your [power chassis, get each one on it's own fuse and NEVER on the same fuse as the lights. That way if something goes wrong in one you will still have the other one and your lights won't be out.

[VicCT]

Oh boy. I have a lot more to learn. I don't even know where the fuses are yet. Thanks for the tip!

[Bob Miller]

Look in the (usually) brown box in the front of the left dinette seat.

[Carol H]

Originally Posted by Bob Miller

Look in the (usually) brown box in the front of the left dinette seat.

Brown box in front the dinette seat?
Which Scamp layout does the OP have & what year trailer?

[Roger C H]

FGRV has a Scamp Owner's Manual if you don't already have one with your Scamp.

http://www.fiberglassrv.com/forums/d...campManual.pdf

Page 9 has a brief explanation of the electrical panel and pages 12-16 contain a troubleshooting area and even a circuit diagram if you really want to get confused!

Welcome to the "Egg World". LOL

For a meter, you can always try Radio Shack:

Specialty instruments, Test & meter equipment, Hobby & Do-It-Yourself | RadioShack

[RogerDat]

Another vote for have them install two. And pick up a small inverter that plugs into a cigarette lighter plug. Inverter will provide 110 volt AC for charging a laptop or camera battery. AC phone chargers tend to charge faster than the 12 volt ones too.

One of the experienced electrical people could weigh in on how many watt inverter you could run and the wire gauge the 12 volt outlet would need to support it.

Me I would (and am going to) put a 12 volt outlet at each end of the camper so I could plug a laptop in to watch a movie or edit pictures at either end and be charging something else like the phone or camera battery at the other end.

[Roger C H]

Originally Posted by RogerDat

Another vote for have them install two. And pick up a small inverter that plugs into a cigarette lighter plug. Inverter will provide 110 volt AC for charging a laptop or camera battery. AC phone chargers tend to charge faster than the 12 volt ones too.

One of the experienced electrical people could weigh in on how many watt inverter you could run and the wire gauge the 12 volt outlet would need to support it.

Me I would (and am going to) put a 12 volt outlet at each end of the camper so I could plug a laptop in to watch a movie or edit pictures at either end and be charging something else like the phone or camera battery at the other end.

Roger, I presume that use of an inverter would be when he is not hooked into shore power, right?

[RogerDat]

Originally Posted by Roger C H

Roger, I presume that use of an inverter would be when he is not hooked into shore power, right?

Yes, off grid and out in the boondocks. Where 12 volt rules...... where I'm still trying to explain to DW why her 1500 watt blow dryer ain't gonna happen. And that she looks lovely without it!

[Bob Miller]

Most of the plug-in inverters are limited to about 100-120 watts which is, in turn, predicated by the usual 10a max load suggested for the 12 DC power outlets.

While mathematically you might use a smaller wire, I would opt to use at least #14 wire for shorter runs and perhaps some #12 if it was over 10 feet(?) from the power chassis.

[Steve L.]

I expect they can accomodate adding an outlet or two, for a cost. They might ask where.

Casita put one outlet in the back corner where many hang their TV. Convenient if you have a 12v TV. I put another one in the footwell by my side dinette so devices can rest on the table while recharging. And another one (a marine one, which only means it's weather/UV resistant) outside on the street side. Some people put them on the curb (door) side but I have a macerator pump I sometimes use with the black water outlet. Plus it's a short (~2') run to the converter.

I don't know for sure the difference between a cigarette outlet and an accessory outlet either but I use the former when talking to someone who might be unfamiliar as pretty much everybody recognizes the term "cigarette outlet" and what it looks like. To the uninitiated, an "accessory outlet" might look different because its named differently. Eventually you realize they're pretty much the same thing except one might not accomodate an actual lighter.

[Carol H]

In case the OP is getting confused about the use of inverters in the 12 Volt plug due to the many different types, sizes and watt ratings of them I thought perhaps a photo of one similar in size to one I use for running laptops and charging camera batteries and phones etc might help. If your going to run a TV or microwave or other high power demand appliances like a electric kettle or coffee machine you will obviously need a larger inverter (read one with more watts).

[RogerDat]

Originally Posted by Carol H

In case the OP is getting confused about the use of inverters in the 12 Volt plug due to the many different types, sizes and watt ratings of them I thought perhaps a photo of one similar in size to one I use for running laptops and charging camera batteries and phones etc might help. If your going to run a TV or microwave or other high power demand appliances like a electric kettle or coffee machine you will obviously need a larger inverter (read one with more watts).

This outlines general wattage demands of common items. Usage Chart: How Many Watts Do You Need?

The one Carol provided a picture of looks typical of a 100 Watt model Ok for charging laptop, camera batteries or phone (notice the handy usb slot to one side)

They make them that will plug into those cigarette lighter plugs up in the 300-350 watt range but that I think might require a 12 volt plug with heavier wire and fuse. Here are a couple of typical examples of the larger ones.

This 175 watt model got positive reviews for it's lack of fan noise and constant draw of fan.
Amazon.com: Go Power! GP-175 175-Watt Modified Sine Wave Inverter: Automotive

This a 300 watt model which might allow running a TV and satellite antenna.
Amazon.com: BESTEK Dual 110V AC outlets and Dual USB 3.1A 300w power inverter car dc 12v to 110v ac inverter dc adapter laptop charger notebook adapter dc charger ac adapter usb charger MRI3011BU: Car Electronics


These will of course draw down your battery as you use them, more watts used = more battery drain.

They are nice used in the car while traveling to keep tablets and laptops charged.

[KenjiFox]

The difference between a 12v accessory outlet and a 12v cigarette outlet is as follows;
The Cigarette outlet will have a ceramic backing with a bimetallic strip in the form of a hook latch riveted to it. What this does is it heats up along with the lighter, and when it reaches a certain temp the clip lets go and the lighter pops.

The socket is designed for high heat. However, the rivet in the center is what is used to make contact with the center positive electrode of a plugged in 12v device. This means reduced contact area compared to the typical concave contact point in an accessory outlet. The reduced contact area along with possible containments should the 12v lighter have ever actually been used to light a cigarette, causes a great increase in heat production when under high amp load.

Typically accessory outlets are a smooth metal tube with no outer perforations. This usually leads to a fiberglass sheet with a brass slug, or formed stainless connection dead center in the rear to serve as the positive connection. Unfortunately, there is no real standard of quality when it comes to 12v ports or accessories. Some 12v sockets fall apart right away, or don't hang onto the plugs well. Others are extremely tight and have well machined and thought out parts.

As a general rule when in doubt I would assume the lighter socket can handle more amps than most of the accessory ones.
This would be if for some reason I cannot inspect the ports and wires leading to them myself. At the very least it is designed to handle heat, so even in the event that it runs hot due to load it will be less likely to melt or start a fire. My stock Geo lighter connector handled 550 watts from MI to CA and back again nearly constant. The socket was hot enough to sizzle if touched with water, but nothing failed. Under the same load my custom (high quality) accessory outlets that I added and power with 8 gauge wire from the battery were barely above ambient temp.


TLDR;
There is no difference between them for low powered items.
Cigarette outlets merely have provisions for handling the actual lighter, as well as resultant heat.

[ruscal]

Originally Posted by VicCT

Hi all,
I want to be able to monitor the voltage so I know when to charge it when it isn't being used.

I realize there is probably a simple answer to this question, but I can't find it.

Vicki,
As others have suggested it is handy to have accessory outlets.
For when your trailer is not being used you should purchase a battery maintenance charger to keep the battery topped up and ready to go. Batteries discharge themselves without use, so instead of checking periodically with a volt meter, you should consider maintaining the battery instead. The built in converter in Scamps is a very basic charger and not optimal for good battery health. Some folks use Products that tend to your battery's needs while in storage. If you don't have power where you store your trailer, you could use a solar setup. The solar can be used while boondocking too, so very useful.
Russ

[VicCT]

Hi all, sorry I haven't checked back in a while! This is all super useful and I will go back and absorb it all, I am just a little overwhelmed at the moment. Had to divert my attention to some other trailer issues for a few days. I did get a battery charger for when my battery is in my basement, which is was until this past weekend. The charger worked fine and also told me how much charge was there when I first attached it. So that's good.

I will have the trailer place install at least one accessory outlet, and pick up an inverter and something (tbd) to measure the voltage while traveling. You all are the best, thanks!

[Steve L.]

Not to pile on, but recharging a lead-acid battery can/will generate flammable gases (hydrogen). It's not really advisable to charge the battery in the house. A garage is better because there's more ventilation. I do sometimes store batteries in the house but take them out to the back patio to charge them. Again, I'm not telling you what to do, only what I do.

A trailer's battery compartment is usually well vented to the outside and sealed off from the inside of the trailer.