Easy & Cheap way to determine battery draw

Inverters efficiency runs in the mid 90s above 10% load so decimal point conversion is accurate enough.

DC Stereos use minimal watts and who listens more than a few hours a day?

And dude; you use a lot of emoticons. :R

Darryl&Rita wrote:

Tom_M wrote:
The OP is talking about boondocking. The Kill-A-Watt would be of little use since most of his power usage would be on the 12 volt side.

TV? Amp? Sounds like 120v A.C. to me.
Cheap and easy? Turn over the device, and read the label.:S
Add up all the devices you want to power, and size the inverter accordingly.

How can I determine battery drain when I turn on a device, like a TV, amp, etc... while boondocking?

Is amp referring to his DC stereo?
He will also need to measure and factor in his DC parasitic load! :S
Otherwise, why bother? :S

Furthermore, measuring current on the AC side doesn't consider the inverter inefficiency. It will require a minimum of 1.25 watts input to every 1 watt out.

Thanks everyone!! Some great suggestions.

Tom_M wrote:
The OP is talking about boondocking. The Kill-A-Watt would be of little use since most of his power usage would be on the 12 volt side.

TV? Amp? Sounds like 120v A.C. to me.
Cheap and easy? Turn over the device, and read the label.:S
Add up all the devices you want to power, and size the inverter accordingly.

The OP is talking about boondocking. The Kill-A-Watt would be of little use since most of his power usage would be on the 12 volt side.

Use the Kila a watt to determine your AC amperage, then you just move the decimal over to get DC amps. One A at 120 volt is 10 A at 12.

Most meters only will measure a few amps in series. Potentiooly dangerous for measuring AC current.

There are lists on the net that give typical amp draw for most appliances.

Cool thing about the Kilawatt is you can leave something plugged in for 24 hours and it records total watts used so it catches the entire profile, not just one moment in time.

hershey wrote:

Tom_M wrote:
One of the most useful meters I have is a DC clamp-on amp meter. Sears sells one for about $55. Here' a link: Sears clamp meter

All you have to do is clamp the jaws around a wire in the circuit you want to measure. Clamping it around a cable that is connected to your battery will tell you the total current you are using.

Take that suggestion to the bank. Its very accurate, considering the accuracy that RVers really need :)
Just clamp it onto a single wire/or cable and it will give you the amperage being drawn at that time.

It's +/-3% +6 counts. Good enough for what you want to do but a shunt with a quality DMM would be more accurate.

Tom_M wrote:
One of the most useful meters I have is a DC clamp-on amp meter. Sears sells one for about $55. Here' a link: Sears clamp meter

All you have to do is clamp the jaws around a wire in the circuit you want to measure. Clamping it around a cable that is connected to your battery will tell you the total current you are using.

Take that suggestion to the bank. Its very accurate, considering the accuracy that RVers really need :)
Just clamp it onto a single wire/or cable and it will give you the amperage being drawn at that time.

You might want to make up a chart of the current drains of things in your RV. You could do this by unplugging fuses one by one and using an ammeter in place of the fuse, turn whatever is on that circuit on, one by one, and read the current. Many multimeters have a 10amp scale that would work fine as long as you don't exceed 10 amps. No one thing in my RV draws more than about 8 amps.

One of the most useful meters I have is a DC clamp-on amp meter. Sears sells one for about $55. Here' a link: Sears clamp meter

All you have to do is clamp the jaws around a wire in the circuit you want to measure. Clamping it around a cable that is connected to your battery will tell you the total current you are using.