Calculating Amperage

[Troutbum]

Hello. I just purchased a Jayco 17-RK Hummingbird, downsizing from a larger Jayco trailer. I will be doing a 3-4 week dry camping trip this summer using a single 100 amp deep cycle battery with several stays. I will also have a 3000 watt generator. I want to estimate the actual draw in amps from the fridge, and other things that consume battery to estimate how long I can go to be within the 80% recommended charge. How does one do this?

[sciencenerd]

The best way is to measure it. Do you have a volt/amp meter? If not, they can be had for less than $10, for example at harborfreight. Disconnect one pole of the battery, and hook up the amp meter inbetween the two open ends. Now turn on/off appliances that you use to check for usage.

We have a x213. I measured about 0.5 amp draw of the trailer without anything on. With fridge on gas, it goes to about 1.5 amps. With an additional 2-3 LED light on, it consumes 2.5 amps. With the occasional USB charging of phones etc, it is probably a max of about 3.5-4 amps. That's our relatively moderate usage. The single 75 Ah group 24 battery that came with the trailer doesn't cut it. I am getting two 6v GC2s this spring.

[Troutbum]

Thanks. I just bought the volt/amp meter. Your estimates are helpful!

[sciencenerd]

Originally Posted by Troutbum

Thanks. I just bought the volt/amp meter. Your estimates are helpful!

Good luck and please post your results when you are done measuring. Other people may be interested too.

[RogerR]

You might consider a single solar panel or a suitcase solar setup to avoid using the generator. Based on my experience a 27 battery might make it, but if you can't recharge completely with solar or genset every day you will kill the battery. 2 - 6 volt golf cart batteries would be better.

Simple test, charge battery and use it in your driveway for 24 hours.

ps tv set, recharging a laptop, Cpap, etc. you will need more battery than you would expect.

[Jagiven]

I see you bought a multimeter with a amp meter clamp. Good choice. It is a very useful tool.

It can be very hard to determine how long a battery will last. A lot depends on your style of camping.

If we just camp and do not care about power usage, two nights is all I can get out of our battery, prior to changing out our incandescent lights to led.

If I do not need heat I can go 5 days on our oem group 27 battery. But it takes some effort. I turn off all my ceiling lights at the light,and turn on the wall switch. When I need light, I turn on the 1 light I need. 12v aux phone charges are only plugged in when needed. They consume power even when not charging a device. I move the slide out and awning where stile connected to the tv (running tv).