Battery life - how many days?

[matt scott]

I am in the process of putting in a battery in my '78 Boler to run a fantastic fan for an upcoming camping trip to the Great Smoky Mountains (there are no hook-ups in the park) & running the car to charge the battery is prohibited by the park.

My question - if I run my fantastic fan [at] night how long will my battery last?

We are not sure how many days we will be there.

Thanks for any replies. Matt

[Terry G]

matt, It's going to depend on two factors--what model of Fantastic Fan you have and the amp-hour rating of your battery. The information I found on line said that the variable speed fan model is .2 to 1.9 amps. The easiest way to calculate your expected number of hours would be to divide your battery's amp-hour rating in half (since you usually can't take a battery below 50% with hurting it) and then divide by whatever amperage you think you'll be using. Plug-in battery voltage meters are cheap and will give you a rough estimate of how much power you have left.

[Matt in SV]

matt, It's going to depend on two factors--what model of Fantastic Fan you have and the amp-hour rating of your battery. The information I found on line said that the variable speed fan model is .2 to 1.9 amps. The easiest way to calculate your expected number of hours would be to divide your battery's amp-hour rating in half (since you usually can't take a battery below 50% with hurting it) and then divide by whatever amperage you think you'll be using. Plug-in battery voltage meters are cheap and will give you a rough estimate of how much power you have left.

I am surprised! Using those calcs for my Group 27 battery (110AH) it would be around 25 hours on high, but 11-1/2 days on low. Moral: stay off that high setting unless you're docked on AC, or have solar to burn!

This has got me rethinking my two, twin-tube 18w flourescent lights, too.

Regards,

Matt

[Terry G]

It's amazing how much power you can save switching to LED bulbs. I've been switching all my interior lights to Revolution LED bulbs. The old incandescent bulbs drew about 1.2 amps. The 2.5 Watt 200 Lumens Revolution draws close to .2 amps. The 1.8 Watt 150 Lumens Revolution draws .15 amps. That's a huge difference!

[James V]

You also need to figure in how old your battery is. and derate the amp hours. Usable hours is about 1/2 rated. Why not get another battery and charge it before leaving?

You will also not be needing the fan as much at night and staying outdoors will help.

I suggest the extra battery trick and then take the car for a drive with it securly in a battery box charging off the 12v outlet if needed. Leave windows open. It would be best to put in the outside bed of a truck. Those fumes can get BAD really fast!!

[matt scott]

You also need to figure in how old your battery is. and derate the amp hours. Usable hours is about 1/2 rated. Why not get another battery and charge it before leaving?

You will also not be needing the fan as much at night and staying outdoors will help.

I suggest the extra battery trick and then take the car for a drive with it securly in a battery box charging off the 12v outlet if needed. Leave windows open. It would be best to put in the outside bed of a truck. Those fumes can get BAD really fast!!

Thanks - I am getting a new battery put in. Can you buy a 12V charger that just plugs in the 12V outlet?

[James V]

There is one that is a jumper cable type. Instead of connecting directly to the battery you use the 12v outlet. Most of these are only for short term and low amps. I suggest that you make one yourself and use #10 wire. You will be putting out 20 amps for an hour or 2 and the bigger wire is needed. Bring extra fuses just in case you blow one.

also: make sure you charge up the extra battery before leaving.