Recently I installed a extra lawnmower battery in my backseat to power all my aux lighting. I have couple LED pods, a few rock lights, and a 22 inch LED lightbar. I have a wire connected from the positive and negative terminals and have connected the lights to that. I have hardly used the lights at all, but everytime I go to use them the battery is ran down. For some reason im having constant power being drained from the batter. Any suggestions on what to change/add or why the battery is being run down? Thanks!

 

put an alternator back there with a gerbil running in a wheel to spin it

 

Ah, the cold temps...

 

Put a bicycle generator in your truck bed and have your wife or gf or a buddy get after it. Peleton style

 

Why in the he11 would you put a lawnmower battery in the.... Oh, nevermind.

 

Why? Obviously because I needed my truck battery to power my lawnmower lights. Seems obvious to me? You should see my Segway. It's got the Honda generator. My plans for the rowing machine will blow you away!

 

Some electronics will still pull power even when they're off. Also, from your post you don't even have enough lights to justify an extra battery...

 

came here for some advice not criticism, but thanks anyway guys!

 

Honestly, I thought this was a troll.

OK, here you go:

Get rid of that lawnmower battery, and connect your lights to the truck's existing electrical system via proper switches, relays, and wiring. Consider upgrading to a 130A 3G alternator if yours is only a 90A unit.

 

The problem with permanently connecting two batteries in parallel is the stronger one will discharge (try to charge) the other battery when the engine is off then vice versa depending on the two batteries amp hour ratings.
With the the long wires going to the (gulp!) lawn mower battery there could be a large enough voltage drop across them to screw up charging from the alternator.
The safe charging rates between the larger and smaller batteries are different meaning the smaller battery could be over charged resulting in degradation and finally failure of the battery.
Further, if the smaller battery becomes dead shorted there is no appreciable impedance to restrict its charging current, a potential fire or explosion hazard.
And even further yet, putting a lead acid battery in the cabin is a potential safety hazard due to hydrogen gas emission another potential safety hazard.