Depending on it's age, it maybe time to buy a new battery for your car and use the old car battery for the gate. The battery would still work especially since the battery would be kept fully charged since the gate use is intermittent.
I'm just saying it's probably near the same price for a car battery as that deep cycle battery for a trolling motor. Just a thought.
Deep cycle batteries hold up much better with trolling motors because they can withstand deep and long discharge periods. Regular car batteries don't hold up as well with long continuous discharge times and recharging. Gate is gonna open how many times per day? How long does it take for the gate to open and close compared to running a trolling motor for 2 hours straight? Points to ponder.
Also, if you have a battery charger, you might give the battery a full charge a few times per year to be sure it's topped off.
We had to get a brand new battery right after purchasing the vehicle in January last year. The battery the dealership had in it was bad-- they had to jumpstart it to bring it to us. It was an expensive battery-- over $100.
This weather is giving me a sinus headache. Been raining but it's 40°. I got the new recliner in and put together, plugged it in to the wall outlet and wouldn't turn on. Stuck an outlet tester in the outlets and it lit up (but I need glasses bc I can't read the small print to say what the colored lights mean). But, when I had the recliner plugged in to bottom outlet and plugged in the tester no lights came on. Unplugged the recliner and put the tester back in to the top and it lit up. Went and got the can opener (that I know works bc I tested it when it was in the kitchen) and plugged it in to both outlets-- no power. So now I have to do more clearing/cleaning to get to the outlet on the other side of the room and run an extension cord. Fun times.
My brother was disheartened bc the recliner only holds 225lbs. My mother was a bit annoyed (even though I told her the weight limit before purchase). She weighs 235. I'm currently the only one in the house light enough to sit in it. So, my bro is not allowed to sit in it.