
Originally Posted by
Dr_Snooz
So guys, this is a battle I fought and lost enough times to realize I can't win it. Keep in mind, I have 2 cars, 4 trucks, a lawn tractor (recently sold), a truck camper and a generator here at my property. All have 12v lead acid batteries and I've replaced way too many of them after they discharged a lot faster than I expected. I'm only one guy, so most of this stuff just sits and waits for me. My first 10 years here, I fought that battle to get 20 days out of my batteries. I'd spend 2 months of Saturdays not doing other more important stuff, chasing down phantom battery drains. My reward was constant dead batteries. Eventually I realized that I was wasting a lot of time and spending a fortune replacing batteries for amp draws that were all within the normal range. I decided that a solar battery tender for $15 was a lot cheaper than a new battery, so I keep tenders on everything and expect 5 days. I've also added a battery charger ($55), a desulfater I got on eBay ($25), a couple sets of jumper cables ($8-50) and a jump pack ($75) to my arsenal. Those have cured my unending battery travails. The desulfater alone has paid for itself 8x over by saving batteries I would have otherwise had to throw away. The jump pack keeps me going until I can desulfate. The jumper cables are backup insurance. It works much better than the old way.
Remember that if you discharge a battery down to 0V one time, it's done. It might have been a 10 day battery that you had, but you held out for 20, discharged it and now it's a 5-day battery. Leave a car out in our summer heat and you'll do well to get 5 days out of the battery. Thus, I only expect 5-days. Twenty-day batteries, 10-day batteries, 5-day batteries, they all need charging after 5 days. Too often, I've had 20 days turn into 3 months before I realized it and turned my 20 day batteries into bricks. I used to replace them, but at $100-150 each time, it's not practical. Now I just desulfate and keep running. After all, I only need or expect 5-days. Even if I buy a new 20-day battery, I want to charge it at 5 to keep it a 20-day battery. So all my cars have 5-day batteries now and all have solar tenders. The tender keeps the 5-day batteries charged and 20-day batteries from turning into 5-day batteries.
The OP can do what he wants, and he should at least check his resting amp draw to be sure it's in the normal range (it probably is), but I don't think anything beyond 5 days is a reasonable, or cost effective expectation.
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