Letter Re: Some Real World Battery Life Data

The recent article by ‘Cactus Jim’ got me thinking about a type of battery rarely mentioned, the ‘dry-charged’ lead acid, where the end-user fills the battery with acid after purchase.

Initial impression is that this type, if kept sealed in a temperature and humidity stable environment, could last indefinitely, only being flooded and charged when needed. Battery acid is stable and does not deteriorate if kept sealed.

Our local NAPA auto parts store stocks small (motorcycle/garden tractor) units and will special order most any size 12v battery. Price is the same as for the equivalent wet-charged units except the acid must be purchased

If you have any experience with these batteries perhaps you could relate the info to your readers. – Steven J.S.

JWR Replies: Be advised that most of the “just add acid” batteries sold by automotive parts dealers are identical to standard production batteries, but merely “spun dry”, after the batteries are factory tested. This leaves traces of battery acid that will cause some sulfation of the battery plates. Also, most of these batteries are designed for engine starting –not true deep cycle duty. But conceivably if you can get dry-condition storage batteries from a battery vendor (such as your local Trojan dealer), then you could leave one of these batteries on the shelf for a couple of decades, add acid, and it would still have a 5+ year service life. In a long-term gird-down scenario, that sure beats the alternative!

When storing carboys of battery acid for this purpose, keep in mind that you’ and your helper will need to have the appropriate safety gear, to wit: an apron, heavy rubber gloves, goggles, boots with thick uppers (or better yet, rubber “mud” boots–called “Wellies” in the UK), and a full-coverage heavy long sleeve shirt. OBTW, one trick that my father taught me to keep plastic acid funnels from tipping: Clamp the funnel’s lip “tab” in a pair of Vise Grip pliers, to use as a handle.