Can batteries self-discharge when they’re not in use…even when they’re disconnected?
Yes, all lead-acid batteries self-discharge. It’s a naturally occurring phenomenon in batteries in which chemical reactions within the battery reduce its charge. You see, batteries are electrochemistry.
Most flooded-cell (a.k.a., wet) batteries self-discharge about 3% of their capacity per month at 77o F, while Hawker® AGM batteries lose just a fraction of that at about 1%! Furthermore, the hotter the battery…the faster the self-discharge rate. In fact, anytime the temperature of a battery is increased by 15o F, the self-discharge rate doubles! So, at 92o F, a flooded-cell is losing about 6%, whereas a Hawker® AGM about 2%. Go up another 15o F to 107o F, and a flooded-cell is losing about 12%, and a Hawker® AGM about 4%.
Now, think of those sweltering-hot Conex boxes used overseas during combat to store batteries. If the temperature in there was 122o F, those flooded-cells were losing a whopping 24% capacity per month, whereas Hawker® AGM batteries were losing 8%.
Therefore, if you have batteries in storage, you can drastically improve shelf-life and slow the death spiral by keeping those batteries in a climate-controlled environment. Better yet, keep them connected to a float-charger!
that the term “load” refers to the amount of current being drawn from the battery, measured in amps (e.g., a 25-amp load). While engine start is typically the greatest single load placed a battery…headlights, instrumentation, comms, BFTs, CROWS, etc., all place additional loads on the battery…especially when the engine is off (as the alternator is no longer providing power).
How often are you replacing bumpers, seats, or doors on your tactical vehicles? Like NEVER? Why, cuz they aren’t really consumables. Now, how often are you replacing batteries? Probably, TOO OFTEN! Wanna fix that? Yeah, but how? Contact your Hawker® FSR today for free Battery Maintenance and Recovery Training (BMRT) in your own motor-pool!