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RedGuy · 08-04-2008, 08:58 AM

When ever I read something on here about batteries it always comes up that you should not discharge you batteries below 50%. So my question is how do you know what percent of discharge a battery is at?

RedGuy · 08-04-2008, 08:58 AM

When ever I read something on here about batteries it always comes up that you should not discharge you batteries below 50%. So my question is how do you know what percent of discharge a battery is at?

Rocky Larson · 08-04-2008, 09:09 AM

Two choices:Checking Battery Charge

RedGuy · 08-04-2008, 09:38 AM

So this route seems like it'd be the most practical way to tell the state of charge while I'm camping.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">A reading of 12.66 volts indicates a fully charged battery; 12.45 volts is 75% charged, 12.24 volts is 50% charged, and 12.06 volts is 25% charged. </div></BLOCKQUOTE>

I didn't realize the voltage would stay so high at those levels of discharge. After my last camping trip my batteries read 12.4 volts so I figured the 5 hours I spent drivng home had charged them, since I was over 12v. So I didn't pull them out and chagre them. This was a few weeks ago, hope I didn't screw them up too bad. I did just pull them and put them on a charger last night as I'm going on another trip soon, they seemed to take a charge just fine, and now read just over 13 volts according to the battery charger (haven't stuck a multi meter on them yet since I charged them).

BryanL · 08-05-2008, 10:34 AM

See batteryuniversity.com for the study he did about depth of discharge versus battery life.

The distribution is rather wide so getting persnickity about 50.0% isn't necessary - it is just a good guide. Note also that float service, which is keeping the battery from going down more than 10% or so, is also not good for the battery.

On a campout, it is easy to check voltage but do so only after the battery hasn't been doing much for a half hour or more. If the voltage starts to get below 12.2v then you need to start thinking about charging. If it gets down to 12.0v, the charging needs to become a priority.

see Basic battery guidelines.