“Riddle me this Batman”

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Originally Posted by SeanC

After a week?

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Possibly. Surface charge will dissipate naturally over time, how fast it dissipates probably depends upon the internal state of the battery. People talk about 'internal resistance'. A good battery will have low 'internal resistance' so probably allows that surface charge to dissipate fairly quickly ~12-24h. A bad battery will have a high 'internal resistance' That high internal resistance may not allow the surface charge to dissipate as quickly. But just my guess.

Batteries are funny things. The chemistry is relatively simple but real world conditions related to the physics of the chemistry like 'transport', 'kinetics' and 'equilibria' together with the physical properties of the electrodes themselves makes them much more complicated things.

Put a load on the battery and the surface charge should dissipate.
My Projecta behaves similarly to the C Tek, I think.

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Originally Posted by DiscoMick

Put a load on the battery and the surface charge should dissipate.
My Projecta behaves similarly to the C Tek, I think.

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We had battery trouble with one of the vans recently,the battery showed 12.5V on a multimeter,but wouldn't turn over the engine.

With the meter on the battery,hit the starter and it dropped to 6.5V.

Surface charge.

This battery actually failed in the middle of the day.
The tech had turned off the engine only 20minutes before,and it wouldn't start.
It had been fine before turning it off.

Sounds right. We had a similar experience with a camper trailer battery at Christmas and had to replace it while on Straddie. Read OK, but with the fridge on it dropped to 9.9. I have it on the Projecta right now, hoping to revive it, but probably won't work.

The battery in my 9 year old iPod is similar. Works fine plugged into a running vehicle, but loses charge when left.

Interesting, I was using a CTEK too. Tim recommends ditching it in place of a small $30 solar panel from ebay.

It's especially the case if you accidentally forget to turn your fridge off or have something extra daining from the battery, which is easily done.

The thing about solar is it excites the cells when the sun is shining and then let's them rest at night.

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Originally Posted by Russrobe

Interesting, I was using a CTEK too. Tim recommends ditching it in place of a small $30 solar panel from ebay.

It's especially the case if you accidentally forget to turn your fridge off or have something extra daining from the battery, which is easily done.

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The reason I leave it on the charger is that randomly and infrequently I get something that is draining the battery. I’m talking a near new battery going from fully charged to the central locking won’t operate in 3 days. Only happened a couple of times. No joy from the auto-electrician. So I keep it on charge when it isn’t being used. Hasn’t happened while camping touch wood.