# What is "activate" mode on a 12v deep cycle charger?



## Tubularfab (Sep 25, 2008)

I have collected defunct battery chargers from people over the years and fix them for my own use. About 90% of the time the home type automotive battery chargers that quit working are due to the current limiting internal circuit breaker going bad. Simply find out what the amp rating is on the old one and replace it with a new one...

Anyway, one of these chargers I acquired that way (hence no operator manual) is built specifically for deep cycle charging. It has a pair of slider switches that both have an "activate" setting. In that setting the charger REALLY hums and makes some heat. What is this mode supposed to accomplish? Is it just dumping a bunch of amps in at once? You can only run it for aomething like 10 minutes according to the front of the charger...


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## Hugh5 (Jan 11, 2017)

how do I see the replies to this question 
I have the same question
Hugh5


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## Sunking (Aug 10, 2009)

Hugh5 said:


> how do I see the replies to this question
> I have the same question
> Hugh5


Simple, there are no replies. The term Activate is just a catchy name and pretty much meaningless, just a gimmick to express some Voltage set point.

Today's battery charger for Pb Deep Cycle batteries use what is called a 3-Stage. The 3 modes or stages are Bulk (constant current), Absorb, (constant voltage), and Float (constant voltage) Some even have a 4th mode called Equalize which is basically the same as Activate. 

All four are just voltage set points. Example for a 12 volt battery;

Bulk = Absorb = 14.4 volts, Float = 13.8 volts, and EQ = 16 volts.

Only place you hear the term Activate is in a good high end Deep Cycle Battery is when the batteries are shipped dry, and the acid is shipped in a different container. So in order to ACTIVATE a dry charged battery is to put the acid in, and then charge at 16 volts until charge current stops to Activate the battery. They do that mostly with Dealers. The battery manufacture sends them dry charged batteries, so they can be Activated quite some time later. It extends the shelf life. Once you add acid the clock starts running to end of life. So the manufacture waits until the battery is sold.

Edit Note:

The higher quality Pb batteries will have two dates stamped on them usually on the battery term post. The manufacture stamps the date the battery was made, and the dealer stamps the Activated date for warranty purposes. Ideally you want those two dates to be as close as possible. A Dry Charged battery has about 1-year shelf life.


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## Hugh5 (Jan 11, 2017)

thanks Derek
excellent explanation 
dare i ask another question.?
Do you think putting an old deep cycle battery with only 30% of its capacity left on activate @16 v help to desulfate it assuming that it has sulphated and not just shaded its plates . it is a D8 255Ah dual duty deep/starting battery on a boat.

Hugh ontario


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## piotrsko (Dec 9, 2007)

If it has actual plates instead of that sintered pressed powder stuff, yes it might.

For desulphating you need a sort of physical removal of the sulphate to expose new lead surface. ARRL experimented 30 years ago and decided that a 2-3khz signal added to the charge would vibrate stuff loose enough to fall to the bottom of the case.

Fla bubbles at about 2.4 volts a cell and these bubbles will tend to loosen stuff also.


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## Hugh5 (Jan 11, 2017)

thanks 
I'll try the activate for 20 mins. At 16 volts the battery draws about 3 amps and the charger goes on and off every minute or so. Why I do not know. I will do this activate after the battery is fully charged.
But as the boat belongs to the sailing club we shall buy new battery next year. I am just trying to get enough charge into it to raise the SG to stop it freezing.
the battery weighs 150lbs + and we cannot get it out easily in the winter.
Hugh


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## Sunking (Aug 10, 2009)

Hugh5 said:


> Do you think putting an old deep cycle battery with only 30% of its capacity left on activate @16 v help to desulfate it assuming that it has sulphated and not just shaded its plates . it is a D8 255Ah dual duty deep/starting battery on a boat.


Hugh I am not a fan of desulfators. There is no credible evidence they work any better than a EQ charge. Having said that there is no harm in trying. A dead horse does not mind if you kick the chit out of it. Pb batteries are considered end of life at 80% rated capacity. After 100 years of documented experience history it is very fast ride to dead. Like having your 80th birthday. each day after that is a blessing.


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