Battery Test?

[Maine Sail]

Originally Posted by MarkSF

However, the point is that with the bank configured as 24V, there are 450 amp hours to be had, not 900.

It was not made clear in the beginning of the thread that it was a 24V system. Still, if we are to believe that the capacity test was done correctly he has about 82% of original capacity for a 24V bank.. I question whether it was done correctly however and this is why he ideally needs to conduct another one..

[undercutter]

I personally find this whole amp hours of capacity confusing. I think kwh are much easier to interpret. Most battery manufacturers list their batteries capacities in kwh as well. The voltage of the system then becomes irrelevant.

After being away from the boat and this forum for a few months I was shocked to see the treatment Jim Cate received for a post expressing his opinion on terminology. I hope the trolls don,t jump into this thread and ruin it as well as I am always interested in learning and I find this forum to be a good place to accomplish this.

Ken,

The first thing I would do is equalize the batteries. This can be accomplished with an external charger after turning your main charger off. They make some good chargers that have a variable voltage control so that you can set the voltage to the requirements of the battery as listed by Trojan. Just make sure that you have no loads on your batteries when you do this and that the water levels are up over the plates. Not too high though as the water may boil over while equalizing. Batteries should be fully charged before starting the equalizing process which can be accomplished with an external charger as well. minimal draw on the external charger when set at bulk charge voltage for your batteries would indicate full charge. Remember no load on your batteries while doing all this.

Just my opinion but Stu may chip in here with some good advice.

[StuM]

Originally Posted by undercutter

Just my opinion but Stu may chip in here with some good advice.

My advise is to follow Maine Sail's advice
(As always!)

[hellosailor]

"equalize the batteries. This can be accomplished with an external charger after turning your main charger off. " One big caveat: The extra-high equalizing voltage can DESTROY YOUR ELECTRONICS and do other damage to systems. So, you might also want to make sure that the batteries are physically disconnected from everything except the charger that is doing the equalizing. If there's the usual Big Red Switch that can disconnect everything, and you plan to rely on that, put duct tape over it. Just in case someone thinks they are doing you a favor and turning it on. Similarly beware of anything hardwired to the batteries, like a bilge pump and alarm. Surely there's a 24v equivalent to our "12 volt bible" and "12 volt doctor" and the other great small books on these topics?

[undercutter]

Originally Posted by StuM

My advise is to follow Maine Sail's advice
(As always!)

Sure, I just don't understand the point of doing this capacity test before equalizing as it seems that if you do the capacity test before equalizing then you would have to do the test again to see if there was any improvement.

Equalize first, then do the test and if the capacity is less than 80% replace the batteries and ensure that the charger is set up properly so that the new batteries are not destroyed as well.

[undercutter]

Here is a link for testing and maintaining your batteries including equalization.

Battery Maintenance | Trojan Battery Company

Hope that helps.

[sailinglegend]

Originally Posted by undercutter

Here is a link for testing and maintaining your batteries including equalization.

Battery Maintenance | Trojan Battery Company

What they say about Equalization - and many other things - is very badly written and misleading! My comments in (red brackets).

TROJAN ON EQUALIZATION:

Equalizing is an overcharge performed on flooded lead batteries after they have been fully charged.

(Should be OPEN flooded not sealed flooded.)

It reverses the buildup of negative chemical effects like stratification, a condition where acid concentration is greater at the bottom of the battery than at the top. Equalizing also helps to remove sulfate crystals that might have built up on the plates. If left unchecked, this condition, called sulfation, will reduce the overall capacity of the battery.

(Charging at the right absorption voltages stops stratification.)

(Discharging is a chemical reaction that always causes Lead Sulfate crystals. Leaving in a PSOC for too long hardens the crystals and equalization won't help).

Many experts recommend that batteries be equalized periodically, ranging anywhere from once a month to once or twice per year. However, Trojan only recommends equalizing when low or wide ranging specific gravity (>0.030) are detected after fully charging a battery.

(Experts usually recommend equalising when batteries can't or haven't been FULLY charged before the Lead Crystals harden - usually after 2-3 weeks.)

Step-By-Step Equalizing

Verify the battery(s) are flooded type.
Remove all loads from the batteries.
Connect battery charger.
Set charger for the equalizing voltage (See Table 2 in the Charging section). If your charger doesn’t have an equalization mode, you can unplug the charger and re-plug it back in. This also will conduct the equalization charge.

(WHAT?.)

Start charging batteries.

(Batteries should be FULLY charged before equalization is started.)

Batteries will begin gassing and bubbling vigorously.
Take specific gravity readings every hour.
Equalization is complete when specific gravity values no longer rise during the gassing stage.

(Not the safest way - a timed period is better if given by your battery manufacturer)