Battery question- water disappear

[birdgod]

Ok, I have 3 deep cycle for my boat, one or engine, two for trolling motor 24v. Recently I notice that my trolling motor is not giving enough power to troll. I check the battery and a have a good reading..... Today, I decided to "fix" it but checking to water level. Open the first one for the trolling motor it look fine. Water level is good. Then I open the second one, and damn there are no water in it at all. But the multimeter still giving a good reading of around 13 v , I check it with other multimeter and it also give a good reading..... I added about half gallon of distiller water unit and put it on a charger. Hope that will fix the problem. I can't help but wonder where the hell are all the water. What can cause battery to loose water like this?

Also, how often does the water need to be check?

And last question, how do check if the battery is at it full capacity? Since multi meter only tells the voltage.....

 

[Another retired guy]

Re: Battery question- water disappear

Batteries lose water when they are being charged. Excessive water loss is usually due to overcharging. If you are using/recharging your batteries frequently, then the water level should also be checked frequently.
Make sure that battery is not leaking - the "water" is not just water - it is diluted sulphuric acid, and you don't want that in the boat
Most auto shops will test the battery at little, or no, cost.

 

[bruceb58]

Re: Battery question- water disappear

And last question, how do check if the battery is at it full capacity? Since multi meter only tells the voltage.....

Get one of these.

100 Amp 6 Volt/12 Volt Battery Load Tester

 

[UncleWillie]

Re: Battery question- water disappear

I will assume that the two batteries are exactly the same Make, Model and Age.
If charged as one 24 volt battery, If one is Smaller/Older than the other, it will tend to lose more water as the Larger/Newer Battery continues to take the charge.

If the Dry looking battery was an AGM, there was not supposed to be any free water above the plates.
There is plenty of room in the case where water could possible be added to allow for the initial fill to soak into the glass mat but it will only look Moist after it all soaks in.

You can take the caps off of an AGM battery and look inside, however it is not recommended.
You will see the plates and the moist mat but no water above the plates.

You can also add distilled water to an AGM battery to make it last longer.
Be sure to add no more than will soak into the glass mat.
That means adding a teaspoon of water and then waiting a minute before adding any more.

The voltage of the battery is an indication of how much it is charged. (Capacity)
If it is above 12.6 volts, it is at full capacity. 12.2 is about half capacity. And 11.8 is considered dead.

This is not a measure of the actual capacity, just the relative capacity.
If it is at 12.7v, it is at full capacity. Whatever that capacity is, depends on the size and age of the battery.

 

[birdgod]

Re: Battery question- water disappear

The are same age and size as it we bought to use with the 24v trolling motor. I will try to use it after water check, will see how it does.