FLA Battery Maintenance

[osprey877]

How often should I need to add water to my T105 batteries? I gather that the more I discharge the batteries, the more they will need charging and that the charging process uses up electrolyte. Thus more use requires more water.

I have noticed that the battery tops are sometimes wet and that the battery box has maybe a tablespoon of battery acid in the bottom. Is this normal or does it indicate poor maintenance (I don't check the batteries as often as I should and usually by the time I do, the top of the plates are almost dry).

Also, does the rate of consumption change with the age of the batteries or otherwise say anything about the state of the batteries?

Am I fine just adding distilled water, or do I eventually need to add more battery acid?

Thanks. My apologies if this has all been covered somewhere else but I did a couple of searches and couldn't find anything relevant.

[Dulcesuenos]

Originally Posted by osprey877

How often should I need to add water to my T105 batteries? I gather that the more I discharge the batteries, the more they will need charging and that the charging process uses up electrolyte. Thus more use requires more water.

I have noticed that the battery tops are sometimes wet and that the battery box has maybe a tablespoon of battery acid in the bottom. Is this normal or does it indicate poor maintenance (I don't check the batteries as often as I should and usually by the time I do, the top of the plates are almost dry).

Also, does the rate of consumption change with the age of the batteries or otherwise say anything about the state of the batteries?

Am I fine just adding distilled water, or do I eventually need to add more battery acid?

Thanks. My apologies if this has all been covered somewhere else but I did a couple of searches and couldn't find anything relevant.

I can't say what's normal, our 6 t105's seem to use about 1 or 2 cups of water total a month.
Ours live in a PSOC, and don't spend as much time in absorption as they should.
We use the caps that connect them all for easy filling and they do not leak at all. Most do not leak a lot of fluid so you may so etching going on or overcharging etc..

[john61ct]

Yes you have been murdering those batts.

Clean them up, if the case is leaking replace them.

How much water they need depends on how your charge sources are set.

Keep them properly watered by **looking** at them very regularly. Start out weekly until you see you can back off but **never** to the point you will take a chance on exposing the plates.

There are filling systems to make it easier, and recycling caps to reduce water losses. But keeping a good eye on them is essential to longevity.

[tanglewood]

Add only water, never acid. Most of the water gets release during absorb, with more released the higher the voltage. So check your absorb voltage to be sure it’s correct. And as batteries age, they will use more water.

When charging, check the specific gravity. That will tell you definitively when the battery has reached full charge, and you can tweak the charge voltages if necessary to minimize over charging.

[john61ct]

Best indicator of 100% Full is trailing amps dropping to mfg spec, or just use .005C, 1/2A per 100AH.

Or as they age, less than .1A drop in an hour works.

No messy hydrometer, works with sealed as well.

And SG needs resting period for real accuracy just like voltage.

[rgleason]

If you sail hard at angle greater than 15 degrees in rough weather, you may see some leaking.

Certain high humidity situations may cause condensation, but generally the batteries are just a little warmer than the surroundings (for us, in the spring & fall, perhaps in the morning after a cool evening, with high humidity we get some condensation)

The other problem related to T-109 we have found, as pointed out by MaineSail (see his article on battery installation) is the orientation of the batteries. There is a correct way and a wrong way. If the long side of the "cell" (not the battery) runs athwartship, your batteries are oriented improperly.


For us, that means we need to make a new battery container, they have been incorrectly oriented for 37+ years! Instead we are going to rewire and relocate the batteries.

[tanglewood]

Originally Posted by john61ct

Best indicator of 100% Full is trailing amps dropping to mfg spec, or just use .005C, 1/2A per 100AH.

Or as they age, less than .1A drop in an hour works.

No messy hydrometer, works with sealed as well.

And SG needs resting period for real accuracy just like voltage.

I disagree on all points.

[daletournier]

Why? Can you elaborate, seems right to me.

[GrowleyMonster]

Originally Posted by john61ct

Yes you have been murdering those batts.

Clean them up, if the case is leaking replace them.

How much water they need depends on how your charge sources are set.

Keep them properly watered by **looking** at them very regularly. Start out weekly until you see you can back off but **never** to the point you will take a chance on exposing the plates.

There are filling systems to make it easier, and recycling caps to reduce water losses. But keeping a good eye on them is essential to longevity.

What he said! CHECK them. Make sure the plates are covered before charging. Top off to just below the bottom of the fill tubes AFTER fully charged. They will make some water during charging and can overflow or burp when the bottom of the fill tube is covered and they can't vent properly. That is probably how u got electrolyte all over the place.

Your charger may be charging wrong. Make sure it is following the manufacturers suggested algorithm. Pay particular attention to float voltage. It is a "smart" charger, right? Check case temp. Should never be hot to touch. Oh, and pull those Batts up and clean out the battery box and the battery cases, especially the tops. Wipe with damp rag, then rag dampened with baking soda solution, being very careful around the caps, then just rag and water again. Clean your terminals and lugs. Apply a film of petroleum jelly or terminal grease to prevent green stuff from happening when you reinstall. Be sure all connections are tight.

It is normal for them to gas a bit but they should not bubble as if boiling. You should hear an occasional "bloop" sound if you listen close, during the absorption phase.

Wear goggles, or better yet a full face shield while servicing batteries. Stuff happens. Keep some water at hand or a charged garden hose in the cockpit or the shower ready for use, for emergency rinse offs.

Get yourself a good book on sailboat electrical systems. Trojans are pretty good batteries but you can destroy them if you don't know what you are doing.

[tanglewood]

Originally Posted by daletournier

Why? Can you elaborate, seems right to me.

A battery is fully charged when the electro-chemical reaction is complete. SG measures that and is the definitive answer to SOC. It is also unaffected by charge or discharge current, though it does need to be temperature compensated. So you can measure regardless of what's going on with the batteries and get a dependable answer.


Judging SOC based on voltage and return current is easier and less messy. No argument there. And with AGMs or gels it's the only tool available.


But return current will indicate fully charged on a battery that is way less than full charged due to sulfation. So you could be thinking you are returning your battery to full charge when you really aren't, and are instead slowly sealing it's death. Measuring SG will tell you if all the sulfur dioxide has recombined, and that's what you ultimately need to know.


SG readings don't have to be done all the time, but it's good to check periodically when you think your battery is full, and see if it really is, or if you need to do some equalizing.

[sailorboy1]

My 6 T105s use maybe a cup of water a month. Its so little that I'm trying to teach myself to check them less often.

[john61ct]

Originally Posted by tanglewood

But return current will indicate fully charged on a battery that is way less than full charged due to sulfation.

Those are aging problems, for those pushing usage past 75-80% SoH

Already covered by the above

> less than .1A drop in an hour

I'm not saying SG is wrong or useless as an additional data point. But it only applies to FLA, cannot be automated, and does require a resting period for accuracy.

Every quality battery manufacturer I've used, specifies the definition of Full for end of charge purposes, including equalization

via a trailing amps spec.

[tanglewood]

The trailing amps spec is how to program a charger since a charger can’t read SG. It’s just the best you can do from a charger. But if you want to check to see if your voltages and times are working, SG is the definitive answer.

Also sulfation can occur in new as well as old batteries. It may be more likely in older batteries, but easy to create in new batteries too if you aren’t recharging correctly.

I don‘t know what your SOH metric is, or how one calculates it.

SG reading absolutely does not require a rest period like voltage readings do. Actually, just the opposite, though rare. As batteries rest, the electrolyte can stratify yielding slightly different SG readings at different depths in a battery. This is more of an issue for very tall batteries like my Surrette 4KS25 (I think that’s the model). Much less so for an L16 or T105. When a battery is being charged it tends to mix the electrolyte so a non issue.

[john61ct]

Thanks, will try to find my source notes on the rest.

Originally Posted by tanglewood

I don‘t know what your SOH metric is, or how one calculates it.

Just residual capacity, industry standard EoL spec is 80%, when a 20-hr load test shows a bank spec'd at 500AH is now actually 400AH.

At the consumer level, except for mission-critical cases, long offshore / RTW sailing, pushing EoL to 70% should be fine.

[daveNZ]

From the top of the plates to a little under the fill spout, on my 12V battery (USBattery) is, at a guess, 10 to 15 mm. That seems like a ‘lot’ of water to add. Is the SG valid only when the electrolyte is at the correct level? (Assume it is mixed and I am not measuring recently added water sitting at the surface). I assume adding water, diluting the electrolyte will be affect the SG??