Can I revive my wet cell, deep cycle batteries?

rreeves0802 · September 2011

I know this question is not entirley appropriate for this forum, but I got here via the Northern Arizona battery FAQ, so please forgive... I'm guessing someone here knows the answer.

The question: can deep cycle, wet cell batteries be "revived" if some of their plate material has been allowed to dry? Will an "equalization" charge have a positive effect in this case (issue is NOT sulphation, but lead exposed to air).

Backstory:

I am cruising, anchored currently off the little island of Moorea in French Polynesia, and am trying to assess the damage I've done to my batteries and, more to the point, if I can repair it. If I can, I sail for Hawaii. If not, I sail to Raietae for new batteries.

Quick Power Overview
-System: 12v
-Banks: two. Start: one battery. House: three batteries
-House Batteries: three deep cycle, wet cell batteries totaling 315 amp hours (SeaVolt brand, which I think is DEKA, sold by West Marine)
-1.5 years old
-Usage: daily (I'm cruising--living on the boat)
-Charge: mostly solar. Five panels equalling 190 watts of charge. Engine when it's cloudy.
-Draw: conservative. I took pains to balance the system. Typical usage is 50 to 70 amps a day, well below the recommended 40% of total battery amphours and within solar recharge range on a sunny day (tropics = sunny).

Recenlty I've noticed a drop in battery performance; that is, after a day of full sun, full solar charge, and an evening of battery usage equaling about 20-30 amps (5amp fridge for a few hours; maybe charge the laptop, etc.), I wake in the morning to find that the "rested" (no draw overnight) voltage of the batteries is around 12.4v or lower, which implies I've used 80ish amps or more (reasoning: 12.4 = about 75% charge; 25% times 315 amphrs = 78 amps).

Another data point: batteries seem, lately, to come to full charge quickly. On a full sun day, by very early afternoon.

Long story short: I check the water level in the batteries and a little lead is exposed in all cells. (Here is where I have the pleasure of admitting I was extremely foolish. I have never checked the water level.)

I fill water, distilled. Full, long charge with engine. Batteries unparalleled and voltage checked: all are 12.65 to 12.67v. All connections checked--are clean.

I perform a load test next day. This is inconclusive. Voltage drops steadily during test, but only to 11.1v. A similar test on healthy start battery drops to 11.2v

Yesterday a full capacity test. My US made, C20 batteries should be able to carry a 1/20th load for 20 hours (in this case, 1/20th is 15.75amps). They lasted only 6.5 hours before dropping to 10.5v. This implies they are running at roughly 1/3rd rated capacity. That is, nearly dead. And this result more closely corresponds to waking in the morning to 12.4v ... I think.

All my reading suggest that lead allowed to "air" is lost forever. True? Will a full equalization charge revive any of the exposed lead? Arranging an equalization charge is tricky in current circumstances, so only want to pursue if it will have a positive benefit.

Thanks VERY much in advance,

RR

Cariboocoot · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

Welcome to the forum.

Sorry to say that the chances are your batteries are ruined. It is possible to refill and cover exposed plates and then recharge. However, much depends on how much and for how long the plates were exposed. The problem being that the portion of the plates exposed can be damaged, resulting in a battery of the same Voltage but reduced capacity (in effect there is less plate area available for use). Once the damage is done there is no way to reverse it. Worst case the plates can short out, effectively remove them completely from the battery's capacity. If they aren't performing like they should, they're probably beyond hope.

Check the specific gravity in each cell. Look for low and inconsistent readings. If you find that you can try an equalization charge to try and bring low cells back to normal. That's about all you can do.

niel · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

get some more batteries as i would not trust sailing 20 miles out with your present ones. even if topping off the batteries and recharging them brings them up some they are still badly compromised and not to be trusted.

i do hope that you are using a controller to prevent overcharging as not using one would boil out all of your electrolyte if left unregulated. always, as a matter of routine, check your battery's water levels at least every month or 2 and use a hydrometer too to check specific gravities on the cells.

Vic · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

Greetings RR,

Sorry to hear of the battery issue you are havin.

Think that you are learning in a very clear way about battery maintenance.

AND, personally, I would not EVER discharge any of my FLA batteries to 11-ish volts per 12 V battery, let alone 10.5 volts. IMHO this is a good way to make certain that you will quite soon be in the market for new batteries.

Sea Volt batts are well made, but, to me, 11 volts is completely dead. Realize that these voltages you state are usually during the test, at substantial current, and that the resting voltage would be somewhat higher ... but ... I would not push things this far.

At best, exposed plates is bad for battery capacity, and battery life, and may lead to complete failure, as noted above.

I do undersantd, that often in sailboats, batteries are often placed low, to act as a ballast(what do I know ?), and this can make it very difficult to check the SG and water level in them, but, especially in the tropics, if is good to check them on a regular schedule. Also, as FLA batteries age, it is often stated that the water consumption increases, often by a considerable amount.

Your batteries may be fairly cool, but are the voltages stated Temperature Compensated values? If not, and the batts are warm, the measured voltages could be even lower than you feel.

You may be lucky, and these batteries may serve well for many months, BUT, I would not discharge them below about 45 or even 46 volts, even for a test.

Just my personal opinions. Good Luck, Vic

Urbandialect · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

beat the batteries...lol, kick them, hit them with a rubber hammer, becareful doe, don't mess up the casing of the battery, do this while they are charging to desulfate them manually, do this for 3 days, after this. remove the acid from the batteries and wash out the slug, then add new acid and distilled water, 30/70 ratio or 1/3 acid 2/3 distilled water, you can get the acid from auto zone for $22, I think it's enough acid to do 8 T105s, this should add more capacity to your battery. You're losing capacity due to the surface area of the lead plates being sulfated. Add a electronic pulse desulfator to the battery for further improvement.

Cariboocoot · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

Urbandialect;

This isn't a case of sulphation, it's a case of accidentally exposing the plates to air. A different monster of the same ilk; it still eats batteries.

Trying to restore damaged batteries, no matter what the cause, is usually hopeless. You may be able to reduce plate sulphation, but you can't eliminate it. Nor can you reverse plate erosion or other internal mechanical damage. Knocking the batteries about might even make the problem worse.

After any such efforts, no matter how successful, you will still have a "suspect" battery that could fail at any moment.

Urbandialect · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

Cariboocoot wrote: »

After any such efforts, no matter how successful, you will still have a "suspect" battery that could fail at any moment.

that's called living life on the edge.. lol, but you are right, if you are able to get the battery to hold a charge, it's on borrowed time, I would suggest discharge of only 10%..

If your plates are jacked then u need to have a moment of silence for the battery, then sprinkle holy water over it, that should make it's cross over to other side peaceful.

BB. · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

With automotive batteries--I had found that if they were "killed" (say over cranking) after a year of service, that it is possible to recharge the batteries and have them seem to work just fine--only to turn up dead one to two weeks later after working well (starting car, running lights, etc.).

If you can "risk" a failure (not critical to your survival/safety), try anything you wish.

There are lots of websites out there with suggestions on how to recover a lead acid battery bank... Just be safe.

-Bill

rreeves0802 · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

Thanks all,

After reading the first two replies (thanks for your quickness gents) and thinking they reflected my own conclusions I weighed anchor and sailed overnight the 75 miles to Isle Huahine and tomorrow the twenty more to Isle Raiatea where there is a battery shop of good repute that has Group 31s in stock.

As a side note, that night I kept on the VHF radio, the small chart plotter, LED running lights and one LED cabin light (roughly 3amps total), and the batteries went from showing full charge to 12.1v by dawn. Ain't much oomph left. And am glad I'm not risking 2400 miles of northing (Hawaii) on this set.

Again, thanks for the thoughtful replies. Glad I bumped into you folks on Google.

Best to the group,

Randall

Aboard S/V Murre
Anchored Isle Huahine, French Polynesia
16.58.3South by 150.39.3West
murreandthepacific.wordpress.com

P.S. It strikes me as amusing that I'm at sea and communicating with a board whose "virtual" location is Northern Arizona.

waynefromnscanada · September 2011

Re: Can I revive my wet cell, deep cycle batteries?

rreeves0802 wrote: »

Thanks all,

After reading the first two replies (thanks for your quickness gents) and thinking they reflected my own conclusions I weighed anchor and sailed overnight the 75 miles to Isle Huahine and tomorrow the twenty more to Isle Raiatea where there is a battery shop of good repute that has Group 31s in stock.

Excellent decision, especially as lives can hang in the balance. Nothing is for sure except death and taxes, but no sense asking for an early signout.

Can I revive my wet cell, deep cycle batteries?

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