Killed Batteries ?

[Dockhead]

I left my boat for two weeks, and one of the bilge pumps got into a feedback loop situation endlessly pumping and repumping a small amount of water which kept flowing back into the bilge from the large diameter pipe the bilge pump pumps into.

The batteries were completely dead. Eight 110 amp-hour Varta leisure batteries arranged as two interconnected 24 volt banks (220 amp hours * 24v each).

The batteries were fairly new -- four of them 18 months old, and four of them less than a year old.

The boat is not in a marina, so I've got no shore power for a continuous long charge to bring the batteries back up. I did manage to get in two overnight charges when I happened to be in a port with shore power. And I have done a couple of equalization charges with my Victron charger.

But although I am able to get the voltage up, and the battery charger switches into float mode, I have not been able to get the specific gravity of the batteries up to fully charged level, and the batteries have very little capacity. And a couple of cells in a couple of batteries show lower specific gravity than the others -- possibly dead cells.

What to do? My Victron charger has a way to force absorption charging for a set period of time -- maybe I need to do that a few times in order to get the specific gravity up?

Will a battery not survive even one such incident? I thought you could bring them back to life after even a few incidents like this -- didn't think you could kill the whole bank in one shot.

Why don't we have switches in our systems which shut off the batteries when they are, say 80% discharged, in order to prevent this kind of damage? Our cell phones shut off automatically before the batteries get down that low. Why not our boats?

[Dockhead]

I wonder if anyone has tried this technique on sulphated batteries:

How to Restore Dead Car Batteries | eHow.com

[Dockhead]

Some more advice:

12. HOW CAN I REVIVE A SULFATED BATTERY?

Lead sulfation occurs when a lead sulfate compound is deposited on the lead electrodes of a storage battery; this is a problem if the lead sulfate compound cannot be converted back into charged material and is created when discharged batteries stand for a long time. When the state-of-charge drops below 80%, the plates become coated with a hard and dense layer of lead sulfate, which fill up the pores. The positive plates will be light brown and the negative plates will be dull off-white. Over time, the battery loses capacity and cannot be recharged.
12.1. Light Sulfation
Apply a constant current from one to two amps for 48 to 120 hours at 14.4 VDC, depending on the electrolyte temperature and capacity of the battery. Cycle (discharge to 50% and recharge) the battery a couple of times and test capacity. You might have to increase the voltage in order to break down the hard lead sulfate crystals. If the battery gets above 110° F (43.3° C) then stop charging and allow the battery to cool down before continuing.
12.2. Heavy Sulfation
Replace the electrolyte with distilled water, let stand for one hour, apply a constant current of four amps at 13.8 VDC until there is no additional rise in specific gravity. Remove the old electrolyte, wash the sediment out, replace with fresh electrolyte, and recharge. If the specific gravity exceeds 1.300, then remove the old electrolyte, wash the sediment out, and start over with distilled water. If the battery electrolyte rises above 110° F (43.3° C), then stop charging and allow the battery to cool down before continuing. Cycle (discharge to 50% and recharge) the battery a couple of times and test capacity. The sulfate crystals are more soluble in distilled water than in electrolyte. As they are dissolved, the sulfate is converted back into sulfuric acid and the specific gravity rises. These techniques will only work with some batteries.

DEEP CYCLE BATTERY FREQUENTLY ASKED QUESTIONS

[Vamonos]

I can't help you with your charging question as I just did something very similar and am interested in other's replies.

However, it sounds like you need a check vavle immediately after the bilge pump. That will keep the water from flowing back into the bilge from the discharge line.

Whale Non-Return Valve

Richard
Vamonos
Pearson 385

[CharlieJ]

Search this Forum for "Equalizing Batteries". Equalization may restore your bank but it won't get back to 100%.
I would not use the procedure you posted. Dumping the electrolyte and refilling with distilled water sounds like an old wive's tale!

Charlie

[daddle]

Sounds like you murdered them. While the auto battery shutoff would save the batteries, the alternative might be a sunk boat.

We are not supposed to have a check valve in the main bilge pump line. The solution is to get the proper type of float switch, or arrange the switch such that it works nicely.

[gonesail]

either install check valve in bilge hose or adjust the float switch so it allows hose contents to flow back without cycling. sounds like batts are toast. good luck.

[Stu Jackson]

Sorry to hear about your mishap.

You could try this: "Breaking In" New Wet Cell Batteries

[Bash]

Originally Posted by daddle

We are not supposed to have a check valve in the main bilge pump line. The solution is to get the proper type of float switch, or arrange the switch such that it works nicely.

I want to second this. Some bilge pump manuals specifically state that they are not to be used with check valves. The better alternative, as daddle points out, is to set up the float switch properly.

[Vamonos]

I stand corrected regarding the check valve. Is the reason for this that there is a potential for blockage?

[Dockhead]

I have solved the question about the float valve (with help gratefully received from CF friends); my question is not about this. I bought a Whale supersub maintenance pump and will mount the big Rule high volume pump higher in the bilge.

My question is about batteries -- murdered by ONE incident? Tell me it's not so!

[Capitain Mike]

Originally Posted by Vamonos

I can't help you with your charging question as I just did something very similar and am interested in other's replies.

However, it sounds like you need a check vavle immediately after the bilge pump. That will keep the water from flowing back into the bilge from the discharge line.

Whale Non-Return Valve

Richard
Vamonos
Pearson 385

Or Jabsco. but Jabsco do not recommend a non return valve fitted into a bilge pump system!!!!! they can get blocked and jam.

But best to set the pump and float higher up so that the run back into the bilge is insufficient to restart the pump.

Or stop the leak into the bilge

[Capitain Mike]

Originally Posted by Dockhead

I have solved the question about the float valve (with help gratefully received from CF friends); my question is not about this. I bought a Whale supersub maintenance pump and will mount the big Rule high volume pump higher in the bilge.

My question is about batteries -- murdered by ONE incident? Tell me it's not so!

It is not so. if you have a battery charger than can be powered from the shore and that can recognise a sulphated battery the charger will take over and put a higher than normal charge into the battery/ batteries for a specific length of time.

Sterling power products. Sterling Power Products: Manufacturers of High Quality Advanced Marine and Automotive Digital Power Products
Battery Chargers
1230CD
1240CD
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I have one and it works fine. but then I also have a solar panel HDRX CONTROLLER and A Rutland 913 wind Gen.

[John A]

I'd always been told anytime the batteries got below 60% of capacity, they'd never return to a full charge and hte more times they were allowed to discharge the lower the capacity would become. Also it's not a good idea to have dissiminilar batteries in the same bank of batteries. True?

Place a anti-siphoning valve in the discharge line, above the waterline when heeied over.

You're lucky your boat didn't fill with water and sink.

[Capitain Mike]

Originally Posted by John A

I'd always been told anytime the batteries got below 60% of capacity, they'd never return to a full charge and hte more times they were allowed to discharge the lower the capacity would become. Also it's not a good idea to have dissiminilar batteries in the same bank of batteries. True?

Place a anti-siphoning valve in the discharge line, above the waterline when heeied over.

You're lucky your boat didn't fill with water and sink.

Also it's not a good idea to have dissiminilar batteries in the same bank of batteries TRUE

I have heard 50%, best to have the same type of batteries in each bank wet in one bank gel or agm in the other