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Old 22-07-2011, 16:20   #16
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Re: Killed Batteries ?

DH, ouch, that's about £1000 worth of batteries if they don't come back up, plus a load of pain dragging them out to a mid river pontoon.

I would use the charger and exercise them vigorously to see what happens. More concerned about the couple with lower cells, they will need monitoring closely.

Having been on board DH's rather nice Moody 54 the one thing we couldn't find is an obvious place for solar. Unbelievable perhaps with 54 feet but there really wasn't. I suspect fitting another small bilge pump as he plans with a valve to operate first before then big pumps kick in is the answer. Then a wind generator.

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Old 23-07-2011, 01:34   #17
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Re: Killed Batteries ?

Here read this by Sterling Power about lead acid batteries its very interesting, !!!! and to long to post here!!!!
Sterling Power Products: What is the best battery to use for an auxiliary charging system?

Sterling Power Products: How effective is advanced battery charging on a battery and can it damage the battery?

and
Lead_Acid_Car_Battery_Repair
LEAD ACID BATTERY REPAIR
The battery that is found in your car, motorcycle, tractor & boat is called a Lead Acid Battery.
Lead Acid batteries are the most economical battery. There construction is simple compared to the construction of say a Lithium Ion battery. The down side of lead acid batteries is there weight and the fact that they become wasted when they are left dead for even a short period oftime.

The maintenance of a lead acid battery is just the opposite of a Cordless Drill battery
because the technology is different. Lead acids do best when left with a full charge where NiCd's found in tool batteries are best left on a low charge.

If you have ever went to start your riding lawn mower or motorcycle in the spring you quicklyfind out that these types of batteries don't hold a charge for several months.

You also find out that even after you jump start your mower or motorcycle that the battery just isn't the same as it once was if it even charges at all. The reason for this is because the lead in the battery is exposed to uncharged raw acid when the battery slowly discharges over time and looses its charge.

The lead in the battery simply rusts, thus blocking the flow of electricity and ability to charge properly. Luckily there is an affordable, readily available compound that will reverse this.
To breathe new life into your lead acid battery you will need to first purchase the chemical Magnesium Sulfate. You probably just asked yourself. "Where in the WORLD do I get THAT!"

Believe it or not, but it is actually a very easily found substance. You won't find it on the shelf of a store if you are looking for magnesium sulfate but you will find it on the shelf of almost every department store and pharmacy if you are looking for EPSOM SALT and its only a few dollars!

To recondition your lead acid battery you will need Epsom Salt and a quart of distilled or rain water. Warm up the water to about 150 degrees (very hot but not boiling). The temperature doesn't need to be exact by any means and will still work even if the water is at room temperature, it just won't work as well. Mix 10 heaping table spoons full of Epsom Salt into the water and stir until most or all is dissolved. Then simply pour this warm solution into your battery where you would normally put water to maintain the acid levels.

Do not attempt to put Epsom Salt directly into your battery because it will not dissolve into the battery acid, only water will dissolve Epsom Salt. Most batteries will be low on fluid so adding this solution will not over flow the battery. It is only recommended to add 1/2 quart of solution to an average size battery.
If your battery is full of fluid already then you will need to drain some of the solution to allow for the 1/2 quart of Epsom Salt Solution. After adding the solution it is recommended to put the caps back on and shake the battery a bit to mix all the chemicals.

Some batteries have caps that come off the top to maintain the acid levels easily but Low Maintenance batteries require a bit more work to recondition. A low maintenance battery has its top sealed shut to prevent evaporation but it also prevents easy reconditioning.
These batteries can still be reconditioned but you will have to look for the "shadow" marks on the top plastic that shows the holes into the cells. Simply drill holes in the plastic to get access to the cells then pour in your warm solution. You will then want to plug these holes with plastic hole caps that can be found at most hardware stores. When purchasing a new battery it is recommended to look for the batteries that you can easily maintain in the future. It is also recommended to purchase a small solar charger to keep your unused batteries charged over the winter to prevent this problem from happening in the future.

This method works most of the time but not all the time. It depends on how bad the cells are decayed. This process can also only be done 3 to 5 times before the cells are worn out, prevent damage with a solar charger!

ALWAYS WEAR SAFETY GOGGLES AND GLOVES WHEN WORKING WITH ACID
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Old 23-07-2011, 02:29   #18
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Re: Killed Batteries ?

Quote:
Originally Posted by Dockhead View Post
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 hasn't been my experience. I killed my batteries, 880 AH lead acid, and brought them back up and they are ticking away six months later. I have a Victron as well. I ran a Honda gen for a while after finding them drained and have a decent solar setup. I gave them lots of time to recover but can't say whether that was part of the solution or not.
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Old 23-07-2011, 07:57   #19
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Re: Killed Batteries ?

Not to disparage, but reconditioning a badly discharged battery that has, in all probability sulphated, is not about magic elixirs and drilling holes in battery caps. It is about knocking the sulphates off the plates and back into solution. This process is called battery equalization and takes as much as 12 hours with a large house bank, is labor intensive, but straightforward. You need a proper charging source that can provide equalizing voltages at a reduce charging current, a hydrometer, distilled water, a pencil and paper.

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Old 23-07-2011, 09:43   #20
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Re: Killed Batteries ?

Quote:
Originally Posted by CharlieJ View Post
Not to disparage, but reconditioning a badly discharged battery that has, in all probability sulphated, is not about magic elixirs and drilling holes in battery caps. It is about knocking the sulphates off the plates and back into solution. This process is called battery equalization and takes as much as 12 hours with a large house bank, is labor intensive, but straightforward. You need a proper charging source that can provide equalizing voltages at a reduce charging current, a hydrometer, distilled water, a pencil and paper.

Charlie
I agree with you entirely
Yes but he said earlier he did not have a proper charging source
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Old 24-07-2011, 11:12   #21
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Re: Killed Batteries ?

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I agree with you entirely
Yes but he said earlier he did not have a proper charging source
He was having problems with the main charger when I visited him last month.

However, is he dealing with heavily sulphated batteries? all that happened is they discharged once rather quickly.

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Old 24-07-2011, 11:24   #22
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Re: Killed Batteries ?

It isn't just about how far your discharge your batteries, its about how long they stayed discharged, allowing the sulfate to build up. If they were flat for a couple of weeks, they are probably toast.

BTW, gel batteries don't suffer from this as much as wet lead acid--I have brought back gels which have been left flat for 6 months to at least 80% of capacity.
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Old 24-07-2011, 11:46   #23
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Re: Killed Batteries ?

kind of surprised the batteries are shot form that incident, although recommendations are to not discharge below...50% is it? I think it is worth a night at the dock to try to charge them really well and see if they come back. Alot of money there. Also, after they have been charging for a few hours, feel each battery, if one is shorted or otherwise bad, you may find it is much hotter than the rest. One battery can bring the whole systom down....
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Old 26-08-2011, 02:39   #24
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Re: Killed Batteries ?

Quote:
Originally Posted by donradcliffe View Post
It isn't just about how far your discharge your batteries, its about how long they stayed discharged, allowing the sulfate to build up. If they were flat for a couple of weeks, they are probably toast.

BTW, gel batteries don't suffer from this as much as wet lead acid--I have brought back gels which have been left flat for 6 months to at least 80% of capacity.
Yes, they were left at 0% for several weeks. Ouch.

I have just spent three weeks on board. The first thing I did was to get the Victron charger/inverter properly installed.

During the whole three weeks, I was careful to charge and charge and charge the batteries. I didn't have shore power most of the time, but when I did, I kept the Victron in forced absorption mode, and did equalization charges from time to time. Off shore power, I ran the generator for an hour or two at least three times a day.

Surprisingly, all this charging did not cause the batteries to lose any water. I would have thought that they would gas at 30 volts and that I would need to be adding quite a bit of water, but I didn't. I have 8x 110 amp-hours x 12 volts making a bank of 24v and 440 amp-hours. The charger puts out 70 amps at 24 volts, and I guess this just isn't enough current to cause a lot of gassing. The alternator puts out 110 amps at 24 volts (and 70 or 80 amps already almost from idle). So a lot of charge got put into the batteries over these three weeks.

Unfortunately, they have not come back very well. I left in a rush after my cruise and didn't have time to measure specific gravity cell by cell (pretty labor intensive with 8 batteries), but I'm pretty sure I will have a number of dead cells. The battery bank performs as if it has maybe 20% or 30% of its original capacity. It will soak up a lot of charging, but then after I have used 40 or 50 amp/hours of power (according to the the Victron battery monitor), they are already deeply discharged. Theoretically, I should be able to get 220 amp/hours of power out of them before they are 50% discharged.

I did measure specific gravity on all the cells at the beginning of my cruise. Although the batteries had been charged overnight and were showing high voltage, specific gravity was low on all cells with a few cells very low -- dead.

They are Varta "Hobby" batteries -- semi-traction -- which are claimed to be good for hundreds of cycles of 60% discharges.

So what do I do next?

1. Throw them away and buy and entire new bank -- 1000 pounds or $1,650 -- ouch.

2. Keep working on them. But now that I have installed the Victron, I can't put an equalization charge on individual batteries, only the whole bank. Maybe the current isn't enough to equalize 8 batteries at the same time?

3. Find the batteries with bad cells, throw away only those, and buy just enough new batteries to replace them. But will the new batteries be dragged down by the year old ones?

What do you guys think?
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Old 26-08-2011, 04:05   #25
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Re: Killed Batteries ?

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2. Keep working on them. But now that I have installed the Victron, I can't put an equalization charge on individual batteries, only the whole bank. Maybe the current isn't enough to equalize 8 batteries at the same time?
If the charger current capacity is the suspected issue, have you considered equalizing two at a time?
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Old 26-08-2011, 04:12   #26
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Re: Killed Batteries ?

Find the duff cells and ditch those batteries, they are doing nothing for you. If that halves the bank then use it for the winter and replace the lot in the Spring.

Or, speak with Barden and see what sort of deal they will offer you with MOA membership etc and when is the cheapest time of year. Whilst they supply a lot of batteries to different markets, is the Varta hobby a boat/caravan/motorhome market? if so it's just about end of season so they may not want to sit on a stock of batteries for the winter.

We have Varta hobbies too btw which use very little water even when we apply a 19% charge (batt cap / max charge amps).

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Old 26-08-2011, 04:16   #27
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Re: Killed Batteries ?

I have just cooked my two trojan batteries due to an incorrect victron setting.

I suspect that before I took over the boat there were two victron units ganged to provide the power required. The shore power unit has an adjuster to constrain the unit taking more than a set number of amps. This is designed to take account of a poor shore power connection only supplying a reduced ampeage and the system overloading. My unit went up to 32 amps, so I had it set to 16 to match the provided shore supply.

I use a microwave/convection oven, and when on shore power, 240v toaster and kettle. I could not understand why the unit kept showing overload on the batteries and I was using a lot of water. I had the shore supply checked and this was good, so I got a victron engineer in, and discovered that first, the victron was trying to share its load with another unit, and that the 32 amp setting was actually really 16 (again because it thought there was a second victron).

The engineer re-set the victron, and I set the unit so that it was actually taking the full 16 amp supply. For the first time since I got the boat, the power board was showing that the battery had achieved full charge and was now in float. Furthermore, use of toaster and kettle simultaneously did not cause the battery to melt down.

It was, however, too late for the Trojans, and I suspect a defective cell.

More money!
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Old 26-08-2011, 06:52   #28
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Re: Killed Batteries ?

I think the severe discharge may have reverse charged a few of the cells and this causes the material to flack off the plates and short them out. As mentioned before, disconnect all the terminals and measure the voltage of each battery, those below 12v are paper weights unfortunately.
Now could be a good time to fit a lithium battery pack and a battery management system so this sort of thing never happens again

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Anyone who is unfamiliar with reverse charging, it’s caused by a cell dropping to zero volts but the other cells still have charge in them so this is forced through the cell effectively reversing the current flow, this wrecks battery cells very quickly.
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Old 26-08-2011, 09:51   #29
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Re: Killed Batteries ?

tough one. if they are only a year old, maybe put the fullest charge you can on the bank, then disconnect all batteries from each other. next morning measure the charge in each battery. replace the bad ones and keep the good ones. ?
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Old 26-08-2011, 10:03   #30
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Re: Killed Batteries ?

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tough one. if they are only a year old, maybe put the fullest charge you can on the bank, then disconnect all batteries from each other. next morning measure the charge in each battery. replace the bad ones and keep the good ones. ?
That's kind of Plan A for the moment.

I'm in the market for a battery tester in order to try to get a better insight into the condition of each battery -- than I can from a voltage test. Another thread on that. Battery Testing Methods
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