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Old 14-12-2008, 04:30   #1
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Reduced apparent battery capacity after refill

Hi,

I have a bit of a problem and am looking for some input.

I recently topped up my 4 130Ah house lead-acid batteries with distilled water. Since I did this, the apparent capacity has taken a nose dive.

Before I added the water, the levels in each cell was above the plates. I filled all 24 cells taking just over a gallon of distilled water to do so. The batteries were close to be fully charged at the time but not full (as I have since been advised they should have been)

I did not measure specific gravity before the refill. I have since bought a hydrometer. Yesterday I used it to flush each cell. ie I sucked in some fluid and squirted it out to try and force some circulation with the denser electrolyte below. About 10 times per cell. Random measures of the specific gravity were in 114-115 range after the 'flush'.

Last night I ran my genset until the batteries were on float as viewed on my Linksys 1000 battery monitor. Measurements of the specific gravity at this point came in at around 117.5. Better but not consistent with a full charge.

Overnight I used 77.2 Ah and the voltage on the linksys measured 11.95V this morning. This is aweful compared to prefill behaviour.

I had filled the batteries up to the bottom of the inspection tube which is correct according to two separate folks here. I have also been told that overfilling can't actually harm the batteries.

The best explanation so far is that I need to take the batteries through several charge cycles to allow the fizzing and bubbling to thoroughly mix the liquid in the cells.

This may in fact be good advice but I want to know if there were other oppinions out there. In particular, advice on how I can reduce the time to restoring the capacity of the batteries.

Thanks in advance.
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Old 14-12-2008, 06:10   #2
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If you have a way to equalize the batteries, the gassing during equalization also helps to mix the electrolyte. Your problem sounds pretty unusual to me though, as I've added nearly a gallon to my 4 batteries this summer without seeing a problem.
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Old 14-12-2008, 07:02   #3
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How old are the batteries?
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Old 14-12-2008, 07:10   #4
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The batteries are about a year and a half old unless the manufacturer put older batteries on the boat. The concern is the delta between before the refill and after as the performance drop feels like I've gone down to one or two batteries out of four.

Equalization sounds like a good idea. Probably better to do this on a dock as running a 20kW genset for 8 hours to accomplish this is not the most efficient thing to do. During the day I get a good bit of fizzing from my solar charger so this is all helping.

Another input comes after my investigation of the battery interconnections. If you imagine the four batteries in series and label them A to D.

The + connection to the house comes off battery A
The - connection to the house comes off battery C
The + connection to the inverter/charger came off battery B.

Not good and probably contributing to (but not cause) of my current situation.

I have since address the latter by moving the charger + cable to battery A.
Moving the - cable to battery D is less straight forward due to available cable lengths and distances involved. I have a plan though which I will execute once I'm past peak solar charging. This will involve exchanging the positions of C & D in the series and running the connection to the house breaker a different way.
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Old 14-12-2008, 07:16   #5
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Quote:
Originally Posted by ess105 View Post
Before I added the water, the levels in each cell was above the plates. I filled all 24 cells taking just over a gallon of distilled water to do so. The batteries were close to be fully charged at the time but not full (as I have since been advised they should have been)

I did not measure specific gravity before the refill. I have since bought a hydrometer. Yesterday I used it to flush each cell. ie I sucked in some fluid and squirted it out to try and force some circulation with the denser electrolyte below. About 10 times per cell. Random measures of the specific gravity were in 114-115 range after the 'flush'.
Not sure putting so much distilled water in is a good idea. I was always told an eight to quarter inch over the plates was enough otherwise you are diluting the acid in the electrolyte. The excess water will eventually boil off though.

Removing some of the electrolyte is definately not a good idea. You are removing some of the acid as well.

Regards
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Old 14-12-2008, 07:22   #6
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I'd say it's time to go back to basics.

The Genset charges them until they float, but what's the voltage they are floating at?
You moved some cables. How did the connections look? Is it time to clean up all connections?
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Old 14-12-2008, 07:25   #7
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Battery connections look good. I forgot to write down the V when they were floating but when I let them settle after stopping the charge they read 12.85V. I will go to float again this afternoon (once solar stops helping) and make a note of the V.
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Old 14-12-2008, 07:31   #8
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Quote:
Originally Posted by ess105 View Post
Another input comes after my investigation of the battery interconnections. If you imagine the four batteries in series and label them A to D.

The + connection to the house comes off battery A
The - connection to the house comes off battery C
The + connection to the inverter/charger came off battery B.
You don't say what voltage the batteries are. Not sure you mean they are wired in series as you would have different voltages on each connection.

Assume you mean they are wired in parallel with suitable cable to take the current, i.e. all the positives connected together & similarly all the negatives. If then the batteries are adjacent to each other it shouldn't make any difference which of the positives & which of the negatives your installations hook up to. The volt drop between them will be unmeasurable. Given a choice I guess a middle battery would be best though.
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Old 14-12-2008, 07:42   #9
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You need to forget about the water being an issue since there is no way filling the batteries would have any affect. Start looking for the other issues. If you get focused on a specific problem you will overlook the obvious.
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Old 14-12-2008, 07:46   #10
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12.85V is not settled. You still had surface charge on there.
Anyway...I'm thinking from your response that you've NEVER done an EQ charge and you have a lot of sulfation. That would be my first choice...15.5V for 8 hours AFTER you have run the batteries down to below 12.2V and done a normal recharging to 100%.
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Old 14-12-2008, 09:44   #11
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No difficulty running them down to under 12.2V They're doing that fairly quickly. To Chuck's point - good one. I'm going to start looking for other possible causes.
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Old 14-12-2008, 10:37   #12
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Bad container of distilled water? If you have any left of that gallon, put some in a clear glass somewhere warm. Let it evaporate and look for whit e residue on the glass. I've often wondered about the quality of water in jugs."Pure" drinking water has often been found to be less pure than some tap water in various news releases. Might the same be true of "distilled"? Also, is it posible that you ar more focused on the readings right now since servicing the batteries... were you paying that close attention prior?
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Old 14-12-2008, 10:39   #13
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I am not clear on how these are wired in prarallet from your description. My understandind is that you connect the pos from one batt to another and connect the load to the last in the chain #4. You do the same for the negs but connect you neg to the first batt #1. Nothing should be connected to the middle terminals batts #2 & #3 except temp. sensors. Your neg shunt shoud be connected neg batt #1 and your loads and POS buss to pos terminal on batt #4. Is that how you are wired up?

The connecting cables for paralleling the batts should be #2/0 AWG.
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Old 14-12-2008, 10:44   #14
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As I used a bit more than a gallon, the gallon container is unfortunately used up. I did get it from Budget Marine here in St Martin which should be good. Even then, I would think bad water would screw up the plates over time, not straight away.

Yes - part of the issue is the extra level of attention I am now giving the system. However, I know for certain the voltage drop between apparent full charge in the evening and the readings I get in the morning is different to previously experienced.

I'm glad of Chuck's advice - advice I'm often quick to give others so I'm mentally standing back and putting together the broader picture. I am now considering the possibility that I am not really fully charging in the evenings. Could my Xantrex be fooled into thinking the batteries are charged. Perhaps it can as I have the solar charger in the circuit and I have been charging before sun down. Tonight I will charge with the circuit breakers to the charger off to see if I can put more amps in from the Xantrex and get better hydrometer readings. After all, they indicated the batteries were uncharged. I know if the fluids aren't mixed this will read low but I don't know if this accounts for all I'm seeing.
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Old 14-12-2008, 10:46   #15
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Sorry - I meant to say the batteries are wired in parallel. When I used the word 'series' earlier, 'sequence' would have been more appropriate.

I have literature and good advice that it is desirable to connect the +ve and -ve connections at opposite ends of the sequence of batteries. Even with thick cables, demand on the batteries can vary significantly if this is not done. So I am told.
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