Monday, March 22, 2010

Re: [Electric Boats] Do I have a battery issue?

 

Mike,


It is inevitable that a string of batteries in series will unbalance over time.   You need to have a method of balancing the string.    The best way that I have found is to use Pro-Mariner's Quad battery charger.   It uses what they call "distributed, on demand, charging"      What this means is if one battery is lower (battery one) than the others it distributes a greater charge to that battery, allowing all batteries to come to float at about the same time.   This tends to give the weakest battery a conditioning charge and adds to the longevity of all the batteries in the string.     Every time you use this battery charger, you condition your batteries and balance the string.    This charger is really 4 battery chargers in the one case.   Each battery can then be individually charged and monitored.

When your Zivan Charger charges the string when it is out of balance it can put to high a charge on the highest voltage battery and too low a charge on the lowest voltage battery, therefore reducing the life of the batteries.    

Additionally, every battery charger should have a battery temperature sensor.

We have a saying that AGM batteries do not die, they are killed.    Its another way of saying,   AGM batteries last a long, long time, if they are properly charged and never completely discharged.

I have 4 x 8D AGM batteries, and 4 x 4D AGM batteries and two Promariner Quad chargers on Kapowai.    

James

Propulsion Marine 



805 455 8444







On Mar 21, 2010, at 7:00 PM, Mike wrote:

 

Well the snow has finally melted and I am beginning to think about the upcoming boating season. But, I am wondering if I have an issue with one of my batteries. Here is the background and some of the tests I have done:
 
The batteries are 8A4D 12 volt 210 amp AGM's that were first installed in June of 2008. There are four of them in series making up the 48 volt bank. All were purchased at the same time from the same Mfg.
 
Battery Lineup
B1 is the most negative connected battery i.e. it's NEG post goes to the negative wire of the controller.
B2 is the second most negative
B3 is the third
B4 is the most positive of the batteries i.e. it's positve post goes to the positive wire of the controller.
 
So I go on board the other day and have had the solar panel and wind generator doing the charging over the winter. These are the readings
BATTERY PACK VOLTAGE = 56.1 VOLTS (so far so good)
B1=13.1 volts
B2=14.1
B3=14.1
B4=14.9
 
I am a little concerned about battery B1 as it seems to be reading constantly lower than the other batteries.  So I put on the ZIVAN NG-1 48 volt charger that immediately goes into the second stage (pulsing) charge mode until it finishes the charging about an hour or two later. I notice that battery B1 does not go over 13 volts but, the Paktrakr is showing the other batteries being charged at up to 16 volts in this mode. Readings taken after the full charge are:
B1=12.9 volts
B2= 14
B3= 14.1
B4= 14.4
 
I then let the battery bank rest overnight with no charging from either the wind generator or solar panels. The reading after 12 hours of rest are:
Pack voltage 50.9 volts
B1= 12.7 volts
B2= 12.6
B3= 12.9
B4= 13.0
 
Should I be concerned about battery B1?  The batteries do seem to be close after resting and the Zivan does charge the bank ok but, I am concerned that the other three batteries do show charging voltages as high as 16 volts while B1 does not seem to go over 13 volts. I am considering buying another charger that will charge each battery individually rather than always using the Zivan which is charging the whole bank. I welcome comments as to what is going on here and how concerned should I be about battery B1.
 
Capt. Mike
 


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