Thanks Ahmet. The charger was draining the batteries while unplugged and on the hard. The battery switch was off but the charger was still sucking power from both banks. The spark came from a charged replacement battery. After discovering the voltage drain, I called the charger's tech support who agreed that the blocking diodes had failed and informed me there was no way the make a repair.
-- Stephen Petri S/V Witchcraft, Ranger 33 No. 161 http://www.teamwitchcraft.com From: [email protected] [mailto:[email protected]] On Behalf Of ahmet erkan Sent: Sunday, April 24, 2011 8:43 AM To: [email protected] Subject: Re: [Liveaboard] Battery Charger Recommendations? Hi again Steve, First of all the batteries should not be "discharging over the winter" due to any loading. Even the lightest load left on the battery bank over the winter will kill a battery bank if the boat is not connected to a charger and shore power is present. You should also verify the charger does not drain the batteries if the shore power fails or gets disconnected. I recommend connecting a 1000 ohm resistor between the battery positive terminal and the positive charger lead and measuring the voltage between the terminals of the 1000 ohm resistor when the shore power is unplugged. You should measure zero or (less than 10mV corresponding to 10micro amps of discharge) Back to the measurements you took. Measuring about 4V between the positive terminal of a discharged battery and the positive terminal of the charger is normal. The spark occurs from the charger output capacitor discharging when you make the connection, nothing to worry about. Connect the charger and measure the voltage between the battery terminals, the battery voltage should be increasing slowly as it charges. The battery terminal voltage should increase slowly and stabilize at 13.6 to 13.8V. Some chargers may take the battery voltage higher (maybe up to 15V) for a period and then bring it down which is called an equalizing cycle which is recommended for batteries that remained discharged or partially discharged for long periods. Good luck buddy. Ahmet _____ Date: Sun, 24 Apr 2011 01:45:55 -0400 From: [email protected] To: [email protected] Subject: Re: [Liveaboard] Battery Charger Recommendations? The batteries were discharging over the winter and didn't seem to keep the charge I was giving them. So I figured the batteries where damaged and bought new ones. While I was connecting the wires from the charger to the new batteries I saw a spark, which surprised me. I checked to see that everything was being connected correctly, and it was. So I used my multi-meter between the battery terminal and the charger lead and found 4.26 Volts was going thru the charger. SWP From: [email protected] [mailto:[email protected]] On Behalf Of ahmet erkan Sent: Saturday, April 23, 2011 9:05 AM To: [email protected] Subject: Re: [Liveaboard] Battery Charger Recommendations? Hi Steve, I must have missed the history of the issue but I like to hear it again if you don't mind. "Completely discharged battery" failure mode has hit me several times and I have become sensitive to the issue. First episode was my wifes bran new Dodge Avenger ending up with a completely dead battery in the garage. After determining the dome light stayed on if the door was not completely closed. I chaged the battery and figured we will just be careful and close the door properly from now on. A year later another battery dead as doornails due to same root cause. My Jeep Cherokee ended up with a completely dead battery at the workplace parking lot. I went to my boat hoping to have a nice day of sailing and found the battery completely dead. After I wised up about this issue, determination of the exact root cause, and taking effective corrective action became important for me. After that long story, let me ask my question : What testing did you do to make the statement "The battery charger's blocking diodes appear to have failed"? Replacing what "appears to have failed" does eventually work but not usually the most cost effective way to correct the problem. Just trying to help. Good luck Ahmet > Date: Fri, 22 Apr 2011 20:31:15 -0400 > From: [email protected] > To: [email protected] > Subject: Re: [Liveaboard] Battery Charger Recommendations? > > The entire unit is potted in epoxy. It's not serviceable. > > Stephen Petri > from mobile device > > > On Apr 22, 2011, at 3:02 PM, "[email protected]" <[email protected]> wrote: > > > > > > > Why don't you just change the diode? > > > > The ouput might be high because some voltage was dropped across the diode. > > > > Norm > > S/V Bandersnatch > > > > > >> [Original Message] > >> From: Stephen Petri <[email protected]> > >> To: Live Aboard List <[email protected]> > >> Date: 4/22/2011 2:38:35 PM > >> Subject: [Liveaboard] Battery Charger Recommendations? > >> > >> I have solved the mystery of the fully discharged batteries. The battery > >> charger's blocking diodes appear to have failed. In addition the > > charger's > >> output is a bit high. So it's time to replace the charger. > >> > >> Any recommendations or units/brands to avoid? We don't need a big > > device, > >> a 20-30 amp two battery system will be fine for our needs. > >> > >> > >> -- > >> Stephen Petri > >> S/V Witchcraft, Ranger 33 No. 161 > >> http://www.teamwitchcraft.com <http://www.teamwitchcraft.com/>
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