Hi Mike-
It sounds like that battery may be sulfated---but it could be recoverable. Before plunking down the money for a new battery, try this:
· Disconnect the battery from your charger
· Obtain a current-limited DC power supply with a rated voltage of at least 20v
· Attach the current-limited supply to your bad battery, turn on and monitor the charging current and voltage
o If the voltage starts out high (e.g. 20v or even 40v)---that's fine as long as the current is just trickling
o As current starts flowing, the voltage should drop and continue dropping while the current increases
· If the voltage gets down below 14v during this charging, that's a good sign---you could stop and switch to your main charger
· If the voltage just slowly goes downward but never going past 14-14.7v as it drops, you'll need to keep charging with this charge setup.
NOTE: Please be sure to monitor it and make sure that the battery doesn't suddenly start increasing voltage, heating and outgassing sulfur! If you smell anything or detect the battery heating, stop charging. Also, if the current has increased to several amps as the voltage drops, be sure to not let this level of current flow for long if the voltage doesn't drop below 15.5v or so.
You may need to do this a couple times or once in a while for each battery on occasion. AGMs may need equalization charges once in awhile. Then again, it's debatable: http://www.sailnet.com/forums/island-packet/18498-equalizing-agm-batteries.html
-Myles
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
Sent: Monday, June 13, 2016 6:40 AM
To: electricboats@yahoogroups.com
Subject: [Electric Boats] AGM Battery Anomaly
Just when I thought I was ready to splash my boat for the season I made a disturbing discovery concerning one of the batteries in the 48 volt propulsion bank. The Dual Pro PS4 battery charger showed battery number four with a blinking green light where as all the others were steady after having been charged. This was a new development as for the past several weeks all the batteries had been charging normally on my visits. For some reason the charger thinks battery four is not yet fully charged. I disconnected the power from the charger to let the batteries sit overnight and make sure it would not fire up when I plugged the extension cord back on my return in the morning.
The next morning I went into the cockpit and threw the switch on the helm instrumentation panel that powers the individual battery meters. My suspicions were confirmed. Battery four is not being charged properly. BTW this battery is the most negative battery in the string. I found some corrosion on the negative terminal of the this battery and using a tester found that the internal resistance was 194 milli ohms. The last time I did the test it was 2.34 milli ohms.
Some photos are here:
http://biankablog.blogspot.com/2016/06/battery-anomaly-part-two-readings-and.html
So now I'm faced with a dilemma. The bank is eight years old. The other three 8A4D AGM batteries seem fine. Do I just buy a replacement battery which will now be much younger than the other batteries in the pack. Though I'm not sure I want to spring for four new batteries if the other three are still good. Any thoughts?
Posted by: "Myles Twete" <matwete@comcast.net>
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a New Topic | • | Messages in this topic (2) |
No comments:
Post a Comment