Originally Posted by Nanuuk
Hello all. I have another newby question. Please treat me like I'm as dumb as a post because I really am when it comes to this stuff. We are in the 2nd year of RV'ing. My trailer came with a 12V battery, but we replaced them with two US2200 6V Deep Cycles. I have removed them from my trailer for the winter and they are in my basement. I have an old trickle charger that outputs 6V 10 amp, 12V 2 amp, or 12V 10 amp. The trickle charger displays the charging status using an old VU meter style display.
I am charging each battery separately. After charging for many hours the status does not show fully charged.
Does this mean I am underestimating the amount of time required for charging? Or am I using an incorrect output (6V 10 amp)?
Thanks in advance of your help.
Hi Bill... I guess the first thing to do is to really test the battery to see if it is "Full".
For this you first need to disconnect for at least 24 hours. Then you have a choice to check with EITHER a voltmeter or a "turkey baster" hydrometer. I suggest you get a hydrometer as it is more accurate AND can let you identify problems in each cell (3 per battery).
Draw enough fluid out of a cell to float the float...the green and red are good indicators of condition...but the numbers are more important since they should be the same in EVERY cell.
In the "dumb as a post" category...wear goggles, have paper towels, and neutralize any spills with baking soda...this is a sulfuric acid solution. Wear old cloths too...ask me how I know!
A reading of 1.277 is perfect. Anything below 1.217 is significant loss of capacity (30%). Anything below 1.172 should be replaced. (50%loss).
To be accurate you need to ADD or SUBTRACT .004 for every TEN degress of temperature above and below 80 degrees.
Of course it is easier and quicker to just check overall voltage with a voltmeter using Boondockings chart above...but hydrometers are better if you are not disconnecting the battery from the coach and for tracing down issues. Sometimes a single cell that reads a bit different than the others simply indicates that an Equalizing charge needs to be applied. Sometimes it is a near dead cell that makes replacement necessary before you have 2 dead batteries!
In your situation, you don't know if the charger is working properly... OR if it is working and the meter isn't... OR if the batteries are sucking wind.
At 10 amps and 6Volts...you should be showing nearly full after a couple of days on the charger if the battery were totally discharged to begin with...BUT...some chargers won't jump start an almost totally dead battery
so a BIG conventional charger must be used.
If you hook up your battery to the charger and take a voltage reading at the posts WHILE charging...you should see a reading on a voltmeter of between 6.6Volts and 7.4 volts...anything outside of this range indicates a problem with the charger or a bad cell in the battery.
Hope this helps.