12V battery not charging when attached to shore power

mike brez wrote:
Touch the +&- leads from meter togeather to verify beep before testing

AND even more important, be sure that all the power is removed from both sides of the fuse before you attempt a continuity/ohms test.

It is generally NOT good to be testing for continuity that way on circuits that normally are HOT.

If the circuit is still live and the fuse IS blown, your meter or it's fuse will probably be the next problem.

Look for something like this



I have one near my converter and one near my batteries.
I had to replace the one next to my batteries because of the same problem you are having.
To test If using the multimeter to measure ohms, the reading should match (or nearly match) the one provided when you touched the two leads. If the fuse is blown, it will not read anything at all, or the meter will display O.L. depending on the brand and type of meter you are using.
If using a digital multimeter set to measure continuity, the meter should beep continuously as you hold the leads to the ends of the fuse. That means the circuit is complete. If it does not do so, the fuse is blown. Touch the +&- leads from meter togeather to verify beep before testing

mmoore43 wrote:
How do I find that fuse between the converter and batteries?

Converters should have a fuse or fuses that are either located on their fuse panel or in their rear that are for protection against over current or reverse polarity hookups. There could also be a fuse, but more likely a breaker, near where the wire from the converter hooks to the battery. No two RV's have these things located in the same place. If you have manuals for the converter and the RV there should be some form of diagram that shows these things.

mmoore43 wrote:
How do I find that fuse between the converter and batteries?

With all external AC power disconnected, including a generator if present, IF you measure the same voltage on the battery as you do on the output terminals of the converter......the fuse is NOT blown and you don't really need to find it now.

mmoore43 wrote:
How do I find that fuse between the converter and batteries?

Follow the main positive cable from the battery.
Mine is 1 foot away.

If there is a fuse in the line to the battery just follow the line from the converter to the battery. There may be fuses in or on the converter it's self. If the converter is working the heavy cable coming off converter should read 13 plus volts when plugged in to shore power or generator power.

How do I find that fuse between the converter and batteries?

mmoore43 wrote:

Does any of this make sense as to why my 12V batteries are not charging when I am plugged to shore power?

I see that there are other answers.

Simply, you can NOT charge a 12 Volt battery with LESS than 12 volts out of the charging source. 10 volts is not near enough.

Your converter/charger has failed.....or has a blown fuse or bad connection.

P.S. And you can not be sure that your batteries are "fine" unless and until you see if they will charge all the way up....and hold that charge when not being used.

If you plug into shore power you should see a voltage jump at the battery, if not, the converter isn't working. Then check to see if there is power to the converter. Check for a tripped breaker and also check to see if the fuse from the converter to the battery is good. Test it, not just look at it.

mmoore43 wrote:
My multimeter reading settings jumps from 10v to 250v so it is hard to read exact measurements. I changed out the transfer switch today and I want to test whether it is now charging. About how long should it take for the 12 v batteries to down if I leave the lights on in the coach?

Mmoore,

Don't do that test. It will prove nothing you don't already know.
If you kill the house bank, you will shorten its useful life.

Go buy a better meter. It should have a 20VDC and 200VAC scales. The cheapy at Hazard Fright will do. I used to give them away before the depression killed my boat work business.

If the house bank is not in the 13.2 ~ 14.4 range on shore power. Test the supply connection to the converter. If it is not the same as the house AC receptacles, then find an electrician to fix that. If it is the same, your converter is toast.

If you go shopping for a new one, get one that says it is three or four stage. If your house mank is 2ea GC2s, you can use up to 60 amp. If it is "deep cycle" 12V batteries, they can not take that, stay with 45 amp.

Matt