Batteries not charging - what is this post?

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

jhughes75

Active member
Joined
Jul 24, 2018
Posts
27
Had a brief power outage at the park I was at last week.  Turned on the lights, nada.  Hit the battery check, it flickered and then nothing. 

Checking them today, they are only reading 12.56V.  The reading on the top of the pictured post (coming from the inverter) is 13.39V, while the bottom going to the batteries is 12.56V.  Turned the switch off and hooked up to a battery tender and they were up to 13.3V within an hour.

Question is, what is this post or is it just a connection point?  Yes I will clean the rust up a bit, but if that doesn't solve the problem I have no idea what I'm ordering.
 

Attachments

  • RV Post.jpg
    RV Post.jpg
    239.8 KB · Views: 108

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
76,141
Location
West Palm Beach, FL
That looks the chassis ground lug, connecting the negative battery posts to the chassis/body.  It desperately needs clean-up!  Your 12v system uses the vehicle chassis as the ground (just like a car).
 

jhughes75

Active member
Joined
Jul 24, 2018
Posts
27
There's 2 posts, and it's the positive charging line located just after the shutoff switch.  One line on top coming from the switch (reading a good 13.3 charge ) and the other line (was only reading 12.6) going to the batteries.  Doesn't appear to be a fuse, there's another fuse line in parallel using a green wire.  Didn't know if it was a voltage regulator or something.
 

grashley

Well-known member
Joined
May 7, 2015
Posts
6,591
Location
Western Kentucky
First, clean those posts!!!!  That may well cure the problems because it appears nothing is grounded.

A fully charged battery NOT being charged should read about 12.56V, so the battery is probably fully charged.
A charger should be producing about 13.3V, so it appears to be working.

My guess is nothing is working because all circuits are broken at the corroded ground block.
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
76,141
Location
West Palm Beach, FL
OK, if there are two posts then it's not the ground lug.  Two posts suggests it to be a circuit breaker, but I don't see any reset button.  A fusible link, maybe (one time use)?
 

Chakara

Well-known member
Joined
Aug 13, 2018
Posts
230
Location
Rio Rancho, NM
I think the other are right and it's a fuse/breaker.  And if so it should read the same voltage on both sides.  I think you have your culprit. 
 

Lou Schneider

Site Team
Joined
Mar 14, 2005
Posts
11,791
Not all two post circuit breakers have reset buttons.  Some are self-resetting after they cool off for a minute or two.

In any case, I'd say that one is kaput.  Even if you clean up the terminals, there is probably internal damage.  Those cases aren't watertight.

See if you can find a current rating on the case.  Or the AWG wire gauge of the wires connected to it.
 

lynnmor

Well-known member
Joined
May 14, 2013
Posts
1,586
Lou Schneider said:
Not all two post circuit breakers have reset buttons.  Some are self-resetting after they cool off for a minute or two.

In any case, I'd say that one is kaput.  Even if you clean up the terminals, there is probably internal damage.  Those cases aren't watertight.

With that much rust it is kuput because any plating on the terminals is long gone.  Since they are not watertight, I mount them with the posts down to help keep the case from collecting water.
 

Rene T

Site Team
Joined
May 20, 2011
Posts
19,487
Location
Farmington NH
Just do a quick test by disconnecting both wires and connect them together with a bolt and nut, See if everything works. If it does, this is your problem. Do NOT leave it connected this way. Go get a new breaker immediately.
 

Gizmo100

Well-known member
Joined
Sep 28, 2018
Posts
3,029
Rene T said:
Just do a quick test by disconnecting both wires and connect them together with a bolt and nut, See if everything works. If it does, this is your problem. Do NOT leave it connected this way. Go get a new breaker immediately.

9 times out of 10 this will work...However that 10th time may not end well.

If something in the system caused the breaker to trip..You may create a dead short...
 

mel s

Well-known member
Joined
Apr 28, 2014
Posts
881
jhughes75 said:
Had a brief power outage at the park I was at last week.  Turned on the lights, nada.  Hit the battery check, it flickered and then nothing. 

Checking them today, they are only reading 12.56V.  The reading on the top of the pictured post (coming from the inverter) is 13.39V, while the bottom going to the batteries is 12.56V.  Turned the switch off and hooked up to a battery tender and they were up to 13.3V within an hour.

Question is, what is this post or is it just a connection point?  Yes I will clean the rust up a bit, but if that doesn't solve the problem I have no idea what I'm ordering.
jhughes75
That looks like an automatic, self-resetting circuit breaker: https://tinyurl.com/yyovk6p6
{Be aware they are available with different amp ratings).
 

Hanr3

Well-known member
Joined
Jul 5, 2012
Posts
392
Location
Central Illinois
Resettable circuit breaker. When it cools it resets. However they fail. As posted, they come in different sizes. When you have the wires off, verify the connections are not corroded too. If they are, best to cut them off and crimp on new ones. I like to use a dielectric grease on all my fittings.
 

Wizard46

Well-known member
Joined
Mar 12, 2009
Posts
2,093
You don't say what make of RV youy have but I have seem similar on my Winnebago motorhome. If so I would call Winnebago and see if they could help identify.
 

catblaster

Well-known member
Joined
Jan 11, 2010
Posts
2,703
Location
Kissimmee, Floriduh
Gary RV_Wizard said:
That looks the chassis ground lug, connecting the negative battery posts to the chassis/body.  It desperately needs clean-up!  Your 12v system uses the vehicle chassis as the ground (just like a car).


  My first impression of this was that it was an isolation lug. A secure mounting place where two positive cables can be joined together. Not a grounding lug.  Either way it is in bad condition and could cause a problem.
 

jhughes75

Active member
Joined
Jul 24, 2018
Posts
27
Yes turns out it is an auto-reset circuit breaker.  Shortstop 12V 50A.  The actual connection points were good and shiny, just external rust.  It wasn't mounted to come off easily, so it came off the hard way.  Now to find a place that carries them or will ship fast.
 

jhughes75

Active member
Joined
Jul 24, 2018
Posts
27
Auto parts stores (NAPA, Advance, Auto zone) do not carry them.  Even the Marine supply store here (Key West) only carries up to 30A with a manual reset.  Got one ordered with express shipping.  Can't do General Delivery with Amazon usually, although having that cap would be nice.  I will mount the new one where it's not as exposed and figure out a cover later.
 

Latest posts

Forum statistics

Threads
123,932
Posts
1,258,133
Members
129,759
Latest member
Whatthenobo
Top Bottom