Another No 12V Power With Battery Only - Ground?

GregT

Good morning!

Recent new member and first time on discussion board.  I know that this has been addressed before but I cannot find a discussion that provides an answer to my questions but that's probably just me not understanding what I'm reading.

My wife and I have a 2017 CS.  We have all functions when we are on shore power or connected to TV.  The battery is new, the battery fuse is good and I have checked all fuses and breakers but we have no 12 volt power anywhere when not on shore power or connected to TV.

It appears we have a ground problem.  When checking w/ a Multitester, we have 12.5 volts between the + and – terminals on the battery but when I test between the frame and the + terminal we have no voltage reading at all (checked between various bolts and locations on the frame).  At this point, I am wondering if we have ever had battery power, we do not remember ever using it.  I am not seeing any location (while I’m under the trailer) that looks like a ground attachment to the frame.  

• Where should I look for the ground attachment on our trailer? 
• I’m thinking that our T@B might not have had the battery system grounded at the factory, is that possible?
• Does this mean I have a short or just not grounded properly?
• Can I install a ground from the frame to the battery directly to alleviate this problem?
• I don't understand "DC floating ground" and if or how this may be part of our problem.

We are leaving on vacation next Thursday (28th).  Where we are camping we will have electric but I’d really like to have this figured out before we leave.

Thanks you all in advance for your help.

Greg

Sharon_is_SAM

This may help:  https://tab-rv.vanillacommunity.com/discussion/comment/171962#Comment_171962

Marceline

Can you post a picture of the wiring on your battery? 

ScottG

Welcome, @GregT.

The chassis ground in a 12VDC system is less important than making sure all negative and positive connections back to the battery are sound. Lack of a chassis ground may cause other gremlins, but it will not prevent your battery from providing power to the camper.

The positive leg is a (probably) red 10g wire running from the battery to the power center. The negative leg is a (probably) white 10g wire running from the battery to the DC negative bus under the driver's side bench. The bus is in turn connected to the power center via another 10g white white. Both wires from the battery connect to the power center via the forward junction box under the front of the camper.

Have you checked all the fuses associated with the battery? There should be one 30A fuse at the battery itself, another 30A fuse in the DC fuse box (labelled "battery charger") and a 40A "reverse polarity protection" fuse also in the DC fuse panel. If any of those fuses are blown, you will not see power from the battery.

Good luck and let us know what you find. 

GregT

Thank you all for getting back so quick!  I just saw your feedback while at lunch.  Hope to be able to look at tonight as soon as I get home from work.  I have not checked the connections to the bus bar or the junction box, but will tonight.  I checked the fuses previously but will check again w/ the meter for continuity to be sure.  I will get a picture posted and let you know what I find out