Why can’t I run off my battery

Herg

Hello.  I just bought my 2017 css.   I can’t get my battery to work when it is not hooked up to the truck or an outlet.  The switch shows zero.  Wat am I doing wrong?

AirBoss

I'm not familiar with '17 320 CSS but some initial thoughts.
Have you checked the battery(ies) to see if they're fully charged? 
Is the battery switch in the "On" position?
When you say you can't get the battery to "work", are you saying you have no power to any 12V lights, fridge, etc.?
Checked all fuses? 

Herg

Hello.  There is a switch I need to turn on to go to battery power? There is no power but everything works with a plug in or running from the truck. 

pthomas745

Open up the propane box, and open up the box with the battery inside.  Look to see if the battery is connected. Then look for a fuse holder that holds a 30 amp fuse, and check to see if it is good.  It will be the first fuse discussed in this thread:

https://tab-rv.vanillacommunity.com/discussion/3512/fuses-for-newbies

Then look for the battery switch.  It looks something like this.  In this picture, the switch is "on", and if the battery is charged and the fuse at the battery is ok, you should have 12V power inside the trailer.

Has 12V power inside the trailer worked before?  If you parked the trailer with the battery switch "On", the "parasitic drain" of the gas alarm, etc, has drained your battery.

If you have been plugged in and the battery switch is in the "OFF" position, the shore power was unable to charge the battery.

Do you have a multimeter or a way to measure the state of charge of the battery?  If none of this works for getting power to the trailer, that would be the next step.

Herg

So the switch has to on for the battery to work correct?  Mine was off.  Should I keep it off when not using it ?  Towing? 

Denny16

You can leave it off when not using the trailer.  While towing, the switch needs to be on for the emergency brake to work, and allow the TV to charge the battery.
To use the trailer light, refrig, etc, when not connected to 120VAC mains, you need to have the battery switch on.
cheers

Herg

But it has to be on for power inside the trailer correct?  Tv to charge the battery?

Herg

So for the battery to be charged when driving the switch needs to be in the on position is that correct?

ScottG

@Herg, yes, that switch should be ON when you are camping, towing, or doing anything with your T@B.

Turn the switch OFF only when the T@B is parked between trips.

Sharon_is_SAM

@Herg, all your lights, pumps, Alde and appliances are wired to accept 12 volts.  When the TaB is plugged into shorepower the TaB converter/charger “converts” the 120 v power to 12 v and allows all your things to run independent of the battery.  You have 120 v outlets that are only wired for shorepower and the air conditioner will only operate with shorepower or a generator.  

The battery switch effectively isolates the battery so that it can not charge or discharge.  That means if you need to charge the battery via the car’s alternator or via shorepower, the switch must be “On”.  Whenever you tow, the emergency break-away brakes are dependent on your battery, so you are obligated to tow with the switch turned “on”.  It has the added advantage of charging your battery and keeping your frig cold while you tow.

Once you get to a campsite you can hook up to shorepower and leave the switch on to charge your battery - but the Shorepower is what provides the power in this case - the battery would just charge.  While boondocking without shorepower, the TaB battery supplies your lights, pump, frig, and Alde control panel.

So, if your battery is fully charged and you store your TaB you can turn the switch off to prevent phantom drain, but you still need to check it to make sure it’s not dead.  You can also turn it off while on shorepower, but it is good to leave it turned on to charge.

While towing and boondocking and charging leave the switch “on”.

Hope this helps.

Herg

Thank you so much

Herg

Hello. I have another question.  When I am running off of battery is their a way to get the plugs working on the back?  Also on the side of the trailer?  They only work when hooked to an outlet. 

Horigan

There are two power systems in the T@b, 12V DC and 110V AC.  The outlets are 110V and won't run off the battery.  You need shore power hooked up to make those outlets functional.

Sharon_is_SAM

@Herg - the 120 v outlets will only work when the TaB is connected to shorepower or a generator.  Another way to operate something that uses shorepower is through use of an inverter.  The inverter uses your battery to supply power to AC appliances.  

JPRoland

Finally! I could not run off of just may battery alone and I was baffled. I kept reading this forum and finally arrived at one of the 15 amp fuses at the battery. I guess i thought a blown fuse would be charred or smell burnt. This fuse just had a small shaded spot near the top of the "horseshoe" shape on the fuse. I passed over it at first, but after looking at it under a magnifying glass a second time, I decided to exchange it for a new one. It worked! That was the whole deal! It's all good now. Thank you!

ScottG

@JPRoland, you didn't indicate what model or year of T@B you have, but on a 320 the fuse at the battery (and there should only be one) is usually 30A, not 15A. I wouldn't be surprised if a 15A fuse continues to blow when you turn on too many devices.

JPRoland

Hi, Scott. My 2021 T@B 320S Boondock came with two separate fuses right at the battery. They are both 15s. It is about a month old. 

Sharon_is_SAM

@JPRoland - can we see a picture of your battery setup?  Is it possible one of those fuses is on the positive lead to your solar controller?

ScottG

I'm also guessing one of those fuses is for your solar, and 15A seems like it could be about right for that. Still, I would expect the main fuse connecting the battery to the converter to be larger. I have no first-hand knowledge of the revamped 2021s, but historically that fuse has been 30A and it is hard to imagine it would be less in a newer T@B (particularly one with an electric only fridge).

Denny16

A fuse in a circuit is normally matched to protect the wire size used in that application, both of which have to be matched to the anticipated load.  The fuse is there to also prevent a fire from a wire overheating and causing a fire, if an oversized load is applied to that circuit.

Cheers

sctab320snewbie

We bought a 2019 320S with a dying battery. Swapped it out for a new one and stupid us hooked it up backwards.  Blew the 30 a fuse immediately by the battery we figured it out and replaced the fuse.  None of the inside breakers or fuses were affected.  Now even w a new fuse we can't get anything to come on 12v.  If we hook to the generator everything works inside including the grid shows battery is full.   If we turn the generator off and  try to run off the battery nada.  Thoughts?  I  am guessing we fried the switch and wiring in addition to the fuse because there's a lovely plastic smell as well in the battery compartment.  Battery was a deep cycle same size as the one we replaced.   At least we finished winterization before this boneyard move!

pthomas745

Welcome to the Forums.  Sorry to hear about your battery mis adventure.

Here is a thread that discusses the loss of 12v power in the trailer.  In the converter, there are also fuses and breakers that protect the battery.  Find the "Scott G " post from May 2017 here that explains the other fuses and breakers that might need to be checked.

https://tab-rv.vanillacommunity.com/discussion/4888/no-12-volt-service

Sharon_is_SAM

Good call @pthomas745.  I was going to suggest those 2 fuses (Reverse battery protection and battery charger) just as Scott mentions.  We don’t think about those fuses much.