Is 12v battery essentially an uninterruptible power supply?

Sam452

As you see, I have a 2008 CS which uses the World Friendship power converter. We're still learning about this camper and seek out the wisdom of this group. When the T@B is hooked up to 30amp power and the 30amp source has issues/flickering, is it reasonable to expect the 12v battery will kick in to ensure power to the devices, like the lights? 
I ask because I'm using a device that is sensitive to the power not being consistent and perceive that when the 12v lights are flickering, that the 30a source is having trouble. If that 30a power goes out, shouldn't the 12v lights not flicker as I presume that the 12v battery source is the source?
Am I right in assuming that the 120v power outlets are not supported by the World Friendship when 30a power is cut?
Reading the manual that came with the World Friendship, it has three modes: Absorption (normal), Bulk (charging the 12v battery) and Float (All good and minimal charging). Is the flicker of the 12v lights when the WF is changing modes?
Thanks for reading and helping me understand more.

ScottG

Sam452, I'm not familiar with that particular converter, but I assume it works like most others. In which case, you are correct--at least in a general sense.

The converter turns 120V AC to 12V DC. When it is operating it will push power to your 12V devices, as well as to your the battery to keep it charged. If the 120V is interrupted, the battery will now automatically push 12V back into the camper to power your devices.

This of course, doesn't explain your flicker. I'm not sure what is going on there, nor am I sure if the converter really has to "switch modes" in some manner. It may just be a slight side effect of the current changing direction. This of course assumes the flicker is in fact from an interruption in the shore power.

You are also correct that the 120V outlets will not work without 120V shore power. To turn 12V DC to 120VC requires an inverter, a different device which you have not mentioned (though some campers have them installed).

Sharon_is_SAM

You don’t say where you are hooked up (assume a camp ground), but are you using a good surge protector?  One that detects low voltage?  Perhaps that is the cause of the flickering?

Mouseketab

The battery does stabilize the power of the converter. I have a 2007 T@B. When I first got it, my television was wired into 12V. A couple of times when bringing it home from storage, I forgot to turn "on" the battery with the cutoff switch, and the 12V items were running solely off the converter once plugged into shore power. Once when I turned on the television, the picture was very grainy and had "lines" running through it. I then realized the battery was "off", and switched it on. The picture cleared up instantly. I have since swapped out the television and it now runs on 110 power. I have also replaced the converter. Same model, direct swap out.

Trailpixie

Yes.

Sam452

Thx for the thoughtful replies. Will look at a surge protector for my 110v device @Sharon_is_SAM
I ask because my device, a cell-signal repeater is presently using the 110v power but to isolate issues I want to wire it up into the 12v system so that it should have a consistent power source. I perceive that the lights in the kitchen area are 12v and would use that as a source. The repeater is 12v driven. That's why I'm wondering about the lights flickering and if the campground/offshore power source is an issue. 
Later on, I plan to post my findings on using this device for those that want better cell service.

Sharon_is_SAM

@Sam452, the surge protector should be used at the campground pedestal.  Not device specific.

davel4wa

If your lights are flickering then your 12v system is fluctuating. When you have shore power the output of the converter is trying to charge your battery at some voltage level. As you describe, the converter has 3 distinct battery charging modes which results in 3 different voltage levels being output to the battery. If the AC input voltage is being interrupted for some reason then the output of the converter charging circuit will go to zero and the 12.6V output of the battery will continue to power everything that is a 12V device. This could cause the light level to vary slightly as the converter voltage output will always be higher than the battery voltage, as is necessary to charge the battery. If this is happening consistently, no matter where you plug in, then you have a problem. Check your converter for loose AC input connections. The converter has a circuit breaker to protect it and it is possible it has become flakey. If you have a volt meter (VOM) you can connect it first to the AC wiring to see if the voltage is changing when the lights flicker. Unfortunately most cheaper VOMs because of their digital displays make it difficult to see fast transients in voltage. Better ones solve that by having an analog type bar display in addition to the numerical display. If the AC input voltage is stable then the DC side is a problem. Do all of the lights in the trailer flicker when this happens? If not, there may be a loose DC connection at the converter or a particular light may have a problem. It's not uncommon in things that bounce over the road, trailers and autos, to have a tendency to show up connections that are not tight or perhaps to loosen connections that were fine at manufacture. Of course, the converter itself could be the problem. Modern day converters are just switch mode power supplies, i.e. they don't have large input transformers, and they too are subject to vibrations from less than stellar roads as well as the normal age related failures of all electronics. Converters can be repaired. It may not be necessary to replace the entire unit. The switch mode power supply will be a replaceable module in all likelyhood. 

Sam452

I left the VOM so cannot troubleshoot that way until I return. Turning on a second 12v light, I can confirm the flickering is affecting the internal cabin. Turning off the campground power, I believe my battery is past its prime as it's not holding much of a charge, so that is likely a factor in addition to the 12v integrity. This is very helpful.