Question about inverter use and power draw on batteries

[tfirma]

I will apologize right off the bat - this is both probably a newbie question - and also a bit convoluted.

So my brand new 1995 Lance has two 12v outlets... I was trying to run a 150W inverter or a 300W inverter - and having all sorts of trouble just running a macbook off the inverter (85W, I believe) I got about 5 different ideas on the issue (everything from "the wiring isn't outfitted for anything significant" to "it should all work fine" which was right from Lance themselves). Finally, the dealership did call me and said the one receptacle is "charging only" - which apparently means it doesn't have the capacity to run ANYTHING significant besides the smallest of electronics. So I focused on the other receptacle for the TV. Lo and behold, I had more luck with that. I COULD power the Laptop...but something strange is happening for which I'd love to get an explanation....

I've got two 12V batteries wired in parallel and a 160W solar package. The solar charge controller reads 100% (which I thought was the level of battery power remaining?) - but then, of course, there is also the meter reading panel for the tank levels, and battery power on the kitchen wall. Electric power has been at 100% - since I really haven't used too much power for too long...just testing things out and using some lights and occasionally the heat. (and I'm not plugged into shore power) HOWEVER - when I ran my notebook - I noticed both the reading on the solar controller went down VERY quickly (within just a few minutes, it was down to 81) AND the meter for battery strength went down to 3/4 and then even 1/4. I assumed that the drain on the batteries was just TREMENDOUS for the levels to go down so quickly. That would surprise me - I realize running off the batteries will drain them - but I can't believe it's THAT fast? But here is the stranger part. I turned off the inverter...and within about 5 minutes... I was back up to 100% on the charge controller AND on the battery meter level reading. I can't imagine the solar could help out that much that quickly - because it was raining all day and not a hint of the sun was out during all of this. I also can't imagine the drain on the batteries could be THAT substantial and so rapid for only using a 150W inverter for about 3 minutes..... But then, since the levels seemed to go right back to 100%, I'm wondering if something else is going on -- or those readings maybe mean something else?

I tried my best to describe the scenario. So the two questions are :
- Is the reading on the solar charge controller (GoPower) the actual percentage of battery power left, or something else related to the panels?
- Is it possible that just using my laptop on a 150W inverter for less than 5 minutes would drop that percentage to 81% AND the battery meter reading to almost 1/3?
- Why would both levels on both meters go right back up to 100% after about a minute of unplugging the inverter?

Thank you so much in advance!

Tom

[MrWizard]

closed at request of OP
see this thread in tech issues

http://forums.woodalls.com/index.cfm/fuseaction/thread/tid/28628198.cfm

[Larryect]

If the plug you are using is right next to the meters, you could be seeing a voltage drop on the meters due to the load the inverter is pulling thorough the smallish wires feeding the plug.

You might try running the inverter again and check the battery voltage at the batteries at the same time

[pianotuna]

85 watts for the laptop equates to 8.5 amps @ 12 volts. The existing batteries are compromised in some way.

Check to see if the electrolyte is covering the plates. If it is not add just enough distilled water to do so then fully charge them--say for 168 hours at 13.2 volts.

After they are fully charged then disconnect them from the RV and do an equalization charge at 16 volts. Then check the specific gravity in each cell using a temperature compensated gauge.

[dahkota]

What you are seeing is voltage drop due to load. From the sounds of it, your batteries are really old or fried.

You should easily be able to charge a laptop with a 100W inverter and a car phone plug. The plugs are typically rated for 108W or about 8 amps. We have run a TV and satellite receiver through one (total 90W) with no problems but, our batteries were less than 5 years old.

Just an FYI: charging a laptop is less of a draw than using a laptop. Also, the biggest draw is to use a laptop when the batteries are low: the inverter powers both the battery charger and the graphics, which can be over 85W total.

[Chuck_thehammer]

if you are using the factory 12 volt sockets built into the camper.. they are for light use... like 1 to 3 amps...

inverters need there own wiring (big) to the batteries.

unless I misunderstood your statement.

[MrWizard]

Sounds like You need new camper batteries
They have a very low capacity,
Like a gas tank full of rocks
The fill up fast and go to empty real fast
No real useful capacity