[encantotom]

a few rambling thoughts.

the question about the power at the fairgrounds......i would be very surprised that the problem was a result of a lengthy run. what a lengthy run does is lower the voltage and is called a voltage drop. shutting off the other breakers would not change anything. our coaches should run on 104-132v. i have the progressive industries power management system on my coach and that is the range of voltage it will "allow" into the coach before shutting it off. most 120v AC devices have a real wide tolerance of voltage operation just for the reason of the many variables that influence voltage in a residence.

what electricians do when wiring up long runs is to do a voltage drop calculation, or most do a rule of thumb of upping the wire size one size for each 100-200 feet. i said rule of thumb because it makes a difference of what starting voltage and what type of wire etc. standard 20a wiring is #12 wire. the indicators of a long run without increasing the wire size is lower voltage and the problem then should have been in your coach. of course, anything is possible.

given that you said it would trip after 10-20 minutes raises a few thoughts from my feeble mind. particularly since you said it didnt matter what pedestal you used at the fairgrounds. it is always a possiblity that the breakers were weak at the fairgrounds, but given that you tried several, that seems to be a low chance.

it seems more likely to me that something in your coach was kicking on periodically that was in conjunction with the other things your were using caused the coach to be drawing 20 amps or more, causing the 20a pedestal breaker to blow. the biggest culprits for current surges are anything with a motor. motors have typically 1.5-2.5x surges at startup (called LRA, locked rotor amps), that can cause amperage spikes. in particular, any type of compressor is the biggest culprit, like a fridge, air con, icemaker, etc. however any electric motor surges.

or anything that will cycle, like chargers, hot water heaters, etc.

all of this is only to do with the pedestal breaker popping. like is said, since there are so many variables, you could have found the perfect combination of things that made it unique to that fairgrounds, which is easy enough to tell if you plug in at another place and it works.

now a few comments about your batteries.

michael and clarke and steve had great comments. having made many battery mistakes in the past here is how i would start, and take it with a grain of salt and merge it with the other folk's comments. i would not rely on the meters in the coach for troubleshooting. get a handheld volt ohmeter if you do not have one. any cheap ol one will work. i have expensive ones and cheap ones. the cheap ones are fine for this. 3 bucks at harborfreight. or spend 20-250 bucks for a radioshack or fluke. start cheap unless you are going to use it a ton.

1. if the batteries have caps you can check the water on do so and add distilled water as necessary. as everyone knows, charging batteries with the plates exposed kills them quickly.

2. then charge them overnite. you can check the "smart charger" by monitoring the voltage at the batteries with a voltmeter. it will start out and progress through different voltages immediately after turning it on. you can see those voltages at the batteries with a voltmeter. get your manual out for your charger and it should tell you the times and voltages. that wasy you can make sure the charge is working right. most likely is, but it will help eliminate things. as elmination is the name of the game.

3. isolate the batteries as michael said and check voltages. in this case, make sure to isolate the batteries or you will be reading combined voltages. like was said before, if one battery is alot different than the other one, suspect it has a dead or shorted cell. these big ol 8D batteries are heavy, so it might be easier to drive the coach to a battery shop to have it load tested (with the batteries disconnected you are checking). btw, i bought my engine batteries at a sams club and they had a load tester capable of 8D batteries. i took the batteries there, but the batteries are a mere fraction of weight compared to me.....a bad cable connection can cause lots of problems. as part of isolating the batteries to test them, i would completely clean each cable end and battery lug or terminal. a bad ground or connection can cause lots of wierd problems.

4. on all of the coaches i have seen of our vintage, there is a huge fusible link on each battery bank. on mine, i thought my batteries for my starting side were bad, and it ended up that the fuse was bad. on mine and most others, it is on the ground and sits on top of the battery. it is about an 1.25" in diameter with flat connection lugs on each side of the cylinder. i would check that as well. isolate it and just check across with an ohmeter.

5. remember the voltmeters on your dash and overhead will display what is on the circuit. what i mean by that is if you are driving and your alternator is putting out 13.4v, that is what will be on the meter as long as the alternator can keep up with the demand. that is even if your batteries are at 12v, the meter will show what is coming out of the alternator within reason. same for being parked and engine off and charger on. with the charger off, engine off, then it will read the combined battery voltage and will go down as the batteries are drawn down.

6. after all of this, hopefully you found something simple. if not, and the batteries are good, the charger is good, the fuse is good etc.

7. if everything still checks out, then you have to start tracing from a good point forward a piece at a time. from the batteries up is where i would likely start.

of course, as usual like i said before, use what works for you.

and someone check my thoughts as i started this earlier than i like to get up.

later

tom