I think this will be my last update on this.* I'd hate for somebody to come looking for a solution to a similar problem, read through all this stuff and end up with no real answer.
After it warmed up today I went fly fishing again.* Didn't catch anything but sure had fun. I like for things to make sense and I things this last post will help close some gaps in the results.* We were gone fishing for about 5 hours and during that time we shut everything DC powered off.* The LED indicator now reads fully charged with the converter shut off.* So, it did get charged up and I'll be monitoring it for the next few days.
About those pesky amp readings from early this morning.* They didn't make any sense so I looked up info on this Digital*MultiMeter*(DMM).* Turns out, anything I clamp it to, including water pipes, ropes, anything, it will give a reading anywhere from 2.5 amps to 4.7 amps.* So....... that's one of the reasons*DMMs have a REL button (Relative button).* So you zero out the amp meter*and then take a reading RELATIVE to the zero.* So I tried that, and it now makes sense.
The first amp reading of the large diameter battery lead was*+.90 amps, that was current running into battery from the converter.
The second reading was after turning off the converter and it read -.20 amps.* That's the current being drained by all the stuff you can't shut off and what makes your batteries go dead after about 3 weeks with no shore power.
The third reading was with the converter off and all the LED lights in the trailer turned on; -7.2 amps.* All the lights using 7 amps and the .2 amps running all the crap you can't turn off.
After doing all this which took about 5 minutes maybe, I switched the converter on and the amperage read*+2.9 amps, that's the converter trying to recharge the batteries after we ran all the LED lights for a few minutes.
What else did we learn:
The truck supplies voltage to the trailer*via pin 4 of the 7 pin connector and pin 1 is ground. If the alternator is charging the voltage will read about 14.4 volts but could be as low as 12.9 if the alternator isn't charging.* Opinions vary concerning how much current the truck can supply to the trailer (5 amps is a common beliefs on all the RV forums) but even at 14.4 volts and 20 amps it only needs to supply 250 watts so 14 gauge wire is more than sufficient.* The voltage to the 7 pin is routed through a 40 amp fuse and then a relay that turns on when the ignition is turned on.* No ignition, no voltage at the 7 pin.* Think about it, lots of people run 1500 watt space heaters on 14 gauge wire (that's 120v and 12.5 amps).**
Turning to the 7pin on the trailer; you can measure the voltage of the batteries via pins 4 & 1.* I checked them with a voltmeter and pin 4 is routed directly*to the battery, which is alarming to me, but that's how it was wired.* Which means you can also measure the output* voltage of the converter using pins 4 & 1.*
Shaun, tech support engineer from WFCO* (converter manufacturer) says:**Your battery is fully charged at around 12.8v. Your converter will not go into bulk charge until your battery reaches around 11v. Shaun)
So, a 3 stage converter will:
Output 14.4 volts when the batteries get down to 11 volts.
Hover around 13.6 volts when the batteries are around 2/3 charged.
Drop to 13.2 to maintain the battery.
If you look at the data below you see a lead acid battery is considered 0% charge when the voltage reaches 11.8 volts, so it's not likely you'll ever see your 3 stage charger output at 14.4 volts (11 volts at the battery).* This warrants further investigation.
If you're wondering why I write all this up; I email it to myself so I don't have to figure all this stuff out again in 6 months or 3 years.**
Thanks again to everyone for your help and ideas.**
Dustin
This past summer I contacted Interstate Battery to get some specifications when I was learning about equalizing deep cycle batteries for my 36 volt golf cart.* Golf cart batteries are now about $180 each and the cart uses 6 of them.* So keeping them in good condition is critical.
Interstate SRM-24* 12v battery Specific Gravity at 100% charge is 1.285
Internal Resistance:* 5.1m Ohm
Float* *2.20v/cell = 13.2 volts (considered fully charged).
This summer project produced this information*on deep cycle lead acid batteries:
Voltage on a fully charged*battery*in good condition will read 2.12 to 2.15 volts per cell (about 12.75 volts for a 12 volt*battery, or 6.40 for a 6 volt)
Voltage readings to determine state of charge (open circuit readings):
State of* * * * * * Sealed or Flooded Lead
Charge* * * * * * * Acid battery Voltage
100%* * * * * * * * *12.70+
75%* * * * * * * * * *12.40
50%* * * * * * * * * *12.20
25%* * * * * * * * * *12.00
0%* * * * * * * * * * *11.80
https://www.energymatters.com.au/bat...age-discharge/
Specific Gravity Readings to determine State of Charge:
12.75 & Above = 100% Charged
12.60 to 12.74 = 85 to 100% Charged
12.40 to 12.59 = 75 to 85% Charged
12.20 to 12.39 = 50 to 75% Charged
12.00 to 12.19 = 25 to 50% Charged
12.00 & Below = Fully Discharged
///// end of data //////////////
Linear Mode
