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post #11 of Old 03-07-2013
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Re: solar charging problem - troubleshooting help please!

I've got to disagree with your advice not to use dielectric grease. Yes, logically, you would be right. But in practice? B&H and some instrument companies actually SHIP the stuff and instruct customers to use it when making connections in their wiring.
In practice what happens is that you make a metal-to-metal contact when you make the connection, even with a screw terminal. The dielectric grease simply keeps water and air from penetrating to attack that metal to metal contact.
It works, and works so well that I won't make a connection without it, and have seen zero failures with it. Heck, if you look at "Gen-you-whine" Western Electric telco splices, the little "button" splaces that they use to connect 24G individual telephone wires? Those button splices are all SILICON FILLED for this purpose. MaBell didn't like doing remakes. (G)

Unlike the old standby of Vaseline, which conducts a little and migrates as it melts in the heat, the silicon dielectric grease (aka brake grease, light bulb grease, vacuum grease, ignition point grease) does a good job of staying put. Sold as "brake grease" for about $6/6oz tube that's usually not quite as thick but way cheaper than buying Ancor brand at the same price for a half ounce.

With just a actually can check amperage, you just need to run the numbers for Ohm's low and use one carefully cut foot of cable or something similar as your measurement base. Basically, you insert the cable in the circuit you want to measure, and then carefully measure the voltage drop across that one foot of cable. If you know what the cable type is (copper, aluminum, gauge) you can look up the resistance, and the voltage drop will give you a good idea of the amperage going through it. That's actually the way ammeters work, except they'll use a "shunt" instead of the foot of cable.

But two 65W panels probably can be safely tested with a $20 multimeter if you find one (Walmart, Target) that has a 10A DC scale on it. Many do.

And if you've just got a 2A scale, there are ways to kludge that too.

Or you may get lucky and find the problem with what you've got.
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