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Old 18-07-2013, 00:25   #31
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Re: Solar Panels w/Amp Gauges

I don't know your specific system, but I'll make a few general comments that might be helpful.

If you have volts, but not amps, then probably either a wire is broken, a switch is off, a fuse is blown, the controller is fried, or the batteries are just so shot that they will not take a charge.

The easy way to measure current is with a clamp-on ammeter, also known as an amp-probe. With these things, you just snap the clamp around an existing wire, & it inductively picks up the current reading.

The one thing you need to watch out for is that you only want to have one wire inside the clamp. If you put both wires in there, then they cancel each other out & the meter will read zero, even when current is present.

The older clamp on meters only worked with AC, but many of the newer ones also work with DC.

This is the quickest & easiest way to see if you actually have current flowing that your panel meters are not reading.
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Old 18-07-2013, 02:12   #32
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A simple test would be to bypass the controller and connect directly to the batteries. Since you're seeing open circuit voltage at the controller, the problem must be something downstream (another water analogy) of the controller input. You should see some current flowing with the direct connection. Remember not to leave it connected too long.
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Old 18-07-2013, 11:00   #33
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Re: Solar Panels w/Amp Gauges

Ok... This just keeps getting better. This morning getting ready to take off & pick up a clamp on type hand held amp meter... I went back to the junction of the three solar panels.. When I isolated the panels I found the 16-17 volts was produced from one 80 w solar panel... One without a diode. I had already installed a diode below deck though for that one panel before connecting to the other two panels. I still need to confirm amps... but so far appears to be working.
The other two panels are Seimens 110 w panels & have diodes already installed in their own connection box on the back of each. Neither one of these two are producing any voltage. I do not see any discoloration of either panel & no apparent damage. Is there a way I can confirm one way or another if they a still good?
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Old 18-07-2013, 11:04   #34
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Re: Solar Panels w/Amp Gauges

If the already installed diode on these two panels were bad, (for what ever reason) would they not show voltage being produced ?
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Old 18-07-2013, 11:25   #35
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Re: Solar Panels w/Amp Gauges

Please forgive me if this is a stupid thing to post, but I just want to be sure that you understand how a diode works. It conducts in one direction with a small voltage drop & acts as an open circuit in the other direction. If you put an ohm meter on a diode & then switch the meter leads to the other direction, one way will show a connection & the other will not. Therefore, if you are measuring voltage after the diode & the diode is in backwards, The diode will block the voltage & you will read zero volts.

The diode conducts when the bar end is connected to negative & the triangle end is connected to positive. The mnemonic to remember that is that drunken electrons go into the bar. Electrons are negative, so when negative electrons are at the bar end, they go in. The bar end on an axial lead barrel diode is normally marked with a white or silver stripe. Other case styles vary in their markings.

If you put a diode directly directly across from the positive to negative of a power supply, like a battery, in the direction in which it conducts, then the diode will blow internally & normally turn into a permanent open circuit with no outward visible signs of the internal destruction. If you put a diode across a battery in the other direction, then nothing happens.
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Old 18-07-2013, 12:33   #36
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Re: Solar Panels w/Amp Gauges

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If the already installed diode on these two panels were bad, (for what ever reason) would they not show voltage being produced ?
Not necessarily. I may be wrong (and someone will certainly correct me if I am) but I think a diode could fail short or open.

Can you bypass the diode to check the open circuit voltage of the panels directly?
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Old 18-07-2013, 13:11   #37
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Re: Solar Panels w/Amp Gauges

When a diode fails from excessive current, it usually fails as an open. When it fails from excessive voltage without excessive current, it will often fail as a short. The max voltage for a diode is called the PIV rating. The lowest PIV that I've seen on commonly available diodes is 50v.
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Old 18-07-2013, 16:51   #38
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Diodes nearly all failure initially to a short , if excessive current then flows , burn out occurs and the junction material evaporates, this result in an open circuit ( and very obvious too )

They can fail,to a resistive short as well.
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Old 18-07-2013, 22:04   #39
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Re: Solar Panels w/Amp Gauges

Dave, your experience seems to differ from mine. Under what conditions have you seen diodes fail first as a short & then as an open & how were you able to determine that it happened that way?

When I have seen polarization safety diodes fail, it was always from over-current in the direction that they normally carry current & those always failed as an open.

When I have seen diodes in flyback voltage multiplier circuits fail, they failed from inductive voltage spikes & often failed as a short.
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Old 19-07-2013, 08:53   #40
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Re: Solar Panels w/Amp Gauges

Update:
Yesterday I spent the day looking for a meter which will read amps. The lower end would only read up to 10 amps without a clamp on. The only other one I could find would read up to 400 amps for $178. Sorry... a little much for a one time usage.

I have 550 ah in house batteries & two 1000 cca starter batteries. I was not able to start the engine this morning with 12.76 volts. How many volts should it take to start the engine ?

Note: The batteries were fully charged two days ago. They are shut off at night & only turned on only when needed during the day. The starter rolled over briefly then nothing. Does this sound more like a starter issue than battery ?
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Old 19-07-2013, 13:15   #41
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Re: Solar Panels w/Amp Gauges

12.76vdc is more than the battery on my diesel reads & it starts every time.

If you don't expect to have more than 10 amps flowing, then the less expensive meter would probably work for you. You would just need to break into the wiring so that you can wire the meter in series with the load.

If you want to stick with a clamp on, then this meter available from Home Depot for about $100 would probably do the job.

General Tools 400 Amp AC/DC Auto Ranging Clamp Meter with True RMS-DAMP68 at The Home Depot

Where are you located?
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Old 19-07-2013, 13:30   #42
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Re: Solar Panels w/Amp Gauges

This looks great Jim,
I'm in Stuart, Florida.
After my last post I remembered that I didn't hear the normal clicking after the starter failed to turn the engine as you would normally with low batteries. I called the people where I had purchased the starter a little over a year ago. He thought perhaps when I had tried starting the engine when the batteries were so low (as in zip) last week, I may have damaged the starter. Does this sound right to you?
This weekend I will pull the starter & have it checed out on Monday.
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Old 19-07-2013, 14:15   #43
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Re: Solar Panels w/Amp Gauges

Trying to run an electric motor on low voltage will draw extra amps & can have a detrimental effect, but if the batteries were really "like zip", then you probably didn't get enough current flowing to have much of an effect.

Another thing that low voltage starts can do is weld the solenoid contacts together. If that had happened, you would know about it because the starter would try to spin until it completely fried & you would still have full voltage at the starter motor now. If that happened, then yes, your starter is completely 100% burnt toast crumbs by now. This possibility is one of the many reasons why it is useful to have a battery switch on a boat.

I would try getting a pair of jumper cables & jump power directly from the battery to the starter & see if the starter kicks. If it does, then you probably have a problem feeding power to the starter. If it doesn't (& you are sure that the battery is OK), then it's probably time to pull the starter.

Depending on what type of bendix you have, it could also be a bendix issue. I don't know what motor/starter/bendix combination you have, so I can only speak in general terms about these things right now.

I'm currently about an hour south of you. If you are really stuck, let me know. I have meters, scopes, jumpers, etc. here.
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Old 19-07-2013, 14:27   #44
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Re: Solar Panels w/Amp Gauges

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Originally Posted by CoCoKnots View Post
This looks great Jim,
I'm in Stuart, Florida.
After my last post I remembered that I didn't hear the normal clicking after the starter failed to turn the engine as you would normally with low batteries. I called the people where I had purchased the starter a little over a year ago. He thought perhaps when I had tried starting the engine when the batteries were so low (as in zip) last week, I may have damaged the starter. Does this sound right to you?
This weekend I will pull the starter & have it checed out on Monday.
Before you do that check the connections on the battery and starter to make sure they are clean and tight. Majority of the time this is the problem with starting. Also bump the key several times on/off quickly. Sometimes that will get it going.
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Old 19-07-2013, 14:35   #45
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Re: Solar Panels w/Amp Gauges

Incredible... Thanks for the offer Jim.
Hopefully I will get this under control without imposing.
Something I did which may have contributed to the issue at hand... When I first
began having low battery problems due to the draw down from the refrigeration load,
used my Honda generator plugged into the shore power connector which powered the Heart Freedom 20 Charger/inverter. Then the Honda seized up. By the time I removed the batteries to be tested & charged... perhaps the starter damage had begun.

Thanks to you too Skip. I will clean the terminals & bump the starter while the jumper cables are in place... They appear to be tight & clean on the starter, but
I'll take them apart to be certain... Before I pull the starter.
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