Better wire for solar panels -> charge controller?
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dwh
Tail-End Charlie
Picky, picky, picky. :b
Ammeter is connect in series, voltmeter is connected in parallel.
Bear in NM
Adventurer
A little levity. Finally made it to Lowe's yesterday (2+ hour round trip). I asked about 12-2 wire, and was directed to the main wire area. As the by the foot spools were up in the air, with no one around, I commenced to feeling all of the wire in the pre-wrapped bundles. About like checking egg cartons at the grocery. That was a pain, and the few that were partially open, well the wire had the stiffness of a number 3 rebar. This can't be right. I finally flagged down a gal and she directed me to a different section, the low voltage stuff. duh.
No wire by the roll here, but I was able to cop enough of a feel of the 12-2 bundles to figure out this was the correct stuff. Got a 100 foot roll, and this wire looks like it will work out well. It certainly has more bulk than #12 wire, bundled with zip ties, but I should be able to walk on it and trip over it without worry.
Thanks for the thread, and tips.
Craig
edit:
Finally got my truck's second battery wired to the back, yesterday. Made a couple of new cables with the 12-2 landscape wire. This stuff is fantastic for my Anderson 30 amp connectors, as the sheathing leaves almost no room in the back of the connector for wire wiggle. Cool.
With the truck wired, I could finally hook up and run the right hand side of my portable control center, a Morningstar duo controller. I connected the fridge to the load side of the control center, and fired it up from ambient. Wanting to run a stress test, of sorts.
I also have one of the inline ammeters (like the Kill-a-Watt for AC) that is wired anderson on both sides, so I can place it in line anywhere in my system. I made up about a 40' length of this landscape wire to run to my panel. By the book, this run should be long enough to see a voltage drop. So I just tested it. First with my volt meter. 19.21 volts at the panel plug, 19.21 volts at the end of the 40' run, at my controller. Then plugged in my ammeter, 4.21 amps at both ends of the line. The amps bounce a tad, but that seemed about the average. So my conclusion from this first test is that while voltage drop cannot be argued against in terms of physics, real world voltage drop may not really mean anything for this small of a system. Or I need a new volt meter that will read to the third decimal.
Craig
No wire by the roll here, but I was able to cop enough of a feel of the 12-2 bundles to figure out this was the correct stuff. Got a 100 foot roll, and this wire looks like it will work out well. It certainly has more bulk than #12 wire, bundled with zip ties, but I should be able to walk on it and trip over it without worry.
Thanks for the thread, and tips.
Craig
edit:
Finally got my truck's second battery wired to the back, yesterday. Made a couple of new cables with the 12-2 landscape wire. This stuff is fantastic for my Anderson 30 amp connectors, as the sheathing leaves almost no room in the back of the connector for wire wiggle. Cool.
With the truck wired, I could finally hook up and run the right hand side of my portable control center, a Morningstar duo controller. I connected the fridge to the load side of the control center, and fired it up from ambient. Wanting to run a stress test, of sorts.
I also have one of the inline ammeters (like the Kill-a-Watt for AC) that is wired anderson on both sides, so I can place it in line anywhere in my system. I made up about a 40' length of this landscape wire to run to my panel. By the book, this run should be long enough to see a voltage drop. So I just tested it. First with my volt meter. 19.21 volts at the panel plug, 19.21 volts at the end of the 40' run, at my controller. Then plugged in my ammeter, 4.21 amps at both ends of the line. The amps bounce a tad, but that seemed about the average. So my conclusion from this first test is that while voltage drop cannot be argued against in terms of physics, real world voltage drop may not really mean anything for this small of a system. Or I need a new volt meter that will read to the third decimal.
Craig
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dwh
Tail-End Charlie
You created two short bypass loops - both with just pv/wire/voltmeter. No surprise they both showed vmp.
Pwm is just a very fast on/off switch, so yea, the amps will fluctuate a bit as the PV is rapidly connected/disconnected to the battery.
Probably not so much in bulk stage where it spends more time with the PV connected than it does once the battery voltage gets to the bulk voltage set point and the pwm takes over regulating the voltage of the charging loop.
Also with the Duo, you have a setting for the battery bias - 90/10, 50/50, 10/90. Not sure if it has any behavioral quirks with just one battery connected.
Pwm is just a very fast on/off switch, so yea, the amps will fluctuate a bit as the PV is rapidly connected/disconnected to the battery.
Probably not so much in bulk stage where it spends more time with the PV connected than it does once the battery voltage gets to the bulk voltage set point and the pwm takes over regulating the voltage of the charging loop.
Also with the Duo, you have a setting for the battery bias - 90/10, 50/50, 10/90. Not sure if it has any behavioral quirks with just one battery connected.
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dwh
Tail-End Charlie
Also, I just remembered a couple of posts where guys mentioned vmp changing due to load or voltage drop and I meant to say something before and forgot.
That idea is totally incorrect.
Vmp, which is just a potential, changes based on solar isolation and PV temperature. Load or charging loop resistance does not affect vmp.
The main benefit from MPPT is that it separates the PV from the battery by creating two loops - one for the PV and one for the battery. This allows the PV loop to operate at vmp rather than being limited to battery voltage as the battery loop (always) is.
That idea is totally incorrect.
Vmp, which is just a potential, changes based on solar isolation and PV temperature. Load or charging loop resistance does not affect vmp.
The main benefit from MPPT is that it separates the PV from the battery by creating two loops - one for the PV and one for the battery. This allows the PV loop to operate at vmp rather than being limited to battery voltage as the battery loop (always) is.
Bear in NM
Adventurer
dwh,
I figured I did not quite understand what I was measuring, as I am still trying to learn all of this stuff. I am not running the SS Duo side much at all, yet, so most of my testing has been on the standard SS side. But yes, between the dip switch settings, and what the "brains" in the Duo are supposed to do when one battery is full, I have much to learn. About the only load I have on my Aux truck battery will be keeping my fridge cold, while driving. Once at my destination, then everything gets connected to the battery bank in my suitcase.
I decided to pick up a Samlex SEC1215A charger, and will finally be able to do some proper stress testing of all the components, here at home. I have a pile of unsophisticated chargers in my closet, and have been afraid of murdering one of my new batteries.
Craig
I figured I did not quite understand what I was measuring, as I am still trying to learn all of this stuff. I am not running the SS Duo side much at all, yet, so most of my testing has been on the standard SS side. But yes, between the dip switch settings, and what the "brains" in the Duo are supposed to do when one battery is full, I have much to learn. About the only load I have on my Aux truck battery will be keeping my fridge cold, while driving. Once at my destination, then everything gets connected to the battery bank in my suitcase.
I decided to pick up a Samlex SEC1215A charger, and will finally be able to do some proper stress testing of all the components, here at home. I have a pile of unsophisticated chargers in my closet, and have been afraid of murdering one of my new batteries.
Craig
dwh
Tail-End Charlie
That charger is like a perfect match for the duo.
Only gotcha is that if there is a load on the battery during charging, it can fool the charger into thinking that the battery isn't full, and the charger could remain in absorb mode indefinitely.
They deal with that by having a dip switch setting for what they call "UPS Mode".
I wouldn't really worry about it myself. I'd just keep an eye on it so the battery doesn't spend more than a day or two at absorb voltage.
Only gotcha is that if there is a load on the battery during charging, it can fool the charger into thinking that the battery isn't full, and the charger could remain in absorb mode indefinitely.
They deal with that by having a dip switch setting for what they call "UPS Mode".
I wouldn't really worry about it myself. I'd just keep an eye on it so the battery doesn't spend more than a day or two at absorb voltage.
calicamper
Expedition Leader
Just as a side note. My 8265 watt system uses 12gauge for a max of 16 285watt panels per 12gauge harness. I think the wire discussion us a tad over heated. Pardon the pun.
dwh
Tail-End Charlie
Bear in NM
Adventurer
Sorry for really hijacking, but it sounds like you are perhaps noting hooking the charger up as the input for the Duo? I was not going to do it that way, per a discussion in another thread where I queried just using a "dumb" amp/volt source, and letting the Duo be the brains. In either case, Duo or single battery direct charge, not likely to be any loads on the battery, as this will be my top off after event, charge. And I think the charger choice was based on one of your opinions in another thread.
Thanks,
Craig
Arclight
SAR guy
The Copper terminal for the Anderson Power Pole comes in 3 different sizes - make sure that you are using the right one for your wire, and that you aren't leaving a big blob of solder to hang up on insertion. For small, bendy wires you can either stiffen them up with a bit of heatshrink tuning prior to insertion, or use a small flat-head jeweler's screwdriver to push them in.
Arclight