Anderson connectors: if too small, is that a bottleneck?

The Anderson connectors will work great in all conditions. No issue to present.

profdant139 wrote:
Ed, I am the OP, and I am again showing my ignorance here -- why would a 120 wat portable panel (like mine) be immune to a voltage drop? Is the drop worse for more powerful solar panels?

Voltage drop is a direct application of Ohm's Law, V=IR. The voltage across a resistance will equal the current through it multiplied by it's resistance; and given any two of them, the third can be thusly computed.

For a 12 gauge wire, for example, the resistance is (based on a quick web search) 1.588 ohms per 1000', or equivalently 1.588 milliohms per foot. A 50 foot length to the solar panel, with 100' total wire (50' for the positive and 50' for the negative), would have a resistance of roughly 0.16 ohms. The 120 watt panel nominally produces 10A at 12V, so the voltage drop would be 10A * 0.16 ohms = 1.6V worst case.

A higher power system, say 480 watts, would produce more current (40A) and--ignoring the fact that this may well exceed the ampacity of the 12 gauge wire--the voltage drop would be correspondingly greater, at 6.4V. However, if the voltage were higher, and a controller or whatever at the far end of the wire converting it to whatever is appropriate, the current would be lower, and the voltage drop also lower, and the fraction of the loss much, much less.

For what it's worth, an Anderson Powerpole connector for 12 gauge wire has a rated resistance of 0.6 milliohms per contact, or about the same as a few inches of wire. It will not contribute significantly to the voltage drop so long as it's properly installed, kept clean, and generally working properly.

profdant139 wrote:
Ed, I am the OP, and I am again showing my ignorance here -- why would a 120 wat portable panel (like mine) be immune to a voltage drop? Is the drop worse for more powerful solar panels?

The more I read the posts on this forum, the more I wish I had taken some electrical engineering courses in college, rather than a bunch of soft social sciences!! ;)

Your 120 Watt panel can only output about 6 Amps max, ( under optimum conditions. ) voltage drop in the circuit is directly proportional to your current.... and to the resistance of your connecting circuit. You have not stated what your connectong circuit is. May I assume you are going to use 10 gage wire and it won't exceed 30 feet? The resistance of that wire and a single connector plug is so minimal for your 120 W panel that it isn't worth fretting over. Use the connector you want. You will be fine.

DrewE wrote:

profdant139 wrote:
Ed, I am the OP, and I am again showing my ignorance here -- why would a 120 wat portable panel (like mine) be immune to a voltage drop? Is the drop worse for more powerful solar panels?

Voltage drop is a direct application of Ohm's Law, V=IR. The voltage across a resistance will equal the current through it multiplied by it's resistance; and given any two of them, the third can be thusly computed.

For a 12 gauge wire, for example, the resistance is (based on a quick web search) 1.588 ohms per 1000', or equivalently 1.588 milliohms per foot. A 50 foot length to the solar panel, with 100' total wire (50' for the positive and 50' for the negative), would have a resistance of roughly 0.16 ohms. The 120 watt panel nominally produces 10A at 12V, so the voltage drop would be 10A * 0.16 ohms = 1.6V worst case.

A higher power system, say 480 watts, would produce more current (40A) and--ignoring the fact that this may well exceed the ampacity of the 12 gauge wire--the voltage drop would be correspondingly greater, at 6.4V. However, if the voltage were higher, and a controller or whatever at the far end of the wire converting it to whatever is appropriate, the current would be lower, and the voltage drop also lower, and the fraction of the loss much, much less.

For what it's worth, an Anderson Powerpole connector for 12 gauge wire has a rated resistance of 0.6 milliohms per contact, or about the same as a few inches of wire. It will not contribute significantly to the voltage drop so long as it's properly installed, kept clean, and generally working properly.

agree on Anderson connectors.

Solar panel ratings are IMHO designed to confuse and give optimistic expectations. First the panel is rated at maximum ideal output with an incident solar radiation that is seldom found and at a panel temp around 70F. And panels near rated output are well above 70F. But the other real issue is a "12V" panel is really around an 18V panel so a typical 120w panel output is typically 1around 8V @ about 5.5A, not 10A.


And if you are using a typical PWM controller the approx 0.8V drop at 5.5A will not affect charging current at all. (assuming the PWM controller is AT the battery, not panel) With a MPPT controller it will drop current slightly again assuming the controller is at the battery.

Now if the controller is on the panel, unless the run is short voltage drop will have a Significant affect on charging current.

profdant139 wrote:
(This question is an offshoot of my question about cables to portable solar panels -- but since the subject of Anderson connectors comes up in a variety of contexts, I thought it would be better to start a new thread.)

Anderson connectors seem to be very useful for "plug and play" electrical power. I did a little research, and (of course) managed to confuse myself thoroughly.

I see that they come in various sizes. To borrow a phrase, does size matter? For example, if I am using ten gauge wire to draw power from my portable solar panel, but I choose a too-small Anderson connector, have I created a bottleneck that defeats the purpose of the heavier wire?

The obvious analogy is to a garden hose -- if you hitch a 3/4 inch hose to a half inch hose, you are going to be limited to the flow rate of the smaller hose.

Does the same limitation apply to the Anderson connector? And if so, how do I choose the right connector for the job?

Thanks in advance for your collective insights, bearing in mind that lots of us who read the Tech forum postings have little or no technical expertise.

There are two different size Anderson connectors that would be applicable to what you want to do.

First, this one.

Second, this one.

For what you are doing, I would use the second. The first (50 amp) will have a larger contact area, but unless you are very anal about getting every milliamp from your portable solar it is overkill.

If you are going to use it in wet locations, and I am not talking about the occasional rain, the Anderson connectors are not what I would choose. I wouldn't use the Zamp (SAE) connector either.

The problems with the SAE connector is one of gender, and they do not seal well. With the Anderson connectors, gender doesn't matter. With the SAE connector, if not wired with forethought, it can have power available on the exposed pin.

I use all of these connectors at work, and for my personal stuff, I use the second link. They are available in 15, 30 and 45 amp versions, and it strictly depends on wire size, that is the only difference.

dieseltruckdriver wrote:

profdant139 wrote:
(This question is an offshoot of my question about cables to portable solar panels -- but since the subject of Anderson connectors comes up in a variety of contexts, I thought it would be better to start a new thread.)

Anderson connectors seem to be very useful for "plug and play" electrical power. I did a little research, and (of course) managed to confuse myself thoroughly.

I see that they come in various sizes. To borrow a phrase, does size matter? For example, if I am using ten gauge wire to draw power from my portable solar panel, but I choose a too-small Anderson connector, have I created a bottleneck that defeats the purpose of the heavier wire?

The obvious analogy is to a garden hose -- if you hitch a 3/4 inch hose to a half inch hose, you are going to be limited to the flow rate of the smaller hose.

Does the same limitation apply to the Anderson connector? And if so, how do I choose the right connector for the job?

Thanks in advance for your collective insights, bearing in mind that lots of us who read the Tech forum postings have little or no technical expertise.

There are two different size Anderson connectors that would be applicable to what you want to do.

First, this one.

Second, this one.

For what you are doing, I would use the second. The first (50 amp) will have a larger contact area, but unless you are very anal about getting every milliamp from your portable solar it is overkill.

If you are going to use it in wet locations, and I am not talking about the occasional rain, the Anderson connectors are not what I would choose. I wouldn't use the Zamp (SAE) connector either.

The problems with the SAE connector is one of gender, and they do not seal well. With the Anderson connectors, gender doesn't matter. With the SAE connector, if not wired with forethought, it can have power available on the exposed pin.

I use all of these connectors at work, and for my personal stuff, I use the second link. They are available in 15, 30 and 45 amp versions, and it strictly depends on wire size, that is the only difference.

one the sae connector problems is that the Zamp configuration is polarity reversed from the same connector used in many auto applications such as battery tenders. Don't pay attention and you can have a real mess on your hands.

And I agree neither is good for wet locations. Damp yes, but not wet.

Ok I have a portable panel and I ordered MC-4 connectors. Major pain in the operating system so I replaced with 40 amp Andersons. Other than mine are the 40 amp size they are the same as

https://powerwerx.com/anderson-powerpole-connectors-15amp-bonded
I have the official West Mountain Radio Anderson crimper. This pair of pliers does a crimp that is As good or better than factory crimps.

I've used other die crimpers and the GP unit as well all work well but I really like my power pole crimper. As a ham radio operator I have lots of power poles and distributrion panels and such

West Mountain Radio www.westmountainradio.com

Power poles. the Tool and "Rig Runner" power strips I have a 4005 and a 4012
(50 amps 5 pair or 12 pair)

So many great responses -- thanks to all who have posted!!

The controller is currently (no pun) attached to the underside of the portable panel -- protected from the weather, but it sounds like I should try to move the controller to be near the battery.

I'm not sure exactly how much juice this "120 watt" panel provides, but it has been a workhorse -- we point it south, tilt it up on its frame, and away it goes. Most of the time, it provides all the juice we can use -- our group 31 battery never gets below 12.2 volts and is usually at 12.7. (I check with a multi-meter.)

When I redo my cable to a full fifty feet, I will monitor the panel's performance and will post a new thread.

Thanks again for all of the help!