Use 7-Pin Connector for Solar Suitcase?

JeffroNC

Has anybody used the 7-Pin connector for a solar suitcase? I was going to install an SAE passthrough on both sides of the rear of our 400 to connect a 100 watt panel with built in controller. Then, I remembered that since most camping spots are back in and the sun I am missing with the factory panel is usually in the front of the unit, connecting to the front might be easier.

I realize that it is not ideal with the distance to the battery. Has anybody tried this? Any idea of the gauge of the wiring from the plug to the battery?
I guess I could get a female plug and try connecting a charger through it to test the current? Would this be a reasonable test? I would discharge the battery and connect a 10 amp charger I have and a clamp on ammeter.

Verna

@rfuss928 had a post where he had an SAE plug on a 7-pin connector. I need to find that as I have the parts, I just can’t remember quite what it looked like. 

pthomas745

Here is the thread. 

https://tab-rv.vanillacommunity.com/discussion/8921/add-portable-panels-to-factory-solar-tab-400

Verna

Thank you, @pthomas745 and @rfuss928!  I took screen shots this time and bookmarked the discussion!  I’m going to print it out now because I have too many pots in the fire right now and I’ll forget it it again until I need it right then.

Denny16

It would depend on the 7-pin connection and the size of wire carrying the charge circuit.  At the minimum, you would be deing more wore between the solar charger controller and the battery, which is not ideal.  

You want the shortest possible connection, and at least 8AWG size wire for solar charger connection.  This is why the SAE plug is often used.  It has no 8 AWG wire pigtail, and can be mounted close to where the battery compartment is located.  The longer the wire run, the more voltage drop you get, the less efficient the charging will be.
cheers

rfuss928

Works great for solar and battery maintainer.

JeffroNC

Thanks all. I have the connector ordered and will perform my charging test. If its a bust, I'll have the 7 pin plug for diagnostics.

JeffroNC

So, this took a while. LOL
I discharged my batteries to 60% and connected a simple 10 amp battery charger to the 7pin connector. Here, I am reading 6.6 amps at the connector harness. The shunt seems to agree.
I read 12.9 volts at the connector while the Victron shows 12.2. If I believe the readings, that is 0.7 volt drop through the wiring to the battery. I plan to get a cheap 100 or 200 watt portable set up with a controller and connect it here. I will also try it connected closer to the batteries in the Tab.
I know it is not the optimum setup, but it is cheap and convenient if it works OK.

ScottG

Nice work, @JeffroNC. I'm a fan of simple, inexpensive solutions that get the job done even if the paper specs are not all optimized.

I also use a "cheap" solar suitcase on up to 40' of 12g wire. (Armchair engineers will tell you that's way too small, but I had it on hand so that is what I used--did I mention I'm also cheap?) 

One way I tried to mitigate the voltage drop was by removing  the controller from the suitcase and relocating it closer to the battery. Since cheap controllers are typically PWM, they waste much of the excess voltage coming from the panel. Therefore, by my simple-minded analysis, I'd rather have voltage drop upstream rather than downstream from the controller.

I realize mounting the controller at the battery would negate the use of the 7-pin pigtail, but mounting it on your adapter (as opposed to on the suitcase) might gain you a little extra juice--particularly if you use a long extension on your suitcase as I do.

That said, my own inner armchair engineer (who is not all that qualified) says the voltage drop you measured (12.9V --> 12.2V) seems pretty high for a 10-15' of 10g wire. I wonder if there is not something else at play here, and the situation may in fact be better than you think.  

JeffroNC

@ScottG yes, the drop did seem high and it might be due to a discrepancy between measuring devices. I would connect my meter at the battery but in addition to being cheap, I'm also lazy. LOL 
I'm thinking about this setup and connecting the controller at the 7pin:
Dokio Panel