PWM or MPPT.

[bazzaboy]

@bazzaboy when you say portable panels are you wanting to be able to connect to other vehicles or is it simply so you can move the panels around to catch the sun?
The best location for this regulator or any regulator for that matter is no where near the panel, mount it as close to your battery as possible. Regulators dont like heat, the sun and the back of panels are great sources of heat. By having the regulator close to battery it increases the effectiveness of the regulator and reduces the voltage drop effects.
Mine is permanently mounted in the patrol, and my panels are easily connected/disconnected via anderson plug extension lead for portability chasing the sun.

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Good info, thank you. This has all come about due to the failure of the original controller that is connected to the rear of one of my twin folding 80w portable panels. I like this set-up as it enables me to relocate them to catch the best sun. I recently had my auxiliary battery fail while away camping. It dropped a cell reducing the battery voltage to 10volt. While checking out the battery I checked the panel's output and found it fluctuating between 7 - 16volts. Not good, and obviously faulty and possibly the cause of the battery cell failure over time.
Taking your advice, and mounting the controller close to the battery would locate it under the bonnet, a place I thought would also be hostile for a controller due to engine heat, or are you suggesting that I locate it in the vehicle? Maybe I should make a small switchboard in the rear of my vehicle to mount the controller and run a red Anderson connector out the back for panel connection, similar to your's, might solve a lot of issues.