#127512  by Meanderthals
 Thu May 11, 2017 3:12 pm
Looking at upgrading my existing PWM controller with a 40A MPPT Controller, probably a Tracer. AA Solar have these in A Series and in BN Series - priced almost the same (only $20 difference). On inquiring as to the difference between these two models, their emailed reply was "BN series is slightly better quality and stronger and has a remote meter, compared to the A series".
I was expecting a greater difference between the models but perhaps AA Solar's reply neatly sums up the position. However could anyone who may have investigated these models give me any further idea as to the pros and cons between the two?
 #127539  by DerekB
 Fri May 12, 2017 6:31 am
I had a BN (30a) before upgrading my solar and now have an A (40a). The A is the newer model and has support for Lithium batteries, but both use the MT50 display.
The A also has a built in display.
 #127553  by Neddy
 Fri May 12, 2017 9:42 am
"The A is the newer model"
The A series came first. Beijing Epsolar Technology Ltd say that the "Tracer BN series is EPsolar’s second generation of MPPT controllers."

" and has support for Lithium batteries"
They both do. Both are fully User programmable.

" both use the MT50 display."
True, and this display is well worth the extra $59.
It enables you to mount the controller in the best electrical position while siting all monitoring and control in the best visual position.

"The A also has a built in display."
One that offers far less functionality than the MT50 unit and if you do get the MT50, any built-in display is redundant and not needed at all.

Take a look at the two controllers. The BN has a huge heat sink and the A....... hasn't.
I know which one will run cooler!

But wait - there is an elephant in the room here. Something that no-one talks about.

The old A series controllers have "positive grounding". This means that, unlike the vast majority of RV solar controllers, all switching, control and regulation is done on the negative output. They are manufactured this way to suit PV telecomm sites which usually operate on Positive Ground circuits to suit the large amount of proprietary 'Positive Ground" equipment used by that industry. That's why the "A" (and "I") series controllers are marketed as "Industrial" controllers.

Such a controller would work with a very, very simple RV system, but things get more complicated if you have the usual negative earth bonding set-up or want to install charging from your tug, or have any "negative earth" equipment installed (eg most any electric fridge).
The first casualty is the solar controller's battery "AmpHours" measurement facility.

There is a lot of information available on the net about this issue. We even have a Forum thread on it.
See http://www.nzmotorhome.co.nz/NZMotorhom ... php?t=5356

Your caravan probably has a "negative ground" wiring set-up - just like your tug. Why make everything difficult for yourself?
Get a "negative ground" controller just like nearly everyone else.

BN controllers are Negative grounded. Lash out. Spend the necessary extra $20 and spring for the MT50 as well. You will be glad you did.

 #127559  by Meanderthals
 Fri May 12, 2017 12:49 pm
Wow, and I almost didn't bother posting about this! Thanks guys. The one line response I got from the supplier was didn't mention the elephant … it must have been hiding under the mat :?

I've found the Manuals and see that these units are a different shape and much larger than my existing 30A Steca (96mm high x 187mm wide) – the Tracer A is 252mm high x 180mm wide; the BN is a whopping 302.5mm high x 182.5 wide. No way am I going to be able to do a simple swap over on my existing powerboard as I had hoped. Could anyone suggest a 40A controller that has a smaller footprint? Or are MPPT controllers just inherently larger because of what they do, required heatsink etc.
 #127562  by Nut17
 Fri May 12, 2017 1:13 pm
Once again Neville, your encyclopedic knowledge in this area comes to the fore once again. :TU :TU

 #127586  by Mick
 Fri May 12, 2017 6:10 pm
Hmmm, I have the Tracer 40A BN Series Controller since 9 month appreciating the big heat sink which pays off in efficiency. Yeah true, I had to re-position it and to re-cable all due to its bulky size taking the chance to throw out some anyway too thin cables. What still remains are the (in my view too thin) cables up to the panels but that's another story & mission.

What concerns me is the positive grounding thing, never thought (and read) about it. I simply connected after the simple and clear signed symbols shown above the connectors saying clearly where to connect + and - of panels, battery and consumers and it works all very fine.
Do I need to worry?

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