"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
"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.