Author Topic: Intronics MPPT25 - any reviews?  (Read 218 times)

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Intronics MPPT25 - any reviews?
« on: February 14, 2012, 04:53:45 PM »
I've decided to take advantage of the now cheaper-than-ever deals (fire sales?) on PV panels and double the size of my small system.  Thus I need another charge controller.  In recent months somebody's been selling an "MPPT25" controller made in the USA by "Intronics".  See manufacturer's page:
or directly to their document about this device:

It sounds like a useful device, relatively inexpensive, compact, and hefty enough to handle up to about 400 watts nominal panel power (with 12V batteries), and up to 70 volts or so input, high enough to handle two typical "high voltage" panels in series.

But, I can't find any user reviews.  Its small size (about 6x6 inches) and no cooling fan (apparently) makes me wonder if it can really handle that much power?  At the claimed 97% efficiency it needs to dissipate about 12 watts worth of heat.  Has anybody here used it?  A search of this board does not find any hits.  Is it worth taking the plunge?

Funny, even with an inexpensive controller and simple mounting, the incremental balance-of-system is now almost as expensive as the $1/watt panels - and that's not counting the inverter and batteries since I'm leaving those as-is!

BTW, since I posted here a few years back about my adventures with the BZ MPPT500 controller,142874.msg959445.html#msg959445  I've had to send it back to its maker 3 times, that specimen was a non-fixable dud somehow.  Finally he sent me a new one to replace it and it worked OK since.  Except that the digital display is flaky, shows wrong and fluctuating values.  He said there was one version of the DVM chip that was sensitive to RFI from the main controller circuit.  Can't seem to fix that, although I'm tempted to try and encase the display section in a sheet-metal shield.


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Re: Intronics MPPT25 - any reviews?
« Reply #1 on: February 18, 2012, 06:52:24 AM »
I have the BZ250 and the BZ500, neither have a fan. An efficient mppt shouldn't be wasting your panel input as heat anyway.

The Intronics switchable absorption and equalization is a step above the BZ line. Intronics makes a lot of other stuff including dc-dc converters, so I imagine they know what they are doing.

Took some strange internet searching to find a price. eBay doesn't list any under Intronics name but they are here for about $200 including shipping:
« Last Edit: February 18, 2012, 06:59:11 AM by dnix71 »


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Re: Intronics MPPT25 - any reviews?
« Reply #2 on: May 13, 2012, 05:10:11 PM »
Well I took the plunge and tried out this controller over the last 3 months.  In its original form I was not not happy, since the voltage fluctuated over too wide a range in my view (while in "float" mode for example). It would not keep the float voltage close to what my batteries should have, often wandering up close to 14V.  Additionally, every hour or so in the afternoon it would rise up over 15V and trigger my inverter's over-voltage alarm.   

Turns out that, beside continuous small adjustments of the MPP for tracking, it periodically re-does a full "sweep" of possible max-power points to make sure it's still running at the overall optimum.  But, during that sweep, which takes about 20 seconds, it had no limit on the charge current and battery voltage, and when my batteries are full that was enough to bring them over 15V.  This is a 12V 450AH battery system and 360W PV.

After some discussion with the makers of this device, they kindly made me a modified version of the firmware chip, and it's been quite fine since.  It runs fairly cool, but warms up enough to affect the temperature compensation as the sensor is internal, I wish it was external to keep it closer to the battery temperature.

Note that this was a fairly new design so the firmware is still evolving. I don't know if the changes I suggested have become standard in their production, but if not then perhaps one could ask them for the same firmware as they made for that pesky guy in Vermont.

The change they made for me included:
* Narrow the voltage range (in float and absorption modes) to 0.25V.  That's about 2%, and the hardware is apparently not able to make the range any narrower than that, but that's 3 times narrower than it used to be.
* Make the "low float" setting 13.25-13.5V.  (In the 12V mode, nominal voltage before temperature compensation.)  This is lower than what was available before, and closer to what Rolls/Surrette recommend for their batteries.
* Make the "high float" setting 13.5-13.75V.  (In 24V mode these are doubled.)
* MPP sweep is disabled if in float (or absorption, which is just a higher-voltage float).  It is done during bulk mode, and in float if the loads bring the voltage down lower than the float range - it essentially returns to bulk mode under such condition.
* More "night time" before switching the AH logger to the "next day".