Tracer 2215RN

on July 11, 2015

I bought the Tracer 2215RN in mid 2014 and wrote a review on it for a previous blog that I no longer run. I will post it here again but add some new information now that I have used it for more than 4 years.

I purchased a Tracer 2215RN MPPT charge controller with the MT-5 meter from Ebay – http://www.epsolarpv.com/en/index.php/Product/pro_content/id/157/am_id/136

I had been researching for quite some time about solar charge controllers before purchasing it. Reading about charge controllers, it becomes quite obvious that an MPPT charge controller is much better than a PWM charge controller. I wanted to purchase an MPPT charge controller mostly because my panel was 24v and my battery was 12v.

Many PWM charge controllers are sold as MPPT, so try not to fall into that trap. Many comments on forums said the Chinese MPPT charge controllers were a waste of money. I didn’t want to spend a fortune and all non Chinese charge controllers are much more expensive than the chinese ones. The Tracer 2215RN had good reviews on Amazon and in other places on the web so I bought it.

To do a good review on the charge controller it is important to get the specifications from your solar panel. Mine has the following specifications:

230 watt 24v solar panel, removed from a house installation. Max voltage 36.78 Max power = 7.53 amps at 30.54v = 230 watts

The output voltage from the panel in full (very strong) sun without being connected to anything is approx 34.7v (measured using my multimeter). The difference between this value and the max power voltage rating can be chalked up to efficiency differences between testing in a lab and the real world and possibly because my panel is 2 years old.

I am using a 12v battery bank so if I was to connect this panel to it (using a direct connection or PWM charge controller) I would get at best 7.53 amps at 12v = 90.36w. This is because when you connect a 24 volt panel to a 12v battery, the panel output is pulled down to 12v. This is where MPPT charge controllers shine, if I didn’t use an MPPT charge controller I would be loosing more than 60% of my (theoretical) solar power output.

Now the 1 million dollar question is – does the Tracer 2215RN do MPPT?

Since the max power output of my panel occurs at 30.54v, you would expect an MPPT charge controller to keep the panel close to this voltage at all times – though this does require enough sunlight to hit the panel for it to be able to sustain that voltage at a decent current output. The 2215RN should charge my 12v battery at approx 19 amps (in a perfect world) when at 30.54v.

To test if the Tracer was doing MPPT I used several different sealed lead acid batteries with capacities between 20ah and 50ah from different manufacturers. All batteries were in working order and were flattened by using the same load – using a 6amp draw (at no load) DC motor. The sun was extremely bright that day (summer in Australia with no clouds), so I know I was getting close to the max amount of sunlight on the panel. When the Tracer was charging a 50% used battery it showed it was charging at 14amps with the panel at 24v. I was getting approx 168w from my panel (14 x 12 = 168w). I was getting more than a PWM charge controller would provide (90w) but I should have been getting closer to my theoretical maximum power of 230w. I tested this on a number of different batteries and settings within the 2215RN. The charge controller was outputting approximately 14amps in all configurations.

Based on the 14 amp current output I get the feeling there is a mistake in the firmware or a deficiency in the hardware where instead of finding max watt output (which is what MPPT is supposed to do) it is outputting the max current. By doing this, it is pulling the voltage of the panel down by pulling more current than maximum power point. If this is true the Tracer 2215RN is not doing MPPT.

Disregarding why it wasn’t, it shouldn’t be providing that much current to a battery as it will damage it permanently. A good rule of thumb for lead acid batteries is to charge at 10% of the rated capacity – 40ah battery should be charged at 4amps. The Tracer was aware of the capacity of the battery as I had programmed the capacity into it (40ah) but didn’t seem to use that setting at all. It seems it just pumps as much power into the batteries as possible (this is confirmed in the manual). This means that the Tracer requires a battery close to 200ah, a smaller battery than this means it will damage your battery(s) over time.

I decided to have a look at the internals of the Tracer so I removed the 8 screws that hold the cover and an easily removed it. There are some interesting components in there:

It uses a STM32 F103C8T6 – if read protection isn’t enabled (untested) it should be possible to pull the firmware from the chip (there is a JTAG interface on the PCB). Then its a simple (for someone with the skills) matter of fixing up some of the issues (battery charging logic, improved MPPT functionality, better timers) in firmware. Imagine a $169 open source MPPT solar charge controller…. The biggest disappointment from finding that it uses this chip is it has a real time clock and yet its not used for the timers, there is even a place to connect the clock backup battery on the PCB. There is a metal plate 5mm that runs behind all the screw terminals so its nice and easy to short it out if your cables are a little too long. The rest of the components look the part but I am unable to see many of them as they are glued to the heatsink. So what are my opinions on the Tracer 2215RN?

Pros

  1. It is cheap in comparison to other MPPT charge controllers.
  2. It does some kind of MPPT, but doesn’t really do MPPT properly.
  3. It doesn’t get hot even in the sun at 14 amps continuous charging
  4. It has an external monitor
  5. It does not have a Lithium or user configurable battery options.

Cons

  1. It doesn’t charge batteries properly leading to them possibly being damaged. The system probably has the ability to limit the current to the batteries but they have not implemented it within the battery charging logic.

  2. It doesn’t have a daytime mode. It’s timers can only be configured so it outputs power at set hour intervals before sunrise and after sunset – this is an oversight. What if I want to run something only during the day and an hour or two either side, e.g. a pond pump?

  3. It doesn’t have a clock so there is no start/stop time options for the output. This would have been a very worthwhile feature because it would have made the Timers extremely useful and not just sort of useful.

  4. The screw terminals are only screws so they don’t get a good connection to the cables unless they are at least 10 gauge. For a few cents more they could have used the screw down tabs – same thing as they currently have except the bottom of the screw is a flat piece of metal.

The Tracer 2215RN has huge potential but it fails at achieving that because of some significant oversights. I could understand if these oversights were expensive to implement but for a total extra cost of a few dollars it could be the go to charge controller for the budget minded (which we all are). The Tracer seems to be an OEM charge controller (sold under many names) therefore the manufacturer can only benefit from more people buying it.

UPDATE:

I have owned this charge controller for 4 years now. I still use it to charge a 105Ah SLA battery that powers my children’s cubbyhouse, my pond pump, pond lights and many garden lights around my house.

My charge controller still works, though it is starting to have problems, which started because ants built a nest inside the controller. The ants shorted out some of the components in the controller until I worked out what had happened and cleaned them out. Current monitoring in the controller hasn’t worked properly since then. I have no plans to change this controller out because it isn’t used somewhere I require efficiency and/or high availability.

I have also installed a Tracer 2215RN at my parents house that charges a 105ah battery using a 250w 24v solar panel. The charge controller turns on at night and powers several high power lights in my parents garden (for asthetic reasons). The charge controller has been doing this job for a couple of years without any issues or maintenance.