Awesome new MPPT controller with bluetooth control for $99 (3 Viewers)

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I got to use the new 70/15 the first time for real Mon/Tues on a quick two day one night beach camping trip where I was up till 4AM using the stereo, some light etc. The history tells me the system made 360 Wh for Tues, the one full day of use while parked with no engine running. The times when the battery got down to 12.64 and 12.75 I turned off the stereo for a while.
360 Wh is I think 30 Ah on a total of 225 Ah of battery, but the max wattage for that day was 62W. I don't know if that's because it's all the charger/batteries needed, or if that's all my 100W panel would give. Anyone want shed some light on that last point?
 
At 12.64, your batteries are still basically full, especially with the sag under load.

Until you really use serious power, you won't know what it can do.

But that really doesn't matter. You're keeping up with your loads, so all is good. Fridge? It almost seems like you are not using much power.
 
It sounds like you could have left the stereo on the whole weekend, and not worry about the whole thing :D
Plenty of power, 12.64 is still pretty much full as Cruiserdrew pointed out.
When I have my fridge drawing power and I'm at a place under the trees for two days, it can get to around 12.0 V. But still no issue, everything works (and I can still start the car, since for me it is the same battery, Optima YT)
 
Sure I know I can easily go lower but I'm trying to keep these $400 batteries going as long as is possible. And tunes just aren't that important. Yeah I'm running a fridge too. An Engel 40. The cooler like ABS one. It really kicks arse. :)

I put in a 125 watt amp over the winter (up from 70w) and am still feeling it out power-wise. Not to mention a phantom power draw in the 2 amp or so range that I just can't seem to locate. Also this power usage down to 12.6 is taking place while the sun is sleeping (and I'm not) so no recharge for a few more hours. Of course as you say it's no major deal, I just gave an update of my time with "Old Blue", with a brief description of my usage.
 
@JCruse - live a little bro...It's OK to cycle those batteries! I would not be afraid to run them down to 12.1 or so. No battery lasts forever. Make them do what they are built for.
 
Grrrrrrr!!!

Now I'm considering upgrading my system.

:clap:
 
Ok, as per Andrew's Rubicon power thread, I have performed a bit of testing to see how connecting a load to the load output would work for data logging.

I set up an electronic load to pulse 4A load on/off continuously. 1 second of 4A load followed by 1 second of 0A load, and repeat. Seems to be a pretty decent stress test of how often the Victron unit samples the load current/voltage to calculate power. Given the typical fridge runs for a few minutes and stays off for a few minutes, the Victron will have no issues logging the used watt.hours.

Anyhow, the results look good. Within seconds of (about 20 minutes elapsed from start of the test) the unit went from 0W.Hr displayed to 10W.Hr displayed which is fairly close to what the W.Hr that the electronic load drew from the battery through the mmpt-75/15 unit.

Quite neat, since it means if you wire your fridge to the Load output you basically have a free data logger that will display how many watt.hours your fridge has used (from clearing the history via the bluetooth connected app) versus how many watt.hours your solar panel has put into the battery. The resolution is in 'chunks' of 10W.Hr (not sure why it is so coarse), but accuracy seems to be much better. Certainly useful enough to check on a daily basis when stationary for a few days to evaluate how much your solar system is pushing into the battery versus what your load has drawn out. Allows you to get a feel for what each few degrees adjustment in fridge temperature means in terms of daily watt.hours versus ambient temperature.

I'm going to send off an email to Victron to get a better idea of why the 10 W.Hr 'chunks' and also some info on the accuracy of the current measurements (into and out of the unit). The current seems to be about 7% off, would be nice if they allowed you a way to calibrate the measurements.

cheers,
george.
 
@JCruse - live a little bro...It's OK to cycle those batteries! I would not be afraid to run them down to 12.1 or so. No battery lasts forever. Make them do what they are built for.


Well this past week I took your advice. I paid little to no attention to the gauges for 24 hours, turning on whatever I felt like and leaving it on. The house and start batts were disconnected from each other too so I could judge the one battery AND not let the phantom drain on the starter batt skew the results - not that I was really paying attention to anything.
I don't think the voltage ever got below the previous 12.6 volts as before, bouncing back quickly when the load dropped, and in the morning (by around 9 O'clock) I had a full battery to play with. :)

Yes I like this controller a lot, and I now know for sure that it is better than my previous $100 PWM controller. Not by a ton but enough to make using lots of juice less stressful. :cool:
 
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I was checking the history tab of the Victron app. I noticed that it had a day where it peaked to 171W, while I have a 175W solar panel. That is quite nice for a solar panel which I did not clean at all :)

Also there was a day where it had produced 610Wh. This is perhaps interesting enough to find a solution to plug it in when it is parked at home, and just have a single panel inverter giving it back to the net, reducing my powerbill just a little bit.
(but this is outside the scope of the Victron)
 
Ok, so got a response back from the US distributor of the victron unit. The official response is that the current readings are not particularly accurate and 7% error is acceptable. No current plan to provide the user a way to calibrate or provide some correction points to the readings. I'm not sure that the actual error range is since it isn't documented.

I have some products that I calibrate during production testing, it isn't hard to arrange and does improve accuracy to 1% or better.

Hopefully Victron will at some point provide the user a way to perform a multi-point calibration. Of course it would be best if they performed that calibration during production testing, but that doesn't help with units already shipped. So, allowing the user to take some current measurements at various load levels and then entering those points via the app would solve that issue. Their firmware would then use the spot readings to correct their readings (to compensate for unit-to-unit errors etc).

Anyhow, I won't be holding my breath. Pity...

cheers,
george.
 
Perhaps you could reply on the page of the bluetooth app, as I think some of the guys in development of the app are responding. Or at least Dutch guys "close to the fire" as it is developed here ( I think )

VictronConnect manual [Victron Energy]

Yeah, I figured the next step was to get onto the forum/blog etc and pose the question there. 7% (and I'm sure the full range could be worse) is quite poor and should be easily handled in calibration or with user supplied data/reference readings.

I'll need to run a few different currents through the load (easy to do with my power supply and electronic load) and see if the error (both in and to the load) is mostly linear. If so, that would exceedingly easy to deal with as a single point ratio correction.

cheers,
george.
 
Posted on the victron forum to see if they have any plans to improve accuracy.

You can see the left column is actual measured current (much better than 1% accuracy). The 2nd column is the current the victron reports as coming from the battery (power supply) and the 3rd column the current the victron reports as being delivered to the load. Clearly about a 6 to 7% error in reported current.

Pretty obvious that the error is linear, so correcting would be trivial. Enter in a correction factor (ratio) and have the unit multiply each current measurement by that factor.

Anyhow, we'll see if victron has any interest in adding that feature to their app...

cheers,
george.

ScreenShot027.jpg
 
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Im sitting on the beach for the third time this week and I just can"t kill this thing. No matter what I do with lights, stereo, and a nice 27 degree fridge the one house battery wont go below 12.7. I cant make it drop below at most 12.6 at night and as of 9 AM its back to full. I really like this charger. Completely care free power use.
 
Well, Victron posted on their forum/blog in response to my measurements/chart that they will keep it in mind for development, so hopefully we'll see an option at some point to enter in a correction factor into their app.

Hopefully...

cheers,
george.
 
Well, I guess you just have to wait. It will probably have consequences on all readings.

Despite that, I'm happy to see that my 175W solar panel seems to be performing well.

As you may notice, the voltages are in fact getting lower sometimes. This is just because I have a door fridge which also has a freezer inside, and is set for pretty cold. And just one Optima Yellow Top. (and this is not on a sunny beach)

Screenshot_2017-07-16-11-59-13.png
 
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Something very strange happened.....

Every time I check history the voltage starts the day at 12 something. Usually 12.7, but always 12. _ .
However the start voltage two days ago says 6.47! I did an overnighter that day but I did nothing different that night. Certanly nothing that could possibly account for that!
I usually turn the low amp fan off for the night while sleeping but it was so hot I left it on. Thats all. And Ive done that before too.

Has anyone experienced any glitch in the history like this? Thats all I can think of.
 
I read through the manual and it says the absorption voltage is adjustable, but it doesn't say how. Is this possible, and does the software explains how?
Drew where can I learn more about my renergy mppt? I have a rover 40amp MPPT and it has the display etc but I cant figure it out at all the manual does nothing and Im pretty good with shiite like this. cant find any decent vids either
 
Drew where can I learn more about my renergy mppt? I have a rover 40amp MPPT and it has the display etc but I cant figure it out at all the manual does nothing and Im pretty good with shiite like this. cant find any decent vids either

You're kind of on your own here. I tried to program a Renogy controller and thought it was confusing as heck. Like they wanted you to do the default settings only. I'd call them as their manual is Chinglish and difficult to get the sense of. Now if you decide to get the MPPT from Victron, I think a bunch of us can help you at this point, and, it's pretty intuitive. I looked briefly at the Renogy website and did not find it particularly helpful. Good luck!
 

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