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cduncan avatar image
cduncan asked

Will my Blue Solar MPPT 100/30 ever work right w/out bluetooth?

I recently had an installer install 3 100W solar panels and the above-mentioned solar controller. The bulk charge light is always on, solid blue, althought the Victron BMV-700 says my 2 WattCycle LiPO4 batteries (100Ah each) are charged to 100%. In a previous RV i used to plug shore power into my Jackery. Worked fine. If the (then 1 100Ah lithium) battery wasn't fully charged, it drew about 300W from the Jackery until fully charged, then negligible. With my current system, with the BMV-700 saying the batteries are 100% charged, plugging into the Jackery always draws a little over 700W. I'm totally new to the solar stuff (except using the Jackery) but in investigating this situation i discovered the rotary switch was on the 2 setting, which is for gel batteries. My installer didn't even know there was this switch. I set it to 7 (lithium) thinking the problem might be that on the gel setting, the batteries weren't really fully charged, but switching to setting 7 hasn't changed the behavior at all. And the blue bulk light is always on. I suspect that the generic 'lithium' setting isn't exact enough to fully charge the batteries i have. I'm pretty ignorant about all the nuances of this, but that's my best (ignorant) theory. If this is the case, it would seem there is nothing i can do about it without buying the bluetooth add-on (and installing it myself, since i'm on the road now). Am i all wet about this?

Bluetooth
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3 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Maybe the BMV isn't configured correctly and jumps to 100% to early?

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chrigu avatar image
chrigu answered ·

From 300Wp you can expect about 800Wh per day in the summer. This is very generalised, heavily depends on panel mounting, obstructions, location and of course weather.


But if we take those 800Wh, you can charge your batteries by roughly 33% in a day. You got 200Ah capacity at 12V thats 2400Wh of energy, some manufacturers specify 14V then it would be 2800Wh.


If your also consuming those same 800Wh every day, then the batteries will never get full, thus the MPPT will always charge in bulk. Even if youre only consuming 400Wh a day, it will take a week or even more for them to reach fully charged state

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cduncan avatar image
cduncan answered ·

Assuming the batteries fully discharge in a day isn't realistic. If i draw it down 1/3, then, according to chrigu's numbers, i should be able to get back to fully charged. The general point seems valid, though. I read this and it enlightened me somewhat as to aspects that hadn't occurred to me:

https://www.solarpaneltalk.com/forum/off-grid-solar/batteries-energy-storage/19316-are-you-killing-your-batteries

i hadn't plugged in since my system was installed but i did the last 2 days and the voltage has gone from 13.7 to 14.4, and the float light has come on and stayed on, even as the voltage dropped back under 14V. The above article makes me wonder whether my 300W of solar panels is capable of charging my batteries all the way. But when the meter reads 100%, i have a full day of sun shining on me, and never even draw as much as 100W, it seems like the problem is not lack of energy but the charging algorithm. Thus my original question as to whether there is nothing i can do about this without getting either a bluetooth dongle or the "MPPT Control" or "Charger Control" products (which i just discovered might also allow customization of the charging algorithm for my particular batteries). If i'd known, i would have had the MPPT Control installed in lieu of the BMV-700.

I still wonder, though, whether tweaking the algorithm's parameters would then get my batteries *truly* fully charged? No way to know without actually trying, i suppose. Now that i'm plugged in and my coach batteries are truly fully charged, when i plugged into my Jackery just now, it drew 130W, dropping down to less than 100W in just 2 minutes. I'm not happy about this situation because (if i'm correct about all this) it means that these "optional" products are, in fact, necessary to proper operation (and not killing your batteries prematurely).

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