Monday, October 26, 2020

Installation and Review of the Victron Energy SmartSolar Charge Controller

OK, all this battery stuff, these last three posts of buying the LiFePO4 lithium-ion batteriesgetting them set up and my backup charging methods, and finally this post on my primary charging method, really happened six months ago now, but I don't ever want to be that guy that writes a review saying "I just got it and haven't used it yet, but it shipped on time and looks good!".

Don't you just want to just reach through the screen and slap that guy silly for wasting your time with his useless keyboard-diarrhea? I know I do. But I felt like I'd had enough real-world experience with the batteries by now that I might have something useful to say.

So here's the wrap-up of my new battery saga.

Now I have my new, and expensive, LiFePO4 lithium-ion house batteries installed and I'm practically bouncing in my seat with excitement (At least until the credit-card bill shows up. . .) but; My primary charging method is via a solar system, a 10 year old solar system.

Y'all know that I'm a strong believer in solar charging for my style of camping, but being 10 years old  means my Solar Boost 2000E charge controller is old enough that it doesn't have the faintest idea what a lithium-ion battery is.

Now you might think charging a battery is charging a battery so why is that important?

(Originally I got pretty technical from here on out, but then had second thoughts about the readability for all but Electrical Engineering geeks - not to mention the impressive length of the resulting post - so I have attempted to simplify - - as much as I know how anyway - -)

(OK, OK, this is now the second try at simplifying this section - -Y'all are just going to have to live with this one.)

The image above is the charge-voltage profiles for the various 12V lead-acid batteries out there, and the profile of a LiFePO4 is actually very similar.

Other than what might look like minor differences in voltage levels (In the battery world 0.1 volts is actually a big deal.) the major difference between lead-acid and lithium-ion is in the timing of the various stages of charge.

For a lead-acid battery the Bulk Phase, where most of the actual charging occurs for any type of battery, ends when the battery is at about 80% full. (Go any farther than that and the electrolyte starts boiling away at a battery-damaging rate whether you have flooded, sealed, or AGM's.) At that point the charger (a decent charger anyway) holds the voltage steady at a pre-set level and starts the Acceptance, or Absorption Phase, during which the charge current will continue to fall as the battery gets closer to being fully charged (which takes many hours with lead-acids) because the voltage difference is decreasing. Once the charge-current drops to a pre-set level or the charger has been in Absorption Phase for a pre-set maximum time, the charger finally drops the voltage down to the Float level and holds it there to keep the battery topped up.

The LiFePO4 is so efficient at charging that the fast-charging bulk phase doesn't have to end until the battery is over 95% full. It then goes through the absorption phase pretty quickly (either one hour for my 200 amp-hours of battery or until the charge-current drops to less than 1 amp, whichever comes first) before reaching the float phase. But this quick-charging, extended bulk phase/shortened absorption phase only happens if the charger knows it's a lithium-ion and not a lead-acid battery hanging off it.

Even with those limitations, technically I could still use my ignorant, but existing and already paid for, Solar Boost 2000E as long as I promised to NEVER push the equalize button. (the high voltage of equalize is not good for lithium-ions!) With that in mind I opened up the back-side of the Solar Boost to tweak the float voltage from its existing 13.8 (Which is honestly too high for wet-call batteries but is a compromise between battery longevity and speed of daily charging) down to a lithium-friendly 13.55 using the adjustment pot.

And I tried to live with it.

I really did.

But after watching things closely for several charge cycles it was clear that not only was I giving up a significant part of the rapid-charge capability of my LiFePO4's, but also, because of the way the charge profile works on the Solar Boost, it would switch right from bulk to float without pausing at absorption. And that's significant because the absorption phase is where the Battleborn's on-board BMS does it's magic cell-balancing act.

So, as if I wasn't in the financial hole deep enough already, I broke down and spent another $160 for one of these.

There are many solar charge controllers out there that understand lithium-ion batteries. I picked this one because at a 20 amp rating it leaves me enough room to add a portable 100W solar panel to my fixed 180W panel if I decide I want to in the future, and mostly because it is featured as one of the chargers that Battleborn has tested, recommend, and sell themselves. (Because of the shipping issue with Battleborn I bought mine on Amazon)

Of course the new charger does diddly-squat for me until I actually install it, so I ripped out the Solar Boost, and while I was at it, the superfluous panel below it that used to be for the charger/inverter that died years ago finally came out too.

This left me with a couple pretty ugly holes. (Which is why I left that inverter panel in there for so long.) Since the Victron charger is a surface-mount, even if it had been exactly the same size as the Solar Boost, which it isn't, I still couldn't use the hole left behind by the flush-mount Solar Boost,

so I resolved that problem by cannibalizing an old-fashioned document holder. (For you youngsters out there, this is what we used to use back in the dark ages when transcribing paper documents, often hand-written paper documents, to computer or - gasp! - typewritten sheets.) I found this one laying in the metal recycling pile out behind the tractor barn. (Around the homestead it's not junk, it's building supplies and spare parts!)

By cutting out a section of the holder, drilling some holes in the proper places, and painting it, I created the recommended non-flammable surface to mount the Victron on, and sized properly to cover up the Solar Boost hole.

I then modified and painted the faceplate for the old charger/inverter to not only cover up that other ugly hole, but to also act as a cable-way/strain relief

and mounted everything back up.

I'm not sure it's any less ugly than the holes were, but it's functional and mostly dwells behind a closed cabinet door, so I can live with it.

Compared to my 25 amp Solar Boost which uses the faceplate as a heatsink, the heatsink on this 20 amp Victron is delightfully robust, but one thing I'm not a real fan of is the wire-connection system it uses.

For one thing, getting a 12 gauge stranded wire into the tiny connector is not a problem if done very carefully to avoid stray "whiskers", but trying to stuff a more robust 10 gauge wire in there, especially with the connectors spaced so close together, is quite a challenge. At the rated output of 20 amps any more than 8 feet of 12 gauge would result in a greater than 2% voltage drop, something I'd rather avoid. (Since I usually see a maximum of 10 amps running through the wire between the Victron and the batteries I can live with the 7 feet of 12 gauge wire that's already installed in behind The Van's walls.)

But the other thing about this type of connector is that they have what I think of as a "soft" connection. That little screw up there on top that is used to pull the wire-clamp closed is - well - little, which makes it difficult to get a good torque on it, and without a good torque the connection is adequate but not what I would call robust.

This is especially true if all you have that's small enough to fit in that tiny hole and reach the slotted clamp-screw is a skinny little jeweler's screwdriver.

So it was a no brainer to sacrifice a "spare" screwdriver to the grinder

and create something small enough to to just barely fit into the hole and big enough that I can at least put a decent torque onto the screw with it.

Because I feel like this kind of connector is vulnerable to vibration as well as expansion/contraction, the modified screwdriver has been permanently added to The Van's tool kit so I can periodically check that the connections stay tight. (Edit June 20: Today is the equinox which means battery checking day and I got an additional quarter-turn out of each of these connections when I tested them.)

OK, the sharp-eyed out there may have noticed that in addition to the solar in and battery out connectors, this model of Victron also has a load out set of connectors.

I could supply The Van's 12V load (Up to a 20 amp max) right from the Victron through these connectors and then, through the VictronConnect app which I'll get to next, I could see the real-time current draw/input on my batteries.

If I didn't already have access to this information, along with much more, through my LinkPRO battery monitor, this feature would be useful, but would require rewiring The Van's 12V system, so no thanks. . .

Unlike the Solar Boost, there are no old-school configuration switches nor a display-panel on the Victron charger, so in the place of those old standbys I had to download the VictronConnect app.  (I'm being drug into the future bit by bit!)

The connection between the Victron and the VectronConnect app lurking there on my phone is via bluetooth. The initial configuration of this was no big deal but connecting up each time I want to check the status of the system is a bit of a pain.

First, since I'm a bit of a freak about security and never leave bluetooth active unless I'm actually using it, I have to turn the phone's bluetooth on then close its connection-request screen before launching VictronConnect. Then, for some unfathomable reason, (after all bluetooth is a short-range device) VictronConnect will not actually see the Victron SmartSolar unless my phone's location feature is also on, which, of course, I always have turned off. So that's one more step (Which I usually forget until I get the error message and have to close the app down and start all over) to making the connection.

After getting my phone to talk to the Victron I was then able to go into the setup menu in the VictronConnect and follow the programming instructions posted by Battleborn to configure this charger for my batteries using the "user-defined" slot in the Victron's battery library.

The Victron comes pre-loaded with different charge profiles for different battery types in its library, and this includes one for LiFePO4 batteries, but the values there differ slightly from the ones recommended by Battleborn and after spending all that money on their batteries I'm sticking with the Battleborn recommendations!

Here I am verifying that the battery voltage displayed by the Victron, which is 7 feet of 12 gauge wire away, matches readings taken right at the batteries with my trusty meter.

OK, I guess I have to concede that there just might be some advantages to dragging myself, kicking and screaming, into the technical world by adding yet another app to my phone.

By moving a switch on the front-panel on the original Solar Boost I could see the battery voltage, (Which actually read 0.15V lower than readings taken directly from the battery) the solar panel input current, or the output charging current. (But only one at a time.)

Through the virtual front panel of the VictronConnect on my phone, in the status tab I can see those things as well as the wattage being delivered by the panel, (I took this photo less than an hour after sunrise on a cloudy day so I thought 23 watts was pretty good!) the amount of current being delivered, and the charge state. (Though I can also see the charge state on the LED's on the Victron itself.)

Here I'm in landscape mode of the history tab and can see the last 30 days of history at once.

But there's also more.

Such as here on the history tab where I can see the charging history for the last 30 days. Up through June 5th I had the empty fridge running just to put a load on the system while The Van was in forced coronatine. Then I turned the fridge off and the rest of the history shows the system dealing with just the parasitic loads lurking in The Van, including the just under 0.1 amp-hour that the Victron sucks down to keep itself operating even when there is no solar input.

Here I'm in portrait mode of the history tab and have to swipe side to side to see more than a few days of history at at time, but the trade-off is that in this mode I can also see more data for each day

 By tapping on one of those daily graph-bars, in either portrait or landscape mode, I can expand it for more detail.

Note that the vertical axis of the history graph is watt-hours and not time. This means that comparing the heights of the bars from day-to-day is looking at watt-hour performance and has nothing to do with time, which can only be ascertained by expanding each day and reading the text in the bar. This was a little confusing at first and it would have been nice if I could toggle between watt-hours and time.

 The data below the graph (In portrait mode) gives me even more information about my system.

I was pleasantly surprised to see that my 10 year old 180W solar panel, which is mounted flat to The Van's roof and not tilted for optimum performance, is capable, in the right circumstances, of producing a peak of 200 watts of power. I've heard of people over-sizing their solar systems by as much as 30% to compensate for the expected drop in output as the panels age, so I would say I'm doing pretty good here!

I took this screen-shot during float-stage so there's not really much happening here.

The trends tab lets me watch two values of my own choosing (Solar volts, current, or watts, as well as Battery volts or current, and if I was using the load output, the load current.) on a realtime graph.

The default is Battery Current on the left and Battery Voltage on the right. This can be changed for each side with the pull-down menu. Unfortunately the app doesn't remember your choices and you have to reset them back to what you want every time you open VictronConnect.

And speaking of opening VictronConnect, there is no buffering of any of these "trend" values in the Victron so I can only see as far back in time as the app has been connected for this particular session. Interesting information but I'm not sure how valuable that really is since I have to stand within blue-tooth range with the app open and displaying for the graph to update. As soon as I step out of range, switch to a different app, time-out the display, or close the display to set the phone down for a minute, the session is gone and I have to start all over again.

To be honest this makes the trends tab seem a little gimmicky. It would be more useful if the data for all the potential values was buffered up inside the Victron SmartSolar and I could reach back at least 24 hours to see just what's been going on.

Oh, and remember somewhere way back in this long-winded post when I said the Victron has front-panel LED's?

These let me know what stage the charge controller is in without the hassle of connecting up the app, which is handy because face it, once the novelty wears off, dragging the phone out of my pocket, logging in, turning on blue-tooth, turning on location, opening the app, and finally tapping on the connection, gets old fast.

But, handy or not, see where the Bulk indicator is a blue LED? You know, the worst color ever for natural sleep?

Well when there is no sun - you know, like at night when I'm trying to sleep - and the Victron is not in any charging mode at all, this LED blinks - constantly - as the controller searches for those solar amps.

And I'm here to tell you that in the dark, in the tight spaces of The Van, that damn LED is BRIGHT! That's right, capital bright.

So I have resorted to a little chunk of black electrical tape, though with the LED bulging out from the case like that it doesn't fit all that well, and when I get over being lazy I'll have to look for some more permanent solution that isn't really permanent, since those LED's are also where I read any error codes so I need to be able to see them.

But, despite all the bells and whistles, the important thing with a charger is does it charge the battery? Does the Victron Energy SmartSolar Charge Controller do the job while treating my very expensive LiFeP04 batteries well?

Oh yeah. It does.

The first day I got the new charger hooked up it was already about 1600, well past prime solar hours, and though it was bright, there were high thin clouds filtering the sun to the point of no cast shadows. Even with those limitations, before the sun set the Victron had managed to pull 240Wh's out of the sky and stuff it into my highly efficient LI batteries, during which I saw the charge current hovering between 6 and 8 amps between the hours of 1600 and 1700, which are the kind of numbers I got out of the Solar Boost with cloudless sky - middle of the day conditions when it was hooked up to the lead-acids.

I think I'm going to be happy with this new battery and charger setup, if The Van ever gets out of coronatine that is.

(Now what do I do with a perfectly serviceable Solar Boost 2000E that has no home?)

Update October 20:

Since installing my new batteries and solar charger, in addition to "driveway simulations", I have managed to sneak in a couple of multi-day socially distanced excursions, including one in triple-digit heat which taxed the hell out of the batteries as they tried to keep up with the constantly-running fridge. 

Spending the money for this lithium-ion system hurt, but like child-birth (or so I've been told any way) the pain soon fades into the distant corners of memory and so far I've been happy with the performance of my new system and have no regrets making the LI plunge.

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