[GUIDE] Victron MPPT Smart Shore & Solar Combined

dreadlocks

Well-known member
I've been searching for a nice ~40A shore charger, the only thing I found suitable was a ProNauticP/Sterling Ultra that had programmable settings, but what I really wanted was a 40A Victron Shore charger which they don't make.. in North America they go up to 25A then a big gap til you get to cabin/ship sized loads.. and their chargers don't take universal voltage inputs either, so no importing european variants for use here.

So I got me a 48VDC 624W Power Supply, a couple of diodes, and wired both AC and Solar charging together and use my SmartSolar, Right now I've got a SmartSolar 100/30 but I plan on adding a SmartSolar 100/50 soon for a dual solar charger setup soon so both of my 325W Panasonic HIT's each get their own controller.. one is fixed, one is portable.. Eventually my portable panel and Shore charger will share one SC, and the fixed roof panel will have its own SC.. but to avoid any issues with panels and shore charger being hooked up at the same time they are isolated from each other by a pair of blocking diodes.. I'll get into this later.

Everything seems to work as expected, the SmartSolar does a great job at regulating current output so you can tune your SC to really any PSU you want, big or small, I did some testing with a noisy 325W 24V psu I had on hand and was able to get it to charge my LFP battery at full output all day w/out overloading.

From my research many people have been using bench supplies to test and AC charge through a SmartSolar for a while.. I find threads all over victrons forums, boating forums, etc.. and other than a long ago fixed bug that caused the Victron MPPT to overload them selves it seems to be considered safe and none of the staff are jumping in and warning of dire consequences.. I've graphed output and voltage for hours and they are steady, and solid.. Victron MPPT algo at least seems to have no issues and performs as any normal shore charger would from my observations with 2 different supplies

Would this work with other MPPT Controllers? Probably, but YMMV.. many don't have any current limiting capabilities like victron and could end up letting all the magic smoke out..
However, proceed at your own risk, try this at home if you dare.

Here's some of the benefits I see w/this solution:
  • Exact Same charging logic for maintaining my LFP w/both Solar and Shore charge sources.
  • I can add a second battery in a series for a 24v setup later, add a second identical power supply and keep same SmartSolar and Charge Rate (Amps will remain the same, voltage will double)
  • Global Voltage Inputs will let me plug it into any source of AC power anywhere I find myself.
  • Advanced Victron Charge configuration, great flexibility.. Multiple SmartSolars in parallel will soon coordinate and won't interfere w/each other's charging algos.
  • Low Temp Charging Shutdown for LFP Protection, Remote Voltage Sense from BMV-712
  • VE.Direct integration/monitoring, on a single SmartSolar setup you could monitor both your charger and solar w/a single MPPT display.
  • Remote Field Programming, I can change charge rate, voltage setpoints, and more in the field easy via App without crawling into tight spaces and twisting pots or pressing buttons.
  • Great for LFP Banks with such wide adjustability and solid current control, you can get up to 100A@48V output w/a single unit and its gonna load up a 50A Genset.
  • Testing Charging profile is much easier w/an AC PSU as you can control a lot of the variables now and not rely on the sun at all.
Choosing a power Supply:
With Victron you only need +5v over battery to start the charge, so really any PSU from 24VDC to 60VDC is going to be suitable for a 12VDC system.. The higher the Voltage, the lower the amperage, which will make connecting it with solar later easier to accomplish.. The important thing to pay attention to is the wattage and make sure it meets your desired output requirements, and then some for good measure. You may be tempted to go buy a cheap china PSU and go with it, and I’m not going to stop you.. However keep in mind they are often very loose with ratings so if you burn it up then you got what you paid for.. Hopefully your MPPT survives.
I wanted a nice quality PSU I could count on for the long haul, this meant it was quiet, efficient, robust and came with a detailed spec sheet.. I used mouser and digikey to look at what was out there and compared em to new old stock being sold on Ebay til i found a good deal. ($65 for a $270 supply).
I'd recommend oversizing the AC/DC power supply adequately it only needs to run at ~80% duty cycle for your maximum desired output.. You'll have plenty of overhead, and be running in an efficiency sweet spot of most switching DC power supplies.

Here’s what I was on the lookout for:
  • Active PFC - High Efficiency, Clean Output
  • Global Input - Takes a wide voltage range w/out flipping dips
  • Variable Fan/Quiet - Nobody wants to hear it hum, especially important for lead batteries IMO since it will be at partial output more often than not.
  • Remote On/Off - I want to be able to switch the PSU on/off via easy circuit.
  • Parallel Connections - I want the option to increase wattage for possible future expansion..
  • Medical Rating - Low EMI Output, High Resilience to transients.. Ive got lots of Radios so this is ideal, but also comes with high MTBF promises too.

Here's the spec sheet for the PSU I'm using:
Screen Shot 2019-11-02 at 9.47.14 PM.png

Connecting both inputs together:
A diode is like an electronic check valve, it only allows current to flow in one direction. Now what I've done is used diodes to isolate the two input sources from each other. This is a blocking diode configuration that is widely used in solar installations. You could solve this many ways with relays, physical switches, etc but the goal would always be the same.. to allow both to be wired up together, but unable to see any voltage or current from each other since they are unlikely to be anywhere remotely close and could potentially damage each other or cause a fault.. We dont really want to use both at the same time anyhow, if you have shore power you dont have much need for solar.

If your going to use small portable panels with an onboard shore charger then they are just a simple safety mechanism and you don't need to think much further.. most of the time you'll never have solar AND shore charging even hooked up and feeding at the same time when boondocking.. but if you did, no harm, no foul.. idiot proof.. Alternatively, you can skip all this and do an external shore charger, then just plug both your solar panels and your shore charger into that external SAE port, and wire that to your SmartSolar.

If your going to use this with a fixed panel then you need to put on your thinking cap and take a few things into consideration.. If your solar outputs more voltage than your PSU, you won't be able to shore charge in good solar conditions. You likely don't want to unplug your fixed solar panel when you are charging so we need to make sure the shore charger has priority, we do that by making sure our shore charger output always a higher voltage than my solar panels.. you likely want to use a 48v power supply for most 18-36v solar panels.. If your higher voltage on the solar end, perhaps consider a relay, physical switch over, or two smaller supplies in a series set at a voltage higher than the panels but much lower than the SmartSolar’s voltage rating..

I’m using Axial Diodes, rated at 100V.. They are 15A and you won't find much axial form in a larger current carrying capacity, so if you go over ~13A on your SmartSolar inputs then you’ll have to figure out another solution, but there are plenty of options..
I cranked my 48v power supply up to 55v, which at full wattage output puts it at ~11A, and my Solar Panels are like ~6A, so well within specs.. Be weary of cheap china blocking diodes that don't perform to spec and make sure the voltages have some overhead too.

Wiring Diagram:
Charger-Simple.png

Diode Box, note the silver end is the output and direction the current flows.. outsides are inputs, middle is output.
IMG_20191109_130427.jpg
IMG_20191109_130855.jpg

Parts List:
Testing:
Charging my LFP at a solid, steady state:
Screenshot_20191108-175742.png

100% output on 320W 24V PSU, current properly limited at 23A output to prevent overloading:
Screenshot_20191108-152147.png

more test data coming soon, just gotta finish em up and gather it.
 
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john61ct

Adventurer
Wow, big post, thanks much!

Will take a while to parse it all, so I'll try responding in bite-sized chunks to make dialogue easier.

Look forward to details on the various diodes.

For ensuring only one of A) panel or B) PSU is active at a time, might want to consider a high-ampacity A/B switch like Blue Sea's.

Or even better, dedicate an SC to shore power.

You really want as "transparent" a connection between your panel and the SC optimizing the MPPT algorithm for best power output.
 

john61ct

Adventurer
You are correct in that the "current limiting" aspect of the Victron SCs is unusually robust.

However, best not to try to push "too far" past the 30/50 whatever amps rating.

Obviously you're not getting more amps than that **out**, and it should not be a problem as long as the loads and/or target LFP bank aren't "pulling" much higher than the rating.

But say a big LFP bank was capable of accepting 5kW charge current, and the alternator or 48V PSU upstream was capable of delivering that. I suspect your little "SC as DCDC charger" may get stressed over time, or even let out the magic smoke.

Obviously needs testing, but meantime I think best to use input sources that are oversized compared to the SC but not by a huge amount.

Obviously if their continuous output is **lower** than what the SC will demand, they will need to have good OCP, overtemp protection, etc.
 

john61ct

Adventurer
I can add a second battery in a series for a 24v setup later, add a second identical power supply and keep same SmartSolar and Charge Rate (Amps will remain the same, voltage will double)
The PSU does not need to be serial'd if that's what you mean, if you want higher **voltage** input just buy a new one.

On the output side nothing required except making everything there nominal 24V.

Paralleling PSUs to double the wattage could be tricky, unless designed for that, IMO better again to just get a new PSU.
 

dreadlocks

Well-known member
This specific PSU is designed for going parallel or serial, has a load sync IO, and then that would provide redundancy.. if one died, I would be at half wattage output.. but yeah, even if I have to buy another PSU I wouldent need another SC.

Definitely do not go over the SmartSolar output rating.. I'm derating my SC too, I'll only be outputting 41A from my 50A SmartSolar.. with LFP running these at full tilt it would be bad..

My test at full tilt on the 24v PSU was mostly to see if it would fluctuate enough to tigger an overload, which I never saw (but I did see it when I drove it too high intentionally).. but yeah that POS would likely let out the magic smoke if I ran it 100% duty cycle all the time.
 

john61ct

Adventurer
I'm derating my SC too, I'll only be outputting 41A from my 50A SmartSolar.. with LFP running these at full tilt it would be bad...
You mean too high a rate for the health of your bank?

That's highly dependent on temperature.

But if you mean your BB drop-in, I believe input amps are capped by the BMS anyway? Def stay well below that spec.

But wrt the SC itself, even continuous input at or very close to their rating (30/50A) should be no problem, within my earlier caveats.
 

dreadlocks

Well-known member
I'm planning on charging my Battleborn at 0.4C, it will take up to 1C charge rate before BMS would interfere.. clearly thats not a healthy rate.. from everything I've been reading 0.4C is good for LFP, much higher and I'd be sacrificing cycles.. I cant avoid needing the generator entirely, so when I do need to fire it up.. I want it running for the least time feasible.. which with my daily average ~50-60AH means I just need a little over an hour of Genset time max, usually less because I can get something out of the solar, even when its not enough on its own.

I dont want the long bulk loads from LFP to burry the Solar Charger, or Power Supply at 100% Duty Cycle for hours on end.. so the SmartSolar 100/50 will be running at 80% Duty Cycle Max, and the AC/DC PSU is also running at 80% Duty Cycle Max.

However I'm running my 100/30 at 100% Duty Cycle right now for testing, it seems to be doing fine but the temps are very mild this time of year.. I suspect it could be another story if it was 120F inside the trailer.
 
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john61ct

Adventurer
Dunno, as above, I think wrt ampacity don't need to worry about those SC, and even in Death Valley their internal temp sensing protects themselves if nothing else.

But sure for your peace of mind doesn't hurt to derate
 

luthj

Engineer In Residence
A MPPT controller will effectively limit current in all situations. The bank won't "pull" anything. The MPPT controller is a two stage DC-AC-DC converter, it sets the current passing through the output stage by adjusting the frequency/pulse width of the internal middle (AC) stage. The output resistance (bank resistance) can't cause the controller to exceed its programmed maximum.
 
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john61ct

Adventurer
The bank won't "pull" anything.
Of course the load pulls current from source. You do know even a small say 200Ah lithium bank will quickly burn up almost any size alternator, PSU or DC converter without robust OCP and/or overtemp protection, if there is nothing in between limiting current, right?



A MPPT controller will effectively limit current in all situations.

The output resistance (bank resistance) can't cause the controller to exceed its programmed maximum.
So are you saying you are confident that continuously charging say a depleted 600Ah LFP bank on output,

to make you happy I'll use "capable of accepting" rather than "tending to pull" a 4C charge rate, and that is due to LFP's very **low** resistance,

and a source capable of delivering 600A @48V on the input side,

will **not** put undue stress on a Victron SC rated at 30A?

I'm not saying it will, just that I'm not so confident it wouldn't. Just as a thought experiment, don't waffle about the unrealistic scenario

which BTW actually could happen in several of my use cases.

Of course testing IRL would be ideal, starting with lower rate examples and good temperature monitoring. . .
 
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shade

Well-known member
I've been searching for a nice ~40A shore charger, the only thing I found suitable was a ProNauticP/Sterling Ultra that had programmable settings, but what I really wanted was a 40A Victron Shore charger which they don't make.. in North America they go up to 25A then a big gap til you get to cabin/ship sized loads.. and their chargers don't take universal voltage inputs either, so no importing european variants for use here.
Thanks for the thorough write-up.

It's a shame that Victron hasn't done more to plug this gap in their products, but they'll probably bring some of those chargers to NA eventually. Good thing you don't have to wait.
 

dreadlocks

Well-known member
Today I did a full charge from my 20% cutoff to 100% SOC, took 2h44m @ 30A.. heres the charge profile:
Screenshot_20191110-223314.pngScreenshot_20191110-223443.png

Another 33% output going from 30A to 40A should bring it down under 2h for the same charge I reckon.

I noticed its going right to absorb for some reason, but Ive got it configured to not stoping absorb til its at 14.4v and holding less than 2A and it seems to be working quite well.. I'll keep on doing various tests on it in the coming week.
 
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