What would be the top 3 best MMPT controller for Lithium?

perceval

New Member
I understand this is an ever changing world, but I'm in the process of building now, so this is is! :)

What would be the top three MPPT controller for charging Lithium batteries, just by selecting the "Lithium battery" in the menu?
My head is spinning from all the things I have to take care of while building my van alone, so, if there was a unit that would be "mostly" plug'n'play, it would really be helpful.

I have a 400ah battery, and planning to have between 300w and 500w solar on the roof.

I have looked at SRNE, Renology, Epever series, Victron, and a bunch of no-name controllers and there's no helpful info saying how the units work, just specs, but nothing how user friendly the unit is!

Thanks a bunch!
 

Pappion

Retired Engineer Tech
I like my Victron Smart SCC. Networks well with the Smart Shunt. Like the bluetooth Smart Phone app. It shows history and setting changes are easy. Downside: Forced updates may fail. Try another phone, and/or keep other bluetooth away. Keep a record of it's PIN.

I had an EPEVER 20A. PIA to setup communication, mostly on the windows end. Some models do not have lithium setting. User Custom setting may not be default power up. Mine lost the settings after extended power down.
 

mikefitz

Solar Addict
I recommend a Victron product. With a 12v battery a Victron Smart solar 100/30 or 100/50 would be suitable.


You have the advantage of user adjustment of settings to get best performance and long life from the battery. Also via the app you have accurate information on performance, including history of the last 30 days solar yield.

The comment on failing of forced updates perhaps explaining.
All Victron products with Bluetooth can be updated via the app. This feature allows you to have the latest operating software in the unit. I have never had a problem with this.


The default setting is OK to get you started but you will find as you gain experience that being able to 'customize' settings easily via the app is a huge advantage. For example if the RV is not is use for a while, having a charge profile that keeps the battery at a moderate state of charge is useful in prolonging battery life.

Solar charging in an RV situation typically results in a variable and relatively low charging current compared to the 0.5C that the battery could take. The effect of charging a 500Ah battery with currents less than 30 amps results in the battery reaching full or almost full charge by the end of the bulk stage. Being able to adjust the absorption stage period to a lower time than default could be useful.

Mike
 

perceval

New Member
Thanks for the answers so far.

Had hoped that a company would've done a nice setup for lithium that wouldn't need too much tweaking!
Takes me 3 hours to wire up a 3-way switch... and a few trips to the breaker!
A few searches on Google didn't come up with much info relating to bulk / absorption for lithium. Why is it such a guarded secret?

My camper gets used pretty much every weekend... unless the weather is really bad.
We have 3-day weekends so we try to escape at least 2 of those days ... usually to the beach.

I was dreading the Victron answer... as it is the product that is the hardest to get over my place (expat in Asia).
Plus, the videos showing the flimsy connectors made for small wires only was kind of a downer, as I was looking at a 40A unit at least.
 

mikefitz

Solar Addict
the flimsy connectors made for small wires only was kind of a downer
The Victron specification for the terminations is a maximum of 16mm2 or AWG6. Pin crimp terminals can be used to give a neater connection.

info relating to bulk / absorption for lithium. Why is it such a guarded secret?
The bulk stage is where the controller pushes as much current as possible into the battery until the voltage on the battery reaches the 'target voltage'. The target voltage may be have the term 'boost' or 'absorption'. Once the target voltage is reached the controller goes into a constant voltage mode for a time duration, the absorption period or in Epever speak, 'boost duration'. Ideally the duration should be terminated when the current falls to a pre determined value. This will be variable depending on battery capacity, type, target voltage and available charge current. To account for all possibilities most controllers have a set time default of two hours.

In an RV application with a large lithium battery and variable low charging currents there is the high probability the battery will be charged by the time the target voltage is reached.
Thus it may be an advantage to have a short absorption period and then drop to a suitable float value.
Unlike lead acid batteries lithium has low self discharge so with a lithium set up one should regard the 'float' condition of the charger as an auxiliary power source to power RV loads, operating in parallel with the battery. Float voltages in the range 13.4 to 13.6 would be suitable.

There is evidence that keeping the lithium battery continually in a high state of charge will shorten service life. Since with most charger default settings the battery will be fully charged each day when the vehicle is not in use ( and has no constant battery loads), having the ability to modify the charger settings so the battery is operating in a less stressful region will be useful.

If its easier to obtain the Epever 40A unit in your area this would give acceptable results. Adopting user settings may be kinder to the battery.

Mike
 

fratermus

Solar Enthusiast
/raises coffee mug to the Victron Mafia out in force this morning :)


A few searches on Google didn't come up with much info relating to bulk / absorption for lithium. Why is it such a guarded secret?

It's not a secret, it's just not relevant to charging lithium {at the rates we do in DIY solar contexts}. It's like asking why it's a guarded secret how much chocolate milk chickens drink each day. They don't.

The terms are in the discussion because multi-stage chargers have historically been used for lead chemistries. In a lithium context they can be understood something like:

* bulk - max charging current is typically restricted to C/2 or less for longevity
* absorption voltage - highest voltage you want the bank to ever see. 100% SoC for 4S LFP is 13.8v but vendors typically specify 14-14.4v overvoltage to allow top-balancing. The excess voltage is used up by the balancing circuits.
* absorption duration - relatively short, just long enough to do the balancing.
* float voltage - fallback voltage after charging in order to keep the bank from sitting at 100% SoC. Typically ~13.4-13.6v. High enough to keep capacity, low enough to avoid the stresses of hanging out at 100% SoC.
* equalization voltage - not used, but should be set to Absorption voltage to keep it from going any higher (lead EQ happens at high voltages unhealthy for Li)
* equalization duration - 0 minutes, or as few as possible.

a nice setup for lithium that wouldn't need too much tweaking!

Configuring setpoints to battery/cell manufacturer recommendations is optimal. I would configure my own to mfg specs over using the fanciest preset on the fanciest controller. Maybe I have trust issues.

{edited to add qualifier and add link}
 
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perceval

New Member
Alright, I see the point of configuring two presets... one for when the battery is not in used, resting at a lower state, and one to bring it fully charge for operation duties.

So.... Victron.
Keying in my data, roughly 400w solar (2 panels of 200w), I get the 100/30 in the MPPT calculator.
That unit is $200 on Amazon with shipping, but locally... $400.

Locally I can get the SRNE, the older bigger box, not the little thing they sell now that I heard catches on fire!
That one, I can get the 40A version for about $75. Quite cheaper.

I'm including the info on the SRNE.

Is the Victron really worth the $125 extra?
 

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perceval

New Member
The cheapest I see the 40A srne mppt is ~$130. Is the the $75 a special deal?




Only you know if it's worth it to you. Victron has a loyal following and I will assume that is for good reason. OTOH, others (like me) do fine with gear of lesser pedigree.
Directly from China, on taobao site... a bit cheaper.

And which one do you have? if you don't mind me asking... :)
 

fratermus

Solar Enthusiast
My main controller is an EpEver BN-series. The portables run on a separate A-series controller. Zero issues after 3 years offgrid in all kinds of temperatures, and with substantial ovepaneling.

BN: the Victron bluetooth app is miles ahead of the Epever app in design and function if that matters to you.
 

Q-Dog

Solar Addict
After reading all of the problems people have when setting up their gear I set up my Victron and I thought I had possibly skipped a step or two. It was simple and took very little time. Has been running without issue for a while now and the only time it was shut down was when I turned it off to neaten up some wiring.
 
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