Any good solar charge controllers that do both lead acid and lithium? (1 Viewer)

[e9999]

especially the iron phosphate ones since it seems that this is where I'll probably be in a while...

Would a regular lead acid controller have flexible enough parameter settings that it can be used for various types of lithium batteries or is that not possible? And I guess that would still leave the balancing issue.

I did contact Victron and asked if they had any such controllers and they said they have some but with no further details except "call our dealers...." And on a cursory glance I did not see any controllers being highlighted on their web site for that purpose.

 

[george_tlc]

lifepo4 batteries are reasonably tolerant of the charge profile, unlike li-ion/poly. You can just set your 'custom' voltage profiles on something like the victron 75/15 (or its various siblings). That's the whole point of being able to enter custom voltage profiles - you can configure them to the battery chemistry you are planning to use.

Or save a heap of money and use standard deep/start marine wet cells. You could buy many decades worth for the cost of a decent capacity lifepo4....

cheers,
george.

 

[Dirty Koala]

REDARC BCDC1225D is the unit I am running. You can select what type of battery bank you are charging (lead acid, AGM, Lithium etc.) It will use charging profiles that are appropriate for the type and voltage range you select.

 

[e9999]

So the Victron charging profile choices (CC then CV etc I assume) is flexible enough that it would work well for lithium, and there is enough leeway in the voltage settings that it would accomodate the lower voltage iron phosphate lithium cells then? And you can do away with the float phase which IIRC is not desirable for lithium? But what about balancing for the lithium cells?

That would be nice if the chargers are that flexible, though, I would like to have to ability to play with lithium batteries a bit. Yup, lead is proven and cheap, but dang these things are heavy and big... And it may well be that in 10 years we won't be able to buy lead acid anymore. There go my 7 or 8 chargers stash...

That REDARC and similar, do they differentiate between the various types of lithium batteries?

 

[Dirty Koala]

Taken from the Redarc site

Multi-stage charging profile

Have the reassurance and confidence that your batteries will be charged to their optimal levels, thanks to a unique multi-stage charging algorithm that provides specific charging profiles tailored to all common battery types. The SEMA Global Media Awarding winning BCDC1225D is perfect for charging AGM, Gel, Standard Lead Acid, Calcium, and LiFePO4 batteries. The unit works with 12- or 24-volt vehicle systems and with either standard or variable/smart alternators.

Dual Input 25A In-vehicle DC Battery Charger

 

[e9999]

Just the iron phosphate then. But that may well be the best one to have or plan for nowadays. If money is no object, that is.

 

[Dirty Koala]

Just the iron phosphate then. But that may well be the best one to have or plan for nowadays. If money is no object, that is.

Yes it looks that way. The LiFePO4's seem to be more tolerant of high/low temps than the regular lithiums...or so I read. I am running my BCDC1225 with regular AGM's, but I got it knowing that if I want to upgrade my house battery to a lithium it will just be a matter of swapping the battery.

 

[e9999]

and nice to know you won't have a volcano of burning lithium going off in the middle of your truck if the charger misbehaves...

Interesting that this unit seems to be built to handle both alternator and solar. Even at the same time is seems.
But I would like to have a built-in meter or an app.

 

[Dirty Koala]

Yes it is an MPPT controler also. The BCDC line of chargers will use solar power over alternator if it is producing enough current.

I want to build in some form of amp monitoring in/out, but have been holding out for Redarc to release their manager 30 in the US market (120v)...last I heard it was targeted for end of this year.

 

[Fj81]

They are bringing the BMS here to the states? That would be sweet! I better start saving.

 

[Dirty Koala]

Last time I spoke to Redarc they were testing the 120v version of BMS

They are bringing the BMS here to the states? That would be sweet! I better start saving.

 

[RFB]

what are you running for

Yes it looks that way. The LiFePO4's seem to be more tolerant of high/low temps than the regular lithiums...or so I read. I am running my BCDC1225 with regular AGM's, but I got it knowing that if I want to upgrade my house battery to a lithium it will just be a matter of swapping the battery.

batteries fuse blocks etc? I may wany to go the redarc route also I have solar and dual batteries now.

 

[Dirty Koala]

what are you running for

batteries fuse blocks etc? I may wany to go the redarc route also I have solar and dual batteries now.

I have two paralell charging isolation systems in my truck.

My start batteries are two Group 31 Duracell AGM's wired in paralell...this is required since turning over the 6BT cummins draws so many amps.

I have a 3rd group 31 AGM in a battery box built into my drawer system, this is what I use for accesseries (compressors, fridge etc).

For primary charging of my auxilary battery I use the redarc BCDC1225D with 40amp blue seas midi fuses on the positive cables.

I also have a blueseas ML-ACR isolator wired in between my starting bank and auxilary battery. This is so that I can combine all three batteries together for jump starting or winching purposes. All of these are mounted inside my rear quarter panel along with and ARB dual compressor and a fuse panel.

 

[e9999]

mmm... I was just looking at some controllers that are said to be specifically for LFP batteries. And I see a mention of floating voltage. Yet, I thought that LFPs do not need nor want floating. Does that mean that those controllers are just ones for FLA batteries where the voltages have been tweaked? It is a happy coincidence I guess that 4 cells of LFP could be charged nicely at 14.4 or 14.6V probably, so very close to the values for FLA.

Disappointed with the lack of response from Victron. And their dealers in Calif are just a few Marine supply types which from I saw have little or no technical expertise in the subject.

Update/Correction: I did talk to a tech from Laurel Technologies, a Victron dealer, who seemed to know what he was talking about. See below

 

[Sandroad]

mmm... I was just looking at some controllers that are said to be specifically for LFP batteries. And I see a mention of floating voltage. Yet, I thought that LFPs do not need nor want floating. Does that mean that those controllers are just ones for FLA batteries where the voltages have been tweaked? It is a happy coincidence I guess that 4 cells of LFP could be charged nicely at 14.4 or 14.6V probably, so very close to the values for FLA.

Disappointed with the lack of response from Victron. And their dealers in Calif are just a few Marine supply types which from I saw have little or no technical expertise in the subject.

One dealer for Victron that can give informed advice is NAWS in Arizona. They sell solar stuff for RVs, including LFP batteries and chargers. Give them a call. Off Grid & Grid-Tied Solar Power Systems | Northern Arizona Wind & Sun

 

[Cruiserdrew]

E-Do you own these batteries yet? A panel? Or is this a thought exercise? I'm sensing ongoing analysis paralysis.

I mean you have been sitting on the solar fence for YEARS, but I do hope you are finally making a move before the beer in your ARB refrigerator gets warm.

Anyway, if you don't own any parts yet, I agree with @george_tlc , that lead acid batteries are still where it's at. Sure they are heavy, but they work for cheap and can be replaced at any Costco. I'd build a practical system around normal batteries. This will save you enough $, to buy every beer you will drink the rest of your life.

And when the future arrives with it's inexpensive and durable lithium batteries, then just buy another charge controller which undoubtedly will then be available. Even a great charge controller at camping power levels, costs less than $150, so it's not like you are talking much money in stranded costs.

But with things changing so fast, and you moving so slow, I would not let cross compatibility of a charge controller influence whether I built a solar system for camping or not.

 

[e9999]

The Tech from Laurel Technologies basically did tell me that, yes, the Victron controllers can be adapted to work with LFP batteries. Essentially by lowering the voltages, but also by reducing greatly the duration of the absorption phase -this last part I did not quite explore as I had to rush out of the call. I need to look more into that bit. As to the float phase, it seems simple enough to set it to the maximum rest voltage which would of course mean no charging, but he may also have said that one can also simply turn off the float phase altogether, don't remember exactly.

I didn't ask specifically if there is enough leeway in the adjustment range of the Victrons to deal with the lower voltage LFPs but he made it sound that way.

That does not address the issue of balancing, but one can get batteries with built-in circuitry for that.

So, altogether, if he's right, it should be OK to use one of the current crop of Victron LA charge controllers and tweak it for LFPs, assuming a suitably equipped battery. Which would greatly add to flexibility in the future, a nice thing.



correction on voltages: see below

 

[george_tlc]

Dear god...

cheers,
george.

 

[spressomon]

 

[e9999]

well, I did some simple checks. My AC LFP charger seems pretty dumb. It just does CC at max amp capability and then does CV forever (as far as I saw). It is advertised as a constant 14.6V (3.65V / cell) but I measured it staying at 14.52V in CV mode with the battery I tested it with. That seems to be consistent with what I read about charging LFP batteries, most say to just keep it at max voltage (3.6V / cell), although I did read someplace that they recommend stopping charging if the current falls below some small value. Looks like my AC charger is not doing the latter, though. But it's a simple inexpensive charger.

Now to transpose this to a solar controller like the small Victrons, well, it seems then that it's as simple as setting both the absorption and float voltage to 14.6V. That way, the duration of the absorption phase should not matter and you will continuously charge at a hair over the max cell voltage when the battery is full. The Victron 75/15 seems able to do that just fine. Hopefully, that's OK for the LFP battery. If worried about that, just set it a bit lower, like 3.5V / cell, the LFP battery should be OK with that, I think, and you would not lose much energy storage, if any.

IOW, if the above is correct, then a good MPPT controller like the small Victrons discussed in the other big thread here, should be just fine for LFP battery charging. And with saved preset settings, you don't have to readjust the voltages everytime you change from LA to LFP or vv. I am content with all that and will long-term test my toys along those lines.






As to LA vs LFP, there are some interesting load tests where the two types are compared. I saw one that was well done if limited in scope. IIRC, his conclusion was that for high discharge rates, the LFP beats the LA for $/Ah generated (!). This is likely because of the Peukert effect which kills the energy available from the LA at high rates. This flies in the face of comments about LA being so much cheaper etc. That was not true at low discharge rates, however. Of course, the LFP beats by far the LA when it comes to lbs/Ah or cycles life expectancy, so if weight is an issue, for example, there is no contest.