Solar controller for lithium batteries

[Canine]

I see Michael hasn't been on for several months, but to answer his original question: Blue Sky Energy controllers can be set to the parameters he wants with the setup he currently has, but he would need the ProRemote if he went with the 3024i to do so. Float mode can be shut off without a ProRemote, but settings on the 3024i are limited down to only 14.0 volts on absorption. With the ProRemote, it can be set from 10.0 to 80.0 in one-tenth increments for either float or absorption or both if that's what you want.

So, yes, 12.4 charging volts without a float is doable with Blue Sky Energy 3024i, BUT only with the optional ProRemote AND all the panels connected in parallel. All three in series would be too many volts.

The 3000i does NOT need the ProRemote; it can go down to 12.0 charging volts and with the float mode off. However, if all three 160 watt panels he has are connected in parallel, that is too many amps making the 3000i too small of a controller. If he connected them in series, that is too many volts, again, this controller is too small. He could connect up to two panels in parallel and that would barely be under the max limit of amps the 3000i can handle. Then he could network another controller for the third panel. The 3000i is an option without the ProRemote, but the system would need one more charge controller if he wanted to keep using all three panels.

 

[John61CT]

Anyone want to recommend off the shelf LFP supplier? I’m probably going to build a very large bank, 500-1000 AH. I don’t want to build up from CALB cells, would rather have a bullet proof BMS-included system to work with.

But all the good "systems" suppliers will likely be *a lot* more than DIY, mostly for wealthy yacht owners

OceanPlanet / Lithionics, Victron, and MasterVolt are the ones I know of.

 

[Technomad]

But all the good "systems" suppliers will likely be *a lot* more than DIY, mostly for wealthy yacht owners

OceanPlanet / Lithionics, Victron, and MasterVolt are the ones I know of.

By “system” I meant combination of battery cells and BMS. This is the most critical part and the thing most likely to get wrong by a DIY project.

My overall system will involve victron components and others. That system I’ll DIY because I know how to do it.

But managing the charging of lithium batteries safely is not to be underestimated.

This is why I mentioned battle born— their cells are packaged with a BMS to manage charging at the cell level.


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[Technomad]

Beware....battle born is even clear on their website that their pre-set specs on the chargers will NOT be the best for longevity.

Can you be specific about what exactly will not be best for longevity? And are you talking about chargers or BMS? I’m looking at their batteries which are a combination of LFP cells and a BMS. There will be many chargers in my system (victron for shore and generator, MPPT controllers for solar.)


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[Technomad]

OceanPlanet is way too expensive, as is Victron when it comes to batteries. BattleBorn is about a %30 markup depending on the value of the BMS. I’ll pay that for an integral BMS, but would think these would be getting closer to commoditization by now.

I first used LFP batteries over ten years ago— I got 18650 prototype cells from A123.




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[John61CT]

> By “system” I meant combination of battery cells and BMS.

Yes that is exactly what I mean.

Even a small such packaged system will cost thousands. You're paying double or triple for the proprietary BMS and a bit of packaging, plus warranty and support.

While buying bare CALB cells can be as cheap as $6-800 per 100AH.

LVD and OVD at the bank level, make sure you don't charge when frozen, is all you really need to protect your investment.

The other BMS protection can be added later if proven "open hardware" ones emerge, and in the meantime just monitor and regulate them yourself. All that takes is a good ammeter and adjustable charge sources.

Active balancing seems more trouble than it's worth when sub-C cycling and avoiding the shoulders.

 

[John61CT]

Drop-ins are a completely separate beast. If that will work for you great, but not really comparable to building a pack from the big prismatic cells.

I'll find my "caring for LFP" summary, thought I'd posted it recently.

 

[John61CT]

Here's my "boilerplate" LFP summary, all feedback is welcome, especially if more "canonical" information from the links cited conflict with my summary.

____

Bare cells: ​Winston/Voltronix, CALB, GBS, A123 & Sinopoly

Systems: OceanPlanet (Lithionics), Victron, MasterVolt, Redarc (Oz specific?)

Note nearly **every** vendor, also those of ancillary hardware touted as "LFP ready", gives charging voltages **way too high** for longevity.

My (conspiracy) theory is that manufacturers would prefer their cells get burned out in under 10 years.

EV usage is very different from much gentler House bank cycling. Most EV people talking "lithium-ion" mean other chemistries not as safe as LFP, much shorter lifetimes, and with completely different setpoints and behaviors.

My charge settings for LFP: 3.45Vpc which = 13.8V max for "12V".

Either stop when voltage is hit, or if you want another couple % SoC capacity, stop when tailing amps hits endAmps of .02C, or 2A per 100AH. Note even at the "low" max charge voltage, letting the charge source continue to "push" even low currents long past the endAmps point is **over-charging, and will** greatly reduce lifecycles.

If you can't then "just stop", set Float at 13.1V, but that is a compromise, and *may* shorten life cycles.

With LFP, you don't need to fill up all the way at all, as far as the cells are concerned, in fact it is bad for them to sit there more than a few minutes. Therefore only "fill up" if loads are present, ready to start discharging, ideally right away.

Store the bank as cool as possible and at 10-20% SoC, or maybe higher to compensate for self-discharge, if not getting topped up regularly (I would at least monthly). Letting the batts go "dead flat" = instant **permanent unrecoverable** damage.

Same with charging in below 32°F / 0°C freezing temps.

Persistent high temps also drastically shortens life.

Charging at 1C or even higher is no problem, as long as your wiring is that robust, vendors may spec lower out of legal caution.

Going above 14V won't add much AH capacity, but will shorten life cycles dramatically.

The point is to look at the SoC vs Voltage chart, and avoid the "shoulders" at both ends, stay in the smooth parts of the curve. And of course, we're talking about gentle "partial C" House bank discharge rates, size appropriately and be careful feeding heavy loads like a winch or windlass.

Following these tips, letting the BMS do active balancing is unnecessary and potentially harmful, just look for LVD / OVD and temp protection. Multiple layers of protection are advised if it is a very expensive bank, don't rely on any one device to work.

Check cell-level voltage balance say monthly to start, then quarterly, finally every six months if there are no imbalance issues, but only if that seems safe to you.

This thread is long but informative

http://www.cruisersforum.com/forums...or-those-using-them-as-house-banks-65069.html

make sure to give both Maine Sail and Ocean Planet your close attention.

Also MS' summary notes here
https://marinehowto.com/lifepo4-batteries-on-boats/

**Everything** at that site is worth reading, very valuable. He also has great articles in Practical Sailor. His new site under development transitioning the pbase content is here

https://marinehowto.com/support, feel free to make a donation to help with those expenses.

Best of luck and do please report back here!

 

[John61CT]

> battle born is even clear on their website that their pre-set specs on the chargers will NOT be the best for longevity

That is true for every. single. vendor.

But you just set your day-to-day charge profile as you think best.

Go a bit higher occasionally with a drop-in, since their internal BMS' active balancing may not kick in until 14.1V or so.

Just set Amps low and leave it going overnight, say every 12-20 cycles as a scheduled maintenance routine like we do equalizing FLA banks.

As long as you follow the real important "DO NOT"s, there's no harm mixing things up a bit once in while, long as the vast majority of cycles follow the " optimum for longevity " recommendations.

Remember 2-3000 really is a pessimistic minimum, and for most people that's already well over a decade!

 

[John61CT]

> would think these would be getting closer to commoditization by now

The mainstream vendors are fighting commoditization tooth and nail, death knell to profits. Eventually Open Hardware BMS projects will win out over proprietary, but that will be a while.

Compared to lead, we're still decades away from LFP building any mass-market penetration.

Pricing won't be coming down either, in fact supply is so limited, as demand picks up prices on bare cells will increase.

 

[John61CT]

> OceanPlanet is way too expensive, as is Victron

Well that is the market pricing for packaged systems.

Which leaves drop-ins, or DIY.

Let's revisit/ what concrete factors are causing you to think you "need" LFP?

I have no doubt they're cheaper than lead long-term ($/AH/yr), but the ROI period is at least a decade, and the up-front investment is thousands including time and infrastructure.

IMO at least 7x lead's pricing per AH.