LiFePo4 batteries

[jonyjoe303]

All I was putting out was lifepo4 will catch on fire. People can believe it or not. Its worst case scenario but it will catch on fire. If treated properly like anything else they are safe, but you have to always plan for worst case, like car wreck or dropping it etc. Myself I wasn't expecting to see the lifepo4 cell catch on fire, I thought it was impossible. 

This applies to home build or store bought, lifepo4 is lifepo4. The lifepo4 cell that caught on fire are high-end cells use on electric city buses, these weren't cheap no brand cells. Too many comments about how safe lifepo4 are thats why I had to share my experience. Some people might get complacent around lifepo4 from hearing how safe they are. I'm still using lifepo4, fire hazard is no worst then the li-ion cells, but its still there. Worst case scenario. 

" I've been using the stock LiFePo4 profile in the Victron controller recently, it matches the manufacturers specs on my LIFEPOs pretty closely, it seems a bit high but works (14.4 bulk/absorb and 13.5 float). I know it seems a bit high, but I heavily use power during the day and it works well. I turn down both numbers a lot when storing. I found when turning bulk down low, like 13.8 volts that it seriously reduced the available AH on the battery. I know what all the lithium theory says, but in use I found it was way too low. If you are a light user of the batteries, or have a bunch of them, maybe that would work." 

To fast charge your lifepo4 you need to set the absorb voltage high, I got mine set to 15.2 volts (because of voltage drop). at that voltage the battery reads about 14.4 volts and then it switches to float which I have set to 14.5 volts. At 15.2 volts I get the max amps the 240 watt panel can put out I seen up to 15 amps, once it switches to float the amps go down to about 2 or 3 amps. That will top off the battery slowly. I never get a full charge maybe 98 percent. I have had these setting for the past 3 months and it works perfect for my lifepo4, it fast charges quickly every day.
I do have a coulombmeter meter connected so I know exactly how many amps I use the night before, and the next day will know if the solar system put those amps back in. I also can read each cell voltage max for lifepo4 is 3.65 volts, the most I ever see is 3.55 volts while float charging.

I notice the higher the absorb voltage is, the more amps you battery will get, even 14.4 volts would be on the low side for me, even for float. I measure all the voltages at the actual battery and go from there. If I rely on the controller the battery will slow charge all day, never using the full potential of your solar panels. Lifepo4 will easily use every amp of power your panel can put out right up 95 percent if its in perfect balance.

 

[tripper]

I have my Victron controller about 2 feet from the battery, it is using 4 gage copper from the controller to the battery so no drop in voltage. On a normal day it will start out slowly at first due to sun angle, but is normally fully charged in 3 hours after first daylight.

I do have a continuous readout voltmeter display in my rig so I can see the voltage of the lifepo. I wouldn't mind a SOC meter but just has never been a priority as I have a good idea when my battery is low. Plus they are a bit expensive.

I have other Victron controllers that are located far from the battery, those ones I do find the voltage drop and adjust the voltage up on the controller to compensate.

I tend to use a LOT of electricity when I am actively using the rig, for example overnight a 120V electric blanket and sometimes CPAP, which bring batteries down to about 50% charge, then actual electric coffee maker, then cook breakfast on induction plate, then charge the e bike battery (52v 15ah). Often have TV/youtube going while doing all of this, plus a 12v compressor fridge and cell booster running continuously. On the stock Victron Lifepo profile it seems to do just fine, when I reduce the voltages I see the battery starts to hit the low end of the voltage scale overnight (12.6), and if it is warm out have 5k ac running.
I did very recently get a 2nd lifepo battery but have not wired it in yet (2nd one is same as the original).

The battery manufacturer even states the bulk absorb should be 14.4, it claims to have a BMS but I have no details on it. The battery does work well.

 

[John61CT]

All I was putting out was lifepo4 will catch on fire.

No one says they can't.

The context is people fantasizing about putting other lithium chemistries to work as mobile House banks. To which the response is No, since they are much more susceptible to thermal runaway, and require sophisticated safety and cooling infrastructure even engineers with huge resources at their disposal are having trouble making bulletproof.

But even with DIY protective systems done by a knowledgeable amateur, LFP is safe. With thousands in use, no known instance of any fires afaik. Soon ABYC standards will even allow for boats to get insurance with such banks - but LFP systems and LFP **only**.

> I thought it was impossible. 

Then you shouldn't be messing around like that IMO.

> Some people might get complacent around lifepo4 from hearing how safe they are. I'm still using lifepo4, fire hazard is no worst then the li-ion cells, but its still there.

Again no. Only LFP is safe enough for that use case. But even lead batts regularly explode an burn the place to the ground. And propane, and gasoline.

 

[John61CT]

14.4 bulk/absorb and 13.5 float

> I never get a full charge maybe 98 percent

You define Full at whatever spec you choose.

As long as you know following the mfg definition, you're sacrificing lots and lots of lifetime, will likely only get mfg spec'd cycles, as opposed to many times more

> the most I ever see is 3.55 volts while float charging.

My Stop point is 3.45V, and LFP should never be Floated if at all possible.


> Lifepo4 will easily use every amp of power your panel can put out

I've never heard of anyone setting that as a goal, seems very odd to me.


> If you are a light user of the batteries, or have a bunch of them, maybe that would work

I consider 200-600AH a normal range for light House bank use, and would never use packs made from the little cylindrical cells for that.

 

[John61CT]

I did very recently get a 2nd lifepo battery but have not wired it in yet (2nd one is same as the original)

That will help with your capacity problem.

If you find you can then make 13.8V (and just stop) work for you, stick with that.

You may get 4-6000 cycles or more, maybe 10K, assuming no catastrophes or abuse.

With those drop-ins, we just don't have expert long-term experience like Maine Sail's with the large prismatics, but LFP is LFP, so should be comparable.

 

[DLTooley]

I'm missing the specific brand/source of LiFePo4 batteries you folks are referring to.

 

[John61CT]

Here's my "boilerplate" LFP summary, mostly from marine electrics discussion forums involving long-term users and professionals, with special thanks to Maine Sail (see below).

See just below for a complete list of known-good brands.

Any and all feedback is welcome, especially if more "canonical" information from the links cited conflict with my summary.

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

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

Best to size your cells for two parallel strings for redundancy, unless you have a separate reserve/backup bank. Don't go past three, or you may see balancing issues that affect long-term longevity, maybe four in a pinch.

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 4S "12V".

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.

Either "just stop" charging when voltage is hit, or if you want another couple % SoC capacity, stop when trailing amps **at your spec'd voltage** 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.

So if you can't then "just stop", set Float well below resting Full voltage, at say 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 consumer loads are present, ready to start discharging, ideally right away.

Many sources claim there is a "memory effect" from keeping charge voltage and ending point exactly the same every time lower than manufacturer specs, that can apparently over time lead to apparent lower capacity. The recommended fix is to "go higher, into the shoulder" every so often, similar to "conditioning" a FLA bank monthly. To prevent the issue, vary your setpoints a bit, sometimes go a point or two higher or lower, vary Absorb time a bit etc. There is no consensus just how serious the problem is.

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.

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

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, so you don't rely on any one device to keep working.

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!

 

[tripper]

The battery I'm using is a drop in replacement EWT battery (EVERWIN TECH CO) EWT BATTERY

[img=325x244]https://cdn3.volusion.com/qqfae.xpkny/v/vspfiles/photos/FZ-12-100-LIFEPO4-2T.jpg?1513280016[/img]

 

[DLTooley]

I found an EWT on Alibaba, around $450 for a roughly equivalent two golf cart battery alternative. **Without Shipping**

https://www.alibaba.com/product-det...ml?spm=a2700.7724857.main07.57.182349bbjDs5Yv

Renogy has one for $900, shipping included - and **sold out**. A 10% off online coupon popped up on my search.

https://www.renogy.com/renogy-lithium-iron-phosphate-battery-12-volt-100ah/

 

[tripper]

I found an EWT on Alibaba, around $450 for a roughly equivalent two golf cart battery alternative.  **Without Shipping**

https://www.alibaba.com/product-det...ml?spm=a2700.7724857.main07.57.182349bbjDs5Yv

Renogy has one for $900, shipping included - and **sold out**.  A 10% off online coupon popped up on my search.

https://www.renogy.com/renogy-lithium-iron-phosphate-battery-12-volt-100ah/

Yes, my 2nd one I got directly from the company via Alibaba, the prices are insanely good.  The first one I bought off of Ebay for $650 or so.  The Renogy I am 99% sure is the exact same battery, only the case color differs. The ribs, bolts and casting marks all in the same place. I used PayPal with a credit card so little chance to get ripped off.

My 2nd one is actually a 50ah little miniature one, looks the same only smaller, I needed it for my ebike for a project, but I tie it into the RV when I am not using it on the bike.

BTW shipping was cheap I think $36

 

[RVTravel]

The EWT batteries say do not store above 140 degree F. Would that be a problem left in a vehicle in the Texas summer heat?

 

[Ticklebellly]

Have four new 50 Ah cells in my hand. Will charge to 3.65 per cell and balance when necessary with a HTRC B6. Battery disconnect is set to 11.8 volts. 3.65 and 11.8 are on the advice of the supplier. Supplier has been building EV cars for more than 11 years and, is local, so will take his advice. Supplier says there is a little surface charge effect evident with the cells supplied and says that if charged to 3.65 per cell then rested, a rested voltage of 3.55/3.54 should be the result and considered to be fully charged for my purposes. For those familiar with the B6 device, popular with the Hobby crowd, it makes doing a capacity test quite an easy task. My supplier expects me to measure a capacity of about 45 Ah at those voltage cutoffs. I will run a few full to empty cycles in the back yard before I do a capacity test.

My current house battery is a 110 Ah AGM that is 10 years old and will not hold more than 12.55. This AGM has had a flogging but still handles the fridge and lights and TV and Laptop, so far. Weight comparison for about 50 Ah usable capacity is 38 Kg for the AGM and just over 6 Kg for the LiFePo4 pack, strapped, and with connectors. Volumetric size of the Lith pack is tiny by comparison and Oh So portable. Longer term plan is to make another Lith pack and do away with long leads to the solar panel when I want to park in the shade.

 

[RVTravel]

Itripper, would you have a link to the 50ah EWT battery you bought?

 

[John61CT]

EV usage patterns are extreme, almost violent, compared to House usage.

Experience in the former does not transfer to the latter with regards to attempting great longevity, in fact all the unlearning would probably make things harder.

LFP prismatics are pretty rarely used in that world, could you link to the cells supplied?

Again, those setpoints are way too high, but if you are willing to accept the rated # of cycles, it's your setup.

 

[John61CT]

The EWT batteries say do not store above 140 degree F. Would that be a problem left in a vehicle in the Texas summer heat?

All batt chemistries' lifespans afaik are **very** negatively impacted by extreme heat.

Sometimes nothing can be done wrt operating conditions other than locating away from obvious heat sources. Expensive banks are much better off inside the climate controlled living spaces, never in engine compartments. Ventilation helps of course.

But for long-term storage, when the bank is not in use, should be as cool as possible.

The idea is, if you're striving for X thousand cycles lifetime, but the bank is unused for long periods, at some point the impact of "calendar aging" becomes dominant, and there low SoC and cool temps are the two major factors.

 

[DLTooley]

Itripper, would you have a link to the 50ah EWT battery you bought?

Here's the EWT page on Alibaba.  I didn't dig deep, but the only 50ah I saw were in quantities of 20 - at a very good price.

That market is going to be fluid, hopefully running downhill - but with the tariff's etc who knows.  Do recall what the oil and gas folks did to Jimmy Carter and the Democratic party re: Nuclear Power and 55 mph speed limits.

http://ewtbattery.en.alibaba.com/

 

[tripper]

I purchased the battery on Alibaba, it was one of the generic EWT ads where you could choose size and quantity. I paid for it via pay pal which itself is linked to a credit card so I had great protection. I don't have the exact link to the one I bought but with some searching you should be able to find it.

 

[Ticklebellly]

New LiFePo4 battery installed and in use.   Saved 31 Kg and about 1.5 cubic foot volume.   Four cells and some electric bits now sit in a re- purposed 6 Pak Esky.    Gained portability and faster charging.   Only negative so far is increased supervision when charging.   Consistent advice has been to charge the battery and do not leave on float so I am keeping an eye on charge progress and disconnecting when charged.   My major energy use is the fridge and I do like to have a cold beer at the end of the day.   Not exactly a "plug and play" replacement but am using existing DC to DC charger and and only added a couple of digital voltage readouts, a Low Voltage cut out, and two keyed battery isolators.   Buying four cells and the few extra bits to build the new system only cost about 15% more than the equivalent AGM replacement for what I had before.

Will buy another four cells and will build another battery when the LV cutouts arrive from online.


Once you go Pee Oh Four, never going back!!!

 

[tripper]

New LiFePo4 battery installed and in use.   Saved 31 Kg and about 1.5 cubic foot volume.   Four cells and some electric bits now sit in a re- purposed 6 Pak Esky.    Gained portability and faster charging.   Only negative so far is increased supervision when charging.   Consistent advice has been to charge the battery and do not leave on float so I am keeping an eye on charge progress and disconnecting when charged.   My major energy use is the fridge and I do like to have a cold beer at the end of the day.   Not exactly a "plug and play" replacement but am using existing DC to DC charger and and only added a couple of digital voltage readouts, a Low Voltage cut out, and two keyed battery isolators.   Buying four cells and the few extra bits to build the new system only cost about 15% more than the equivalent AGM replacement for what I had before.

Will buy another four cells and will build another battery when the LV cutouts arrive from online.


Once you go Pee Oh Four, never going back!!!

I set my float to just barely below the resting voltage so that when my fridge kicks on float will also kick on and throw enough power in to compensate for the fridges use (or anything else that may be drawing power).  When nothing is drawing power the float is not constantly charging. For example if the battery resting full charged is at 13.3 volts, I may set the float to 13.25 volts, usually any device kicking on will drop the volts enough for the float to kick in, and when I shut off the device the voltage rises high enough that the controller is not outputting anything. This way the battery is always at 100% charge when night comes so i have full usable capacity.

 

[John61CT]

 Buying four cells and the few extra bits to build the new system only cost about 15% more than the equivalent AGM replacement for what I had before

Let me guess, Australia?

Links to your cells and supplier?