LifePO4 3.2V Batteries vs. "Drop in Replacements"
- Thread starter VerMonsterRV
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VerMonsterRV
Gotta Be Nuts
Hey luthj, we have lived on sailboats for about 20 years now with the last 18 years using 6 6V Trojan wet cells for our house bank. This ends up being a 675amp hour bank and has worked well for us. So given a 50% usable capacity that gives just shy of 340amp hours. With a 300amp hour BB bank at 80% capacity would be at 240amp hours. With 4 it would be at 320 amp hours. Our plan is to move off the boat and into the new RV to head around the world a second time, so this would be our full time home.
dreadlocks
Well-known member
I agree with @luthj, you dont need as much capacity when you can go from 20% SOC to 100% SOC in ~3-4h, vs the 8h+ it takes to get from 60% SOC to 100% SOC on lead..
I'm planning on ~600W Solar Setup for my 100aH of Lithium, since the battery gladly takes 30-50A till its fully charged with no absorb.. I can drain the battery to 20% SOC every night and have it full the next day by noon.. since camping all it seems I ever see is a few hours of direct sunlight that seems to be the best way to tackle this, and if its cloudy its just a few hours of generator use instead of idling it all day long for a few measley absorb amps.
Not to mention its basically 99% efficient on what you put in you get out, even with high loads.. A 100aH usable lead capacity ends up only being 40-60aH of actual capacity when you have a high power load on it like an inverter/microwave/etc.. Lithium gives you pretty much the same output capacity if your loads are 2A or 20A or 80A, thats a huge variable on lead and results in even larger battery capacity requirements as load increases.. with lead 1A at 12h will drain battery far less than 12A for 1h, with lithium this problem is pretty much eliminated, so again less capacity is required.
I wasent kidding when I said the move to lithium has been a paradigm shift, like everything you think you know about batteries throw it out the window.. reading on the internets and researching I thoguht i knew what to expect, and I did.. but its still shocking to see a battery at 5% SOC and holding 12v, its requiring me to recalibrate my thinking and assumptions Ive gained over last 15 years of experience.
I'm planning on ~600W Solar Setup for my 100aH of Lithium, since the battery gladly takes 30-50A till its fully charged with no absorb.. I can drain the battery to 20% SOC every night and have it full the next day by noon.. since camping all it seems I ever see is a few hours of direct sunlight that seems to be the best way to tackle this, and if its cloudy its just a few hours of generator use instead of idling it all day long for a few measley absorb amps.
Not to mention its basically 99% efficient on what you put in you get out, even with high loads.. A 100aH usable lead capacity ends up only being 40-60aH of actual capacity when you have a high power load on it like an inverter/microwave/etc.. Lithium gives you pretty much the same output capacity if your loads are 2A or 20A or 80A, thats a huge variable on lead and results in even larger battery capacity requirements as load increases.. with lead 1A at 12h will drain battery far less than 12A for 1h, with lithium this problem is pretty much eliminated, so again less capacity is required.
I wasent kidding when I said the move to lithium has been a paradigm shift, like everything you think you know about batteries throw it out the window.. reading on the internets and researching I thoguht i knew what to expect, and I did.. but its still shocking to see a battery at 5% SOC and holding 12v, its requiring me to recalibrate my thinking and assumptions Ive gained over last 15 years of experience.
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luthj
Engineer In Residence
Lead has a total energy efficiency of around 75-88%. Lithium is usually in the 92-99% range, regardless of how long its been sitting at partial SOC. As mentioned by @dreadlocks, all this stuff combined to make a lithium bank between 50 and 40% the usable AH of lead equivalent or better in actual usage.
If you are building your own bank this is basically the bible in my view.
http://nordkyndesign.com/assembling-a-lithium-iron-phosphate-marine-house-bank/
Designing your whole system around a lithium bank can yield some pretty awesome results. It is important to note that you need to be aware of the temp limitations. Storage below something like -20F can cause cell damage (depends on cell brand). Charging below 40-35F also causes immediate damage (not discharging though).
If you are building your own bank this is basically the bible in my view.
http://nordkyndesign.com/assembling-a-lithium-iron-phosphate-marine-house-bank/
Designing your whole system around a lithium bank can yield some pretty awesome results. It is important to note that you need to be aware of the temp limitations. Storage below something like -20F can cause cell damage (depends on cell brand). Charging below 40-35F also causes immediate damage (not discharging though).
Joe917
Explorer
Luthj, good link. There is no question Lithium is a better battery than lead. The Question is, is it better value... not even close. Lead acid is far cheaper over the life of the install still. The big cons with lead are weight (Jon won't notice any difference) and available amperage. Pulling high amps out of a lead acid bank (for a microwave for example, 150 amps) is hard on the batteries, Rolls Surette would not give an exact number but advised keeping loads under the 10 hr rate. This for us is the limiting factor in bank sizing, not amp/hrs used. Charging is a non-issue with a reasonable solar set-up,(solar watts=battery amp/hrs). Our lead battery bank will take 90amps in the bulk stage no issues.
luthj
Engineer In Residence
It depends on your cost of install of course, but more DIY oriented lithium installs which are conservatively used can have about 1/2 the cost per AH delivered. And remember that the lead acid life cycle ratings rarely match up in real life usage. This is because lab testing, which results in a full charge every cycle, is ideal for lead, but actually slightly detrimental to lithium. The opposite is true for real life usage. In most mobile/boat/RV installs the batteries are not fully charged every cycle, and spend lots of time at partial SOC. This is detrimental to lead, but actually improves the life of lithium batteries.
For example, I have a 510AH lifeline AGM pack that has 65,000AH of delivered capacity. Which equates to about 255 50% cycles. Charging was off grid only with 600W of solar and alternator. The bank is at about 94% of new capacity. At this rate I expect to get 850 cycles (at 50% SOC equivalent) before capacity drops to 80% of new. Or about 217,000 AH. The lab tests show 1000 50% cycles to 80% original capacity. At this age the bank is also becoming less efficient. Total energy efficiency has dropped to about 83% from around 88% new. These batteries cost 1500$ or so. So real world usage is about 144AH/Dollar.
Compare this to lithium cells which do not experience efficiency losses like this due to aging.
My average DOD per cycle is about 19%, or about 96AH overnight.
That 1500$ could buy this kit, 180AH of calb cells with BMS, regulator, and box.
http://www.manzanitamicro.com/produ...page=flypage.tpl&product_id=52&category_id=19
These cells are rated for 3,000 cycles to 80% DOD. Or about 432,000AH life. At my overnight draw of 96AH, that is a DOD of 50%, with 30% reserve. Total cost is around 288AH/Dollar. If I adjusted my charge and discharge parameters to avoid the top 1% of charge, and the bottom 25%, the total delivered AHs could be increased to 500,000 or so, as the battery will see much less internal aging.
Lithium batteries also have no trouble with high currents. In fact they actually suffer from less voltage drop, and almost no capacity reduction at high discharge rates. They also have no issue with partial discharge, so there is no worries with leaving them half charged, or cloudy days, etc.
Obviously they have downsides, but the cost of cells is low enough for it to make sense for full time live-aboard installs.
For example, I have a 510AH lifeline AGM pack that has 65,000AH of delivered capacity. Which equates to about 255 50% cycles. Charging was off grid only with 600W of solar and alternator. The bank is at about 94% of new capacity. At this rate I expect to get 850 cycles (at 50% SOC equivalent) before capacity drops to 80% of new. Or about 217,000 AH. The lab tests show 1000 50% cycles to 80% original capacity. At this age the bank is also becoming less efficient. Total energy efficiency has dropped to about 83% from around 88% new. These batteries cost 1500$ or so. So real world usage is about 144AH/Dollar.
Compare this to lithium cells which do not experience efficiency losses like this due to aging.
My average DOD per cycle is about 19%, or about 96AH overnight.
That 1500$ could buy this kit, 180AH of calb cells with BMS, regulator, and box.
http://www.manzanitamicro.com/produ...page=flypage.tpl&product_id=52&category_id=19
These cells are rated for 3,000 cycles to 80% DOD. Or about 432,000AH life. At my overnight draw of 96AH, that is a DOD of 50%, with 30% reserve. Total cost is around 288AH/Dollar. If I adjusted my charge and discharge parameters to avoid the top 1% of charge, and the bottom 25%, the total delivered AHs could be increased to 500,000 or so, as the battery will see much less internal aging.
Lithium batteries also have no trouble with high currents. In fact they actually suffer from less voltage drop, and almost no capacity reduction at high discharge rates. They also have no issue with partial discharge, so there is no worries with leaving them half charged, or cloudy days, etc.
Obviously they have downsides, but the cost of cells is low enough for it to make sense for full time live-aboard installs.
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VerMonsterRV
Gotta Be Nuts
Ok, since we had to hang out waiting for Florence to pass I had a bit of time to look more into the LifePO4 batteries. So I went back to the "drop in replacement" batteries to look at them closer. It seems like BattleBorn is the most common one in this market in the USA at $950, but I also looked at Alibaba to see what is going on as I am pretty sure the internals of BB are from China (don't know, but I think it is a pretty safe bet). So I came across this Green Life Battery which seems nice but are $1,250 each here in the US. So looking at Alibaba I see GSL Battery which after a few emails are $425 each with ~$600 shipping for 4 (they also offer a 200Ah version for a bit less than 2 100Ah batteries). From the looks of the case they seem to be the same battery. Anyone had any luck directly buying batteries directly from China as the price is easier to handle?
dreadlocks
Well-known member
I've not bought LiPo's from China but I've imported a ton of electronics over the years (through AliBaba and others) and generally had great results.. once yeh get past the language barrier and shipping costs/times.. I havent tried to import anything since all these tariffs have been in place, before pretty much everything was duty free if under $800.
Its a safe assumption that BB and others are using Chinese cells, AFIK there's only one Lipo battery manufacturer in US and Tesla is too busy putting em in cars and powerwalls to be a cell wholesaler yet.
Its a safe assumption that BB and others are using Chinese cells, AFIK there's only one Lipo battery manufacturer in US and Tesla is too busy putting em in cars and powerwalls to be a cell wholesaler yet.
CoyoteThistle
Adventurer
I recommend you read through as much of this as you can stand:
https://marinehowto.com/lifepo4-batteries-on-boats/
See especially his opinions on "drop in" batteries. He identifies several big potential downsides to using these. He also tries to talk you out of DIY ;-)
Bottom line for me is that the drop ins cost a lot more, have a questionable (at best) BMS, and use cells of unknown quality. I also have little confidence in the manufacturers since they market these as drop ins for vehicles (they are not!) and are willing to reveal little or no information about what is inside the box (many folks have hounded them for answers).
I went DIY (CALB cells), learned a lot, saved some money, and have high confidence in the results. I had a good experience with Electric Car Parts Company for the cells (best price, very well packaged for shipping, consecutive manufacturer serial numbers, etc.) - shipping was about $65 for four 100Ah cells. PKYS Inc was a great source of the control hardware.
Best of luck with it!
https://marinehowto.com/lifepo4-batteries-on-boats/
See especially his opinions on "drop in" batteries. He identifies several big potential downsides to using these. He also tries to talk you out of DIY ;-)
Bottom line for me is that the drop ins cost a lot more, have a questionable (at best) BMS, and use cells of unknown quality. I also have little confidence in the manufacturers since they market these as drop ins for vehicles (they are not!) and are willing to reveal little or no information about what is inside the box (many folks have hounded them for answers).
I went DIY (CALB cells), learned a lot, saved some money, and have high confidence in the results. I had a good experience with Electric Car Parts Company for the cells (best price, very well packaged for shipping, consecutive manufacturer serial numbers, etc.) - shipping was about $65 for four 100Ah cells. PKYS Inc was a great source of the control hardware.
Best of luck with it!
VerMonsterRV
Gotta Be Nuts
Thanks for the links and info. From a bit of bouncing around the web it looks like the best bet, if you wanted to get drop in batteries is from a reputable US based company that will stand behind any warranty claims. Given that our plans are for out of the US travel, if we go with LifePO4 it will be with the 3.2V prismatic cells. I just sent an email to Electric Car Parts Company (ECPC) about the needed items. Looking at the "Fortune 100Ah" cells (pretty sure they are made by Frey Battery in China). They have aluminum cases which are supposed to dissipate heat better than the plastic cased cells. ECPC also sells a programmable BMS which they recommend, I just inquired though about 3 different charging sources (solar, DC-DC from alternator, AC charger) and what else I would need.
VerMonsterRV
Gotta Be Nuts
Very cool, I was just wondering about batteries with a claimed 10 year life (all LifePO4 based batteries) but with a 2 or 3 year warranty. Good work Battle Born.
VerMonsterRV
Gotta Be Nuts
So I have been doing some more reading about our possible lifepo4 battery pack. So I think now it will be a 4p4s battery pack made up with 16 Frey 100Ah 3.2v prismatic cells. I can either order them from EPCP or straight from Frey in China. I might go the China route as I have gotten a price of $72 a cell with $518 in shipping, including all connection bars and plastic cases. Seems like a pretty good deal. Plus the shipping is air using UPS so 5-7 days. I would need to wait for a container to arrive at EPCP as they are out of stock.
I do think I will go with the BMS/Monitor and balancers from EPCP. It looks like it would do what I need at a reasonable price. Mains charging will be a Sterling ProCharge Ultra that I have, around 1000watts solar (still need to do this bit) and a Sterling 24v to 12v DC to DC charger from the alternator.
So does this setup sound like a decent start?
I do think I will go with the BMS/Monitor and balancers from EPCP. It looks like it would do what I need at a reasonable price. Mains charging will be a Sterling ProCharge Ultra that I have, around 1000watts solar (still need to do this bit) and a Sterling 24v to 12v DC to DC charger from the alternator.
So does this setup sound like a decent start?
Hillbilly Heaven
Explorer
Carefully check their shipping cost as it may not include broker fees and custom duties. One day you might get a nice surprise in the mail from UPS saying they are holding your shipment pending importation fees.