Building a compression rig for these 105Ah (336Wh) prismatic LiFePO4 3.2V EVE cells. Also a couple of quick internal resistance tests. hakadibattery....
I find the info about batteries changing shape as they get used fascinating especially given the force figures you were quoting. Maybe with the next set you could integrate a load cell to measure the stress rise as you charge and discharge the packs. Stay safe!
So cool! I've been wanting to pickup some of these. No idea what I'll do with them, but I just love the tech and the idea of running something in my home off free energy.
belive it or not they are at the bottom of the quality line but i wanted to check em too.. in my country in europe they sell em for the cost of LFK and it s a shame.. so directly from china is better way
running my first project with some similar and i m quiet happy . they deliver average 80% of their capacity and i need em for 50% of their load capability . . when compressed em (not much) .. they performed +15% as for capacity but when torqued a bit more than spec about to 5,5 N per nut .. the voltage beween cells was stabilized and i gained my final 3.6kw clean used energy not measuring the losses from inverting for 16s with safety parameters on bms and on normal test!!! lets see after a year with some more tests... /// they dont need to be compressed hard.. you just need to avoid bloat em.. i let em sit fully charged slowly for 15 days i think and not a single bloat.. but dont risk it... keep em under 70% as long as you didnt make your pack !!!! my pack is 16s btw ./..I BOught same woud as yours to finish my box and added a plexiglass to prevent shorts from above
Julian, there are hundreds of videos on youtube about LFP cells - Will Prowse is probably the best source of info and teardowns, Lithium Solar, Ray Builds Cool Stuff, David Poz Compression is done using threaded rods and metal plates. Bus bars should not be flat - they should have a hump which will bend to relieve stress on the terminal posts.
AFAIK cell compression is only usefull during the first one or two charge/discharge cycles. And since these cycles should already be done at the manufacturer there is no real advantage in building a compression rig yourself.
Odd then that the data sheet has a full set of instructions on how to construct a compression rig. It recommends 8mm metal plates, 6mm threaded rod and nuts.
I thought Andy came to the conclusion that compression was not important to the longevity of the battery. He did several videos on the subject,@@JulianIlett
Keep in mind at 3.4V a LFP cell is 100% SoC with no load/charge, exactly already at 3.37V. The datasheet says up to 3,65V but with a charge current no lower than 0.05C - which is 5 Amps here! Everything else is overcharging - resulting in bulging probably!
@@JulianIlett No, you have to keep charge current above 0.05C otherwise the cell voltage goes too high! If charge current is lower than 0.05C and you are already at 3.65V the cell is beeing overcharged! Most ppl. dont the this right 😉 At 3.37Voc the cell is at 100% SoC already!
@@JulianIlett Yeah, most ppl don't care about this and ridiculously overcharge there cells - resulting in bulging! You just need to charge higher than 3.4V when balancing, because at this level the cells separate in terms of voltage. The ones that run higher 3.45+ first are full and probably have lower capacity than the others in series. If there is only a few mV difference all is fine - no balancing needed.
Its a big step taking a lash up on a bench and putting together properly into a conventional battery case. Lots of construction engineering to do and attention to detail. You cant just throw it all in a shoe box and expect it to operate reliably and safely - year in year out (and in a mobile platform like a golf cart). Think of a car and how we all take for granted the way auto electrics are put together - decades of user experience goes into to that level. Notice the basic 6mm "Lucas " pattern push fit spade terminals - they work under arduous conditions all over the world. Been thru all that, took me a month of triple care. I would now be very suspicious of cheap charlie drop in batteries used to replace AGMs. you are just buying a black box with a wish and a prayer.
Quite funny and quite useless job of compression! Typically you will use 4 threaded rods (Gewindestangen) in M6 or M8 and compress the cells between 2 solid plates of hard wood or aluminium etc. I have exactly the same cells directly from EVE but without these M5 bolts, just M4 holes in the contacts.
I would have expected the iR to be much lower, as the EVE 105Ah cells I work with have an iR of 0,32 mOhm, measuring around 0,35 mOhm. Your cells also look to have a top M6 20mm steel pinol screw which is perhaps press fit into the alu plate welded on top of the cell, essentially making a sandwich with the busbars on top. We went away from that solution and instead first screwed and later welded busbars directly onto the battery terminal, both solutions using a steel M6 Helicoil inserted directly in the terminal under the busbar. Torqued nut set to around 4Nm.
Measured IR varies depending upon state of charge. These cells measured about 0.3 mOhm out of the box. Once fully charged, they will probably measure lower.
from my understanding and seeing alot of professional using these batteries, there is no use in compression those battery. you cannot use enought force and its mostly useless.
I would Start looking into Fire Proofing the Shed - Steel Office Cabinet Install flight case wheels (use PowerLock PowerSafe 500A 800A ) - Outdoor Industry Waring labels / plaques of lithium metal fires for firefighters on the door Make you own Diy Fireproof & Heat proof Shielding / Dividers - Perlite + Plaster of Paris + Sodium silicate 100% Pure + (Wood PVA Glue / pool paint to make A putty) - FireTrace UK Automatic Tube Seeking Fire Extinguishers (2 / 4 nozzle indirect (Powder D class)+ Trigger seeker Tube)
@@JulianIlett Cant really argue with that it has been A Damp Wet Spring Summer this year last year was So dry that Everything just would go up with ease
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thanks for showing this seller, LFP batteries (the cells) continue to drop in price over the last 4 yrs.
I find the info about batteries changing shape as they get used fascinating especially given the force figures you were quoting. Maybe with the next set you could integrate a load cell to measure the stress rise as you charge and discharge the packs.
Stay safe!
I watch Andy’s channel too, I don’t even have a solar setup or a battery systems and I still find it interesting!
So cool! I've been wanting to pickup some of these. No idea what I'll do with them, but I just love the tech and the idea of running something in my home off free energy.
Hi Julian, those are some nice looking cells - I had no idea about pre-forming LiFePO4 cells - thanks for the info!
belive it or not they are at the bottom of the quality line but i wanted to check em too.. in my country in europe they sell em for the cost of LFK and it s a shame.. so directly from china is better way
On some battery teardown vids, the manufacturer simply compresses them with friction welded strapping. Looking forward to part 2
Don't underestimate some tape for compression. Fiber packaging tape and kapton tape are amazing at holding compression.
At last, a use for my pet elephant!
running my first project with some similar and i m quiet happy . they deliver average 80% of their capacity and i need em for 50% of their load capability . . when compressed em (not much) .. they performed +15% as for capacity but when torqued a bit more than spec about to 5,5 N per nut .. the voltage beween cells was stabilized and i gained my final 3.6kw clean used energy not measuring the losses from inverting for 16s with safety parameters on bms and on normal test!!! lets see after a year with some more tests... /// they dont need to be compressed hard.. you just need to avoid bloat em.. i let em sit fully charged slowly for 15 days i think and not a single bloat.. but dont risk it... keep em under 70% as long as you didnt make your pack !!!! my pack is 16s btw ./..I BOught same woud as yours to finish my box and added a plexiglass to prevent shorts from above
Julian, there are hundreds of videos on youtube about LFP cells - Will Prowse is probably the best source of info and teardowns, Lithium Solar, Ray Builds Cool Stuff, David Poz
Compression is done using threaded rods and metal plates.
Bus bars should not be flat - they should have a hump which will bend to relieve stress on the terminal posts.
good, how long did the delivery take. Thank you
AFAIK cell compression is only usefull during the first one or two charge/discharge cycles. And since these cycles should already be done at the manufacturer there is no real advantage in building a compression rig yourself.
Odd then that the data sheet has a full set of instructions on how to construct a compression rig. It recommends 8mm metal plates, 6mm threaded rod and nuts.
I thought Andy came to the conclusion that compression was not important to the longevity of the battery. He did several videos on the subject,@@JulianIlett
Keep in mind at 3.4V a LFP cell is 100% SoC with no load/charge, exactly already at 3.37V. The datasheet says up to 3,65V but with a charge current no lower than 0.05C - which is 5 Amps here! Everything else is overcharging - resulting in bulging probably!
Don't you mean "no greater than 0.05C"?
@@JulianIlett No, you have to keep charge current above 0.05C otherwise the cell voltage goes too high! If charge current is lower than 0.05C and you are already at 3.65V the cell is beeing overcharged! Most ppl. dont the this right 😉 At 3.37Voc the cell is at 100% SoC already!
Ah, you're talking about the end-of-charge cut off. Got ya.
@@JulianIlett Yeah, most ppl don't care about this and ridiculously overcharge there cells - resulting in bulging! You just need to charge higher than 3.4V when balancing, because at this level the cells separate in terms of voltage. The ones that run higher 3.45+ first are full and probably have lower capacity than the others in series. If there is only a few mV difference all is fine - no balancing needed.
Hi my friend.
I order eve cells and they send me the same as yours.
Do you measure the capacity of cells?
You are happy with them?
Thanks 👍
Are they real Eve grade a cells with valid QR code?
Good in of itself, but by the time you add all the paraphernalia, you may as well buy a ready-made battery.
Unless you enjoy the learning process :)
Its a big step taking a lash up on a bench and putting together properly into a conventional battery case. Lots of construction engineering to do and attention to detail. You cant just throw it all in a shoe box and expect it to operate reliably and safely - year in year out (and in a mobile platform like a golf cart). Think of a car and how we all take for granted the way auto electrics are put together - decades of user experience goes into to that level. Notice the basic 6mm "Lucas " pattern push fit spade terminals - they work under arduous conditions all over the world.
Been thru all that, took me a month of triple care. I would now be very suspicious of cheap charlie drop in batteries used to replace AGMs. you are just buying a black box with a wish and a prayer.
Quite funny and quite useless job of compression! Typically you will use 4 threaded rods (Gewindestangen) in M6 or M8 and compress the cells between 2 solid plates of hard wood or aluminium etc. I have exactly the same cells directly from EVE but without these M5 bolts, just M4 holes in the contacts.
Anybody else out there who has bought Hakadi?
Anybody have them ship from China?
I would have expected the iR to be much lower, as the EVE 105Ah cells I work with have an iR of 0,32 mOhm, measuring around 0,35 mOhm.
Your cells also look to have a top M6 20mm steel pinol screw which is perhaps press fit into the alu plate welded on top of the cell, essentially making a sandwich with the busbars on top. We went away from that solution and instead first screwed and later welded busbars directly onto the battery terminal, both solutions using a steel M6 Helicoil inserted directly in the terminal under the busbar. Torqued nut set to around 4Nm.
Mine are grade A and had IR of 0.25mOhm.
Measured IR varies depending upon state of charge. These cells measured about 0.3 mOhm out of the box. Once fully charged, they will probably measure lower.
from my understanding and seeing alot of professional using these batteries, there is no use in compression those battery. you cannot use enought force and its mostly useless.
It's a shame that the data sheet doesn't provide more detail on why, when and for how long compression is required.
@@JulianIlett check out "@OffGridGarageAustralia" he has the best video i found.
5:46 I recommend using a car screw jack to compress.
I would Start looking into Fire Proofing the Shed
- Steel Office Cabinet
Install flight case wheels
(use PowerLock PowerSafe 500A 800A )
- Outdoor Industry Waring labels / plaques of lithium metal fires for firefighters on the door
Make you own Diy Fireproof & Heat proof Shielding / Dividers
- Perlite + Plaster of Paris + Sodium silicate 100% Pure + (Wood PVA Glue / pool paint to make A putty)
- FireTrace UK Automatic Tube Seeking Fire Extinguishers (2 / 4 nozzle indirect (Powder D class)+ Trigger seeker Tube)
Rain every alternate day helps a lot :)
@@JulianIlett Cant really argue with that it has been A Damp Wet Spring Summer this year
last year was So dry that Everything just would go up with ease
Remember these are LFP with no thermal runnaway.
@@moestrei Thermal runaway can still happen with LiFePO4 batteries, it just takes a lot more heat than with normal Li-ion batteries.
@@rocketman221projects Incorrect, you can shoot at a cell, short it out, puncture it....just any abuse: It will not catch fire.