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Weasel

LiFePo4 Cells 38120

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I've been playing with these batteries from china, Headway 38120 10Ah cells. Yes that means they are 38mm diameter and 120mm long. What drew me to them is cost per watt is less than a 18650 and they have beefy bolted connections. 

First did a discharge at + - 0.5 C and let the BMS cut out at 2v per cell, i recorded a full charge at + - 0.2C and then recorded another discharge again 0.5C. The idea is to test the capacity as well as the round trip efficiency, the BMS cutoff discharged at the same rate gives me a zero point, any power i put in from zero point and extract again to zero allows me to calculate the round trip efficiency.

Here's my results and i have to say i'm super impressed with them, I'm curious to know what you guys think and if you can think of anything i could test further. I think these things can be stuck into just about anything, 93% at these discharge rates ill sommer make a powerwall :D

Charge             
Rated capacity    10 A        
Average Current    2.201 A    
Charge Rating    0.220067883 C
Max Charge rating    0.3902745 C 
Average Voltage    14.053 V    
Average Power    51.475 W         
Total applied power    140.713 Wh        
Total Charged current    10.214 A       
             
Discharge             
Rated capacity    10 A       
Average Current    5.564609317 A 
Discharge Rating    0.556460932 C
Max Discharge rating    0.5895413 C
Average Voltage    12.45113542 V   
Average Power    71.27238361 W
Total Drawn power    130.768265 Wh        
Total Discharged current    10.47799797 A        
             
Round Trip Efficiency     92.93257653    %     

SAM_0649.JPG

discharge.jpg

charge.jpg

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Wow. Great data and very well done! They look great. I have been very much looking for lithium batteries for our Solar Wifi highsite. Currently have a 120A victron Gel up there. The metal battrey box is well shaded by the solar panel. However the router in the cabinet reports temps of 28C on summer days. Not to great for the gelled battrey I'm sure :(. I have been very much looking for a drop in lithium replacement will be great for space saving as well. Keen to hear your thoughts. Awesome work again!

Sincerely

Jay

 

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I'm thinking it might be a bit overkill for a WiFi high site, especially considering 100Ah 12V will cost around R14k and you would hopefully not need 500A discharge rating. Apparently the lead crystals do better in higher temps and it could be a better option, I've tested some of those the other day that where badly abused and i was quite impressed, came in dead flat on 6V and after a proper charge gave 110% capacity. 

But I've got a ghetto solution you might like, as you probably know the renesola SA branch closed and they sold out all their old stock. There's a battery backup box they sold for the LED panels which contains 12 x 18650 2200mah batteries, neatly in a pack with a protection board. They are however 3.6V li-ion making up a 10.8V pack at 8.8Ah but if your hardware can handle that then i reckon its a win. The best part is that 12 of these boxes will run you in R2400 and you'd have 105Ah at 10.8V for 1.1kwh       

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Posted (edited)

@Weasel I see you are online and hope you will give the quick answer then Chinese co.. I made an enquiry for the same cells you already bought, so while I am waiting for the price from Chinese , how much did they charged you for them ?

regards

Edited by ibiza

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4 hours ago, ibiza said:

I made an enquiry for the same cells you already bought, so while I am waiting for the price from Chinese , how much did they charged you for them ?

I see some Aussie dude on Ebay is selling boxes of 8 cells for USD90 which works out about R140 per cell - so if dead keen then it may be worth jumping on (the above excludes shipping obviously).

https://www.ebay.com/itm/Lifepo4-Cells10AH-38120-Headway-Brand-Price-is-for-box-of-8-cells-Aust-Stock/183099679811?epid=2164667973&hash=item2aa1976443:g:iGgAAOSw5U9Zij7M

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Posted (edited)
2 hours ago, ibiza said:

for 48V 300Ah battery lowest price is about R35K which is no so bad at all.

3.2V * 16 cells = 51.2 V @ 10ah

So 300ah = 480 cells @ 330 = R158 400 without the bms, cables, fuses etc.

Are my calcuations correct?

Pylontech's for me I guess ;)  6x 14000 = R84000...

 

 

Edited by Mark

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6 minutes ago, Mark said:

So 300ah = 480 cells @ 330 = R158 400 without the bms, cables, fuses etc.

Or you could get 60 boxes of 8 cells at USD90 from the Aussie dude which would run you about R67,500 before BMS, Cables, Fuses...and shipping! Probably about R75k when all in place and ready to run (or R5.5k/kWh as apposed to Pylontech R6k/kWh)

So Pylontech with a backup and warranty is still better deal for now in my opinion, but It is worth keeping an eye on because not long ago R10k/kWh was unbeatable.

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Posted (edited)

Eish dude - that is AUD120 = USD90!!!

NOTE: This ^^^ was in response to IBIZA comment that the Aussie dude had raised his price from US90 to US120 - so I pointed out that the price listed was AUD120 = USD90 - then he deletes his comment leaving me looking like a mindless poepall (Afrikaans speaking members welcome to correct my spelling of poepall!)

Edited by pilotfish

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Hehe. All in all I don't think these will compete with a pylontech. Pricing on them might get better but to me it's more a case of the ability to build a special pack for that special application. A pull cart or gate motor or e bike whatever. I started looking at them because..... and I don't want to say too much but I've got a 180v 4A DC motor and two 170sf panels kicking 200v. I need a light battery for 200v that can handle some amps.:D

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Oh and its probably worth mentioning ive been scouring for reputable 18650 suppliers but the problem there is the amount of fakes out there. specifically i liked the HG2 from LG for its specs but thanks to the extreme popularity under the vapers i have no idea what is real. heard horror stories like you receiving a genuine sample but the rest is fake. i think even the local suppliers thereof aren't sure what they are selling and they are doing so for R180 per cell. found a place eventually and if i recall it was 11$ us per cell but eventually they could not supply us here in SA. batteries have a lot of flight restrictions and its a real pain. in the end i figured these headway cells live up to their capacity claims and cost beats any other cylindrical cell per watt. they also do a 100Ah cell :o wouldn't want to drop that thing.

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2 hours ago, pilotfish said:

Eish dude - that is AUD120 = USD90!!!

NOTE: This ^^^ was in response to IBIZA comment that the Aussie dude had raised his price from US90 to US120 - so I pointed out that the price listed was AUD120 = USD90 - then he deletes his comment leaving me looking like a mindless poepall (Afrikaans speaking members welcome to correct my spelling of poepall!)

sorry

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4 hours ago, Weasel said:

flight restrictions

I think you are allowed to fly them if it is a cargo plane and they are discharged. The LFP batteries I imported both had to come by sea and with the second one it ended up in storage one day, which is normally free but not for hazardous goods... so I got nailed for the storage. R500 for small crate...

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36 minutes ago, plonkster said:

I think you are allowed to fly them if it is a cargo plane and they are discharged. The LFP batteries I imported both had to come by sea and with the second one it ended up in storage one day, which is normally free but not for hazardous goods... so I got nailed for the storage. R500 for small crate...

I saw somewhere that powertool makers Dewalt got around some restrictions by having some mechanical disconnect in the battery pack splitting it in two. not sure how true it is or what the restriction was but interesting still

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