Beginners Guide to Processing 18650 Cells | Cell Database


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Herebus Hell Build
#1
The journey starts.

I'm looking at a 48v system, as many of the inverts are sitting in this range, in addition the current draw is less (less loss to heat) for the same wattage compared to low voltages.  For commercial system,  the DC voltage is much higher for efficiency, however at 100v up it gets dangerous....at 50v you will feel it.  I am basing this voltage on 14S52P (14 modules in series, with each module of 52 batteries in parallel) which will give me around 12kwh.  14S rather than 13S seems to be where members are leaning as the preferred build.  It is expected for a 12wkh system to have  80% usable power (battery longevity) , so in actual real terms  should have ~10kwh true available power. I have decided to go with 5000mah as they are the most cost effect for the price point for new batteries.

I have been buying:
New 18650 5000mah from DHGate ~$1.74AUD a cell.
Battery  holder Module - 13*4 52 holes for 48v 10ah li-ion battery pack from Aliexpress ~$10 a set of 2....would like to get them cheaper.

Need to get:
Copper flat bar 15mm x 3mm x 250mm; battery side bus bar. (130AMP (6Kw peak current at 48v * 130A) per module based on AWG ~ 50 degrees C)
Smaller copper rod bus bar for top of batteries...not sure on the size?
0/2 AWG Lugs and associated hookup wire.
Heat Shrink tubing to colour code bus bar ends.
0.5 mm tinned copper fuse wire (~35AMP burnout)
Inverter Charger or Hybrid Solar Inverter (5kw), as I have 5kw of solar.
Gas Soldering torch to solder copper bar.  A soldering iron will not handle the heat loss of the bars.
14S Battery Management System (BMS)

Need to consider:
Over Temperature (fire) isolation.
Eliminate easily combustible materials around battery pack construction.
Reduce risk of module  shorting.  Lithium batteries have a very low internal resistance and will happily dump their load in a very short period of time; melting/fusing and generally self destructing.




With luck nailed in 12 months [Image: shocked.png]
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#2
5000 mah ??

You might need to ask seller more questions I think..
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#3
(12-31-2016, 12:51 AM)hbpowerwall Wrote: 5000 mah ??

You might need to ask seller more questions I think..



Thanks for this, I will follow up with the supplier.  

Regards
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#4
(12-31-2016, 12:45 AM)Herebus Wrote: New 18650 5000mah from DHGate ~$1.74AUD a cell.

Yup fake capacity, highest capacity available is 3400mAh
Beware some 9000mAh cells actually tested as 900mAh, so actually terrible.
Expect to pay $8-$10 for new high capacity cells, which you aren't going to get from China.
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#5
Update 2

The 18650 5000mah from DHGate ~$1.74AUD a cell arrived and were tested with the Opus Charger.  From the first  batch  8 cells were tested , which came out to be around 1200mah.  And of those  one cell was boarder line..so not even close to the stated 5AH stated in the specifications....we live and learn.  I have made it clear to the seller I was not happy and currently going through the dispute process.



So I have changed track, given my remoteness, getting hold of second hand packs of cells is problematic, so I am sourcing 100 cells for review directly from a cell manufacture through Alibaba...not AliExpress (see attached)...cutting out the middle man.  So far the process is going OK.  I am looking at 2400mah batteries with 2C discharge @ $1.70AUD. I have seen cheaper, but lets see how it goes....need to get a rung on the ladder.
Cheers  


Attached Files
.pdf   GEB18650 3.7V 2400mAh.pdf (Size: 94.65 KB / Downloads: 41)
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#6
On youtube there's a video of someone doing a test of all those Chinese 18650 batteries: https://www.youtube.com/watch?v=4no9Lz_p...YvA1kzKZ8a
Seems the best source of good batteries are 3rd party laptop batteries (he even provides a link to the ones he buys).

That might be an option for you if the alibaba doesn't work out?
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#7
(01-18-2017, 08:51 AM)rumey Wrote: On youtube there's a video of someone doing a test of all those Chinese 18650 batteries: https://www.youtube.com/watch?v=4no9Lz_p...YvA1kzKZ8a
Seems the best source of good batteries are 3rd party laptop batteries (he even provides a link to the ones he buys).

That might be an option for you if the alibaba doesn't work out?

Thanks for that.  I will look into it.

I just purchased new 850 x 18650 at $1.25 each, with shipping of $250, cost me ~$1335 US.

This was through Alibaba, and in general it was hard work dealing with sales.  As I have Zero faith in Chinese sellers....too many times burnt.  Seems laws changed at the start of this year in relation to shipping lithium batteries...especially bulk.  So shipping is problematic.

Anyway, its a start....~6kwh.
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#8
I haven't actually purchased anything from these guys yet but when I'm ready I planned to source from https://liionwholesale.com/

Anyone have experience with them?
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#9
(01-20-2017, 08:49 PM)frasernator Wrote: I haven't actually purchased anything from these guys yet but when I'm ready I planned to source from https://liionwholesale.com/

Anyone have experience with them?

No, but what I have found from my journey there is a heap of battery manufacturers claiming to have particular brands.  Its very difficult to determine what is legitimate, fake or just copies.

Given that we cant physically test the batteries before they send them, there has to be trust.  'llI let you know how I go with the mob that I just purchased from, as they are cheaper than liionwholesaler.

I should have the batteries by the first half of March.

Cheers
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#10
I managed to get a refund on the DH Gate batteries...which is an upside.

Downside the wire I ordered from Aliexpress for the fuse was 0.1mm not 0.2mm as requested.

Here is a shot of the 5kw solar panels that will power the batteries.  The other photo is the wiring underneath, using stainless catenary; with plastic inset washers to ensure stainless and aluminium don't touch.
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