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Author Topic: Efest 18650 & 18650  (Read 1956 times)

Offline Stan

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Efest 18650 & 18650
« on: September 04, 2013, 07:50:53 AM »
There are two Efest 18650 batteries, one 1500 mAh and the other 2000 mAh.
Both IMR and they are Li-Mn. I can't see any difference apart the mAh. The obvious choice would be the 2000 mAh.

1500:
http://www.ebay.co.uk/itm/2x-Efest-IMR-safe-chemistry-18650-1500mAh-flat-top-3-7v-Li-Ion-case-/290967886695?pt=UK_ConsumerElectronics_Batteries_SM&hash=item43bf099b67

2000:
http://www.ebay.co.uk/itm/2x-Efest-2000mAh-IMR-flat-top-18650-3-7v-18650-li-Ion-batteries-protective-case-/290971255467?pt=UK_ConsumerElectronics_Batteries_SM&hash=item43bf3d02ab

Which one would be better for genesis attys (0.9 to 1.3 ohms)?



Offline TopCookie

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Re: Efest 18650 & 18650
« Reply #1 on: September 04, 2013, 08:06:29 AM »
Typically, capacity comes at the expense of discharge rates...  so I would imagine that the 1500mAH would have the higher C rating of the two...  But for the builds you have in mind there Stan, you can go with the 2000mAH version, no probs, and enjoy the extra capacity...  :)

Offline gaffer

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Re: Efest 18650 & 18650
« Reply #2 on: September 04, 2013, 08:26:46 AM »
AFAIK they are just capacities with the 1500 being an older (cheaper) design.

Offline BigT

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Re: Efest 18650 & 18650
« Reply #3 on: September 04, 2013, 12:07:10 PM »
now that I looked I have both, hummmm....
BigT

Offline Stan

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Re: Efest 18650 & 18650
« Reply #4 on: September 04, 2013, 08:56:03 PM »
From what I can see, the internal resistance is different:

1500 mAh - 40
2000 mAh - 91

That means nothing to me I'm afraid, not sure whether one would perform better than the other.

Offline gaffer

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Re: Efest 18650 & 18650
« Reply #5 on: September 04, 2013, 09:29:58 PM »
From what I can see, the internal resistance is different:

1500 mAh - 40
2000 mAh - 91

That means nothing to me I'm afraid, not sure whether one would perform better than the other.

hmm interesting, i didn realize they had different internal resistances. the lower the internal resistance the less voltage sag and  higher drain battery should be able to handle IIRC

Offline GothVaper

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Re: Efest 18650 & 18650
« Reply #6 on: September 04, 2013, 10:40:41 PM »
The 1500 mah can handle upto 10 amps

http://budgetlightforum.com/node/17136

The 2000 mah can only handle 4 - 7 amps max

http://budgetlightforum.com/node/19074
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Offline Stan

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Re: Efest 18650 & 18650
« Reply #7 on: September 05, 2013, 09:30:36 AM »
OK, the 1500 mAh it is then  :)+1

Offline CraigHB

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Re: Efest 18650 & 18650
« Reply #8 on: September 06, 2013, 11:49:50 AM »
That's how it usually works with Li-Ions and other battery types that use plates.  Lower capacity for a given volume results in lower internal resistance and a higher C rating.  Higher capacity for a given volume comes at the cost of a lower C rating.  The reason is that the plates are thinner to fit more in there for a higher capacity.  Thinner plates have more resistance which increases heating and lowers the drain limit.

I good rule of thumb is to use double the drain limit for your worst case load.  So, if you're using a 1 Ohm atomizer, highest drain would be about 4 Amps so you'd want a cell with at least an 8 Amp drain limit.  You could use a cell with a 4 Amp drain limit for a 4 Amp load, but you get big losses and heavy wear when you run a cell at its limit.