How to compute for actual discharge rate

[dlcountpau]

Hi guys, just a quick question on mods with more than 1 battery.

If im using a mod with 3 batteries does that mean, assuming they are all full charged: i have 12.6volts (4.2x3), 60amps(20x3) CDR?
So if im checking for the CDR for my coil (.35ohms) the should it be like this? 12.6v/.35ohm=36a CDR????

Thanks in advance for helping

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[suprtrkr]

Hi and welcome. It depends on how the mod is wired, but you don't ever get 12.6V and 60A. for a series mod, you get 12.6V and 20A, and for a parallel mod you get 4.2V and 60A.

 

[BillW50]

You are probably talking about a regulated mod, right dlcountpau? If so, what the battery(s) are putting out in voltage and amperage is totally different voltages and amperages your coil(s) get.

Reuleaux RX200 for example.

Input
3x18650-25r (9.0 to 12.6v), 2500mah, 20A max

Output
0.00 to 9.0v, 0A to 50A

So how can the batteries drain at 20A, but the regulator is putting out 50A? Quite simple, the input side has 12.6v @ 20A = 252 watts. So for an output of 50A, we need 5v which also equals to 252 watts (well 250 really). Of course some others may mention that this is at 100% efficiency. And there is no clear cut value for efficiency. Since it is constantly changing anyway. But many use 90 or 92% efficiency for an average. So it is like 250 watts in and 225 watts out.

 

[Neunerball]

...for a series mod, you get 12.6V and 20A, and for a parallel mod you get 4.2V and 60A...

This is true, if you're using 3 batteries with a CDC (continuous discharging current) of 20A, and in a mech mod. However, not true for example, when utilizing 3 Sony VCT4. Therefore, it should be mentioned, the proper formula for a series mech mod is voltage = the voltage of a single battery times the number of batteries, the A = the CDC of a single battery. For a parallel mech mod, voltage = the voltage of a single battery, the A = the CDC of a single battery times the number of batteries. So, to get back to the VCT4, which has a CDC of 30A, in a series mech mod with 3 VCT4, you get 12.6V and 30A, in a parallel mech mod, you get 4.2V and 90A. In addition, it should also be mentioned (for the beginners reading this thread), the batteries should be the same type of batteries, e. g. all 25R, or all VCT4, etc., and ideally married, in order to avoid unregular discharge of either one of the batteries.

 

[dlcountpau]

Thanks guys! A new thing to learn everyday


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