RCR123 vs Primary, mAh and voltage difference?

TyJo · Jul 1, 2011

I have heard that AW RCR123 protected batteries should supposedly provide half the run time of a primary cell in HDS lights. Lets assume that the RCR123 have 700 mAh and primary is 1400 mAh. My question is where does voltage come into play.
An AA eneloop has 2000 mAh (around 1.2v).
An Surefire primary has around 1400 mAh (around 3v).
An AW RCR123 has around 700-750 mAh (around 4.2v).

I realize mAh is a measure of capacity, but doesn't voltage have an impact on this. I know an Eneloop AA doesn't have more capacity then a Surefire primary??
Any information/explanation is appreciated.
Thanks.

Mr Happy · Jul 1, 2011

mAh is only used to compare similar cells or batteries. If the batteries are of different types or voltages then mWh (a measure of total energy) should be used to compare capacity. Energy is voltage x current x time, so an estimate of mWh is given if you multiply the capacity in mAh by the average discharge voltage.

For example, an eneloop by this measure would be approximately 1900 mAh x 1.2 V = 2300 mWh. An RCR123 would be approximately 700 mAh x 3.7 V = 2600 mWh.

TyJo · Jul 1, 2011

Mr Happy said:
mAh is only used to compare similar cells or batteries. If the batteries are of different types or voltages then mWh (a measure of total energy) should be used to compare capacity. Energy is voltage x current x time, so an estimate of mWh is given if you multiply the capacity in mAh by the average discharge voltage.

For example, an eneloop by this measure would be approximately 1900 mAh x 1.2 V = 2300 mWh. An RCR123 would be approximately 700 mAh x 3.7 V = 2600 mWh.

So what type of runtime could you expect from an RCR123 compared to a primary? 2300mWh for the RCR123 and 1400 x 3v = 4200mWh?? So the half runtime estimate is probably correct?

HKJ · Jul 1, 2011

TyJo said:
So what type of runtime could you expect from an RCR123 compared to a primary? 2300mWh for the RCR123 and 1400 x 3v = 4200mWh?? So the half runtime estimate is probably correct?

A CR123 is not 3 volt on a flashlight running in high, it is maximum 2.5 volt. On many high power flashlight the RCR123 will have longer runtime at full brightness than CR123, because the CR123 can not supply enough power. At lower brightness the CR123 wins.

cave dave · Jul 1, 2011

Its better to understand the behavior in an actual flashlight. The HDS is particularly special since the brightness is the same on either cell but there are different cutoff algorithms depending if it detects a LiIon or a primary. The HDS is designed to protect the LiIon but will deplete a primary.

In the case of my HDS 170cn test results were as follows:
(10sec 170lm Burst then Max 120lm till first step down)

Battery Station US made Primary: 82Min
AW RCR123: 63 Min

What is also interesting to note in these tests is that once a healthy LiIon hits that first drop down it is only has a few min of runtime till it is blinking at the min level. In the case of the primary once it dropped out of max I was able to switch to 10 lm and had several hrs more light.

TyJo · Jul 1, 2011

Thanks for the replies everyone.

cave dave said:
Its better to understand the behavior in an actual flashlight. The HDS is particularly special since the brightness is the same on either cell but there are different cutoff algorithms depending if it detects a LiIon or a primary. The HDS is designed to protect the LiIon but will deplete a primary.

In the case of my HDS 170cn test results were as follows:
(10sec 170lm Burst then Max 120lm till first step down)

Battery Station US made Primary: 82Min
AW RCR123: 63 Min

What is also interesting to note in these tests is that once a healthy LiIon hits that first drop down it is only has a few min of runtime till it is blinking at the min level. In the case of the primary once it dropped out of max I was able to switch to 10 lm and had several hrs more light.

I remember reading some of your tests, I noticed my rotary dropped through modes rapidly when the RCR became depleted. After reading the HDS FAQs it sounds like they are pretty equal at the higher brightness settings because of the internal resistance of the CR123s.

RCR123 vs Primary, mAh and voltage difference?

TyJo

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Mr Happy

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TyJo

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HKJ

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cave dave

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TyJo

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