Rechargeable v. throwaway batteries

I have plenty of rechargeable NiMH batteries and a good charger, so I
have recently started using rechargeable batteries in my blinkies.

But the rechargeables do not seem to last as long, or to be as strong
even at the beginning, as the disposables. I haven't measured, so
these are subjective judgements.

Am I mistaken or is there some electrochemical reason to account for
my observations?

Andre Jute
"The first American car was sold to an American on April Fool's Day,
1898." -- Ralph Stein in "Vintage and Classic Cars", Bantam Books,
1977

On Oct 5, 6:38*pm, Andre Jute wrote:
I have plenty of rechargeable NiMH batteries and a good charger, so I
have recently started using rechargeable batteries in my blinkies.

But the rechargeables do not seem to last as long, or to be as strong
even at the beginning, as the disposables. I haven't measured, so
these are subjective judgements.

Am I mistaken or is there some electrochemical reason to account for
my observations?

Andre Jute
*"The first American car was sold to an American on April Fool's Day,
1898." -- Ralph Stein in "Vintage and Classic Cars", Bantam Books,
1977

NiMH batteries have a lower cell voltage than alkalines (1.2 vs. 1.5).
They also have a high self-discharge rate. Only the best NiMH have amp-
hr ratings close to alkalines. The high internal resistance of
alkalines makes them poor in high current applications. I use NiMH for
my main lights, alkalines for my blinkies.

On Oct 6, 12:17*am, Peter Cole wrote:
On Oct 5, 6:38*pm, Andre Jute wrote:

I have plenty of rechargeable NiMH batteries and a good charger, so I
have recently started using rechargeable batteries in my blinkies.

But the rechargeables do not seem to last as long, or to be as strong
even at the beginning, as the disposables. I haven't measured, so
these are subjective judgements.

Am I mistaken or is there some electrochemical reason to account for
my observations?

Andre Jute
*"The first American car was sold to an American on April Fool's Day,
1898." -- Ralph Stein in "Vintage and Classic Cars", Bantam Books,
1977

NiMH batteries have a lower cell voltage than alkalines (1.2 vs. 1.5).
They also have a high self-discharge rate. Only the best NiMH have amp-
hr ratings close to alkalines. The high internal resistance of
alkalines makes them poor in high current applications. I use NiMH for
my main lights, alkalines for my blinkies.

Thanks. Peter. I think I'll stick with the rechargeables on the font
blinkie, which is anyway so strong that besides aiming it twelve
degrees off the centreline of the bike I have also turned it
appreciably downwards, all in order no to blind or irritate drivers
while still drawing attention to my presence; it is a better light for
a slightly weaker battery! But on the back I think I'll return to the
alkalines; the Cateye TL-LD1100 is bright enough to be visible in
direct sunshine only with the strongest batteries.

Andre Jute
Photochromatic

On Oct 5, 4:17*pm, Peter Cole wrote:
On Oct 5, 6:38*pm, Andre Jute wrote:

I have plenty of rechargeable NiMH batteries and a good charger, so I
have recently started using rechargeable batteries in my blinkies.

But the rechargeables do not seem to last as long, or to be as strong
even at the beginning, as the disposables. I haven't measured, so
these are subjective judgements.

Am I mistaken or is there some electrochemical reason to account for
my observations?

Andre Jute
*"The first American car was sold to an American on April Fool's Day,
1898." -- Ralph Stein in "Vintage and Classic Cars", Bantam Books,
1977

NiMH batteries have a lower cell voltage than alkalines (1.2 vs. 1.5).
They also have a high self-discharge rate. Only the best NiMH have amp-
hr ratings close to alkalines. The high internal resistance of
alkalines makes them poor in high current applications. I use NiMH for
my main lights, alkalines for my blinkies.

The self-discharge rate is the main annoyance with NiMH cells. I've
been switching out my batteries for ones with newer low-self-discharge
chemistry (sold in shops as "pre-charged") which has a smaller
capacity in mAh but lasts longer for a lot of uses like blinkie lights
or an occasionally used camera or flashlight.

On Oct 5, 8:51*pm, pm wrote:
On Oct 5, 4:17*pm, Peter Cole wrote:





On Oct 5, 6:38*pm, Andre Jute wrote:

I have plenty of rechargeable NiMH batteries and a good charger, so I
have recently started using rechargeable batteries in my blinkies.

But the rechargeables do not seem to last as long, or to be as strong
even at the beginning, as the disposables. I haven't measured, so
these are subjective judgements.

Am I mistaken or is there some electrochemical reason to account for
my observations?

Andre Jute
*"The first American car was sold to an American on April Fool's Day,
1898." -- Ralph Stein in "Vintage and Classic Cars", Bantam Books,
1977

NiMH batteries have a lower cell voltage than alkalines (1.2 vs. 1.5).
They also have a high self-discharge rate. Only the best NiMH have amp-
hr ratings close to alkalines. The high internal resistance of
alkalines makes them poor in high current applications. I use NiMH for
my main lights, alkalines for my blinkies.

The self-discharge rate is the main annoyance with NiMH cells. I've
been switching out my batteries for ones with newer low-self-discharge
chemistry (sold in shops as "pre-charged") which has a smaller
capacity in mAh but lasts longer for a lot of uses like blinkie lights
or an occasionally used camera or flashlight.- Hide quoted text -

- Show quoted text -

rechargeables are good for regular commuting'; but on rides that get
dark I prefer the reliability of the alkie- a large pack can be had
for fairly cheap- I've had enough incidents coming back reciently that
25-50 cents or so per ride is not too much for a bit of extra safety.

Peter Cole wrote:
On Oct 5, 6:38 pm, Andre Jute wrote:
I have plenty of rechargeable NiMH batteries and a good charger, so I
have recently started using rechargeable batteries in my blinkies.

But the rechargeables do not seem to last as long, or to be as strong
even at the beginning, as the disposables. I haven't measured, so
these are subjective judgements.

Am I mistaken or is there some electrochemical reason to account for
my observations?

Andre Jute
"The first American car was sold to an American on April Fool's Day,
1898." -- Ralph Stein in "Vintage and Classic Cars", Bantam Books,
1977

NiMH batteries have a lower cell voltage than alkalines (1.2 vs. 1.5).
They also have a high self-discharge rate. Only the best NiMH have amp-
hr ratings close to alkalines. The high internal resistance of
alkalines makes them poor in high current applications. I use NiMH for
my main lights, alkalines for my blinkies.

Aren't LiPo batteries available in convenient sizes yet?

On Oct 5, 8:03 pm, raamman wrote:
On Oct 5, 8:51 pm, pm wrote:



On Oct 5, 4:17 pm, Peter Cole wrote:

On Oct 5, 6:38 pm, Andre Jute wrote:

I have plenty of rechargeable NiMH batteries and a good charger, so I
have recently started using rechargeable batteries in my blinkies.

But the rechargeables do not seem to last as long, or to be as strong
even at the beginning, as the disposables. I haven't measured, so
these are subjective judgements.

Am I mistaken or is there some electrochemical reason to account for
my observations?

Andre Jute
"The first American car was sold to an American on April Fool's Day,
1898." -- Ralph Stein in "Vintage and Classic Cars", Bantam Books,
1977

NiMH batteries have a lower cell voltage than alkalines (1.2 vs. 1.5).
They also have a high self-discharge rate. Only the best NiMH have amp-
hr ratings close to alkalines. The high internal resistance of
alkalines makes them poor in high current applications. I use NiMH for
my main lights, alkalines for my blinkies.

The self-discharge rate is the main annoyance with NiMH cells. I've
been switching out my batteries for ones with newer low-self-discharge
chemistry (sold in shops as "pre-charged") which has a smaller
capacity in mAh but lasts longer for a lot of uses like blinkie lights
or an occasionally used camera or flashlight.- Hide quoted text -

- Show quoted text -

rechargeables are good for regular commuting'; but on rides that get
dark I prefer the reliability of the alkie- a large pack can be had
for fairly cheap- I've had enough incidents coming back reciently that
25-50 cents or so per ride is not too much for a bit of extra safety.

Whatever I might happen to be running in my Planet Bike Blaze 1-watt
headlight, I keep a pair of Duracell Ultra Alkalines in my messenger
bag. They make the headlight very bright, and last a pretty good long
time in storage or in service.

Tosspot aka Frank Leake wrote:
[...]

Aren't LiPo batteries available in convenient sizes yet?

Lithium-Polonium?

--
Tom Sherman - 42.435731,-83.985007

On 2009-10-06, pm wrote:

The self-discharge rate is the main annoyance with NiMH cells. I've
been switching out my batteries for ones with newer low-self-discharge
chemistry (sold in shops as "pre-charged") which has a smaller
capacity in mAh but lasts longer for a lot of uses like blinkie lights
or an occasionally used camera or flashlight.

Sanyo calls them "Eneloop".

--
Gregory S. Sutter "How do I read this file?"
"You uudecode it."
http://zer0.org/~gsutter/ "I I I decode it?"

On Oct 5, 6:38*pm, Andre Jute wrote:
I have plenty of rechargeable NiMH batteries and a good charger, so I
have recently started using rechargeable batteries in my blinkies.

But the rechargeables do not seem to last as long, or to be as strong
even at the beginning, as the disposables. I haven't measured, so
these are subjective judgements.

You're pretty much right. Most rechargeables, whether NiCd or NiMH,
have a lower voltage and lower capacity than a good alkaline. This
causes me problems not with lighting but with my digital camera (a
Nikon, no less - I figured that they made good stuff that wouldn't
give me issues despite the fact that it has a menu option for using
NiMH rechargeables, it does not properly recognize state of charge and
will shut itself off after a few pics, but works fine with a pair of
alkalines.

That said I have been using NiMH C-cells in my 3W Task Force
"headlight" and they seem to be OK for the riding that I do. I've
only really used them for two real rides so far though (I was using
alkalines previously.) I still keep it on the bike when I'm riding at
night as when it's really pitch black a Lumotec halogen alone isn't
really getting it (although I'm sure I could get home just fine with
only the Lumotec, I don't feel comfortable riding at normal speed)
plus redundancy is good (even if/when I get a better primary
headlight, I will still likely carry the Task Force along just as a
backup.) If that were my only light, I would seriously consider
carrying a pair of alkalines in my tool kit just in case.

nate