Cycling Mob: Road Cycling, Mountain Biking and More - View Single Post

01-01-2007, 04:18 PM

On Sun, 31 Dec 2006 19:19:23 -0000, Richard B
<blueSPAMMENOTrandonee@gmail.com> wrote:

>Mike Ellis <news@mellis.me.uk> wrote in
>news:4596dcc2$0$2754$c3e8da3@news.astraweb.com:
>
>> dgk wrote:
>>> I like to use rechargable batteries in my lights, and for the most
>>> part using a rechargable AA in place of a regular battery works fine.
>>> But with cold cathode bulbs on my bike, the little transformer thing
>>> needs 12 volts. So I replaced the normal 8 AAs with 8 rechargables.
>>> And it sort of works. But one bulb starts dimming after a half hour
>>> or so. Checking with normal batteries, this doesn't happen.
>>>
>>> I looked a bit closer at my rechargables, which are, it turns out,
>>> 1.2 volts, not 1.5 like regular batteries. All rechargables that I
>>> looked at are 1.2. So, 8 * 1.2 = 9.6, not 12. Other stuff, like CD
>>> players, work fine on the rechargeables, but the cold cathodes have a
>>> bit of a problem. Obviously, 10 batteries instead of 8 should do the
>>> trick, but I don't have, and can't find, a case that holds 10
>>> batteries.
>>>
>>> So, why do some things work fine with 1.2, and others not? And why
>>> aren't rechargeables 1.5?
>> Some things work fine whilst others don't because the application
>> isn't so voltage critical. It could also be that the internal
>> circuitry reduces the input voltage to a lower value so that lower
>> voltage cells will work. The reason that rechargeables are only 1.2
>> volts is because the chemical reaction only produces 1.2V whereas the
>> chemical reaction of regular batteries produces 1.5V. I'm afraid its
>> all down to the chemistry.
>>
>> Mike
>>
>
>Why not susbtitute a small sealed lead acid battery, AKA a Gel Cell...
>
>Look at this site:
>http://www.zbattery.com/sla.html
>
>Or if you really want to get ceative see:
>http://www.powerstream.com/SLA.htm
>
> Richard B.

Thanks. I do have a spare SLA battery from an old Nite Hawk bike light
that I don't use much anymore and I considered using that. I thought
it was 12 volt but I just looked and apparently it's only 6 volts.
Anyway, it weighs a lot. It's the type that fits the water bottle
cage.Nah, I think I'll stick to the NiMHs.

01-01-2007, 04:18 PM	#15 (permalink)
dgk Posts: n/a	Re: When 12 volts is not 9.6 volts On Sun, 31 Dec 2006 19:19:23 -0000, Richard B <blueSPAMMENOTrandonee@gmail.com> wrote: >Mike Ellis <news@mellis.me.uk> wrote in >news:4596dcc2$0$2754$c3e8da3@news.astraweb.com: > >> dgk wrote: >>> I like to use rechargable batteries in my lights, and for the most >>> part using a rechargable AA in place of a regular battery works fine. >>> But with cold cathode bulbs on my bike, the little transformer thing >>> needs 12 volts. So I replaced the normal 8 AAs with 8 rechargables. >>> And it sort of works. But one bulb starts dimming after a half hour >>> or so. Checking with normal batteries, this doesn't happen. >>> >>> I looked a bit closer at my rechargables, which are, it turns out, >>> 1.2 volts, not 1.5 like regular batteries. All rechargables that I >>> looked at are 1.2. So, 8 * 1.2 = 9.6, not 12. Other stuff, like CD >>> players, work fine on the rechargeables, but the cold cathodes have a >>> bit of a problem. Obviously, 10 batteries instead of 8 should do the >>> trick, but I don't have, and can't find, a case that holds 10 >>> batteries. >>> >>> So, why do some things work fine with 1.2, and others not? And why >>> aren't rechargeables 1.5? >> Some things work fine whilst others don't because the application >> isn't so voltage critical. It could also be that the internal >> circuitry reduces the input voltage to a lower value so that lower >> voltage cells will work. The reason that rechargeables are only 1.2 >> volts is because the chemical reaction only produces 1.2V whereas the >> chemical reaction of regular batteries produces 1.5V. I'm afraid its >> all down to the chemistry. >> >> Mike >> > >Why not susbtitute a small sealed lead acid battery, AKA a Gel Cell... > >Look at this site: >http://www.zbattery.com/sla.html > >Or if you really want to get ceative see: >http://www.powerstream.com/SLA.htm > > Richard B. Thanks. I do have a spare SLA battery from an old Nite Hawk bike light that I don't use much anymore and I considered using that. I thought it was 12 volt but I just looked and apparently it's only 6 volts. Anyway, it weighs a lot. It's the type that fits the water bottle cage.Nah, I think I'll stick to the NiMHs.