On Fri, 10 Jun 2016 15:17:16 +0100, RJH <
patch...@gmx.com> wrote:
>On 10/06/2016 09:40, T i m wrote:
>> On Fri, 10 Jun 2016 08:44:20 +0100, Andy Burns
>> <
feb2017...@adslpipe.co.uk> wrote:
>>
>>> Andy Burns wrote:
>>>
>>>> Comparing LiDL's LSD types, the newest AA (18g) feel closer in the hand
>>>> to the previous AAA (13g) than the previous AA (27g).
>>>
>>> Seems they only hold about half their rated charge ...
>>>
>>> <
http://budgetlightforum.com/node/47141>
>>>
>>
>> But I note that discharge test was done at C/5 and I'm not sure that
>> is the right way to test that sort of cell (for capacity)?
>>
>
>What does C/5 mean please? I've recently bought an Xtar VC4, and a
>problem with estimating the capacity is getting the battery down to a
>sufficiently low (about 0?!) level, then charging it back up.
I'm not sure there are any rechargeable cells that should be
discharged beyond a certain level. I NiMh for example wouldn't
normally be taken to below 1V.
>
>> Picked up 4 packs yesterday (reduced) and can test them at any rate I
>> choose on my fancy chart-plotting rig. I'll test some and let you
>> know. ;-)
>>
>
>I tried the charger out on some Tronic 4000mah Cs that I use in a DAB
>radio. The radio was showing 30% remaining, and the charger stuffed 2800
>in. So probably not that far off.
The problem with that is the battery capacity meter may be calibrated
for say Alkaline cells (nominally 1.5V / cell) and you are using NiMhs
which are nominally 1.2V/ cell. As few of these meters measure voltage
drop V current / time but just the voltage, they probably aren't that
accurate.
The only way to measure the true capacity of a cell (or battery) is to
measure the power being delivered down to a specific threshold voltage
over time and at the rate as suggested by the manufacturer.
A good example of that in action is the batteries used in UPS's. Say
they are 7Ah lead acid batteries and you measure the UPS on-load as
pulling 7A, you might assume they will last 1 hour ... not the ~10
minutes they actually last. ;-)
Cheers, T i m