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Looks like the Panasonic N-1700SCR: https://www.rapidonline.com/panasonic-n-1700scr-nicd-sub-c-size-cell-tagged-rechargeable-1-2v-1700mah-59-5608
https://www.omnitron.cz/_dokumenty/2782019161905808/n-1700scr.pdf
are rated for up to 8C discharge (if that's what the 'lt' on the graphs means) and an internal resistance of 4 milliohms means a series stack of 15 totals 60 milliohm. So when you pull 8A you get 0.48V dropped in the pack and 17.52V available for the tool, giving a power of 140W. The cells are 1700mAh so the total pack is 18*1.7=30Wh, roughly two mobile phones worth, compared with 96Wh for a 5Ah ltihium tool battery of similar size.
Not as good as lithium, but better.
Hello all,
I have an old B&Q own brand (Pro) 18 volt cordless set of drill, circ
saw, recip saw, and torch which ran on NiCads, which now do not run as
the batteries are buggered.
They get intermittent use. When they are needed, they are very useful indeed.
I was thinking of buying battery adaptors so that another brand of
(widely available) batteries can be used.
I know that the batteries must carry the BMS circuitry, and not the
tools which eliminates some brands.
I thought that the Bosch Power 4 All system (also 18 volts) would do the trick, despite them having a hefty price.
Anyone done this, or have any advice or ideas about it?
why I can't just buy a spot-welding tool and a cluster of
shop-bought ni-cads and make up my own array to stuff back into the
casing?
On 20/08/2025 22:00, Nick Odell wrote:
why I can't just buy a spot-welding tool and a cluster of
shop-bought ni-cads and make up my own array to stuff back into the
casing?
No reason at all, not to, but to make it worth the effort - make sure
you buy quality NiCads. I recelled a Makita drill battery some years
ago, it's still good, better than when new.
Smart charging attempts to drive a constant current through the cells</snip>
until the voltage starts to *drop*.
On 21/08/2025 11:28, The Natural Philosopher wrote:
<snip>
Smart charging attempts to drive a constant current through the cells</snip>
until the voltage starts to *drop*.
Drop not rise?
Andy
On 21/08/2025 11:28, The Natural Philosopher wrote:
<snip>
Smart charging attempts to drive a constant current through the cells</snip>
until the voltage starts to *drop*.
Drop not rise?
Andy--
On Mon, 25 Aug 2025 12:00:55 +0100, Vir Campestris <vir.campestris@invalid.invalid> wrote:
On 21/08/2025 11:28, The Natural Philosopher wrote:
<snip>
Smart charging attempts to drive a constant current through the cells</snip>
until the voltage starts to *drop*.
Drop not rise?
Andy
ISTR that the voltage drop is proxy for the cell gets warm, which is proxy for
the electricity can't be stored any more, i.e. the cell is full.
Thomas Prufer--
On 25/08/2025 12:00, Vir Campestris wrote:
On 21/08/2025 11:28, The Natural Philosopher wrote:
<snip>
Smart charging attempts to drive a constant current through the cells</snip>
until the voltage starts to *drop*.
Drop not rise?
Yes.
It's called 'delta peak' charger. If you ever had an RC car you would
have had one.
Ive still got one left over. In general you can recharge from flat in
around 20 minutes
Although the nickel cells get pretty warm!
https://en.wikipedia.org/wiki/Battery_charger
"For NirCoCd and NirCoMH batteries, the voltage of the battery increases slowly during the charging process, until the battery is fully charged. After that, the voltage decreases because of increasing temperature,
which indicates to an intelligent charger that the battery is fully
charged. Such chargers are often labeled as a +oV, "delta-V", or
sometimes "delta peak" charger, indicating that they monitor voltage
change. "
I am not sure its the temperature that causes the drop in voltage though.
On Mon, 25 Aug 2025 12:00:55 +0100, Vir Campestris
<vir.campestris@invalid.invalid> wrote:
On 21/08/2025 11:28, The Natural Philosopher wrote:
<snip>
Smart charging attempts to drive a constant current through the cells</snip>
until the voltage starts to *drop*.
Drop not rise?
Andy
ISTR that the voltage drop is proxy for the cell gets warm, which is proxy for
the electricity can't be stored any more, i.e. the cell is full.
On 2025-08-25, Thomas Prufer <prufer.public@mnet-online.de.invalid> wrote:
On Mon, 25 Aug 2025 12:00:55 +0100, Vir Campestris >><vir.campestris@invalid.invalid> wrote:Three terminal cells have a thermistor to sense the temperature rise.
On 21/08/2025 11:28, The Natural Philosopher wrote:
<snip>
Smart charging attempts to drive a constant current through the cells >>>> until the voltage starts to *drop*.</snip>
Drop not rise?
Andy
ISTR that the voltage drop is proxy for the cell gets warm, which is proxy for
the electricity can't be stored any more, i.e. the cell is full.
On 25 Aug 2025 15:34:44 GMT, Bernard Peek <bap@shrdlu.com> wrote:The RC car world has been using delta peak since I fisrt used NiCd on a
On 2025-08-25, Thomas Prufer <prufer.public@mnet-online.de.invalid> wrote: >>> On Mon, 25 Aug 2025 12:00:55 +0100, Vir Campestris
<vir.campestris@invalid.invalid> wrote:Three terminal cells have a thermistor to sense the temperature rise.
On 21/08/2025 11:28, The Natural Philosopher wrote:
<snip>
Smart charging attempts to drive a constant current through the cells >>>>> until the voltage starts to *drop*.</snip>
Drop not rise?
Andy
ISTR that the voltage drop is proxy for the cell gets warm, which is proxy for
the electricity can't be stored any more, i.e. the cell is full.
Probably much better than "charge until it gets so hot that the resistance changes".