As I don't have the time or money (or knowledge) to design my own electronics I'm taking an existing product and modifying it :-) It runs off three 1.5V watch batteries in series. I'd like to replace this with a single
4.5V rechargable battery and charge it from a USB port. Does a 4.5 volt battery exist that would take up a similar amount of space? What sort of cicuit would I need to charge the battery (if any).Many thanks, Michael
"Michael C"
........... Phil
4 batteries (1.2v each) = 4.8 (a touch more than 4.5 but good enough) then add usb port
If you have power available all the time it's no more difficult to design and build a voltage regulator to eliminate batteries than a battery charger.
AFAIK you won't get any rechargeable batteries that are compatable in size to watch batteries.
Nor are watch batteries all the same technology. The best and most expensive are silver oxide, for which cheaper options exist if the voltage stability isn't critical.
-- John H
Hi John,
The device is USB but it is wireless so won't always have power. I do have a fair bit more space than the 3 watch batteries, probably enough for a single AA battery. I was thinking that I could have a usb plug on the device that was used for charging only, instead of supplying the customer yet another charger.
Michael
"Michael C"
** Had to DRAG simple fact that out of the PITA prick.Go check the WES catalogue for Akai Video Backup Batteries.
Cat # BVS8 = 4.8 volt, 80 mAH.
Costs = $10 .
........ Phil
WES Components at Ashfield (NSW) list a 1.2V 80mAh NiMH that measures
16mm x 6mm (tagged for PCB mounting). It's code no. is RB80. They're somewhat more expensive than watch batteries (probably close to double).Four in series would give you 4.8 volt.
-- John H
When I originally posted I didn't have that much space but came up with a better way to do it.
Thanks phil, I'll give them a call next week.
On Sun, 09 Oct 2005 19:49:48 +1000, John_H put finger to keyboard and composed:
How would you go about charging them from a 5V source?
-- Franc Zabkar
Please remove one 'i' from my address when replying by email.
"Franc Zabkar"
** Boost regulator........... Phil
What's one of them then?
Michael
"Michael C"
** Try Google.......... Phil
LM2750 -- $5.81 from Farnell (awaiting stock).
-- John H
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