Replace batteries with resistors possible ? - Page 1
Forum section: electronics / beginners

author: Sjokolade
author_rank: Regular Contributor
timestamp: May 31, 2025, 12:15:18 am
content: The NiMH batteries in this haircutter is holding no charge and the haircutter has problems starting when plugged into powersupply - I removed batteries believing it would start easier but it doesn't start at all without batteries.Is it possible to put in two resistors instead of the batteries to make the circuit believe it has batteries so it will start when plugged into powersupply ?If it matters U1 is a CCE7101 and the batteries are aaa 750mAh 30mOhm.

author: Smokey
author_rank: Super Contributor
timestamp: May 31, 2025, 12:30:39 am
content: While you have the thing open... How about replacing the batteries with.... batteries?

author: Sjokolade
author_rank: Regular Contributor
timestamp: May 31, 2025, 12:39:27 am
content: When this haircutter failed I put in new batteries in another similar type haircutter that only has 1 hour charge time, the one pictured here I want to use without batteries as it has 8 hours charge time.

author: Smokey
author_rank: Super Contributor
timestamp: May 31, 2025, 01:18:01 am
content: Right answers:1) Just replace the batteries and let the thing charge. Do you need to cut your hair more often than every 8 hours?2) Use the other "haircutter" that you just said you have and throw the old one with dead batteries away.Wrong answers:1) Replace the batteries with a corded connection.Here's why. Most battery operated stuff isn't designed to run from either batteries OR a corded supply. The corded supply is only for charging and can't usually support the full run current that the batteries supply to the system. The charge port probably goes through a charger circuit and doesn't directly power the thing anyway. If it does it probably doesn't have the current rating.If I'm wrong about all that then just solder/crip the power supply cord to the battery terminals. But don't do that. See right answers above.

author: Sjokolade
author_rank: Regular Contributor
timestamp: May 31, 2025, 01:28:40 am
content: Quote from: Smokey on May 31, 2025, 01:18:01 amNo I do not but I was planning having this one as a spare as Braun says in manual : 'If the rechargeable batteries are discharged, you may also use theappliance by connecting to an electrical outlet via the special cord set'Thank you for taking time to answer me

author: themadhippy
author_rank: Super Contributor
timestamp: May 31, 2025, 01:37:06 am
content: alternatively chuck both sets in the bin ,let the hair grow and put the money spent on clippers and time taken for a trim to a better use

author: Sjokolade
author_rank: Regular Contributor
timestamp: May 31, 2025, 01:38:52 am
content: Thanks

author: calzap
author_rank: Frequent Contributor
timestamp: May 31, 2025, 02:16:45 am
content: If you want to use the device without batteries at all, an alternative would be to buy a wall wart that has the voltage and power output of the batteries. Get rid of the batteries, the charging device and its cord. Connect the wall wart wires to the battery output terminals or leads, using correct polarity.Mike

author: Smokey
author_rank: Super Contributor
timestamp: May 31, 2025, 02:26:57 am
content: Quote from: calzap on May 31, 2025, 02:16:45 amWhile this may not be the case for something this low power, but be heads up that DC motors draw quite a bit of current when they start spinning. So if your thing draws 1A while running, it might be 8A for a short peak. Make sure your supply can handle that.

author: Sjokolade
author_rank: Regular Contributor
timestamp: May 31, 2025, 02:27:59 am
content: Yes that is a possibility Mike, I was hoping to use the original powersupply and have the on/off button work as both haircutters use the same supply and they both are watertight.I'll see what I can do with this spare.Thanks Mike.

author: reodor
author_rank: Contributor
timestamp: May 31, 2025, 09:02:43 am
content: A large capacitor might be worth a try. The charge circuitry will charge the capacitor to 4.2V per cell, and the stored charge may be enough to get the motor started.