Remove battery from beard trimmer?

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MartinGZ

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#269963 17-Apr-2020 12:06

Is there any reason why I cannot permanently remove the knackered batteries from my beard trimmer? I could solder a couple of new batteries in, but I wonder why waste good batteries if I can use it mains powered. My electronics knowledge is fairly basic.

Circuit supplied at 5.3 VDC from mains powerbrick. The batteries I believe are 2 off 1.2 V NiMH in series, the model details are not visible until the batteries are removed. But as can be seen in the photo, the batteries are connected in parallel to the power circuit to the DC motor.

I use it mains powered, but it needs to sit on the mains for about 30 mins before the batteries stop sucking all the power in an attempt to charge. During this time it is unusable as the motor stalls - which is not fun when it grabs and pulls a couple of hairs! Ouch.

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Brunzy

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#2464103 17-Apr-2020 12:31

If the batteries need to charge , then it probably isn’t mains powered , and even if it was by removing them I’d say there would be no power going to the motor , looking at the circuit.

Just looked at the second pic again, if you plug in the power pack with the batteries left as in pic 2 , if it works / doesn’t you have your answer.

Dynamic

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#2464107 17-Apr-2020 12:36

If you cut the battery wire in the middle, you can then test to see if the trimmer works or not. If not, you can join the wire again.

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Brunzy

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#2464116 17-Apr-2020 12:47

He doesn’t have to do that. Look at pic 2 there is no return, therefore they cant charge .

Dynamic

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#2464142 17-Apr-2020 13:24

At least one of us has our eyes open :)

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Brunzy

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#2464147 17-Apr-2020 13:36

😷😷

MartinGZ

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#2464181 17-Apr-2020 14:13

Sorry should have included this picture as well. The battery has welded strap to series them. The bent pads connect to the 5.3 VDC in supply.

As I see it, while mains is connected, voltage is applied to the battery all the time, but also the motor. I've sketched what the circuit seems to be.

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clive100

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#2464185 17-Apr-2020 14:19

The batteries are in series providing 2.4V to the trimmer. The power socket only supplies a small current to charge the batteries via diode & limiting resistor.

Unfortunately the charger pack is not suitable voltage or current to run the trimmer directly.

MartinGZ

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#2464244 17-Apr-2020 14:49

clive100:

Unfortunately the charger pack is not suitable voltage or current to run the trimmer directly.

Many thanks for that, it was good I asked.

It would be nice to get direct replacement batteries, but that configuration of tags is not common. Planned obsolesce I guess - nothing wrong with the rest of it.

surfisup1000

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#2464293 17-Apr-2020 16:20

On the Philips company website, they say...

https://www.philips.com/a-w/about/sustainability.html

“At Philips, we fully embrace sustainability, because of its benefits for society, and because we believe that it is a driver for innovation and economic growth. That’s why sustainable development is an integral part of our company strategy.”

I own a Philips bodygroom trimmer. This product shows Philips up for the fork-tongued charlatans they really are. They don't care about sustainability at all.

This comes with twin soldered rechargeable batteries which are a few micrometers smaller than a normal AA battery. They also fail fairly quickly.

So, even if you manage to disassemble the case without breaking it, you need to find rechargeable AA's that you can hopefully hammer in without destroying the internal battery slots.

There is no reason why Philips couldn't have designed this with replaceable batteries. At the very least, not using soldered 'slightly smaller' than normal AA batteries.

pipe60

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#2464540 18-Apr-2020 07:52

Get a 2.4v or 3v plug pack, connect in place of batteries .

MartinGZ

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#2464955 18-Apr-2020 16:47

pipe60:

Get a 2.4v or 3v plug pack, connect in place of batteries .

Nice. The other idea was possibly use a voltage divider.

In the end I decided to use a couple of old batteries I had that are slightly better than the originals. Pulled the original tags off and soldered to the new batteries with heavy soldering iron. Seems to work OK and charging as I write.

Thanks everyone for the feedback.