Remington Shaver HC6550 not to full Power

[THX1138]

I have a Remington Shaver HC6550 (cordless) and it doesn't seem to be working at full power. I don't know what's the problem. I have tried to charge it several times and it stills behaves the same way. The problem is that I can power it on and then it shuts down after 5 seconds. I read it could be a thermal switch. Any help would be appreciated.

 

[dave9]

Can you measure battery voltage at the charging contacts (if it has any that are accessible)? If so then compare full charge voltage to the voltage at the point of shutdown. It might just be a dying battery. How old is it?

If you have no external measurement points then you have to open it, paying attention to gaskets' positions for waterproofing if present. It may never be waterproof again, some gaskets only work well on first assembly.

Once inside, you can measure power or if a thermal switch trips you can measure closed and open circuit resistance across it. You could also substitute a different battery or disconnect the battery and supply an alternate power source of same voltage. If you don't have an alternate source, consider it is Li-Ion powered, so probably 3.7-ish voltage would work like 3 x AA cells in series could be rigged up to approximate that if nothing else, ideally NiMH since alkalines aren't good for as much current.

Unless it is extremely bogged down (motor seized, not working, and even then...) I doubt a thermal switch after only 5 seconds.

I suppose something super-sophisticated could measure motor RPM and shut it off if it is too low, meaning maybe (probably not, lol) the possibility that it just needs gunk cleaned out.

 

[Martaine2005]

I would also guess the battery too.
After returning three units within 10 months each.


Martin

 

[THX1138]

Can you measure battery voltage at the charging contacts (if it has any that are accessible)? If so then compare full charge voltage to the voltage at the point of shutdown. It might just be a dying battery. How old is it?

If you have no external measurement points then you have to open it, paying attention to gaskets' positions for waterproofing if present. It may never be waterproof again, some gaskets only work well on first assembly.

Once inside, you can measure power or if a thermal switch trips you can measure closed and open circuit resistance across it. You could also substitute a different battery or disconnect the battery and supply an alternate power source of same voltage. If you don't have an alternate source, consider it is Li-Ion powered, so probably 3.7-ish voltage would work like 3 x AA cells in series could be rigged up to approximate that if nothing else, ideally NiMH since alkalines aren't good for as much current.

Unless it is extremely bogged down (motor seized, not working, and even then...) I doubt a thermal switch after only 5 seconds.

I suppose something super-sophisticated could measure motor RPM and shut it off if it is too low, meaning maybe (probably not, lol) the possibility that it just needs gunk cleaned out.

I opened it up and found 2 batteries. Each battery has a voltage of 4.2V and I found no voltage drop when the device was on. The device is labeld as 12V, 1.2 A. I got it since about 11/2020.

 

[THX1138]

 

[kellys_eye]

Those are lithium batteries and 4.2V (per battery) is the correct, fully-charged voltage so they aren't the 'problem'. The 12V 1.2A notice is the supply voltage to the internal circuitry which will have onboard battery charging functions that uses the 12V to deliver the correct charge voltage/current to the batteries.

The 'closing down in 5 seconds' is likely as a result of the circuitry measuring discharge current - fitted to protect against battery short-circuits and potential fire hazards as a result. Some Lithium batteries have this protection built-in. Nominally the batteries look like 18650's which represents diameter and length in mm so 18mm diameter, 65mm long and if the battery measures LONGER than 65mm it may have the built-in protection circuitry I mentioned. These AREN'T 18650's but the number printed on the side will tell all.

The batteries look to be replaceable - can you remove them and see the labelling? Google the number on it and see what it turns up - it may even mention that they have built-in protection - who knows? Fitting other batteries or even attaching a stable power source in place of them might eliminate the actual batteries as the problem.

 

[dave9]

I agree it could be a protection circuit, trace the power route between battery and motor and you should find some tiny IC, maybe instead a transistor it operates too, in series in this path. However it could be a blown chip due to heat, or could really be that the motor is shorting out or gunked up and slow running so pulls more current than it should.

I once had a work light that kind of fell into this category but it was a marginal design that used only 1 x 18650 cell, then when I put two more in parallel for more runtime, the cells' voltage drooped less, so more current through the LED array, causing an SSF8205A IC to shut it down in a few seconds. Once the batteries had discharged some, it would run all day without that happening.

 

[THX1138]

Without having to pull the battery out of the cb because it seems to be either glued or soldered in, it seems it's a 14650 1200mAh 3.7v 4.07 wH. I'm not sure about the last part.

 

[kellys_eye]

it's a 14650 1200mAh 3.7v 4.07 wH.

Sounds (and looks) about right. 4.07wH is simply the voltage multiplied by the capacity.

You can try measuring the actual physical length (65mm) and if it's 'over' (by only a mm or so) then the battery may include the internal protection I mentioned. Another way is to carefully peel away the plastic at the top to see if there is a small circuit board attached to the top of the cell.

Either way, you can easily eliminate the battery as the issue by finding the pos/neg connections and connecting them to an external source instead (three alkaline AA's s will be good enough) and see if the device allows full power operation. Given I have a reasonable set of test equipment I'd by slapping my twin output variable PSU in their place and running it up but we have to deal with what you've got!

Another way would be to fit a different MOTOR - if you have a basic commutated battery toy motor (any voltage will do) fit that in place of the original and see if you can get it to run 'constantly' - then grab the spinning motor shaft (carefully!) to load up current and see if it stalls or cuts off. It really SHOULD cut off (the protection circuitry cutting in).

In fact, take the origjinal motor out anyway (still connected) to check that there isn't a physical resistance stopping the motor turning i.e. can you actually spin the shaft with your fingers (power off)?

 

[THX1138]

The length is barely 64-65mm. I don't see any cb to the top of the cell. Pictures are of the top portion. Could I purchase a type of small switch to attach to the motor with 3 AA's in order to see if the problem lies with motor?

 

[THX1138]

The motor's print states:
JSK-2805A-18162V
D/V7.4 200618-06
MADE IN INDIA ++

 

[THX1138]

Pics of the motor. How would I open it?

 

[CircutScoper]

...I have tried to charge it several times and it stills behaves the same way. The problem is that I can power it on and then it shuts down after 5 seconds...

Do you have to recharge it before each 5 second running? If so then the problem is very likely (a) defective battery(s).

 

[THX1138]

No. The device does not to be recharged. I don't have a twin output variable PSU so I think I'll replace the motor as stated previously by kellys_eye. I'm just not sure what kind of motor I should get.

 

[THX1138]

Could I use a motor like this? https://www.amazon.com/Topoox-15000...ric+motor&qid=1653175151&sr=8-5&tag=coa_us-20
Correction
The motor's print states:
JFK-2805A-18162V
D/V7.4 200618-06
MADE IN INDIA ++

 

[CircutScoper]

No. The device does not to be recharged. I don't have a twin output variable PSU so I think I'll replace the motor as stated previously by kellys_eye. I'm just not sure what kind of motor I should get.

So the shaver works, but only for 5 seconds per button push? How long do you have to wait between pushes before it will start again for another 5 seconds of operation?

In any event, it doesn't sound like a defective motor problem to me.

 

[CircutScoper]

...Each battery has a voltage of 4.2V and I found no voltage drop when the device was on...
View attachment 55208

Are you saying that the total battery voltage remains a rock-steady 4.2 + 4.2 = 8.4V even while the motor is running? If so, that's amazing -- and very unlikely. It should drop at least a little.

 

[THX1138]

So the shaver works, but only for 5 seconds per button push? How long do you have to wait between pushes before it will start again for another 5 seconds of operation?

In any event, it doesn't sound like a defective motor problem to me.

No wait at all.

 

[THX1138]

Are you saying that the total battery voltage remains a rock-steady 4.2 + 4.2 = 8.4V even while the motor is running? If so, that's amazing -- and very unlikely. It should drop at least a little.

The needle vibrates a little so I guess it drops a miniscule of voltage.

 

[bertus]

Hello,

A DMM (Digital Multi Meter) might give you a better resolution than an analog meter.

Bertus