Someone has given me a handheld hoover to look at. It is a HoLIFE HLHM036ADUK which I presume came from the middle isle of a German supermarket.
It "charges up" but then pressing the on button results in a second of motor action before it turns off.
Disassembling the unit reveals a battery pack made up of four 18650 Li-Ion cells, 2200 mAh at 14.8 Volts, with a date of 2018-09-28 which I presume is the assembly date of that pack.
Testing each individual cell on my cheap multi-meter shows:
4.08
4.11
4.12
4.13 volts (or thereabouts), and the ammeter showed 14 or so Amps for each.I cannot test again just yet as the fuse (10 Amp) blew. Of course.
The electronic circuit attached to the cells within the pack shows 16.4 Volts and an unknown current; this attempt to test the current is what I presume blew the fuse in the multi-meter.
Can anyone suggest any ideas what might be wrong?
Is it likely that new battery pack will resurrect the machine? (I was just about to order one but thought I'd ask here if anyone can see any reason why it'd be a waste of time and money.)
I've had 2 of the things, and they've both failed in the same way. I think that the control board fails in some fashion, and I doubt whether replacing the batteries would make any difference. I would chuck it in the nearest skip - or at least hand it in at somewhere like Currys to be recycled.
On the Dyson handhelds, pulsing or cutting out is a result of the filter getting blocked. The airflow is used to cool the motor, so if the filter is blocked the motor overheats and cuts out.
Clean or change the filters (there are two, the post-motor filter is often overlooked) and it comes back to life.
I had precisely the same fault with a Bush hand-held hoover, though this one had more cells.
The fault was a bad connection between the battery pack and the main PCB. There were two connectors on two separate cables, a two-way high-current power connector, and a multiway lower current battery monitor connector. The latter had worked loose, and the hoover cut out after about a second, just as you describe.
PS. Don't test battery current with your meter. It's unlikely to tell you anything useful, and may damage something other than your fuse.
My multimeter is quite old, and I've only measured current a couple of times, and that was with 10mA currents or so (I measure circuits which are intrinsically limited, on amperes). The fuse has never been tested by an activity of mine. There are just so many stories of blowing the fuse :-) Notice that the meter has a duty cycle spec printed in the plastic "make a measurement for a couple seconds then let the shunt cool off for *15 minutes* ". This avoids the solder inside the meter, melting and the shunt floating away. You cannot measure 10 amps DC on a regular multimeter for an hour on end. The meter is limited as to how long it can take that situation. While the warning print is hard to read, each multimeter has that ampere measurement warning on it... somewhere. The warning is concerning operation very near "max".
This is the circuit before analysis.
Your battery seems quite sprightly, and the fact the motor operates for a second, indicates there is some energy there. The voltages indicate a fresh charge to me, and the cells will drop back to 3.7V if measured
To measure current, the meter goes in series. A wire needs to be cut (or disconnected) to make a measurement with a conventional DC ammeter. Digital meters have (+) or (-) sign next to digits, so the polarity of the meter connection is not an imperative. Only an old Simpson analog meter, did you need to know what you were doing. As you could bend the indicator needle by connecting it backwards. (+) (+) +--amps--+ +--amps--+ | | | | +---X X-- controller --X +---+ (+) | total motor | ----- amps amps | --- | ----- | --- 16V Motor ----- (fully charged, | --- relaxing) | ----- | --- | (-) | | +------------------------------------------+
Something could be malfunctioning in the controller. The controller could be acting as the BMS (battery management system) and protecting you from surprises. Placing a short right across the battery pack, by placing the ammeter across it, may cause the fusible link inside a battery cell to open (which is a level of protection separate from a BMS action). Once the fusible link opens, the pack is ruined as it were. That's the "final level of safety" in the pack, the four fusible links, one per cell.
The BMS can disconnect the load, when the pack voltage is too low. But such a low condition could be sensed by the BMS, simply because a wire on the left side is thin and ohmic and there is excessive voltage drop in the cabling.
*******
You can measure current, without using the multimeter. My protocol, is to use my multimeter for voltage and when measuring a resistance in ohms on the scale. The separate holes for amps, almost never get used on the handheld multimeter.
I have a clamp-on AC/DC ammeter similar to this one. It is based on a Hall probe, which is a contactless means of measuring mag field. The wire coming from the battery, has a mag field proportional to the
10-20 amperes of current. By placing the jaws of the meter around the wire, I can measure a DC flow, and since it is contactless, the meter has no effect on the circuit whatsoever. No flashover, no arc, no explosion. These are priced for business users, rather than home users.
formatting link
DC Current Range 40A, 400A <=== this is why we buy such a meter.
"No fuses to blow" "Does not interfere with circuit" "Place clamp around wire needing current measurement"
It's not very sensitive on the low end. You can barely see 30 milliamps DC with it. It tends to drift (Hall probes do that), and needs to be zeroed with the jaws off the wire first, before taking a reading. There is a zero push button, on the instrument face.
Clamp meters come in two types. AC/DC (more expensive, Hall Probe). AC only (current transformer type, cheaper). That meter is the most expensive metering device in the house. It was bought on the expectation I would be fixing things. I have measured
150 amps DC on the car starter motor start cycle, as the largest current it has measured. The portable vacuum will need a DC measurement.
Something on the right hand side of your circuit diagram, is more likely to be at fault. Assuming you haven't ruined the pack, the pack part on the left seems good.
On some devices, the manufacturer pours a polymer resin over the controller, to prevent the home owner from repairing it. It isn't always the case, that it was designed for repair or analysis.
With a DC Clamp ammeter, I would not hesitate in this case, to check the motor current flow level. It could be overloading the circuit components on the left of the diagram.
The clamp meter, if measuring mains, there is a hot wire and a return wire. The mag fields cancel. The clamp on meter measures zero if you clamp the two wires together. To do mains work, you need a short extension, with the three wires in the cord exposed (a loop of wire for each), so that the clamp meter goes around *one* of the wires only. Then you can make a meaningful measurement.
*******
Say that we were in the era before clamp-on Hall Probe ammeters. How would you safely make the measurement then ?
With a manganin shunt. The example is a four point shunt. This is merely a replacement for the much smaller shunt inside your multimeter. You can ruin a shunt, and your multimeter might survive to run another day.
formatting link
The small screws are the voltage sense points. You connect your multimeter on volts, to the small screws.
The shunt still goes in series with the load, as in the multimeter drawing. That's what the larger screw points are for, the current flow connections.
Let's say I buy a RSN-100-100b. That's a 100 amp shunt, to be run at no more than 60 amps (for thermal reasons), where the voltage sense terminals put out 60mV when 60A flows. This means the voltage calibration on your multimeter, now measures Amps, even though the meter is set to 200mV full scale. If the meter reads 60mV, it is telling you that 60 amps are flowing in the shunt. That's why I picked a *specific* shunt, so the meter reading would be a "rational" one.
The shunt is made of two metals. Manganin in the center. The voltage sense points should still be embedded in manganin. If the manganin gets burning hot, the resistance of manganin changes little with temperature. Manganin and Zeronel are alloys used for making shunts. The voltage sense points (small screws) go to the multimeter. You never connect the large fat current flow cables, to the small screws.
The brass ends, where the current connections are made, the resistance there is "uncontrolled". Brass/copper have terrible coefficients. If you were measuring the resistance between the end terminals, with temperature, it would not be a constant. It is for these reasons that we do four point measurements -- the voltage points connected to the "precision" part of the circuit, the current points to the loosey goosey part of the shunt. That shunt has very little effect on circuit operation, as the shunt is 0.001 ohms total or so. Many of the connecting wires in the portable vacuum, have a higher resistance than that.
Manganin must not be dropped on the bench. You're not supposed to shock it. When it was manufactured, it was annealed as part of the process. This means you'd probably screw it to a piece of board. Notice how it has holes on the end, in the plastic, for the mounting hardware. And you would not torque the living shit out of the hold-downs either. The idea is not to stress the manganin sample too much, inadvertently. As that will throw off the cal.
Now I've never used one of those shunts, but that's the theory :-)
You can tell from the length of this message, that current measurements are not done nearly as casually as voltage measurements. Blowing the fuse is all part of the fun. As far as I know, it's a fast blow fuse, for best protection properties.
I used to have a hand-held vacuum cleaner - would run for a few seconds then stop. Turns out the dust filter pad was choked with fine dust. Gave it a good wash and dry and it was OK after that.
I've had experience of three different hand held, battery operated, small vacuum cleaners and I found that their ability to vacuum anything diminishes rapidly if the filters are not washed and dried out on a very regular basis. In most cases the removable plastic dust collection container needs a periodic swill through with water.
For my current Gtech cordless vacuum cleaners I have a set of replacement filters that I swap over every time I empty the dust collecting container, allowing the ones removed to be washed and then dried, which can take a day.
For bigger vacuuming jobs My Henry, using disposable HepaFlo bags, is a lot less hassle to clean. I've done nothing more than just change the bag in the last year or so and even in the past when vacuuming up plaster dust etc. the plastic tub has only had a quick squirt with the garden hose. The filters still look near pristine after a decade of use, and without being replaced or washed.
With mine, it wasn't just the suction ability that was affected but I think it used the air after the filter to cool the motor. No filtered air > no cooling > motor overheating > shut-off.
Henry Quick handheld works well - it uses small bags ('pods') which last a few weeks and save a lot of cleaning of parts. The normal Henry bides its time under the stairs, brooding and plotting its revenge.
There's still a post-motor filter. In the HEPA versions (not sure if the DC59 has those, the V6 that shares parts does) it's a removeable unit that can be replaced, on the non-HEPA versions it's a ring of foam at the outlet, inside the motor housing. Both can clog up, especially if you vacuum up fine dust like plaster or flour.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.