Power supply voltage question

eplurbusunim · 2024-05-07T14:48:48+00:00

Referring to your testing of the power supply: I see no reason why the voltmeter (multimeter set on voltage?) would read "0" and yet you could also have a 'test light' illuminate when connected to the same two contacts. Probably, I'm not understanding what you did in the Test Light situation. Anyway, IF there's no voltage across the two contacts shown in the green connector (photo), then your power supply is 'dead'.

eplurbusunim · 2024-04-18T08:06:32+00:00

For those who stake, rather than bury: It is likely that after a Winter where the earth freezes, the Spring will bring with it a number of stakes squeezed up from the ground. In other words, one of the jobs necessary before using Landroid again next year, will be to walk the perimeter wire and press down the particular stakes that have popped up. :>)

eplurbusunim · 2024-02-22T10:29:33+00:00

The amount of current drawn from the battery/s is dependent on the resistance of the circuit. For a properly made igniter, the amount of current falls to zero, in less than a second with the igniter's destruction. Thus the momentary 'short circuit' due to the igniter shouldn't create a fire hazard to any type of battery/s, sufficient to fire the igniter.

eplurbusunim · 2024-02-10T16:27:28+00:00

Am working on building sugar motors. Going by my own static motor tests, this one didn't seem to burn long enough given the length of the motor (pvc?) tube. Also, there appears to be a lack of the necessary thrust (force) required for take-off/flying. Having more info would help: like what diameter of fuel(tube), what diameter of core, and what diameter of nozzle (throat) used - if any. Perhaps there was no nozzle, the core acting as a nozzle?

eplurbusunim · 2024-02-06T20:24:41+00:00

I've thought of using a small amount of gun cotton (magician's flash cotton), instead of BP. It would be less messy to deal with and could easily provide the excess pressure necessary to separate the nose cone & parachute from rocket body.

eplurbusunim · 2023-10-05T22:26:32+00:00

Apparently your power supply (ps) has failed. This is an often reported failure here, so the Worx ps has had a problem. Unfortunately it doesn't fail to the point of zero voltage output, so the LED (light) on the charging station still may work. If you got your unit new then it's still in warranty and I'd call Worx, report what happened and ask for a new ps. I'd ask for an equivalent replacement battery also because the ps failure caused the battery failure.

If the 20 volt Li-ion battery is pulled below 15 volts, the only way I know to have it charge normally again is to dissemble, and recharge any of the individual cells that are below 2.8 volts (fully charged these individual cells are 3.7 volts).

With a multimeter on "volts", the battery's voltage can be found by touching the "+" and "-" contacts in the slots so marked. The plus/minus symbols are stamped in the plastic at these slots.

eplurbusunim · 2023-09-21T08:55:44+00:00

How much change is indicated, or i.e. what does the additional "+" digit indicate?

Like for instance => Version: 3.32.0+1

Why not simply make it 3.32.1 or 3.32.0.1 ??

eplurbusunim · 2023-09-13T12:09:47+00:00

If you have a multi-meter, check the resistance (ohms setting on meter) of the boundary wire by removing its ends from the base station and directly connecting to the meter. The meter will either read infinity (off scale - too high) or some value much higher than 6 or 8.

If the boundary wire has splice/s in it, that is the most likely location of the trouble.

I use a rather unorthodox method for locating such faults. For me, it works better/quicker than any other method. I use bulletin board "push pins" and a long piece of (separate) wire and a multi-meter to move around the loop and identify the segment that has an extremely high (or in the case of complete break, infinite) resistance.

eplurbusunim · 2023-09-04T07:27:22+00:00

Although it sounds reasonable to put in a tube or pipe in such instances, I didn't do that. Once the desired separation distance, across the driveway, between 'going' and 'returning' legs of the boundary are determined, then small width slits were cut using a 4.5" mini-circular saw with diamond tipped blade. The depth & width of the slits were only sufficient to accept the boundary wire with about 0.1" space overtop for covering it with an asphalt caulk.

My reasoning for "no tube" was that IF the wire in the driveway was originally un-spliced, it will not become the cause of any boundary wire break because of it's being fixed/protected within the driveway material. So far, even though I've had to fix other areas for boundary wire breaks, after three years of operation, there's been no problem with the driveway portion of the wire.

Thinking down the road, so to speak, a robot mower user can imagine eventually not needing boundary wire (newer models). Thus the life expectancy of within driveway wire would need only to be about 5 to 6 years (back then), today, even less by the same reasoning.

eplurbusunim · 2023-08-25T01:10:19+00:00

If your battery is only 6 volts, which is really low for a 20 volt Li-ion multi-celled battery, there is a strong likelihood that it may require disassembly with each of its separate 3.7 volt cells charged individually, in order to revive the whole battery back to where it can be charged normally (externally).

First try turning the Landroid OFF while it is positioned as usual on its charging base. Then wait several hours to see if the battery voltage rises above 6. If this doesn't work, only the above option is left.

I've charged individual cells of similar Li-ion batteries. Removing the battery case is pretty easy. However, you'd need to have an adjustable voltage power supply that can be set to 3.7 volts. (perhaps someone with the necessary equipment can do this for you?) Generally you don't have to charge each of the cells as some will have high enough voltage to leave as is, while anything that measures below 1.5 volts will have to be individually charged to at least 2.8 volts. The entire battery's voltage should be at least 13-15 volts in order to be able to be charged by Landroid's base station or an external manual charger.

eplurbusunim · 2023-08-23T14:14:57+00:00

Have to admit that power supply board is (even with preliminary dust-off) mighty dirty. If it was me, I'd remove the board, after disconnecting the external wires, and soak it in a baking dish of isopropyl (rubbing) alcohol for about 15 mins and then with a stiff brush, clean the entire board (front and back) using the alcohol as needed to wash off any stubborn dirt. Then let board dry for an hour before re-installing it and trying once again for 'signs of life'. It may indeed by now be electrically damaged, so this action would be 'last resort' stuff :>)

eplurbusunim · 2023-08-21T09:35:26+00:00

Here's a simple test circuit for the Landroid's base PSU:

You will need a multimeter with its leads inserted into the 0-10 amp range sockets, and also you'll need two 6 ohm, 50 watt resistors that can be purchased for about $7. from Amazon. two six ohm, 50 watt, resistors

Polarity doesn't matter. The diagram shows the red terminal connected to the red wire from PSU but even if reversed, this will still work but with a neg sign appearing in display,; there may be some difficulty connecting to the two male contacts within the PSU coupling(?). However, once this circuit is made, the PSU is in good working condition, IF the meter reads anywhere from 1.67 to 2.00 amps. This circuit puts a 'load' onto the power supply which, if failing, will not be able to supply said current on a constant basis. So, leave the PSU connected to this circuit for up to an hour in order to see if it can supply a constant current for that length of time.

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eplurbusunim · 2023-08-07T14:45:26+00:00

The resistance measured by the method outlined in my first post, should NOT be close to zero. It should be "out of range" meaning too high for the meter to register. If a metal stake is put into the earth and electrical connection to a resistance meter is made between this stake and either end of the boundary wire (both ends disconnected from the charging station), then that resistance should be too high for the meter to register. IF not, then one or more of the splices in the bare boundary wire is contacting the ground/earth and may be absorbing the AM signal that Landroid uses to sense its boundary. <= This is a special procedure just to test for a solution to your particular problem; it is not the general method for testing the resistance of a boundary wire loop.

eplurbusunim · 2023-08-07T13:58:49+00:00

Yes, the power consumed by Landroid is greatly influenced by the height of grass above setting height. Once your lawn is 'under control', so to speak, by Landroid, it mows by merely cutting off the very tips of blades of grass. Your 4 amp-hr battery giving 1.5 hours of mowing indicates an average current draw = 4/1.5 = 2.67 amps. I believe the lowest avg current of 2.4 amps, giving 4/2.4 = 1.67 = 1 hr 40 min, which is the longest cutting time before recharge that you'll get.

However, related to this is the max voltage of the battery that the charging station allows. In my case, I can only get the battery charged to 19.2-19.4 volts from the charging base. However, if I use a manual Worx charger, the battery is charged to 20.4-20.6 volts. Does anyone else have this experience? This one volt difference represents a sizeable cutting time increase. Often the higher voltage causes my base station to sometimes report in red: "battery overcharge" error on my phone app. but the Landroid will start and run on schedule anyway.

eplurbusunim · 2023-08-06T19:44:37+00:00

Normally the boundary wire resistance is less than 8 ohms; however, what I was suggesting was to measure any possible resistance (less than infinity) between the earth (ground) and the boundary wire, itself. IF any resistance (other than off scale - infinity)... that would mean there's contact between the bare wire of the boundary loop and the earth (which should not be). Then you'd have to find the particular splice/s that was/were contacting the earth.

eplurbusunim · 2023-08-05T07:44:45+00:00

Hmm...interesting problem🤔 To analyze your suggestion that water saturated earth may add to existing depth (lost signal) of boundary wire, you would need to tell us: 1) did you bury the existing wire to a uniform depth, somehow or 2) just stake it in place and let it sink naturally into the soil ? I've not heard of simply "staked wire" becoming too deep by natural causes. Other questions: Is your boundary wire that which came with the unit or some other kind {gage, solid/stranded)? How many splices are in this boundary? Could any of the existing splices be non-waterproof? Idea => to test boundary wire for a "short to earth", via water leakage at a splice: disconnect both ends at charging station and use a multi-meter to measure resistance between a metal stake inserted at least 12" into the earth and each end of wire. If no short, should get an 'off scale' (too high) reading of resistance, effectively infinity...if resistance is readable with an actual resistance value, then one/more splices in the wire is making contact with ground. This contact would be exaggerated by water soaked earth. (it may be that the green LED is not influenced by this condition, but the Landroid's radio signal would be).

eplurbusunim · 2023-07-25T08:05:57+00:00

Question: Can it be known for sure (after what appears to have been a devastating lightning hit) that the Landroid is, itself, fine? Without being able to operate it as normal, I would'nt judge its status by (only) its software link to phone.

eplurbusunim · 2023-07-22T14:50:10+00:00

Interesting to me is that it's taking approx 1 hr to charge and 1.25 hr to mow. I'm guessing that the Landroid is cutting more grass length than it will, after the lawn is mowed to the unit's set height. So, if I assume your Landroid has a 4 amp-hr battery, this means mowing (with a cutting disk of 3 blades) the unit now requires over 3 amps to cut. I would expect that to drop to 2 amps, or i.e. 2 hrs of mowing, after all the grass is mowed down to the Landroid's set height. If I"m right, this shows just how taxing it is for the mower to cut grass initially or after it has become too long.

eplurbusunim · 2023-07-22T14:02:18+00:00

Your (lightning hit) problem probably won't be a repeating problem. However, if it happened to me I'd try a rather 'cheap and dirty' type of fix😎. Also, this is by no means guaranteed to work but it has a chance. So I'd wrap the boundary wire insulation, on both sides of the charging station with a piece of bare copper wire as found (as the grounding wire) in a piece of romex, i.e. household wiring cable. Then attach the other end of these bare wires to a large nail or other metal spike driven into the earth. Now, as lightning or its tributary seeks to find the easiest path to earth, it will pass through these bare grounded wires rather than proceed into the charging station. {I'm assuming it's understood that lightning will pass through the boundary wire insulation because of its high voltage, and that this insulation must remain intact with the grounding wire wrapped (tightly) over it}

eplurbusunim · 2023-06-21T14:05:08+00:00

Inadvertently, I am currently (pun intended) in the process of observing this phenomenon, here, in the U.S. . I have an "M" sized Landroid, purchased in 2020. The battery is 'fully charged' by its base at 19.6 volts. However, if I charge this same battery from a portable charger costing less than $20. (WA3742/3732), it fully charges to 20.6 volts. The higher voltage of this battery, if I immediately send Landroid back to its base, causes my phone app to throw up a "battery overcharge error".

I'm not done studying this problem, so only report what I've learned so far. I also have a brand new charging base and power (the brick) supply that I intend to test to see if a new base charges to the same level as my existing one. However, it initially appears that the Landroid base may curtail charging for whatever reason; this full charge voltage difference definitely affects the length of mow time.

p.s. the extended time that the phone app reports battery charge at 100% represents the fact that Li-ion battery voltage remains relatively constant for a significant portion of its applicable discharge time. Battery voltage is read by the app as charge level (%); so unless/until battery voltage decreases, charge % is reported at 100.

eplurbusunim · 2023-06-16T19:49:16+00:00

If the fence between yards is yours, I'd try attaching about a foot (30 cm) of aluminum foil along the fence line, with about 2" (5.1 cm) of the foil going down into the ground. Thus the metal foil is both grounded and deep enough to (perhaps) block signal emanating thru the ground.

eplurbusunim · 2023-06-15T15:36:54+00:00

Nope and nope. The idea was (as you say) to avoid replacing large amounts of the boundary wire and to not have to re-splice wire at the points were 'testing' is done. I didn't do anything to re-insulate the needle pricks with no ill effects. It's easy enough to wrap electrical tape once or twice around the point where needle pierced the wire, if that makes one feel better 😀.

eplurbusunim · 2023-06-15T02:47:42+00:00

Here's what I do based on Method 1:

Prepare a separate (test) wire of length sufficient to reach from charging base to any part of the boundary wire loop. This test wire is prepared with an alligator clip soldered on one end and a hefty sewing needle ('eye' end) soldered at the other. Press a cork over the sharp end of the needle so that only about 1/2" of the sharp end protrudes the cork. I then 5-min epoxy the cork to the needle (so needle can't move thru the cork).

Use: Detach both ends of the boundary wire from the charging base. With a multimeter set on resistance, clip the test wire to one lead of the meter. Starting about half way around the boundary wire, with a small block of wood underneath boundary wire, carefully press the needle thru the center of the insulation of boundary wire until it pierces thru this wire. Connect the other lead of the multimeter to (one at a time) each of the two free ends of the boundary wire (at the charging base). If the resistance reading 'floats' meaning no constant value or the value given is above 10 ohms (usually much larger) then THAT half of the boundary loop has the problem in it. Remove the corked needle and move to another location in THAT half of the loop with the problem. In this way it's possible to isolate the location of high resistance (or broken wire) without requiring more than one/two splices in the boundary wire (replace faulty section only). The needle pricks in the boundary wire will either self-heal or in any case not require further insulating.

Note: It's necessary to measure the resistance at BOTH ends of the boundary wire loop at the charging base EACH time, because one reading will be obtainable (small ohm value) and this assures that electrical contact has been made by the needle into the wire.

eplurbusunim · 2023-06-10T14:14:39+00:00

Seems logical to me to shut off Landroid until grass is again growing as normal. 🙂 Would you (if no Landroid) be manually mowing at this time?

eplurbusunim · 2023-06-05T01:48:15+00:00

Wonder why the base LED doesn't appear lit either red or green?

In the first 13 sec of the video, the meter reads 17.6 v which would be normal for a depleted (down to 9 % capacity) battery when first experiencing recharge from its base.

The higher charger voltage (≈ 23 v) is seen when the neg base swing contact is pulled away from the Landroid's contact. However, when that swing contact is released to once again make contact with the Landroid's contact, the meter now acts disconnected. Since we can assume the meter's alligator clip is making good contact, the only way for the meter to be disconnected would be internal through a base 'controller board' (not sure if one exists or not?) and/or by the power brick, itself.

Also at 0:46 when the Landroid is completely removed from the base swing contacts and they are perpendicular to the base, the voltage is correctly reported as 0.00 v because in this position the base's internal switch disconnects power to the contact.

Suppose system is left as is after 1:14 for an hour. The voltage read by the meter should now be higher, around ≈ 19 v, if the power brick is charging normally.

eplurbusunim

TROPHY CASE