Volt/amp meter

[duncan webster 1Participant @duncanwebster1]

We’re having a bit of an issue with our solar panel, used to power the signals. I’d like to have a meter which monitored volts and amps from the battery, but the amps can be both ways depending on whether the battery is charging or not. Does anyone know whether one of these will emit the magic smoke if the current is reversed? https://www.ebay.co.uk/itm/363258889234?_trkparms=amclksrc%3DITM%26aid%3D1110018%26algo%3DHOMESPLICE.COMPLISTINGS%26ao%3D1%26asc%3D20231016072011%26meid%3D55983e13669c4b4198fe040f8c68fe2f%26pid%3D101877%26rk%3D10%26rkt%3D25%26sd%3D185815679393%26itm%3D363258889234%26pmt%3D1%26noa%3D0%26pg%3D4406038%26algv%3DPromotedCompV3WithHighAdFeeAndToraFilterV1AndItemCfCoviewWithEnhancedMultimodalRecall%26brand%3DUnbranded%26fpg%3D0&_trksid=p4406038.c101877.m1851&itmprp=cksum%3A36325888923455983e13669c4b4198fe040f8c68fe2f%7Cenc%3AAQAJAAABMCkIPTw3NUNbhvYe%252BO6zKuXx7%252BsHjfy6Rxfmc5XuQ%252FqJ1rMkoi%252B3EcfhhWGxwNt5kOKNyM%252FS7L3AEak%252FavJ9w34gS7%252B4eHEVsiXpod6QA%252FspsCsFqLCKpJn3XPCidoWhhxw%252Fhkg9gYu0kv2a4P2c1TilQ37pndna3wqHbVL8kfWfRWUWJSBCSdCOpu6Gl%252BML1NrtperDO%252FQ52lKP5%252B6k251B%252FX1itXuKOEIeZN%252BBpcESmfVz%252FZtskodvM5vmrAjHfQ6x878OrA%252BzljMPjz8Cvzh3wbE8rB69X84FgBfAXihXsxRoS0sXiXdA5HM0qZNOez77cpgf4syQNiZooMPrGPru3xAcTe2ye7D%252Bpg9vuorst5ju0p9TNH5ixMni2BJQ7j725iCXGX%252FwnnoeEyqfWWE%253D%7Campid%3APL_CLK%7Cclp%3A4406038&itmmeta=01HVVA3AZQHRH72A02DN9K6QRV

[BazyleParticipant @bazyle]

I think you are better off with a clamp on ammeter as it is not as if you are going to be sitting there all day watching it. An occasional quick reading is all you will actually do.
If it is at your club track the chances are that the damp will kill it in a few months.

I suspect your problem is something cheap connected to the battery is starting to leak, bad diodes or capacitors, and that is draining the battery overnight.

[SillyOldDufferModerator @sillyoldduffer]

I think it will smoke, but even if it doesn’t, the display won’t show which way current is flowing.   I think one of these is more like it.

Dave

[duncan webster 1Participant @duncanwebster1]

Thanks for that. At £34 I’ll just use a cheapo voltmeter and my DVM for the time being, I was just looking for something I could leave in place.

[Grindstone CowboyParticipant @grindstonecowboy]

Something like this?

Rob

Links to https://www.ebay.co.uk/itm/326093508102

[noel shelleyParticipant @noelshelley55608]

For current a centre 0 ampmeter, but what current are you reading small amps or big ones ? Noel.

[duncan webster 1Participant @duncanwebster1]

Maximum drain when signals on and no charge is 300 mA, so Grindstone’s meter wouldn’t notice. Not sure what max charge would be if the panel was working. Quite a bit more I suspect.

[Paul LousickParticipant @paullousick59116]

I use one of these on my solar system when camping. (no blue smoke if connections are reversed)

Only costs $17.85 delivered and comes with 2 x Anderson plugs.

https://www.ebay.com.au/itm/305394195106?itmmeta=01HVW6XHA622T8R8T11MK15S0X&hash=item471ae99aa2:g:GpgAAOSw6PRll9Dw&itmprp=enc%3AAQAJAAAA4D8FmhbZ4nI3QdtUIMWb5UfpF41pL%2FLIOVIgBPyrU3TZmvUPdELk65gnsZlU6ZJt4hir9Ihvjth37mBZX208Hm9%2FMwL4k5wgcXmHRMUtyKUZGFfXv8HouQ7IcX78ibzb9f4WoPIYgw4aa2iVuVsV%2FjaQ%2F5ZAXK37xiS4IQQIRU2l5vhARZ6Pd2jCensA2OqcvbnjjtW0ewRz%2FYb0LXXu2ryZ0K0eeTEHQHEgRrcrUHoCoVsW5KfoAbGZixUq%2Fev9GeHsCEK2yBF%2Bnr0ZdRco%2BMvqR1xnKzIqSfZALBUHOcxn%7Ctkp%3ABFBMspX2ht9j

[duncan webster 1Participant @duncanwebster1]

That looks useful, available in UK at ~£10, thanks.

[Paul LousickParticipant @paullousick59116]

Having Anderson connectors on all cables enables you to plug in the meter at different locations to measure volts and amps. Input and output from the solar controller will give you an indication of its efficiency.

I have replaced my original PWM controller with a Victron MPPT which is more efficient. It is controlled from my phone and monitors power usage throughout the day.

[Paul Lousick]

On Paul Lousick Said:

I use one of these on my solar system when camping. (no blue smoke if connections are reversed) …

 

I don’t think Paul’s meter does what Duncan needs.  Digital ammeters seem to come in 3 varieties, all provided with a choice of shunts between 10A and 100A:

1. Most basic, measuring positive amps only, and I guess the device will probably fail if the output voltage is raised higher than the input.
2. Better version of the above, Paul’s example, protected with a rectifier so that the output voltage can safely be higher than the input.   But as far as I can tell from the spec, these don’t measure negative amps, would probably read zero A, which isn’t what Duncan needs.
3. Meters measuring both positive and negative amps, equivalent to Noel’s centre-zero analogue meter, that measure when a battery is charging or discharging.    They seem less common, but the giveaway is ± in the spec, and a minus sign on the amp display.

When I looked yesterday I couldn’t find anyone selling centre-zero analogue ammeters!   They must exist, but perhaps yet another technology going the way of the Dodo!

Ought to mention that digital ammeters are sold in both professional and consumer grades, the later description being a euphemism for “cheap and cheerful!”  The pro-grade versions are 4 to 6 times more expensive and may be worth the extra if the installation is exposed (not inside a comfy house), mission critical, or difficult to replace if the meter goes wrong.

However, if easy to replace, not mission critical, and the installation is done by a volunteer, then the domestic version is likely good enough for amateur purposes because up to 4 or 5 replacements will be cheaper than coughing up for one good one.    Different game when a North-Sea Oil Rig needs a meter to be reliable for 10 years, and an installer has to be helicoptered in to do the work.  In those circumstances, the purchase cost of the meter is small beer, so don’t economise on ebay!

Dave

 

 

[noel shelleyParticipant @noelshelley55608]

Dave has beat me to it I don’t think Pauls item will work as Duncan wants ! The connectors are a clue to the sort of amps involved big ones not 300ma. checkout The Component Shop for small digital meters. My multi meter would do it but at nearly £300 15 years ago although waterproof it gets looked after. If something is leaking electricaly then a run through the wiring and system should find it, have the panels got tired, or the battery died ? Noel

[duncan webster 1Participant @duncanwebster1]

I think the answer might have dawned on me. If I put one of those meters I linked earlier in the feed from the panel to the charge controller it won’t have to cater for reverse current, and it will tell me if there is current coming from the panel.

Thanks for all the replies, made me think a bit more at least

[duncan webster 1Participant @duncanwebster1]

• Well I went to the club today armed with 2 proper digital meters and a couple of little cheap voltmeter so I could measure volts and amps at several places at the same time, only to find that the panel has now stopped sulking and had charged the battery. Even with the signals switched on it was putting current into the battery, so I’ve either got an intermittent fault or we’ve been having the wrong sort of sun. As fellow UK residents will know, sunshine has been a rare commodity of late, but we have plenty of rain. Today we had a rare appearance of large yellow object in the sky. I’ll just keep monitoring it and see how it goes.

[noel shelleyParticipant @noelshelley55608]

Duncan You may have the answer ! I have a set of solar lights that come on at dusk ! In the winter they will last about 3Hrs then die ! Now they can last most of the night and in the summer all night. Good sunlight has been short so far this year. Check on direction and elevation as if not correct then it will cause poor out put ! Auto tracking is best but needs more complexity.  Noel.

[SillyOldDufferModerator @sillyoldduffer]

Having record breaking volumes of rain this year may be a clue:  wet electrics develop all sorts of weird faults that disappear when the problem area dries out.

I hate intermittent faults.  Much rather have a broken component catch fire than look for one that only works most of the time!

Dave

 

[Harry WilkesParticipant @harrywilkes58467]

during my years in the local steel works intermittent faults very recorded as NFF (no fault found) if the same fault was persistent then we would try a say a larger fuse to see if we could make something go ‘bang’

H

[duncan webster 1Participant @duncanwebster1]

Just an update, when I arrived at the club today the voltage output from the solar panel controller was all over the place, rapidly switching over a range 12-15 v. Someone had disconnected the battery. I’d sent out some instructions for the temporary set up, why do some people just act at random?

[Harry WilkesParticipant @harrywilkes58467]

It happens at club’s to many cook’s

H

 

[noel shelleyParticipant @noelshelley55608]

That’s not random ! They thought they knew better . Ah well. Noel.

[Howard LewisParticipant @howardlewis46836]

Measuring voltage is faiorly nsimple, since the neter connects to both feed and return.

To measure currernts which may be flowing in either bdirection, you need the sort of Ammeter used on older vehicles. These indicate how much current the dynamo was delivering to the battery, or if the load was taking more than the dynamo was capable of delivering, to show a discharge.

The simplest were just moving iron devices, but C A V produced a high quality moving coil model.

The shunt on the back was quite substantial pice of metal.

Howard

[noel shelley]

On noel shelley Said:

That’s not random ! They thought they knew better . Ah well. Noel.

You are probably right there, Noel

… in which case a ‘technical explanation’ from the miscreant might make interesting reading 🙂

Probably some misguided nonsense.

MichaelG.

[Michael Gilligan]

On Michael Gilligan Said:

On noel shelley Said:

That’s not random ! They thought they knew better . Ah well. Noel.

You are probably right there, Noel

… in which case a ‘technical explanation’ from the miscreant might make interesting reading 🙂

Probably some misguided nonsense.

MichaelG.

Chances are this mistake was due to ‘Common Sense’, that is the widespread belief that everyone has, or should have, an innate understanding of the obvious.  It’s a fallacy,  not to be compared to taking an evidence based approach or applying the rules of scientific method.  Some folk believe strongly they have it, whilst everyone else is an idiot.

As nothing in life is obvious, ‘common sense’ boils down to what we pick up over the years, which is usually a mix of sensible life experience, plus a percentage of misunderstandings, old wives tales, special cases, and conclusions derived from insufficient data.  Strong believers in common sense are likely to be anti-authority,  macho, impulsive, and to have feelings of personal invulnerability.   They are not the people you want running a roll-on-roll-off ferry, piloting aircraft, exercising a nuclear reactor,  or managing the economy.

‘Common sense’ saves time when built on valid experience and nothing has changed in the meantime, but practitioners have to be certain that there are no differences.  They also have to be wide-awake to the ‘Normalisation of Deviance’, where because corners have progressively been cut without ill-effect, everyone comes to believe the practice is safe, when actually it’s tap dancing on thin ice.

A big advantage of common sense is it relieves us of the need to keep up-to-date, think and plan.   No requirement to learn new tricks,  check facts, or ask permission just go for it.   And if the behaviour works out, it reinforces the idea that ‘common sense’ delivers, and experts “know nothing”.

I suspect someone in Duncan’s club found a new to him problem and did what he thought best without asking.   There should be an enquiry to confirm Duncan wasn’t guilty of assuming his ‘common sense’ view that the gear should be left alone was obvious to club members.  And also, that the Club isn’t relying on members ‘common sense’ to manage operational details.

Common sense has a dreadful Health and Safety record, often due to well-meaning chaps using their initiative thoughtlessly.   In the good old days it was thought sufficient that trained electricians would ensure power was off before they worked on equipment.  Nope.  Next stage was to insist red ‘do not operate’ notices be hung on OFF switches before maintenance, which helped considerably, but some folk still assumed notices didn’t apply to them and zapped team mates, colleagues and themselves.   Modern switchboards are padlockable, much safer, but there are still a steady stream of accidents, often because common sense was allowed to override the system.

At the moment I’m in favour of shooting anyone who defends ‘common sense’ so be careful what you say!  Feeling extra grumpy this morning due to belly ache, can anyone tell? The pain might be distorting my judgement, causing me to believe in the shortest way with the dissenters.

😎

Dave

 

 

[NealebParticipant @nealeb]

There must be an appropriate punishment, akin to pushing believers in a flat earth off the edge of the world.

I still remember the time when my mother nearly electrocuted my father, fortunately the only result being a minor explosion in my test meter. Since then, I tend to do electrical work with any relevant fuse safely in my pocket. A practice made more difficult by the use of MCBs…

Perhaps Duncan’s fellow club member was concerned about the solar panel overheating in the sun and wanted to reduce the load on it until the clouds came?

[duncan webster 1Participant @duncanwebster1]

I emailed all club members to state I’d fitted an external battery, but I have had someone proudly tell me that he didn’t read instructions when he was struggling with something else. As someone else said, Artificial Intelligence is no match for human stupidity.

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