voltmeter usb outlet

I like to have a voltmeter. I find them useful to show the battery condition before starting and charge voltage when running.
I needed a USB outlet to run my Garmin.
I bought this NZ$19 , it looks to tick both boxes.

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Evans wrote:

I like to have a voltmeter. I find them useful to show the battery condition before starting and charge voltage when running.
I needed a USB outlet to run my Garmin.
I bought this NZ$19 , it looks to tick both boxes.

[You must be registered and logged in to see this image.]

I got this one from Amazon. It is able to supplies the higher amperage needed for newer devices. [You must be registered and logged in to see this image.]

I've got one of those on my Convert, works very well. On my GRiSO I wired in an SAE plug, and have a USB/Voltmeter plugged into it.

As I'm sure you all know, there IS a Voltmeter in the display already ?
On the left-hand hand grip, set the switch to MODE, then toggle thru the displays.

And which do you believe if the two meters display different data ??

Harsh but fair

A voltmeter will display, within its accuracy/tolerance, the voltage it is measuring at that part of the circuit. If you are expecting battery volts, then you need to connect it to the battery terminals.

Elsewhere, the voltage displayed is what is left over after all the losses in the wiring harness are taken into account and multiplied by the noise in the circuit.

So is there a difference between these add ons and the dash?

The dash voltage is reporting the voltage at the dash. While indicative, it's not battery volts. Mine has a difference of 0.8 Volts between the dash display and the actual battery voltage - the battery is higher. I have measured this with a known good-quality, digital multi-meter, with revs around 3,000 rpm (maximum charge rate should be achieved at these revs).

Simply compare the battery voltage to what's displayed and do your own calculation.

So reading into it, the dash voltage readout, plus 0.8 volts = battery voltage.

Probably more important is to know you have a healthy charging system AND a battery in good condition.

In time, dirty/ageing connectors will have this displayed voltage lower than you would think. But then again, we are dealing with 'talian 'lectrics... and that's another story.

The alternator (on the CARC models, at least) is a Denso unit putting out a pretty good charge rate - as long as that's healthy AND you know it, should be good to go. 'Snot rocket science...

The one that I use is only $16 on Amazon, and I have had zero issues:

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Thanks.

I use it to see if the voltage is greater than 12v while running and that's about it.

The way mine works on my Cagiva Elefant, is when I turn on the ignition I can see the voltage that the battery is holding and when running what voltage my charging circuit is putting out.
I've not installed mine yet but I assume that I'll get the same info from it on the GRiSO.

Evans wrote:

The way mine works on my Cagiva Elefant, is when I turn on the ignition I can see the voltage that the battery is holding and when running what voltage my charging circuit is putting out.
I've not installed mine yet but I assume that I'll get the same info from it on the GRiSO.

Wellllll..... you can't see what voltage the charging system is putting out, because that is measured in amperes, not volts. Imagine you're filling a bucket (battery) with water(electricity). The volts is the pressure in the fill hose, the amps is the gallons or liters per minute coming out said hose. That said, it depends on where the volt meter is attached, whether it's reading line "pressure" or bucket "pressure." Often, folks will complain it takes a few minutes for their charging system to start charging, because they have a volt meter and no ammeter.

Now, if I've misspoke, or gotten something wrong, someone please point it out. I'm just a dumb farm boy y'know.

rick pope wrote:

Now, if I've misspoke, or gotten something wrong, someone please point it out.  I'm just a dumb farm boy y'know.

Consider this response as "pointing it out". It was so wrong, I cringed.

beetle wrote:

rick pope wrote:

Now, if I've misspoke, or gotten something wrong, someone please point it out.  I'm just a dumb farm boy y'know.

Consider this response as "pointing it out". It was so wrong, I cringed.

Okay, I accept that, but please let us know what's incorrect. I did ask for clarification.

Chill peoples.

Voltage going into the battery when charging is "indicative" of a healthy system. Rick you are correct it's the Amperes doing the actual charge at a certain voltage. Let's not get hung up with this.

The alternator puts out around 500 Watts (OK might be some maths in this...)
Considering this is a nominal 12 Volts system, the actual specs state 13.8 Volts to keep your 12 Volt system happy.

Why for you ask Kemosabe?

If the charging system puts out 12 Volts and your battery is 12 Volts, the difference is nett zero - so your battery will not charge properly. If your charging system is putting out 13.8 Volts, then there is a difference which results in your battery getting charged. How much the battery gets charged is dependent on a few things, such as:
- the condition of the battery itself
- the electrical load while the bike is running
- what sort of battery you have
- the condition of the charging system and the connectors between the alternator and the battery (including fuses)
- the overall condition of the wiring on the bike

Assuming everything is healthy, or near to ('talian 'lectrics remember), the alternator can put out 500 Watts. Breaking this down:
P = V x I
where P is power (Watts)
V = Voltage (Volts)
I = Current (Amperes)

therefore I = P/V
Substituting for P and V
I = 500 / 13.8
therefore I = 36.23188406 Amperes (I know, pedantic right?)

Therefore you can charge your battery at up to around 32-33 Amps as the running bike will also consume current to keep it running - think injectors, ECU, Dash, coils, Lights etc.

If your battery requires 30 odd Amps - YOU HAVE A PROBLEM!

Most batteries in our bikes are 20 AH capacity. This means that is "should" deliver 20 Amps continuously for 1 hour. The assumption is that the battery is indeed in a good enough condition to perform as designed - most aren't unless it is brand new! To start, the battery pumps out over 200 Amperes for the starter motor. Therefore it needs charging to put that energy back into the battery and this will take "some" time, depending on battery technology being used.

if you are charging at circa 30 Amps, your indicated battery voltage will not be as high as 13.8 Volts, it might actually be lower than 12 Volts, and you probably wouldn't have much luck in starting anyway.

So to round this up, having a battery voltage of around 13-14 Volts, "indicates" that two things:
- the charging system is working (presumably as designed) and
- your battery is in the healthy range

Now every individual bike is different (yes you GRiSO is different to the next one - it's Italian designed...) and you will get differences in the numbers I have stated here - THIS IS NORMAL!

For instance, mine has around 14 Volts into the battery when charging. so if my dash reads 13.2 Volts, I do a mental calculation and add 0.8 volts to it and gets a mental result of 14 Volts. To me this says my charging system is healthy, my battery is probably OK and there is nothing else untoward happening on the bike.

Amen. I'll pass the plate around - what a sermon!

My apologies for the above sermon, boring day at work and I find little motivation in changing things...

Stealing my thunder, Tony?



Here's the response I wrote, in simpler terms, without invoking Ohm.



For current to flow, the voltage at the source needs to be greater than the voltage at the battery. When the  engine isn't running, the charging system is not functioning. If you were to measure the battery volts at that moment, with the key off, you would read what I will call the "no-load" voltage*. When the engine is running, and the charging system is working, the voltage on the battery will be greater then the "no-load" voltage. This is more-or-less the charging voltage, ignoring any losses in the wiring loom and connections, and the load of the working electrics.


If you have a battery all by its lonesome (in good condition), and you measure the no-load volts, it might read, say 12.6V. You then attach your battery charger and the volts is now reading, say 13.8V. That's your charging voltage.





*Its not really "no-load", because the dash is active even with the key off.

Mark, I didn't intend to steal your thunder, just got carried away in "sermon" mode. It started out simple but you know how these things sometimes go, especially when you get wound up...

I thank you both. I guess I was trying to over simplify it by using the bucket analogy, since we can see how full a bucket is, but we can't "see" electricity.

I've learn that on many vehicles, the volt meter reads somewhere near the meter, not at the battery, thus the voltage drop Tony described. It also contributes to the meter not "keeping up" to the actual charging rate.

In the old days, vehicles had ammeters, (and 6v systems) to tell us what was happening. Not so now.

Again, thank you both for a clear explanation.

Lucky we don't have "old" Le Mans where the charging was through a lamp in the dash. Light fails and the rider has no idea there is a problem as the light didn't come on.

Glad we moved away from 6 Volts systems, Positive earth systems and old rectifier stacks and the like.

Ammeters give a real indication of what is happening, shame we don't have them any more. Alas we have volt-meters and the "dark magic" that goes with them. Progress? The jury might be out on that one...

Oz1200Guzzi wrote:

I didn't intend to steal your thunder,

Well, it wasn't really thunderous, was it?

Could have been "fire 'n brimstone" - like the olds kool preachers, instead a bit of a fizz...

'
I'm just a nuts & bolts savvy old bikey and don't pretend to be any kind of expert.

I personally like to completely isolate my battery from my bike systems, as even a clock can run the battery down
if left for long periods and lead acid batteries never recover from a major discharge.

The  voltmeter on the Cagiva comes on when I turn on the ignition. No doubt it is not giving an exact reading of the battery voltage
but if it's around 13 volts and consistently the same then I know that my battery is healthy, when running it gives a readout that
I presume is the state of the charging system.

As for the amps, an ammeter is fine but how often do you look at it ?
I rely on an intelligent warning light. I've fitted them to both the Cagiva and the GRiSO and they seem to work fine.
They're as cheap as :-

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Works for me but quite possibly the experts will point out where my systems aren't up to scratch.
Always keen to learn.  Evans

Evans wrote:

I like to have a voltmeter. I find them useful to show the battery condition before starting and charge voltage when running.
I needed a USB outlet to run my Garmin.
I bought this NZ$19 , it looks to tick both boxes.

[You must be registered and logged in to see this image.]

I put a similar unit in my Stelvio dash instead of the stock cigarette lighter port. I opted for the two fast-charge USB ports instead of the voltmeter (there is already a voltmeter in the dash).