Battery Voltage

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Re: Battery Voltage

Postby Pieter Huizinga » 07 Oct 2014, 12:02

Forest 1100 wrote:Well, in a way, it does make sense. I'm no electrician but I know that to push 30 amps through a clothes dryer circuit, (North American standards) you need 240 volts. A normal house circuit supplies 15 amps max at 120 volts. The power transmission lines across the country need hundreds of thousands of volts to push the massive current they carry.

Sorry, no, that doesn't make sense. :mrgreen:

Electric power is measured in Watts, where 1 Watt is the power of 1 Ampere at 1 Volt. Or W = A x V. (Not too sure about the symbols you are used to but it should look like this). A battery has a limited amount of power it can deliver at once. It follows that when the power W remains the same and the current A increases, the voltage V lowers. (To illustrate this, put your volt meter across the battery and hit the starter).

Consider a transformer where V x A primary (in) is always equal to V x A secondary (out). In other words, power in = power out.
To charge your phone with a current of 0.5 A at 5 V, it consumes only 0.02 A at 110 V or even 0.01 A at 220 V. Do the math.

As to your examples:
A side effect of higher current is that the leads need to be thicker to prevent them from heating up. (The leads actually become a resistor). The heat is in fact lost power, so the more heat the leads dissipate, the more power you lose. (This is one of the reasons why car batteries have gone from 6 V to 12 V, or even 24 V in trucks, and also why in Europe common voltage is 220-240 rather than 110-120. You can use thinner wire, and there is less fire hazard from overheated circuits).

1. A tumbler dryer consumes about 3200 W. At 220 V this means a current of ~ 16 A. At 110 V the current will be ~ 32 A. So you don't "push 30 amps through the circuit" but you push 3000 W through the circuit. It is much more efficient to do this at a higher voltage because then the current is lower so you don't need leads of arm size - which you would if you used 110 V.

2. The voltage used to transport electric power over greater distances is very high (in excess of 22000 V) for exactly the same reasons. You lose less power at low currents, and you don't have to use thick wires.

[Edit 8 Oct.: As another example, look at your starter cables. Why so thick? Because they must carry a high amperage at low voltage!]

Here endeth today's lesson. :mrgreen:
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Re: Battery Voltage

Postby alans1100 » 07 Oct 2014, 15:18

Pieter Huizinga wrote:
Consider a transformer where V x A primary (in) is always equal to V x A secondary (out). In other words, power in = power out.
To charge your phone with a current of 0.5 A at 5 V, it consumes only 0.02 A at 110 V or even 0.01 A at 220 V. Do the math.



I thought your figures a bit strange to charge a Phone or a Tab and so I had a look at our Samsung travel chargers.

Automatic Voltage input from 100-240, 50-60hz and 0.35 amps (we use 240V)
Output 5.0 V = 2.0A into a USB port as the charge cable doubles a USB cable for phone/tab connection to a PC

I don't know what the = symbol means but it's double the length shown
-------------------------------------
I found this site.....not sure if will help but it might give some understanding of how the thing works.

http://www.electrosport.com/technical-r ... stem-works

Quote

The no load voltage of a fully charged battery is about 13 Vdc. For charging it the charging-system should provide a voltage of about 14.4 Vdc and this should be a constant voltage at all engine-speeds.

The generator itself is located in or on the engine, and on most bikes there is a separate regulator-rectifier unit located somewhere on the frame. The reason for this is that almost all motorcycles are equipped with a three-phase AC (Alternating Current) generator, while the electrical system on the bike is a DC (Direct Current) system. The rectifier part inside the regulator-rectifier takes care of converting the AC-current to the DC-current the battery needs. The three-phase AC generator is used so often because it is much more efficient and reliable than a DC-generator. It can produce power for charging the battery even with the engine idling. The regulator part of the regulator-rectifier is used to regulate the output-voltage (to the battery) to the 14.4 Vdc that is needed

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Re: Battery Voltage

Postby mbrST1100 » 07 Oct 2014, 15:20

uhh... now its getting really complicated... ;)
Raising I (current) increases R (resistance) of conductor (wire... those also exist inside the stator) -> causing voltage drop... lower U => raised I, etc...
(to line that out including the correction factors for stranded copper wires would require quite a lot of algebra... ;) )

And for home appliances in the US: IIRC is a 240V outlet over there not already 3-phase?? ;)
(in Europe we've only 230V 1-ph and 400V 3-ph, both 50Hz...)

And the humming lines of the power grid are operated with 10 to 1000kV to keep the voltage drop caused by the cable resistance at a minimum...


As for the 26A charging system of the pre '95 ST1100:
The stator has 4 windings, 3 for output, 1 for aux control voltage
So it actually has a 3-phase AC output, which is converted to DC by a rectifier (located inside the VRR)
The VRR also has a voltage sensing circuit to keep the on-board voltage between 12,6 and 15V max (the by the stator delivered AC voltage constantly alters with the engine RPM)
Any excessive voltage will be fed back into that 4th winding of the stator, once this sees current it creates a magnetic field, disturbed by this the output of the the 3 mains windings will decrease... until the VRR senses the voltage drop, lowers/cuts the output to the 4th winding, mains output raises/stabilizes...
So under ideal circumstances and loads the system will settle at around 13 and the maximum of 14.5V...
At least this is how this charging system got explained to me...
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Re: Battery Voltage

Postby Pieter Huizinga » 07 Oct 2014, 17:54

alans1100 wrote:I thought your figures a bit strange to charge a Phone or a Tab and so I had a look at our Samsung travel chargers.
Automatic Voltage input from 100-240, 50-60hz and 0.35 amps (we use 240V)
Output 5.0 V = 2.0A into a USB port as the charge cable doubles a USB cable for phone/tab connection to a PC

I gave the theoretical values, Alan. It was an example.
Your charger provides 5 V x 2 A = 10 W.
Theoretically it should use 10 W / 240 V = 0.04 A. If it was using a transformer. Which it probably isn't.

In Real Life, there is quite some loss in the electronic converter - today's phone chargers do not have a transformer anymore.
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Re: Battery Voltage

Postby Forest 1100 » 08 Oct 2014, 01:39

Ok, there you go. I told you I wasn't an electrician. :? Who can remember learning all that shit from high school days anyway? :lol: Good luck with that Bill.
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Re: Battery Voltage

Postby Pieter Huizinga » 08 Oct 2014, 09:13

In a PM exchange I just made this clarification which I think is good to repeat here.

I must admit there is a language gap, for a lot of things I know about electricity I just have to make an educated guess what the corresponding English terminology is. Then there is the various flavours of English. But that's what you get with a board with global visitors. :mrgreen:

There of course always is some sort of transformer involved. What I meant to say was they don't use a "classical" transformer anymore, instead some sort of electronic transformer. For an example see http://electronics.stackexchange.com/qu ... ransformer.

Besides, as I pointed out, there always is and will remain a difference between the theory and Real Life. :mrgreen:

All of this said, I can't for the life of me think of a circuit where the voltage would go up when the load increases. It just doesn't make sense to me. If it is correct I'd really like to understand why. I'm always keen to learn something.
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Re: Battery Voltage

Postby Baldeagle » 08 Oct 2014, 10:01

I have went ahead and purchased a new rectifier as everything else(wiring,connectors etc) checks out as per the manuals (Honda shop,Haynes and Clymer).
Once it arrives I'll post results,hopefully good ones. :)

Thanks for all the comments on this,they were of great help as I don't really understand electrics too well. :?
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Re: Battery Voltage

Postby mbrST1100 » 08 Oct 2014, 10:03

alans1100 wrote:Automatic Voltage input from 100-240, 50-60hz and 0.35 amps (we use 240V)
Output 5.0 V = 2.0A into a USB port as the charge cable doubles a USB cable for phone/tab connection to a PC

The 100~240V, 50-60Hz tell it as a standard "global" charger...

I don't know what the = symbol means but it's double the length shown

Typically visualizes that its DC, the actual symbol would have a dotted line at the bottom to ID the positive, but the avail fonts doesn't give us this here, so:

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These days the chargers for all low load equipment (cells, satnavs, cameras, etc...) work on MOSFET voltage divider, but I don't know what the exact limit on secondary current is...
Larger chargers, especially quick-chargers (cordless power tools, RC model batteries, etc...) which have to supply some real and steady juice still have a rigid transformer inside...


Anyway, back to the original problem:
Despite any philosophical and theoretical essays posted in between, are there thousands of ST1100s running with the 26A system on which the VRR/charging system/voltage behaves exactly as I'd researched in the official literature and observed in nature on my very own motorcycle with named 26A system...
So according to the vicious reality of things, is there no use on speculating about what could or might be going on, only on what should be happening...

On non of the bikes existing with the 26A system, the voltage increases under load, nor does it even go beyond 15V, the OEM workshop manual makes it very clear that 15V are the absolute maximum this system is allowed to have by its design...
Thus: if the kit is not behaving like shown in the manual, the therefore logical conclusion is, that something is off...

The 12,6V of the battery don't irritate me in this, the bike will crank with that, a not fully charger battery will only draw a slightly higher charging current, adding to the general load, thus lowering the on-board voltage even more (marginally, but still...)

Back to the to-do items for circling it down:
- check wiring
- check the 3 stator windings (ohm and voltage readings)
- check the VRR (there is a measuring protocol avail in the w/shop manual)
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Re: Battery Voltage

Postby Pieter Huizinga » 08 Oct 2014, 10:20

mbrST1100 wrote:On non of the bikes existing with the 26A system, the voltage increases under load, nor does it even go beyond 15V [...]
Thus: if the kit is not behaving like shown in the manual, the therefore logical conclusion is, that something is off...

Amen. Well said.
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Re: Battery Voltage

Postby Pieter Huizinga » 08 Oct 2014, 10:47

hui-yang$715122354.jpg
A "classical" transformer
hui-yang$715122354.jpg (9.04 KiB) Viewed 8321 times


Electronic_transformer_led_transformer_led_driver_Product694.jpg
An electronic transformer
Electronic_transformer_led_transformer_led_driver_Product694.jpg (6.7 KiB) Viewed 8321 times
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