I want to install this ammeter

[Fritzhund]

Hi all,

I want to install an ammeter on my 1983 GS450L somewhere near the battery. I will custom fabricate a bracket for it. I saw this one on eBay and was wondering if anyone had any thoughts on it. It is a 6V and I was hoping I could just get away with changing the bulb out to a 12V or not using a backlight at all.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=130400870859&viewitem=&sspagename=STRK%3AMEWAX%3AIT

Thanks, Mark

[posplayr]

I was actually looking at this a while back but could only find automotive amp meters that went to 60 amps. This one is built for a motorcycle so may be better suited.

There are a couple of other issues, you want to measure the current from the R/R I suspect but that is in excess of 10 amps continuous. So it would be better to limit the measurement to the charging current to the battery (between 0-4 amps).

Next you need to be careful about putting anything in between the R/R and the battery as a voltage drop will keep you from adequately charging the battery. I dont know how much resistance that amp meter has, but if it is significant ( greater than 0.1 ohms) it would be an issue (4 amps times 0.1 would be 0.4 volt drop to the battery). This issue could be avoided if you use a 6 wire Honda R/R which uses a sense wire and will put out 0.4 volts more to compensate for teh amp meters resistance.

I attached a schematic

[Fritzhund]

Thank you very much! I really appriciate your input.

The schematic is a nice touch.
Would you happen to have a part number or a model year/size bike of that Honda R/R? I think I am going to do this!

Mark

[posplayr]

Thank you very much! I really appriciate your input.

The schematic is a nice touch.
Would you happen to have a part number or a model year/size bike of that Honda R/R? I think I am going to do this!

Mark

There is a guy here that selles them tested and with connections. I think he recently raised his price to $47 delivered. PM Duanage

I would measure the reistance and or voltage drop FIRST to see what happens with the amp meter installed. It might not be a problem.

If it is an issue, the Honda should get rid of the undervoltage as the battery.

[tom203]

Why an ammeter instead of a volt meter? You could be delivering 4 amps into a dying battery ( ever try to revive an old battery ?) , so I'm not sure how this is informative. Besides, if this ammeter was designed for an old british bike, it might have had a dc generator and not an alternator like your suzuki. The r/r makes a pulsing output , relying on the battery as a reference sink to hold a stable output- an ammeter needle might jump around too much. Some kind of volt meter setup would seem to offer more info about the battery and charging system.

[trippivot]

a comment on the schematic, I have installed mine differently

I have mine in series on the negative ground wire and the negative pole of the battery.

looks great on the auction.. I'd rather know the amps not the volts..

amps charge the battery not volts.. and having a 100/80 light up front really uses a lot of ampreage. you should know if you have too many accessories and lights. this gauge will tell you


a volt meter won't.

[rustybronco]

Ammeters have been used on car/truck alternators for years and most are 3 phase full wave rectification systems. I don't see how it would be any different when used on a motorcycle or when used with a DC generator. all it does is indicate the amount and direction of current flow.

also, the needles oscillation dampening is done in the ammeters d'arsenval* movement.

*thanks for the reminder Jim.

[posplayr]

a comment on the schematic, I have installed mine differently

I have mine in series on the negative ground wire and the negative pole of the battery.

looks great on the auction.. I'd rather know the amps not the volts..

amps charge the battery not volts.. and having a 100/80 light up front really uses a lot of ampreage. you should know if you have too many accessories and lights. this gauge will tell you


a volt meter won't.

It depends on how you have your grounds wired of course but putting the ammeter in the negative side is the same as the upper side(same current flow). The benefit of the low side is that it is less likely to short anything if you hit the back terminals. Otherwise the gauge action should be the same; both are measuring battery charging/discharging current.

The downside of the lowside current amp comes from the point I raised earlier is if there is significant resistance in the ammeter (see the discussion below; for a 10Amp range the internal resistance is .05 ohms so 4 amps of charging current will be 0.2 volts drop to the battery. This is probably OK, except it is usually hard to get less than 0.20 V drop and so you are really going to be running double that 0.40V drop. The 6 wire Honda will compensate for the 0.05 resistance on the positive side, but not on the negative side. So in that regard high side is better.

http://www.allaboutcircuits.com/vol_1/chpt_8/4.html

[posplayr]

Why an ammeter instead of a volt meter? You could be delivering 4 amps into a dying battery ( ever try to revive an old battery ?) , so I'm not sure how this is informative. Besides, if this ammeter was designed for an old british bike, it might have had a dc generator and not an alternator like your suzuki. The r/r makes a pulsing output , relying on the battery as a reference sink to hold a stable output- an ammeter needle might jump around too much. Some kind of volt meter setup would seem to offer more info about the battery and charging system.

The frequency of the pulsing is 1/10 of the RPM for an 18 pole generator so at idle that is only 100 hz which is pretty slow. Depends on the gauge as to how much it will bounce.

I'm not sure that a bad battery will accept current. I have an ammeter on my charger and if the battery is dead I have to bring it up slowly, current tends to be indicative of charging. A bad battery won't accept current. The usual problem though is that the charging quits, not that the battery goes bad during a ride.

In order to see a series meter on your handlebar, were talking about routing a bunch of wire. My volt meter just taps off of a plug in receptical (next to my left hand controls on the bars) I wired directly to the battery.

[Steve]

Why an ammeter instead of a volt meter? ... Some kind of volt meter setup would seem to offer more info about the battery and charging system.

... I'd rather know the amps not the volts..

amps charge the battery not volts.. ... this gauge will tell you, a volt meter won't.

Always interesting to see two opposing opinions.

My opinion is that they are both right, but neither one is complete.

It actually takes voltage to charge the battery, but the voltage is just the electrical "pressure" that will push a bunch of electrons around. How many electrons get pushed is what is called "current" and is measured in amps. In other words, it takes volts and amps.

From personal experience on vehicles that had BOTH, an ammeter and a voltmeter, I can tell you that I prefer a voltmeter. Yes, an ammeter will show a charge or discharge situation, but you need to know where it is measuring. The electrical system on our bikes is not that different from that of a car, if you look at it carefully. There is a single point where the battery, charging output and the "load" (the rest of the vehicle) all meet. On our bikes, that is the crimped connection in the main harness where the r/r meets the wire that runs from the battery to the ignition switch. It is possible to mount an ammeter in any one of those three legs and you will get different readings in each one. In the battery leg, you will see + and - readings, depending on whether the alternator is providing more than enough to power the bike (the excess goes into the battery as a charge). If you mount it in the "load" leg, it will only show a discharge, as the bike will only draw current, never generate it. If you mount it in the alternator leg, it will only show a charge, unless there is a dead short in the r/r.

With an ammeter mounted in the battery leg (the most logical location), if your load exactly matches your output, you will not see anything in the way of a charge on the meter, but the bike will basically run forever.

With a voltmeter installed, you can mount it basically anywhere in the system, it should all be pretty much the same voltage. Knowing that a battery that is being charged has a voltage higher than 12.6, you will know whether it is being charged or not. In the event of total failure, like an r/r failure, you will see the status of your system and know how much you have left. An ammeter will only show you that you are discharging at 5 amps, but will show that until your battery craps out. If you have not been watching the gauges to see when it started discharging, you have no idea what is left.

Since you can think of this as "electrical fuel", put it into "liquid fuel" terms.
Would you rather know that you are using gas at the rate of 3 gallons an hour or that you have 1/2 tank left?
Hint: it's going to show that same 3 gallons per hour right up to the point where it starts sucking fumes.

.