The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: muskrat on 08.08. 2014 21:44
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G'day all. I can rebuild a motor one handed in my sleep, but never been that up on electrickery.
My '51 isn't charging. Dynamo runs up to 19v on open circuit, flashed to + earth, all wires and connections good, brand new DVR2 (replacing a V-reg2 thought to be the problem), converting to 12v for Boyer. The only part of the system that isn't kosher is the amp gauge which doesn't show either charge or discharge with or without the motor running. I thought as I'm getting voltage to the ignition and lights it shouldn't matter. Is this correct?
She ran out of puff last Sunday and had to stay at a mates place in the company of two Bultaco's, god knows what bad habits she's picked up. *eek*
Cheers
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Hi Musky,
The charge normally goes from the regulator over the ammeter to the battery (and the rest of all electrics). The ammeter is wired in series, so if it's broke, you won't have any juice further up. This means that as long as the battery is charged your lights and ignition will work, even with a broken ammeter, as the lights pick up power after the ammeter until the battery gives up.
You could test this by connecting both wires at the ammeter together, drive it for 1/2 an hour and check your battery's voltage before and after the ride. If it stays on 12V then your ammeter has gone to heaven...
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Measure the voltage at the regulator output and at the battery with the engine running for starters, Musky.
If it is OK at the reg and not at thebattery go looking for the open circuit.
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Thanks morris, Trevor.
The plot thickens. Took a charged battery and rode her home (45 miles). Did the old open circuit test and got nothing. Dropped the timing cover off and found the SRM belt had streched to the extent of no more adjustment. Hooray I found the problem. NOT. Did the test again and got 19v at the reg connector. Hooked her up again with a volt meter across the battery. 12.5v motor not running, 12.3v with ignition on motor not running. Start motor, at idle 12.2v with revs got to 12.6v. My cafe runs the same system and reads 14.5v at revs.
Came up to check in here.
Will try morris's suggestion first. Trev, to measure the reg output I would cut into the wire from the reg to the ammeter or that wire to earth?
Cheers
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Tried morris's joining the two ammeter wires together with no change to voltage across the battery. Made up jumpers to connect the reg to harness and broke into the reg to ammeter wire. Tried with volt meter from reg to ammeter wire, 12.5v nothing on but dropped to zero with motor running. Same if I put it to earth. *problem*
GMF.
Cheers
Time for another beer.
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Some mal-wiring somewhere? sorry can't help from here.
Regarding checking charge, just a general tip about a clamp-on ammeter, see http://www.a7a10.net/forum/index.php?topic=2526.msg16573#msg16573, they don't cost much and very easy to use. Used together with a multimeter for voltage measurement, one can see everything that's going on (or what's not going on!) Check ebay for AC/DC Mini Clamp Meter for some crazy low china pricing for 'probably good enough' meters.
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Owe you an apology Musky *red*
After checking the wiring diagram it came clear that the lights take off power before the ammeter. The battery is behind the ammeter, so if anything is wrong with the ammeter, you would have no lights except with the engine running but no charge to the battery.
The only thing I can imagine at fault is the voltage regulator and a stuck ammeter needle.
Now I'm in need of a beer... Cheers
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it came clear that the lights take off power before the ammeter
I've been trawling through various A10 wiring diagrams Morris, regarding the above it seems some before some after and some as well as, *smiley4*
(the bit that confuses many (and me for a while) is the lack of any indication of the internal, contact in the switch)
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Clean your commutator and check free movement of the carbon brushes. You get voltage at open circuit but being as you have no load you do not draw current. As soon as you connect the regulator you start to draw current and any high resistance in the circuit will drop the voltage down.
Had the same thing with a friends bike. All looked good but after trying everything else Resorted to cleaning the armature segments and wiped over the brushes and alls now well. Hope its the same for you, no cost solution. Good luck Dave
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In case you read the post I just removed from here and planned to answer, thanks anyway. Problem solved, or, maybe, no problem.
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I hoped this thread would lead me also to a solution but I don't think it has, not quite anyway.
12v A10 with solid state regulator, not sure what make.
The lights are great with the motor running, dimming when revs drop, so I am sure the dynamo is fine. The lights are good with the motor not running and I have charged the battery, so the battery is ok.
But the ammeter needle doesn't move whether the motor is running or not, and doesn't move when I switch on the lights and the battery goes flat when I'm riding with lights on.
Am I in the right area to conclude that the regulator and the ammeter are both probably faulty?
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Am I in the right area to conclude that the regulator and the ammeter are both probably faulty?
Not sure about the regulator, but it seems your ammeter needle is stuck.
As you are on 12V I suppose it has electronic ignition? Electronic ignition takes a large chunk out of the power budget. If I do a quick calculation only for the lights, most tail/stop lights are 8/20W, add to that 10W from the pilot bulb (I run it on pilot) + 5W speedo light makes 23W and up to 43W when you hit the brakes. All this sure makes the dynamo work hard for the money
I have to charge my battery from time to time (about once every 6-8 weeks). When it's fully charged at around 13V, after each ride with lights on I seem to have lost about 0.10V. At 11.5 volts it stabilises and stays at 11.5V for about 3-4 weeks, and then it starts to drop to 10.5V. By that time I can see the lights go dim at low revs, and I know then it's about time to hook her up to the charger. If I let it drop any lower, the ignition starts to advance to much, and she starts to backfire.
I am considering LED tail and stop lights to have a bit less consumption.
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Thanks Morris .... still has magneto ignition (with recently rebuilt mag) which makes matters simpler. Tomorrow I will start checking all connections and earths.
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Thanks Morris .... still has magneto ignition (with recently rebuilt mag) which makes matters simpler. Tomorrow I will start checking all connections and earths.
Looks like there's definitely a charging problem then. Have you tried to bypass the ammeter? Could be something wrong there.
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hi k1100, do you have a voltmeter that can measure amps as well? if so you could disconnect a battery connection and place it in the circuit and measure the amps being charged and discharged that way. The bikes ammeters are not really accurate and really only tell you when there is a big problem, on 12v your ammeter may only move half as much compared to if it were on 6v as well.
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G'day all.
Progress report. Gave her a full re-wire. It was a bit of a mess after 32 years of add on's and re-positions.
Ammeter is shot but still passing current so I ignore that. Everything works (lights, horn) and the head light glows brighter with more revs and dulls at idle so I assume it's all good. I'm still waiting for the clamp on ammeter that I ordered to test with that. So far seems all good.
Cheers.