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Battery Failure #745147 08/10/18 6:31 pm
Joined: Aug 2018
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Bill Harrison Offline OP
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Hi,
have just acquired a 350 Goldie but have electrical problems. Initially the dynamo was seized but I've sorted this, the dynamo motors correctly and I've fitted a new voltage regulator (solid state) I'm still only getting a slight charge at lowish revs but more concerning is that 2 new lead acid batteries have failed whilst out riding. They drop down to 4.3 volts, won't charge and despite all efforts appear totally U/S. Could it be vibration? Any idea how to check if the voltage regulator is working?
Ta

Last edited by Bill Harrison; 08/10/18 7:32 pm.
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Re: Battery Failure [Re: Bill Harrison] #745181 08/11/18 1:57 am
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Jerry Roy Offline
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Originally Posted by Bill Harrison
Any idea how to check if the voltage regulator is working?
Ta



Disconnect the battery.
Get a 12 Volt headlight
hook the headlight up to the battery leads
Start the engine
Does the light glow at idle? If yes, rev the engine
If no, rev the engine
Does the light get brighter?
If yes, measure the voltage across the light terminals while revving the engine. It should read about 7 volts
If it does, alles ist in ordnung
If it doesn't, measure the voltage across the output wire of the dynamo and it's case
It should read the same as the leads to the headlight (roughly)
If it doesn't, read the voltage from the field terminal to the case
If there is no voltage, or very little, get another regulator or check the continuity of the field wire from the regulator
Hook some jumper wires to the battery, hook the appropriate polarity jumper to the dynamo case, (ground) and touch the other battery lead to the field terminal.
Do not leave it on for more than 15 seconds or so, and while it is connected, rev the engine and check the voltage of the dynamo output. (terminal to case)
It should go way up
If it doesn't, rebuild the dynamo. If it does, the dynamo is working and the fault of no charge is probably the regulator
Most importantly, make sure you wired the regulator correctly, they do not handle reversed polarity voltages well

For extra credit, BING "flashing the field" and ponder the vagaries of electrical components.

Have fun JR

Re: Battery Failure [Re: Bill Harrison] #745182 08/11/18 1:58 am
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Jerry Roy Offline
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Originally Posted by Bill Harrison
Any idea how to check if the voltage regulator is working?
Ta



OOp's, I double posted, so this is a total edit

Last edited by Jerry Roy; 08/11/18 2:00 am.
Re: Battery Failure [Re: Bill Harrison] #745195 08/11/18 10:31 am
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Rich B Online Happy
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Dumb question.....is the dynamo wired correctly internally? The bush wires must cross each inside the dynamo. If they don’t there will be no output from the dynamo, but it will motor. eek


Never underestimate the human ability to elevate stupid to a whole new level!.
Re: Battery Failure [Re: Bill Harrison] #745202 08/11/18 11:45 am
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BSA_WM20 Online Content
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Yes they most likely failed due to vibrations.
You will need to fit a battery with AGM
Absorbent Glass Matt wich goes between the plates for mechanical support
or
Fit Cyclons which are spiral would like a big cap and being a spiral suffer less from vibrations.
Having larget plate area are harder to overcharge
Being sealed do not gas and do not self discharge.



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Re: Battery Failure [Re: Bill Harrison] #745293 08/12/18 2:32 pm
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Kerry W Offline
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My Cyclons died in no time at all..


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Re: Battery Failure [Re: Bill Harrison] #745295 08/12/18 3:25 pm
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Swan Offline
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I found good information about magdynos, including "flashing", testing, wiring, and more, on this website when I had issues with my dynamo.


1966 Triton
1962 BSA DBD34 Gold Star
1966 Triumph Bonneville
Re: Battery Failure [Re: Swan] #745365 08/13/18 2:33 pm
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Allan Gill Online Happy
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Originally Posted by Swan
I found good information about magdynos, including "flashing", testing, wiring, and more, on this website when I had issues with my dynamo.



Swan may well have hit the nail on the head, has the dynamo been flashed to the correct earth (positive/negative, depending how it is wired) it would explain the batteries being killed, is the battery fitted with an inline fuse? if it has been flashed the wrong way it would have blown the fuse.... least it will if the output is high enough....


beerchug
Re: Battery Failure [Re: Allan Gill] #748914 09/12/18 6:19 pm
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Bill Harrison Offline OP
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Now the old original battery has failed. I was out doing plug chops, going quite fast in top gear, serious blasts, then some slight misfiring then oooggghh stopped. Turned on lights, back light illuminated , headlight on, everything went out, no spark (coil ignition), so I think this is about 4 batteries that have failed, so have ordered some dinky little 6 volt jobs that are gel filled-AGM as mentioned above, hopefully they will survive the battery eating monster!!!!

Last edited by Bill Harrison; 09/12/18 6:27 pm.

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