The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: cus on 21.07. 2009 09:04

Title: Charging System
Post by: cus on 21.07. 2009 09:04
G'day All,
I'm a bit suspect on my charging system, its still early days & haven't covered many miles, but I don't think the system
is maintaining the battery well enough. Dynamo has been tested & reconditioned, new Yuasa 6v 11a battery & solid
state volt. reg. When bike is idling, the ammeter shows a slight discharge, then when I rev it, it goes into the +. I've
put the multi-meter on the terminals when running, is at 6v when idling, & only goes up maybe less than 1/2 amp when
I rev the bike, thought it would show more of a return charge than that, & not sure about this discharge at idle?
Any feedback woul be appreciated,

regards, Cus
Title: Re: Charging System
Post by: Triton Thrasher on 21.07. 2009 10:15
The discharge at idle is probably because of a badly designed solid state regulator.

Switch your headlight on. The ammeter should show a bigger discharge at idle. With lights still on, rev the engine- the ammeter should at least reach zero, probably go into the charge side for a while. The indicated charge should slowly reduce as the battery becomes fully charged.
Title: Re: Charging System
Post by: BSA_54A10 on 21.07. 2009 11:41
The charging system will only charge if it needs to.
So if you put a fresh fully charged battery in the bike and start it there will be on reading on the amp meter as the battery is already full.
You need to put a load on the charging system by either turning on the lights and putting your foot on the brake or discharging the battery by running the headlamp for 20 minutes or so.
You should see an initial high rate of charge slowly dropping off to around 0 as the battery attains a full charge.

Turn every thing on without the motor running and note the reading on the amp meter then start the bike and compare the running reading.
Title: Re: Charging System
Post by: cus on 21.07. 2009 12:31
Thanks for the replies,
If the battery dropped a volt or so & the headlight was dim etc., how long of a ride with the headlight off would you
expect the battery to be charged again,

Title: Re: Charging System
Post by: Triton Thrasher on 21.07. 2009 14:12
Even with a low battery and the lights on, the voltage across the terminals should be at over 6V when engine revs are up, because the battery will only take a certain amount of charge current.
Title: Re: Charging System
Post by: BSA_54A10 on 22.07. 2009 10:26
The cells are 2V each so the battery can only drop 2V or 4V.
Any reading not a multiple ( well almost ) of 2 is due to resistance.
I have had members complaining about their dim lights and when we measured there was only 2.5 V at the lamp socket.
Very little dirt corrosion or oxidization will make a big difference on a 6V system so keep them contacts clean.
Title: Re: Charging System
Post by: cus on 22.07. 2009 11:52
Had a chat with the guy that restored the magneto, dynamo & supplied the s/s regulator. He said that if the battery is getting
quite flat the regulator won't allow acharge back to the battery, "not sure about that!" but that pretty much is what happened.
The battery was getting fairly low, but I thought the generator would top it up, but when I went for a spin, the ammeter didn't
move, once I charged the battery, all was back to normal, ammeter showing positive charge once reved. Does it sound like

regards, Cus
Title: Re: Charging System
Post by: trevinoz on 22.07. 2009 22:50
Cus, ask him what make of regulator he supplied. As I told you , he has palmed off some rubbish to a mate of mine.
Title: Re: Charging System
Post by: cus on 23.07. 2009 06:45
G'day Trevor,
I'll see if it gives me any more greif, & if so I'll send it back,

regards, Cus
Title: Re: Charging System
Post by: Brian on 23.07. 2009 06:54
Throw the regulater in the bin and buy a DVR2. I have three of them now and are about to buy the fourth, I simply can not fault them, they work perfectly in every way.
Title: Re: Charging System
Post by: Dynamo Regulators Mike on 23.07. 2009 07:20
Yo'ure too kind Brian *red*
Not all electronic regulators are the same of course. The slow speed discharge (into dynamo) field and inability to start up with low battery are symptoms on one type which has helped to give these devices a bad name, but has been around for many years.
Perseverance wins through in the end  *smiley4*
Title: Re: Charging System
Post by: beezalex on 23.07. 2009 14:03
I agree with brian.  I recently fault tested my DVR2: The ammeter fell apart and shorted on the headlamp bucket.  Not only did the DRV2 passes with flying colors, but the dynamo was revived with only a repolarization.  A different short in the wiring had done in the previous regulator of a different brand and burned the dynamo armature.  Nice going, Mike.  I think we have a winner.
Title: Re: Charging System
Post by: cus on 23.07. 2009 22:55
Just ordered one Mike, sounds like that will fix the problem,
thanks everyone for the help.

regards, Cus
Title: Re: Charging System
Post by: RichardL on 23.07. 2009 23:17
Cudos must go to ManorMike, this time, not for the DVR2, for those of us with one know how it has made our lives better. Instead, these cudos are for letting us do the advertising for him while he graciously provides the sage clarity of facts without self-promotion herein. Thank you, Mike.


Richard L.