The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: Sam C on 17.08. 2015 09:04

Title: Newbie electrical woes
Post by: Sam C on 17.08. 2015 09:04
All

Don't forget I'm new to this (so be patient!). I very recently bought and started riding my first bike: A10 Golden Flash, bought from my step father in law.

Last night I had to be rescued by the AA (Breakdown recovery). This was because my battery died.

Bike is still 6v. It has electronic ignition. It also has indicators which (crucially) I fitted, and is the only change I've made to this bike. They're 6v 15w bulbs - sold specifically for this bike.

I would appreciate getting your thoughts on my battle plan to fix this. Here goes:

(1) Buy new 6v battery (because a completely flat battery will never be as good again). I'll charge up flat one and use it as emergency spare.

(3) Using multimeter, check that battery is charging - am guessing 7.5v at revs? I think that won't happen straight away, but rather will 'kick in' above a certain rev range - I think there's a switch that causes that (the 'regulator'?). I also assume voltage shouldn't then go any higher regardless of revs, but may drop back to 6v or less if I turn on electrics that start draining more than the bike can supply through the bike version of an alternator (dynamo?)

(4) If battery not charging, assume dynamo is bust and send off to be repaired. 

(5) If battery is charging but it's not a neat switch from 6v (or less while head lamp / indicators are on) to 7.5v at certain rev range then assume the regulator is bust. If so, replace it - I assume it's quite cheap.

(6) If battery is charging but something (most likely the indicators) is just 'too much for it' i.e. it all works fine until the indicators come on, at which point the dynamo can't cope, consider ditching those or maybe having dynamo repaired - dependant on likely cost. I've heard people talking about a 'rewind' - I assume that over time the dynamo becomes less effective and needs some sort of service - and this is it.

Some relevant points:

- Unlike me, my step father in law is technically very strong with things like electrics and learnt to ride on this type of bike. I think everything he did will be good (e.g. the electronic ignition system which he fitted - and he said he chose it because, while it's quite expensive, it should be good and it uses little power).

- I think there's something wrong with my indicators that I fitted because they keep blowing a 10amp fuse. I've checked for shorts and insulated the hell out of everything so I don't think it's that. I wonder if there is something wrong with the flasher unit or switch. They work fine with a 15amp fuse but my mate said 10 amps should be fine for 6v 15w bulbs - so I'm worried that my indicators are the problem.

All thoughts hugely appreciated: I'm off to buy a battery and a 6v charger in the mean time!!

Cheers

Sam
Title: Re: Newbie electrical woes
Post by: groily on 17.08. 2015 09:52
I'd follow Dutch's suggestion at the end of the other, earlier thread and call b'mac. Dyn or reg are equally likely candidates probably. Things work sort-of as you outline, but there's a bit more to it obviously and faults aren't necessarily mutually exclusive to one part as opposed to another. With the elec ign and flashers etc you need a charging system to avoid troubling the recovery bloke too often and being forced to sit in pubs for hours (lucky sod!).
10A fuse may not be enough to heat up cold 6v bulbs at 30W between them - cold filaments can require a lot of current (amps) to get them lit (up to twice their rating).  As a rule of thumb, if you double the current required to carry all loads including your ignition system and fit a main fuse that will take that without blowing, then you should be OK. I'd use at least 15A on any 6v bike, and with indicators fitted I'd make that 20A. Any fuse will safely blow in the case of a dead short, so the fact that there might be a few spare amps capacity doesn't matter. If you wanted, you could put individual smaller fuses in individual circuits, many people do. Think I would if I had indicators on anything.
Good luck!
Title: Re: Newbie electrical woes
Post by: Johnny J on 17.08. 2015 13:24
To confuse you a little bit more. ;-)
I use this one on my bike: http://www.ebay.com/itm/WaterProof-5V-11V-to-12V-10A-120W-DC-DC-Step-UP-Power-Converter-Regulator-/301173896517?hash=item461f5cf545

Advantage is I can use ordinary 12V LEDs both in blinkers, rear, brake and headlight.
The total power now used is very low, around 25W tops.
Still using 6V for battery and ignition.

Disadvantage is I had to use new cables for both + and - to all lamps, i.e. a separate electrical system for the lights.
Title: Re: Newbie electrical woes
Post by: Greybeard on 17.08. 2015 19:12
I use this one on my bike: http://www.ebay.com/itm/WaterProof-5V-11V-to-12V-10A-120W-DC-DC-Step-UP-Power-Converter-Regulator-/301173896517?hash=item461f5cf545

Wow, that looks cool! Could I hide one in my headlamp cowl purely to be able to use a 12v headlamp bulb?
Title: Re: Newbie electrical woes
Post by: Johnny J on 17.08. 2015 19:54
Not straight away, have to separate the lamp from ground first since this is a "non-isolated" converter.
Can not touch any of the outcoming 12V (+ or -) to ground or -6V.

A 12V LED headlamp can be used quite easily since they are normally not attached to ground, but have separate cables for + and -.
The problem is to adjust the fitting of the lamp physically, had to do some grinding and used zip ties to fasten it.
Title: Re: Newbie electrical woes
Post by: Sam C on 21.08. 2015 12:30
All

Thanks for help so far. My investigations have been hampered by the fact that I'm still waiting for replacement battery (technically I have the battery but the shop brilliantly didn't supply the acid: which has to be transported separately these days).

However, having just had a very helpful chat with a friendly local auto electrician who also loves old bikes, I think I have a better theory:

(a) He reckons nothing wrong with a 15 amp fuse per se. And probably my indicators and indicator circuit is absolutely fine and shouldn't be more than the dynamo can cope with.

(b) He is certain that the issue is most likely to be the regulator. This is because:

- indicators are fine 'in the garage' and 'to begin with' when heading out, they only blow 10 amp fuse mid way through journey.

- most likely what's happening is my dynamo is cooking the circuit, and my battery, through the regulator failing to regulate the amount of power going into the system

- way to test this is to use multimeter to check power across terminals when everything off (6.5v with new battery), then once things are running at low revs (a little bit less to deal with power being taken for electronic ignition) and then a bit more at revs (7v), at which point the dynamo ought to begin to put power into system, but never more than that. If it's creeping up to 7.5v or even 8v then that's the problem - and as it creeps up further eventually it will blow a 10amp fuse in my indicators circuit and destroy the battery.

- Normally this problem blows the headlamp bulb but some bikes had some sort of 'sink' that protects the headlamp bulb from this - which might be the case with my bike.

All still entirely hypothetical until I get this damn battery sorted out, and charged properly, and everything tested with a multimeter (which given other commitments isn't now going to be until next week - frustratingly). However all thoughts appreciated in mean time!

(c) As an aside, he's also said it makes a lot of sense to tidy up the earths - since any problems there are never good. Sort of 'good housekeeping' I guess. No different to old cars then! I think I only have one: under the seat, beside the battery - sound right to everyone?

Cheers all

Sam

Title: Re: Newbie electrical woes
Post by: Greybeard on 21.08. 2015 18:47
When I restored my A10 I bought a new wiring loom. I was glad to see that the loom has earth wires in it. I think the original wiring relied upon the frame for earth return. You might like to think about providing dedicated earth cables.

The other thing to say is about this forum. To begin with I was bamboozled by reading several slightly different opinions on aspects of these machines. I suggest that you read all responses and gradually you will get the overall knowledge that will allow you to make a decision.
Title: Re: Newbie electrical woes
Post by: bsa-bill on 21.08. 2015 20:08
Quote
You might like to think about providing dedicated earth cables.

Yes that's a good suggestion, an earth from both headlight and tail light to the frame where the battery earths takes out any IFs about conductivity
Title: Re: Newbie electrical woes
Post by: trevinoz on 22.08. 2015 01:56
You may have regulator problems but I doubt that is the cause of you blowing fuses.
You should blow the bulbs with too high voltage but to blow the fuse a high current is going somewhere. Maybe an intermittent short circuit to earth?
If an auto electrician gave me that story I would quickly go somewhere else.
"Protective sink"? "Cooking the circuit"?
By all means measure your output voltage,  that is the first thing to do. Measure it at different times to see if heat is causing problems.

The quickest way to find the fault is to remove the fuse and put a nail in the holder. The smoking wire will be the culprit.   *smile* *smile*
Title: Re: Newbie electrical woes
Post by: muskrat on 22.08. 2015 04:53
I'd say the "Protective sink" is a zener diode used in the later A65/50's with an alternator.
As Trev said, high voltage won't blow a fuse but high amps will eg chafed power wire shorting to earth.
It might be time to do some reading   http://www.a7a10.net/BSA/lucasmain.htm  and another from another site. With other info here  http://www.bsawiki.co.uk/chaps/8-chapter-list
Cheers
Title: Re: Newbie electrical woes
Post by: duTch on 22.08. 2015 07:02

 Hi Sam, May have missed if you have a mechanical regulator, but they are very simple- even I kinda figured out how they work.  Can't recall the exact figures offhand, but there is a cutout/in solenoid switch built in that does its stuff at about 6v(in) and 7.8v (out)....kinda fun to play with. ....
Title: Re: Newbie electrical woes
Post by: Sam C on 25.08. 2015 09:50
Right

Battery now charged and ready to be fitted.

I've read through the Haynes guide for how to check the regulator and this has thrown up another problem I'm not sure how to deal with:

- Haynes says to use a multimeter to check the voltage across specific terminals (D and E) on the regulator, while the bike is running, but with the negative lead disconnected from the battery.

- I can't do this, because I have electrical ignition - so battery needs to be connected in order for the bike to run.

- Given this, should I continue to check the regulator using the multimeter across D and E terminals (as Haynes says) or instead should I be checking across the  battery terminals - or somewhere else - and in either case what should the readings be.

- Haynes says that with the battery disconnected, and the bike running, the terminals should give out 7.6 - 8.0 volts (any more or less and it should be adjusted).

- Similarly the Haynes says that cut-out should operate between 6.3 and 6.7 volts.

Thanks all - appreciate much of this must seem stupid to most on here.

Cheers

Sam
Title: Re: Newbie electrical woes
Post by: Greybeard on 25.08. 2015 11:03
...much of this must seem stupid to most on here.

Not to me  *conf2*
Title: Re: Newbie electrical woes
Post by: bsa-bill on 25.08. 2015 11:14
Quote
much of this must seem stupid to most on here.

 on behalf of those of us of a certain age - please never forget that WE do, a little re-enforcement of the little grey cell is always welcome
Title: Re: Newbie electrical woes
Post by: Sam C on 25.08. 2015 15:08
Right - an hour in the garage and this is where I am now:

- Regulator is aftermarket podtronics jobby. I just left it alone and didn't try to work out how to test it in line with Haynes instructions.

- Bike is fitted with a voltmeter but it's always just gone bananas as soon as the engine is turning over at any revs - I thought that was just a problem with the voltmeter I.e. it's no different to my speedo which also just goes bananas and is of little use. I'm now forming a different view.

- Multimeter across the battery terminals shows this:

(a) At rest, no engine on, gives 6.25 volts, dropping to about 5.9volts once everything is on (headlamp, rear brake light, indicators). that seems fine to me i.e. my indicators are working the way they're meant to. I'm going to say they're fine and the blown fuses are caused by something else.

Voltmeter on the bike also shows a small shift to 'negative' once everything is on as above, so also suggests voltmeter actually works fine.

(b) Engine turning over at a little higher than tickover: something like 7.8v  - regardless of what electrical things I turn on - so far so good. HOWEVER - every so often the reading is some strange number, almost random, bouncing around into the teens. It's like it's intermittently switching from 7.8v to a random series of other numbers, but always coming back to 7.8vish as an average.

Voltmeter just goes bananas and is useless, as soon as engine is turning.

(c) Engine running at tickover: multimeter gives even weirder readings: virtually no readings that seem 'about right' - all strange numbers in the high teens, then low, then just all over the place. Really weird.

(d) Engine given some revs: voltmeter goes completely mental - bounces around all over the place. I haven't found a way to use the multimeter while revving yet (bit pushed for time). Will check later but my suspicion is the readings would be 'all over the place'.

From this my diagnosis is:

- There is probably something wrong with my regulator and I'm just going to replace it. Costs £30 - dead easy to replace - worth a shot.

- My indicators are probably fine, but what's happening is that regulator is not doing its job properly and this is causing fuses to get blown in my indicator circuit (which is its own circuit - with its own fuse).

- my voltmeter is also fine and is simply trying to display the 'all over the place' nature of my dynamos effect on my battery.

Thoughts always appreciated!

Cheers

Sam
Title: Re: Newbie electrical woes
Post by: morris on 25.08. 2015 22:03
Just a thought, but something similar (voltmeter bouncing all over the place) once happened to me. It appeared to be a bad earth between dynamo body and engine case. To be sure, try an earth wire from the dynamo cover screw to the frame. I run mine permanently like that now.
The blowing fuse could be nothing more than voltage dropping to low. As a rule of thumb you can say that when the voltage is dropping by let's say 20% (corresponding to 1.2V on a 6V system) amps will go up by 20% as the item in use at that time will draw more current (amps) to compensate for the loss in tension. A 15 amp fuse which normally would be fine will then blow. That's also the reason why wires on a 6V system have to be thicker than on a 12V system
Title: Re: Newbie electrical woes
Post by: duTch on 26.08. 2015 04:04
Quote
...a bad earth between dynamo body and engine case. To be sure, try an earth wire from the dynamo cover screw to the frame. 
I ran a wire from the brush/field earth screw straight to the battery, the alloy end cover doesn't quite work the same
Title: Re: Newbie electrical woes
Post by: Sam C on 26.08. 2015 09:11
Confession time (and this is very embarrassing):

I have a cheap multimeter. I was resting the multimeter on the frame by the battery when I took my previous readings. I'm an idiot.

Having moved the multimeter as far away from the bike as I can, I don't get that 'bouncing around' - move it closer to the bike and it returns. What an idiot I am. I guess the electronic ignition or something else is messing around with the multimeter.

So sorry for the wasted time and thoughts I've inflicted on you. What a tw*t I am (or for our American cousins: a d*ck).

I'll post another post in a second starting again - self flagellation has been done, I assure you.
Title: Re: Newbie electrical woes
Post by: Sam C on 26.08. 2015 09:31
So, moving on!:

In case people of forgotten: original issue here is my battery drained flat mid journey. And weirdly, my indicators (that I put on) keep blowing their 10amp fuse mid journey (but not in garage), but a 15amp fuse is fine. I've taken a wrong turn with the 'readings moving around' (very embarrassing).... but I now have a better set of readings (taken at the battery terminals - with a new battery) that are shown below:

7.9v > 10 v at low tickover (higher end of this range when all electrical items are turned off, decreasing down with each item that is turned on i.e. the lowest reading is when lights, indicator and footbreak all turned on: 7.9v)

8.2v > 8.45v at high tickover (this time higher voltage being when all electrical items are turned on(!)).

8.8v > 9.2v at high revs (higher voltage when electrical items turned on - but couldn't work out how to do this with the footbreak too - not enough hands / good enough balance!)

So the question is: is that normal or, as it instinctively feels to me, a bit too high (as an average). Similarly, should there be this amount of variation - since I expected the regulator to just 'regulate' everything at about 7.8v all the time (unless the dynamo couldn't deliver enough to match the pull of electricity - perhaps when 'everything' is turned on, or revs drop below a certain range - in which case it would drop suddenly to something less than 6.25v).

Given this, an observation that seems very odd to me is that from the moment the bike is running the voltage jumps markedly from the 6.25v resting to something around the 9v - 10v mark) i.e. if I'm reading it right the dynamo is 'always on' and 'always delivering (a lot of) charge to the battery'. But surely that's just impossible?!

So... very.... confused.

Cheers all and apologies once again for wasting people's time with earlier post!

Sam
Title: Re: Newbie electrical woes
Post by: muskrat on 26.08. 2015 10:43
G'day Sam. I'm not the best with electrickery but that sounds way too high. If the F & D wires from the dynamo are joined and run through a multimeter to earth and motor started it won't take long (a few seconds) for the reading to climb to 20v. Once connected to the reg it shouldn't exceed 7.5 - 8 volts even with nothing turned on. So your original problem would be the reg has cooked your battery.
I'll now duck for cover as more knowledgeable sparkies shoot me down. 
Cheers
Title: Re: Newbie electrical woes
Post by: duTch on 26.08. 2015 11:44

 yeah Sam, what muskie said- should have no more than 8ish(?) for 6v.... I tried to add a Lucas reg page I have but file is too big..What reg and other specs (not the things on face for visualizing) do you have...?
Title: Re: Newbie electrical woes
Post by: Sam C on 26.08. 2015 12:56
Thanks both.

Regulator is a modern job - I wonder if I've frazzled it when I was messing around fitting the indicators. Another is in the post - only £30.

I'll try fitting that to see if that helps.

I appreciate the quick response - cheers!

Sam
Title: Re: Newbie electrical woes
Post by: muskrat on 26.08. 2015 13:01
Is the reg polarity sensitive? Make sure and flash the dynamo to be the same.
Cheers
Title: Re: Newbie electrical woes
Post by: duTch on 26.08. 2015 13:21
Quote
Regulator is a modern job

 Whadda yea mean...'modern'..?  you mean non-mechanical...??

 When I say
Quote
should have no more than 8ish(?) for 6v
. that is subject to criticism from those who know..
Title: Re: Newbie electrical woes
Post by: Johnny J on 26.08. 2015 13:52
Actually for a normal lead acid it should be max 7.2-7.5V, higher than that and the lead starts to boil away...the higher voltage the quicker.
Title: Re: Newbie electrical woes
Post by: Sam C on 26.08. 2015 14:23
Yes the battery is a normal lead acid battery - not even a sealed one, I had to put the acid in separately.

The regulator is non-mechanical. It was swapped, I think when the previous owner (my step-father in law) fitted electronic ignition. It's one of these:

http://www.ebay.co.uk/itm/271947548026?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D271947548026%26_rdc%3D1

I actually still have the old mechanical one, which is tempting to fit, but probably easier just to wait until the replacement arrives.

I think this is sounding very much like the right explanation for my woes - at least in terms of killing the battery.

Thanks all - responses have been amazing. Very much appreciated.
Title: Re: Newbie electrical woes
Post by: Sam C on 26.08. 2015 14:33
And I'm going with the knackered battery as an explanation for the indicators' fuse getting blown too... unless there's any view that contradicts this?

Cheers all

Sam
Title: Re: Newbie electrical woes
Post by: Greybeard on 26.08. 2015 15:11
There is a forum member that manufactures a really good voltage regulator. Don't buy a cheapie until you have researched the...can't remember the name at the mo. I'll go and do a search and come back here. Don't go anywhere.

It's the DVR2. It is dual voltage, virtually bomb proof and a very nice chap sells them.
www.dynamoregulators.com
Title: Re: Newbie electrical woes
Post by: Sam C on 26.08. 2015 16:35
Thank you Graybeard.

I have a regulator ordered now. With the benefit of hindsight I should have waited and shopped around - I'll definitely give your man a go if there are any issues once new regulator fitted.

Cheers all - been a massive help so far.

Cheers

Sam
Title: Re: Newbie electrical woes
Post by: trevinoz on 26.08. 2015 22:23
I don't think a knackered battery will cause a fuse to blow unless it has developed a short circuit which could cause a high generator current to flow.

Morris, if the voltage drops the current cannot increase to compensate if the resistance stays constant. Current is calculated by dividing the voltage by the resistance.
Title: Re: Newbie electrical woes
Post by: worntorn on 27.08. 2015 02:26
Digital multimeters are useless when testing with a running engine. The RF interference from the ignition causes them to read in error.
Most analogue ( old fasioned kind with a needle)multimeters will give a good reading when close to a running engine.

Glen
Title: Re: Newbie electrical woes
Post by: morris on 27.08. 2015 22:48
Morris, if the voltage drops the current cannot increase to compensate if the resistance stays constant. Current is calculated by dividing the voltage by the resistance.

Thanks for getting that right Trev. I got a bit carried away there. The only thing that'll happen is that the bulbs will shine less bright.
I'm more used to working with electric motors.
Title: Re: Newbie electrical woes
Post by: Greybeard on 31.08. 2015 14:30
Sam,
Are you still with us? I've sent you a couple of private messages.  *computer*
Title: Re: Newbie electrical woes
Post by: kiwipom on 04.09. 2015 04:00
hi guys, anyone know anything about these or would they be a benefit to us/our bikes, food for thought,cheers