The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: owain on 30.09. 2020 10:56
-
I've had this problem for a bit of a while and thought I'd share to see what a fix may be. I have 6v electrics on my bike with a DVR2 regulator and fitted with 6v incandescent bulbs. The sidecar light is also connected in parallel to the bikes lighting and also has a 6v bulb.
The issue is that when the headlamp is on, the battery gradually discharges. If I keep the revs high then I'll get bright lights but the engine tends to spend most of it time working at low to medium revs. I checked the battery with a voltmeter with lights off and the battery voltage does increase slightly from 6.2v to 6.4v at a mid rev range (I have no tacho, so not sure of the actual rpm). Although with the headlamp on the battery slowly discharges at a mid rev range.
The A10 is 1950 and as far as I know, the dynamo has never been refurbished. My initial thoughts were to buy a dynamo belt-drive kit as I've heard that they will increase the dynamos rpm....or do you think a dynamo reconditioning is the better option? Eventually I'd like to get both done but for the time being I can only afford the one. Opinions please?
-
First thought is to check the brushes for wear and clean any carbon build up on the commutator if the battery is OK. Also check earthing point. Is it clean and free from dirt and corrosion? Might be a good idea to fit LED lamps have a look at Paul Goff's site plenty to choose from there.
-
Check that the dynamo has a good connection to the engine/earth. Paint on the dynamo can insulate it.
-
First thought is to check the brushes for wear and clean any carbon build up on the commutator if the battery is OK. Also check earthing point. Is it clean and free from dirt and corrosion? Might be a good idea to fit LED lamps have a look at Paul Goff's site plenty to choose from there.
Yes, a good clean up might do the trick.
LED bulb is another option, I'm very pleased with the performance of the bulb I got from Classic Car LED's, (he sells them in singles) Very helpful, cheaper, superior quality control, and not brusque and patronising with his customers.
-
You should be seeing 7 V with lights off.
Can the D and F leads joined together light a headlight bulb brightly?
-
Owain,
What wattage bulbs are fitted?
If your wattage is exceeding or near the top end of the dynamo output the battery will discharge
John
-
Owain,
What wattage bulbs are fitted?
If your wattage is exceeding or near the top end of the dynamo output the battery will discharge
John
That's the first question that should have been asked really.
He could have a perfect charging system, but have a boy racer million watt headlight bulb fitted.
-
Might the classic 6 V 30/24 W head bulb be in his future?
-
As it happens, I tested the plunger’s electrics yesterday (6V with incandescent lamps all around).
I measured 8 amps on high beam with brake light on. A 6V system with a dynamo in decent order leaves you about 2-3 amps extra and therefore should be capable of feeding a couple of small wattage sidelights.
A set of new brushes and a commutator clean up is a good start. Check the bearings too. Particularly the small bearing, commutator side. And while you’re at it, disconnect the coil and measure it’s resistance. Should be about 2.8 ohms. After getting all that right, upgrading to a DVR belt is a good investment. That will squeeze an extra 10-15 watts out of the dynamo
If there is something really wrong with either coil or armature you wouldn’t almost have any output at all.
-
Some sound advice there. I'll check the wattage of the bulbs this evening and take the dynamo out of the bike to test on a bench. The dynamo isn't painted so I don't expect a poor earth to be the problem, although I'll give it a good clean none the less.
-
Righto, I checked out the bulbs;
Headlight: 6v 35/35w
Sidecar: 6v 4w
Taillight: Lucas 334 bulb (24v 24/6w??)
So I think it's safe to say that the tail light is the problem. That being said, I decided it'd be a good idea to give the dynamo an inspection and a decent clean. The armature and field coil were covered with a decent layer of grime and I also noticed abit of damage to the brass near the top of the armature (i.e. just before the part where the brushes touch).
Anyway, my thoughts are either A) Just replace the bearings and shove it all back together after a thorough clean or B) Replace the armature (and field coil) whilst I'm at it. Thoughts?
-
I'd check the segments of the armature and the field coil for resistance and if OK re-use. The 'pound in your pocket' is better there than in someone else's.
-
Hi Owain,
A normal tail light bulb would be 6v / 5/21watt
The tail light element should be the 6w and the brake light the 24w so you can usually leave the brake light out of the calculation
I think LED bulbs would help a lot
If the dynamo, regulator and battery are good and the voltage rises to 7.2 volts with lights off all should be good
6 volt systems need careful attention to connections, switch contacts and wiring to give their best
A failing battery where the voltage will not rise to the cut off point of the regulator (7.2v) will rob the energy from the dynamo in a bid to raise the voltage to 7.2v
John
-
Righto, I checked out the bulbs;
Headlight: 6v 35/35w
Sidecar: 6v 4w
Taillight: Lucas 334 bulb (24v 24/6w??)
So I think it's safe to say that the tail light is the problem. That being said, I decided it'd be a good idea to give the dynamo an inspection and a decent clean. The armature and field coil were covered with a decent layer of grime and I also noticed abit of damage to the brass near the top of the armature (i.e. just before the part where the brushes touch).
Anyway, my thoughts are either A) Just replace the bearings and shove it all back together after a thorough clean or B) Replace the armature (and field coil) whilst I'm at it. Thoughts?
Are you sure that the tail light bulb is 24V? That would be one for a lorry then...
Anyway, the 6W would be for the tail light and the 24W would be for the stop light. I don’t suppose that you ride with your foot on the brake and have your stop light on all the time... *smile*
Your constant consumption with lights on would be around 45 watts then, which the dynamo should deliver easily (normally minimum 60 watts, and with a belt drive may go up to 80 watts)
If the field coil measures around 2.8 ohms, I would just change bearings and brushes, clean out the grooves between the commutator segments and give it a test run. When cleaning the grooves make sure you make a straight cut. A ground down hacksaw blade is a good tool for this purpose.
On the bench, driven by a drill, you should measure an output of at least 14-18V depending on the speed of your drill
-
Owain. With care and taking a light cut with a sharp tool, the commutator segments can be machined back to produce an as new running surface for the brushes, and the insulation between the segments then cut back as already pictured. Depends on the existing thickness of the segments, and the depth of the wear.
If you do go down the new armature road, the cost of 6 Volt and 12 Volt components are not too far apart, and it is worth going for a 12 Volt system with a higher output.
Like RD recommends, I'd try checking the armature and field coil against electrical spec. and if satisfactory, cleaning up the segments. Stick with what you've got for now, meanwhile researching options for a possible upgrade. The cost of those pounds will certainly clear the mind as to the way you go.
Swarfy
-
Hi Owain,
Its all or nothing when converting to 12 volt, the components must match as the 12v armature and field coils have different number windings and wire gauge.
You can use a 6v dynamo and 12v regulator, but it's a different regulator for a 12v converted dynamo
(When using DVR2 regulators)
Ya I know it costs, but well worth it in my opinion
John
-
The simple bit to answer is yes, your field ohm measurement is ok.
-
but it's a different regulator for a 12v converted dynamo
(When using DVR2 regulators)
John
Am I missing something or just being thick John? As long as the thing has its field coil wired F to E, I think the standard DVR2 works fine on '12v' parts (provided you have the full kit as you say, not half-'n-half), same as it does for '6v' dynamos asked to run at 12v. Certainly have done for me, anyway - except when folk have specifically demanded enhanced current regulation, when I have fitted DVR4s and rewired the field to suit (because for them you have to).
While it's right, per Swarfy's point above, that you'll get more power at lower rpm with the '12v' bits than you would by simply fitting a 12v regulator on an original 6v instrument (because of the lower cut-in speed), the total power available is in fact strictly limited to 60W on the these upgrade parts. The finer windings are a tad wary of excess current,
At 6v as original, you've got 10 amps to play with as Morris said. At a system voltage of just over 7v when the regulator is doing its stuff, the current involved in producing the continuous-rating limit of 60W is actually a bit less, so there's a safety margin of sorts if 10A is a strict limit. With the fine-wound after-market bits, you've only got 5 amps to play with, and again actually it's rather less at a regulated system voltage of 14+.
The thicker coils on an original dynamo will withstand higher-than-normal loads running at 12v - up to a constant 75-80 Watts in fact - but the purpose-made '12v' bits are more sensitive. The downside is the higher cut-in rpm with the thicker original windings. As ever, there are no free lunches. You 'pays yer money and takes yer choice' basically.
For me, urban or low-speed riding (especially with incandescent bulbs) = fit 12v bits or stay at 6v; for country boys (like me), original parts and a DVR2 set at 12v is fine.
Or - heresy - get a bike with an alternator and enter another world entirely!
Just for my own peace of mind, have discussed use of DVR2s with finer-wound dynamos with ManorMike - and he confirms they will work fine "as well as ay and better than most". With their only weakness being the lack of current limiting.
He also stressed to me again the need to respect the 60W limit of the 12v upgrade parts.
-
In the 60's having an alternator was definitely another world - of darkness. I frequently removed alternators and fitted dynamos (commercial and marine). In those days alternators were no more reliable than the (UK) weather and with marine versions costing upwards of £400 .......
Another advantage of dynamos (expecially on marine) was the ability to tune the regulators to charge nearer to 15v, thereby ensuring faster battery charging (don't do it on a sealed battery). Happily, today's alternators are reliable and efficient.
-
Really appreciate the words of wisdom given. It might be worth mentioning that my A10 has a pretty heavy sidecar outfit attached, so top speeds is certainly no more than 60mph with the wind behind me (I haven't bothered attaching the speedo, so can't be sure of this). Either way the engine is under load all of the time and rarely gets to see high RPM. I like to ride day and night, so decent lighting is pretty important and something I haven't been able to achieve on the A10 thus far.
I also made the wiring loom myself, I'm curious whether I've wired it up so that the 24w brake light is on constantly with the brake pedal activating the tail-light *conf*.
I've already got the DVR2 regulator fitted so that avoids the cost of buying a new regulator if I choose to run 12v electrics. I've read the 6v Vs 12v thread and there seems to be a lot of owners recommending an upgrade to the 12v system. I think I'll need to get a dynamo repair kit either way as my armature is a bit knackered as it stands. So if a 12v system would provide a more reliable and brighter lighting for the bike at a lower rpm then it sounds like the way to go...
-
Hi All,
Bill,
I believe the DVR has built in current limiting for the field current
The 6 and 12 v field coils require different limiting values,
This is what I remember from Manor Mike's posts (or am I talking bollox?)
*conf2* *conf2*
John
-
Not quite certain John, and never bollox! I thought that the standard DVR2 didn't have it, whereas the DVR3s & 4s (which ManorMike has moved into other hands now) do.
The quoted requirement is that the field coil resistance for use with a DVR2 should be north of 2.5 ohms, which I assumed meant it'd work OK with the higher resistance '12v' field coils. Although the DR Ltd literature makes no express mention of suitability - it just explains that the max power of the finer-wound parts is very definitely limited to the 60W it says on the tin - I think it's a fair inference that it'll do the job. I'm guessing ManorMike would have explicitly stated if the regulator couldn't be used with the 12v bits, as all the tekkie documentation, and FAQs, are very carefully drafted. But . . . I dunno 100%, can only say I've used them!
The literature goes on to say you can safely get a continuous 80W out of a standard-wound E3L + DVR2. I know I have run my A10, also AMC twins, with continuous loads of 70W+, with heated grips and a 35/35W incandescent bulb, and didn't have any problems. Others have run electronic ignition, even power-hungry Boyer B systems, plus (non-LED) lights, using them. For max power, the standard E3L running with a DVR at 12v is a safe option - IF the higher cut-in speed can be suffered. Which for Owain here, it clearly can't.
RD - I very deliberately didn't say whether that other world of alternators was an inhabitable or uninhabitable one! Different gremlins all of their very own, couldn't agree with you more.
But, as with electronic regulation of our dynamos, modern gizmos that rectify and regulate the output from permanent magnet alternators have made them reliable in my experience. As much as anything because so many possible points of failure in the wiring & switchgear departments can be eliminated.
I have never even thought of using LEDs on my two Lucas alternator bikes (Notruns that do), because the juice is there, like the water pouring over Niagara Falls: there's nothing to stop it! Nor have I thought to invest in an Alton ortenater for any of my dynamo bikes, although a significant number of folk here in France have done so - they have been made pretty reliable now.
-
Thanks for consolidating the info Groily. I have to admit that I like the idea of keeping the original 6v dyno but seeing as I ride tend to ride around rural North Wales with no street lights and having seen Dutch's posts comparing 6v and 12v lighting https://www.a7a10.net/forum/index.php?topic=11047 (https://www.a7a10.net/forum/index.php?topic=11047). It looks like a sensible option but the cost of replacing everything makes just a 6v reconditioning of the dynamo more appealing for my wallet.
After reading a bit it seems to me that the only real advantage of the 12v systems are a wider choice of bulbs/LEDs (although my bike is negatively earthed which seems to limit the LEDs a bit) and brighter lights...
I guess the overall question is...would a complete 12v system (12v E3L, 12v regulator, 12v battery, 12v bulbs) provide me bright lights that won't disappear after 20 mins of riding around at 30-40mph or could a complete refurbished 6v system provide the same performance and reliability?
-
Hi Owain,
12 volt systems are more efficient than 6v
Current losses on a 12 volt system are half that of a 6 volt , lower current then means less voltage drop = brighter lights
John
-
I do a lot of miles at night too, a good deal of it on unlit motorways and 'A' roads.
I fitted an LED headlight bulb at the start of this year, (Classic Car LEDs) the improvement is very noticeable indeed. Also, of more interest to you, the drain on the battery is much, much less.
The one I got was not much bigger than a standard H4, and it fitted in a smaller 5 and 3/4 inch headlight......just!
Not cheap, but I'd recommend one to anybody, especially with marginal watts to spare.
-
owain I have 12v on mine and it charges at just under 30mph with v belt drive, maybe you could be ok with 12v with side car gearing on the engine.
-
I have an A7 converted to 12v and an A10 on its original 6v. For low speed riding and in town, I prefer the A10 as it comes on charge that little bit sooner. Out and about I prefer the A7 as much as anything because it has heated grips - lovely! Both bikes have LED stop/tails and BPF headlights. Both are ok on unlit minor country roads up to 50 mph - fast enough in the circumstances. I always have headlight on in daylight and I don't have any problems with the dynamos not being up to the loads.
-
Hi Owain,
My A10 still has a 6v dynamo fitted (not reconditioned in my time) and is converted to 12v and like you I also have a sidecar fitted, so in addition to the bike we have a stop light and a front light on the sidecar, plus I’ve fitted indicators with a warning light and a buzzer, so lots to drain the battery. My battery is a Motobatt AGM and I’ve not had reason to charge it by an external charger all this year so the 6v dynamo seems to be coping ok for my use.
Having said that I don’t ride much in the dark. In certain circumstances I like to have daylight riding lights on but then I use the pilot light, which being a 1.5W LED is actually brighter than my headlight. As I don’t ride in the dark very often headlight is rarely switched on.
My A10 has a belt drive for the dynamo and a DVR2 regulator fitted, which helps with the 6v dynamo’s charging. Also I’ve changed every bulb on bike and sidecar, except for the headlight, which is a BPF Quartz Halogen 35/35W. Even the indicators warning light has an LED bulb. LEDs will keep the amps used down considerably, for example a normal 12v rear/stop light 21W (1.7 Ah) / 5W (0.42Ah) as opposed to an LED rear/stop light 4W (0.33Ah) / 1.25W (0.10Ah).
But - fitting LEDs can be very tricky and can cause all sorts of weird things to happen. They take so little current that it can back-feed through earth wiring and light up bulbs that shouldn’t be lit. It took me ages to eventually get everything working properly. I’m not an expert and others may be able to explain this phenomenon better.
As has already been said only buy quality LEDs from a specialist supplier such as Paul Goff or Classic Car LEDs.
-
As said by Roger, but I had no problems at all fitting LEDs to every light.
I also fitted a car battery in the sidecar boot.
The outfit has had a few changes since this video was made.
https://www.youtube.com/watch?v=k5Gm_IPW8Ek&feature=em-comments
New rear sidecar light unit.
-
Hello Roger.
They call the lighting of other bulbs that shouldn't be lit 'bleed through' and it can be a right pain in the backside.
On mine, stuff lit up when I put the brake light on.
The electricity bleeds from the stop light 'filaments' to the tail light 'filaments' in the bulb itself..... It then travels up the wire from the tail light connection to any other bulbs further along at something like half voltage or watts.
My problem was solved simply by fitting better bulbs after a few hours of head scratching.
-
Didn't get all this bother with acetylene lights. I'm currently in the process of fitting diodes to prevent feed-back from the tail light to head beam etc due to the way the light switch is configured.
-
My LED oil pressure light “bright idea” flashed in time with the alternator.
-
Great to hear how other outfit riders have found it. I decided to order a 12v armature and coil for the dynamo now. It seems that a properly working 6v and 12v dynamo can do the job fine. Although I liked the idea of a 12v dynamo cutting in sooner in order to charge a 12v system. Hopefully I won't come to regret the decision! In hindsight, replacing the lights with LEDs and checking my wiring to the taillight (i.e. making sure the stop light wasn't on all the time) may have done the job but reliability is really what I'm after. It's not too nice riding in the middle of nowhere with no-lights.
-
On mine, stuff lit up when I put the brake light on.
When riding solo I changed to LEDs without any problems (bear in mind I still had a BPF Quartz Halogen in headlight) but after fitting the sidecar and swapping its bulbs for LEDs when I applied the brake the pilot and speedo lights came on as well *conf*. If I put a normal incandescent bulb (I used the 2.2W speedo bulb) in the system all worked ok. In the end I changed the sidecar's LED stop light to one from Paul Goff and then it was ok. The fun started when I fitted indicators, also from Goffy. I was also using a high quality electronic relay from Classic Car LED's but still they wouldn't flash correctly. The sidecar side was fine but the bike side flashed intermittently *conf* . Even more puzzling was the fact that the indicator's wiring circuit was completely separate from the bike's wiring, except for battery live and earth connection to frame. Also to confuse the issue they performed faultlessly without the engine running and that led me to believe it must be interference from the magneto or HT leads (even Paul Goff thought that). What solved it was removing the indicator's earth connection from the frame's main earth bolt (under seat) and connecting it straight to the battery earth terminal - and it's been working faultlessly all this year *smiley4*.