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Charging issue- help to narrow it down.

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Charging issue- help to narrow it down.
Started at 05:33pm on the 8th July, 2018 by Davedup
Davedup Subject: Charging issue- help to narrow it down.
Hi folks, I have an issue with my Super Meteor.
Actually broke down the way home following a club run. Have traced it down to not charging and not being enough power for the electronic ignition.
The bike has been converted to 12V, has a two wire rotor and is fitted with a Zenor diode. It also has a boyer power box and contactless ignition fitted by the previous owner.
If I run the bike off a battery charger (with battery still connected) it runs fine, as soon as I drop the battery charger it will not rev and eventually stops. Have connected a voltmeter across the two wires from the rotor and I'm getting 14-16v (is this about right?), across the battery without the charger is 12V which drops when revved (then she splutters and cuts out).
The zenor diode on its' mounting plate is getting very hot, even too hot to touch after less than 10 mins.
The rectifier seems to be kicking out the right Dc voltage.
Should the zenor get that hot so quickly? Where else can I check?
Any ideas?
Many thanks
Dave
Posted: 05:33pm 8th July, 2018
Adrian Subject: Charging issue- help to narrow it down.
Dave, I think you'll find the rotor has no wires at all! The stator, yes...

How come it has a Boyer Powerbox AND a separate rectifier and zener diode fitted, unless that's the TCI black box for the ignition?

Assuming it's the classic 12V rectifier and zener diode which are actually responsible for your regulated DC supply, and your post rather suggests they are, we might be looking at a failing zener which has over-charged the battery. Zener diodes do run hot, did the previous owner fit the thing on a decent sized finned alloy heatsink and mount it where it gets plenty of breeze? Have you also checked that your battery can still hold a decent charge?

I'd replace the separate rectifier and zener with a modern single-phase rectifier/regulator (these need a decent airflow too), this will let you simplfy the electrics while you're about it.

A.
Posted: 06:06pm 8th July, 2018
Davedup Subject: Charging issue- help to narrow it down.
Hi Adrian, thanks for the reply again, yes I meant the stator, too hot to think clearly at the moment LOL
The boyer box is purely linked to the electronic ignition which is a Kirby mk8 and is not a power box (my bad!)
. The zener is mounted on a heatsink under the headlight but was too hot to touch very quickly, and it gets plenty of airflow there. The battery was ok but I've stuck it on a slow charger and will have a look.
I'll look into replacing the zener and rectifier with a combined unit . Any come out as favourite on these bikes? is it worth going for the Boyer Powerbox?
Cheers
Dave
Posted: 07:06pm 8th July, 2018
Adrian Subject: Charging issue- help to narrow it down.
The Power box is probably one of the dearest, it has a built-in capacitor which you might not need. For alternatives, try Al Osborne/Paul Goff/Max's Speed Shop/Tri-Supply (Andy Gregory).

A.
Posted: 09:21pm 8th July, 2018
Davedup Subject: Charging issue- help to narrow it down.
Thanks Adrian.
For an update: years ago I bought a box of crusader bits which included a full kit to convert to 12v which I've never bothered to use. I had a feeling there was a rec/reg in there so had a rummage and found it is actually a used power box!
Fitted it this evening, disconnected the zener and bike fires up happily. Still blooming hot in the man cave so only jury rigged it
Not sure if this episode has taken the battery out as I had the battery on charge for a while and when I stuck the lights on it drained the battery very quickly and voltage dropped massively.
I've put the battery on a trickle over night but might need a battery. Can now get shot of the zener and sort the wiring out properly.
Many thanks for your help.
Dave
Posted: 09:30pm 8th July, 2018
Beezabryan Subject: Charging issue- help to narrow it down.
I'm afraid your battery is cooked or some such word !
Posted: 08:42am 9th July, 2018
stinkwheel Subject: Charging issue- help to narrow it down.
Glad you have it sorted. Not relevant now but I dimly recall some mates with classic bikes saying one of the best things to do with a zennor was to bolt it to the back of an alloy numberplate for heat sinking purposes.

Also worth pointing out there is no reason you can't use a reg/rec off a Japanese bike on a 12v Enfield. This gives the option of getting one of the more modern mosfet / switch-mode ones which are highly effective and unlikely to fail. Most Japanese bikes have three coil stators but you can just leave the redundant phase disconnected. I have a ZX6R reg/rec on my bullet.
Posted: 09:59am 9th July, 2018
Adrian Subject: Charging issue- help to narrow it down.
That's a good point about using a 3 phase reg/rectifier, they can be had very cheaply on ebay. However, if that Boyer Powerbox is still OK then I'd use it, though possibly with an oriental unit to hand as a back-up.

I'd not heard of the Kirby Mk8 ignition until now, a quick search reveals it is one of Kirby Rowbotham's Boyer-based ignition kits:

http://www.techeng.force9.co.uk/info~mk8.htm

One of the advertised features of the Boyer Power Box is that it will let you run your bike battery-less, but if you're going to give this a try, pray that Mr Rowbotham has used a Mk4 Boyer ignition on yours and not a Mk3! If you're just going to fit a new battery (and it looks like you'll have to), don't worry.

A.
Posted: 11:20am 9th July, 2018
Davedup Subject: Charging issue- help to narrow it down.
Thanks guys, for the cost of the battery, I'll order a new gel one.
At least it should last a few years (as long as it doesn't cook again!)
Back number plate would be a great mounting point, better than the front on the forks where mine was, doesn't look great, just functional.
I'll wire the boyer powerbox in properly and give it a go.
Dave
Posted: 07:42pm 9th July, 2018
Adrian Subject: Charging issue- help to narrow it down.
Might be a bit vulnerable to road muck in that position, for my Super Meteor-framed AVL hybrid I stuck the reg/rectifier on an alloy plate in front of the left-hand rear shock absorber, it seems OK there.

A.
Posted: 08:47pm 9th July, 2018
Aethelric Subject: Charging issue- help to narrow it down.
It is difficult to know what will happen with both the powerbox and the zener diode in the circuit. For example if one is at the bottom end of it’s tolerance (say 14V) and the other is at the top end (say 15V) then the higher one will never contribute.
A zener diode has to dissipate much more power then a rec/reg. A zener working alone will have to get rid of most of the total output of the alternator - 100-200W.
A rec/reg works by shorting the alternator out before the rectifier so most the power is dissipated in the alternator.
So if your zener still gets hot it’s doing it’s job. If not then it’s on standby until the powerbox fails. (you probably won’t notice depending on how it fails - short circuit or open circuit). If the zener does not have sufficient cooling it will fail very quickly.
The number plate MAY be ok as a heatsink but I doubt that it will be thick enough to conduct the heat away.
Posted: 08:55am 10th July, 2018
Beezabryan Subject: Charging issue- help to narrow it down.
Don't know if my addled old head is reading this correctly or confusedly. Using zener and powerbox together is a bad idea, one or t'other but not both.
Posted: 10:34am 10th July, 2018
Adrian Subject: Charging issue- help to narrow it down.
Gentlemen,

you don't appear to have read Davedup's follow-up posts to this thread properly. He has not been using a Power Box AND a separate rectifier/zener together, he realised he had merely mistaken the ignition's TCI box for a Power Box. I suppose it's an easy mistake, they're both black boxes with wires coming out and both made by Boyer Bransden.

Where an actual Power Box does now come into the story is as a REPLACEMENT for the zener and separate rectifier. So the Davedup's Super Meteor now has/is getting a Boyer Power Box (originally intended for a different bike) as the sole means of rectifying and regulating the alternator output, as well as the Boyer TCI box already fitted to control the electronic ignition.

It's too hot for all this...

A.
Posted: 12:41pm 10th July, 2018
Aethelric Subject: Charging issue- help to narrow it down.
Oops, you are right - too hot to take it all in.
Back number plate should be fine for the power box, - but maybe a bit exposed to road dirt as Adrian says.
Posted: 01:28pm 10th July, 2018

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