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[Hugh]

Morning all. Wonder if you can advise here. I have a 1957 350 Bullet with magnito ignition so as you know no battery needed to start. Bike starts easily (great Lucas SR1 magnito) and runs well. This was almost first start after bike being idle for 5 months. Problem is battery not charging. I have a multimeter and pre fitting the battery carried a reading of 12.8 volts as it had been on trickle charge. When bike running with multimeter across the positive and negative terminals on battery no change to this reading of 12.8. In past has gone to about 13.5-14 volt as alternator fed battery when doing odd random check on alternator output and battery. This reading of about 14 volts is a consistent reading effect across my other bikes when they are running so would expect this type of reading/effect with the RE. All lights working with battery fitted to bike and loud horn. Remove battery and just leave bike running and we have all lights and horn (although horn a bit weak). As lights etc work with no battery in bike assume alternator is pumping out power but seemingly charging effect not getting to battery. I also assume rectifier is working for lights to light up. Only change to standard 1957 set up is a 12v system which has worked well for some 8 years or so. If there is a break in the alternator feed line to the battery why is everything working as I would assume none of the electrics would work. The wiring is nearly all original from 1957. Any ideas why lights etc all work irrespective of battery being in or out yet no charge seemingly getting to battery? As not really electrical expert where to start so would appreciate confirmation alternator/rectifier OK from what I have said above. I assume I will need to follow all wires connected with charging to see no break but still confused as to why things work if there is no such break. Thanks, Hugh

[Mark M]

You say “rectifier” but if converted to 12 volt l’d expect a modern regulator/rectifier to be fitted. A modern black box? If so it could be the regulator portion that is faulty, not allowing any more than 12v. REgards, Mark

[Adrian]

Perhaps a little more info, taking Mark M's point about whether you're using on old-style rectifier and zener diode or a more modern combined unit?



It could be that your black box (if that's what you have fitted) has a built-in capacitor, some do, some don't, which is intended to allow for battery-less running. But I notice that one of my bikes which currently has a duff battery, and has magneto ignition and alternator 12V everything-else, will still run the lights even though the reg/rectifier has no capacitor as far as I know.



How old is the battery? If the one you fitted dates back 8 years to when you did the 12V conversion it might be on its way out. I'd also be checking the connections including the fuse holder and fuse. Try a new lead to the battery directly from whatever voltage regulator you're using and see if it makes a difference. I rewired a '57 Bullet for 12V a few years ago, and while some of the original wiring was still in surprisingly good condition, yours will now be 62 years old.



A.

[Hugh]

Thanks for this. I said rectifier as since the system was updated to 12v by a dealer (RE expert but no longer with us) I assumed a rectifier had been fitted. No Zener so far as I know.

I'll have to track down exactly where and what is there first and to see what he fitted. I assume its under the petrol tank but have never actually seen it although this will obviously give me an opportunity to explore wiring condition in some hidden places. Generally from what I can see the wiring is actually in quite good condition for 60 years old. My wiring diagram for 1957 6v shows a rectifier (no zener) linked to the alternator (light green and dark green wires with third alternator wire green and yellow to light switch) and rectifier to lighting switch (rectifier connected in lighting switch dark green to No.1 purple to No.3 (and on to ammeter and battery) and light green to No.7. This light green colour wire continuing the link from alternator) but none of the books/manuals I have tell me where the rectifier was originally located. As said I had assumed in my original post this was just a straight swop to cover increased capacity of system when changed but maybe the dealer introduced some sort of power box.

Thanks again.

Hugh

[Mark M]

The original rectifier was attached to a bracket on the top frame tube, sitting just under the nose of the tank in the air flow. The change to 12v means the battery will boil more easily without a regulator hence the need for one. 8 years tor these early reg/recs is not a bad life. REgards, Mark

[Adrian]

The rectifier would have lived under the tank if what was on my '57 was original.



Your wiring diagram is for the old 6V system, but what it shows for the charging side is no longer applicable. Usual practice for the 12V conversion, assuming the original alternator is still up to it, is to wire the stator so that it's permanently on full output, with the reg/recifier (or zener diode on **older** 12V systems) stopping the battery from overcharging when bikes is running but the lights are off. Your diagram won't show a zener diode as they weren't used on British bikes until after the Redditch Bullet ceased production. On the 6v system the alternator was only on full output with the lighting switched on.



One of the benefits of the 12V conversion is that it makes for much simpler wiring where the charging circuit is concerned. You just have one wire from the out put side of the reg/rectifier to the ammeter terminal with the wire to the main light switch from the same ammeter terminal. From the other terminal you just need the wire to the battery via the fuse and the horn supply, the brake light switch feed comes off that side too. Which ammeter terminals supply which will depend on whether your bike is now wired positive or negative earth. Having a magneto also makes for a simpler wiring loom.



To help identify what you have fitted, the generic modern reg/rectifier looks like this:



http://accessories.hitchcocksmotorcycle ... -cat/37670



while if you have the Boyer Power Box it will look like this:



http://accessories.hitchcocksmotorcycle ... x-cat/3206



Hope this helps.



A.

[Adrian]

Beat me to it, Mark!



A.

[Hugh]

I'll do all the continuity testing as the problem as described seem a little like Adrian's. The battery is brand new as the old one had been in there since 'time out of mind'. I may have pulled the wiring when refitting as its only just gone on. I rewired the bike (2007) on the old 6v system as described above using the old harness plus the odd new wire and the 57 wiring diagram. This was a bit of a challenge but a good learning tool as for example every earth was triple painted with what appeared to be bitumin so none were connecting to frame for example. I only upgraded to 12v for more powerful horn given the absence of night use.

I'll take the tank off and have a look for the power box or what ever was fitted when upgraded to 12v. I don't normally use the bike at night as said but will leave the battery and see if it discharges. I don't know how to test a power box or rectifier other than to test the output to the battery. Once the continuity test (per Adrian's rewire advice) shows the potential for power to get to the battery this would seem to indicate if it goes flat that the 'controller'/rectifier or otherwise could be the fault. If I prove continuity one last piece of advice if possible should the alternator when activated as of now before any further testing raise the voltage across the battery terminals to about 14v as per my Norton irrespective of power box or rectifier fitted? Mark suggested a possibly capped capacity as I read that email to prevent overcharging - if so I presume its above 12.6v but no real idea here.

It will take me a while to get round to doing this but will update you when done as its always nice to know what happened.

In the mean time thanks again.

I am hoping to get to the celebration gathering of Bullets later in the year mentioned on the site so may see you there.

Hugh

Hugh

[Mark M]

You obviously understand the next steps so let us know how you get on. As to what voltage you should see at the battery: the 12v lead acid battery has 6 cells, each of which has a charge rate of 2.2v (because you need a bit more energy to go in than come out) which means the minimum total charge rate will be 6 x 2.2v or 13.2v. In the real world this gives you a minimum charge rate at the battery of 13.5v. Too much and the battery over-charges leading to the liquid acid (electrolyte) over heating or even boiling, battery explosion possibly resulting! So the upper limit is about a volt higher, 14.5v and that's the range you should see. One last point, Enfields of this period used a switched alternator, in other words when you turn on the lights you switch in the 3rd set of alternator coils to balance the extra load. I can't imagine how the wiring might have changed from your description but it's a point worth keeping in mind!

REgards, Mark