Lemans 3 charging problem

Hi All,
Had the Lemans 3 down to faro last week,ran like a top all the way down,but developed a charging fault on the way back.Using a multimeter,i get no voltage rise at the battery terminals.I was able to make it back by charging the battery in campsites all the way home.I may be wrong but i do not suspect the battery,as i charged it overnight,disconnected it,and left it idle for an hour.It read 13.2-13.4v just after charging,and 12.8v after letting it settle for an hour,and it remained at 12.8v after rechecking 3hrs later.
I did notice that now the charge warning light is not illuminated when i turn the key,but that is a new development,it did glow a little when i first noticed it was not charging well,and it went out when it reached approx 2000rpm.
I checked and cleaned the alternator brushes,and there is continuity between the slip rings and the soldered connections on the brushes,so i don’t suspect a problem there.And that is where my knowledge of the charging system ends-If any of you can advise on how to check the remainder of the system from here,i’d greatly appreciate it.

Thanks in advance.

Joe

If the charging bulb has a bad joint or even blown the charging system will not work

Thanks,i had the bulb in mind alright,but i was not sure.Hopefully it’ll turn out to be a cheap fix!

Just fixed (with a friends help) a charge problem on the Lario.
I replaced the charge light bulb and found that the failure was a result of the problem rather than the cause. Hope you have better luck.
I’ve posted some links on the tech section re electrical checks…
Guzziology has some useful tests noted as do the Haynes manual and the factory manual available via the links on the site.
Best of luck
Steve

A. brushes ~ but seems they’re OK? Not too worn? Genuinely making contact with slip rings?

It’s possible only one is and when you did the slip ring to brush solder joint test it was actually completing a circuit through the other one and the rotor winding so only ‘looks like’.

B. rotor winding open circuit, did you ohmmeter across both slip rings? Should be 3.4 Ohms (if your meter can measure that).

C. is regulator working.

However dim / twinkling charge lamp (as it started as) usually means duff brushes, so I still think a brush isn’t making proper contact. Your description of how it happened sounds exactly like brushes packing up. Even had one get stuck in its holder so lost contact as it wore away.

Hope it isn’t ‘B’
Mike H2012-07-29 20:48:45

Thanks for the suggestions gents,will be a few days before i get to the bike again,so i’ll update when i get a chance to do a proper check.Much appreciated.

Joe

I had the same problem with my Le-Mans many years back, and like you had to recharge the battery every night on french campsites, turned out the connector to the regulator was loose, but your fault could be the same or something completly different, check all your earths are clean and tight and do all the checks Mike H has put forward, including undoing all connections to the regulator and rectifier and checking them for broken wires, yes it takes time but you dont want to spend money replacing things if the problem turns out to be a simple thing like a broken wire, if after that the fault is still there try to beg borrow or steal a suitable battery which is known to be in good order and try it with this battery, if that is no better and none of the other ideas work it could all point to the alternator being at fault, either the stator or the rotor or if its your unluckly day both, not very likely but ?

The Bosch altenator does run very hot and the wires do break down IF you have to replace them make very sure you buy cable with High temp insulation, it is often braided fibre also you will need ceramic or high temperature spade terminals,

Someone had replaced mine yrs ago with brass spades and only plastic insulators they literally melted as did the “wiring” made a hell of a mess 'till I replaced that part of the loom with the High temp resistant stuff. guzzibear2012-07-30 12:10:13

Well,

i got to have a closer look at the bike today,and with the stator removed from the bike,i tested the rotor as advised.My Meters’ Ohm range begins at 200,so i used that.I get no reading across the slip rings,or to clarify, “1” appears on the screen when i switch the meter on,and this does not change when the meter probes are applied to the slip rings.Do you think it’s looking like new rotor time?.
Thanks again.

Joe

No not a new rotor.
A reconditioned one from Guzzibits or Westcountry Windings.
Cheaper and better.

Dagnammit it’s ‘B’.

Presume you made sure meter is reading right by touching probes together to get ‘0’ (apologies for being obvious)

[QUOTE=iandunmore] No not a new rotor.
A reconditioned one from Guzzibits or Westcountry Windings.
Cheaper and better.[/QUOTE]

Thanks,i see gutsibits are doing a new ‘bosch type’ one for £59?
As an aside,has anyone done a brushless alternator conversion,gutsibits offer one,not cheap,but as i intend keeping the bike long term,maybe it is worth a look?

[QUOTE=Mike H] Dagnammit it’s ‘B’.
Â
Presume you made sure meter is reading right by touching probes together to get ‘0’ (apologies for being obvious)
Â
 [/QUOTE]

Yes,the meter reads 0 momentarily when i touch the probes,then back to 1 pre measuring.

[QUOTE=Fledermaus] [QUOTE=iandunmore] No not a new rotor.
A reconditioned one from Guzzibits or Westcountry Windings.
Cheaper and better.[/QUOTE] Thanks,i see gutsibits are doing a new ‘bosch type’ one for £59? As an aside,has anyone done a brushless alternator conversion,gutsibits offer one,not cheap,but as i intend keeping the bike long term,maybe it is worth a look? [/QUOTE]
Not worth the bother, the bosch ststem is easy to work on and very reliable.
Whilst it is all in bits change the brushes if reasonably worn (get a new pair to compare, you will need them one day) and clean all the connections.

Thanks Folks,
All advice taken on board and appreciated. Fledermaus2012-08-01 15:55:32

my t5 was intermitantly loosing the ability to charge, the bushes has warn to the point of running out of wire and restricting the movement ( after 43k miles)new set of bushes sorted it.other faults i had was the instrument cluster earth to the frame causing no change due to surface rust

I have the brushless version on my spada mine is the eurolast unit higher output
http://www.euromotoelectrics.com/Articles.asp?ID=135

works a treat and at a much lower rev range

[QUOTE=Fledermaus] [QUOTE=iandunmore] No not a new rotor.
A reconditioned one from Guzzibits or Westcountry Windings.
Cheaper and better.[/QUOTE] Thanks,i see gutsibits are doing a new ‘bosch type’ one for £59? As an aside,has anyone done a brushless alternator conversion,gutsibits offer one,not cheap,but as i intend keeping the bike long term,maybe it is worth a look? [/QUOTE]

Buy brushes either from a Bosch dealer OR take the old ones in to a BMW dealer and tell them it is an old R summat mate …alot less than from Guzzi

One i repaired earlier

Ah that’s the other thing that can happen