850 T4 not charging

Technical Big Block Tonti and Loop Frame models
1

Hello everyone,

I would be grateful if anyone could sanity check my charging troubleshooting steps with my ‘82 850 T4.

  • Initially I found I had a battery which wouldn’t hold charge and failed a load test.
  • New Gel battery, was showing 13.01V, 12.7V with the engine running at idle, 12.3V at 3000 rpm.
  • Checked the main earth, most of the wiring connections. Cleaned a couple of connections
  • 1.8W battery indicator bulb is working.
  • Checked the voltage at the 3 yellow phase outputs on the stator, 0.5V AC.
  • Checked the resistance of each phase at 1.1 - 1.2 ohms.
  • tested the Electrex regulator/rectifier which passed unloaded and at 200W. This of course tested the wiring up to the male block connector with 3 Yellows, brown, black and orange.
  • I’ve checked continuity from the female block connector back to the 3 Yellows, brown and black at the stator.
  • haven’t checked the orange connector forward from the regulator/rectifiier.
  • lifted the brushes off the rotor and tested the slip ring resistance at 3.4 ohms.
  • The soldered joints on the stator look ok.

I’m suspecting the stator still and the last test I have in mind is to start the bike, run a connection directly from the battery +VE to the brown connector on the stator and test the AC voltage outputs at the stator.

Does anyone have any other suggestions?Have I missed anything?

Thanks in advance everyone.

2

Everything you’ve done looks great and more thorough than most. What are your symptoms ?

It really looks as if everything is ‘working’. What I haven’t seen is that you’ve confirmed you have a REALLY good earth going to the Electrex reg/rec. If not, the box is likely to regulate you down and the battery won’t charge properly. Actually, the power feed, switched power and earth to the reg/rec need to be really good. That’s why the Electrex technical chap stresses that you put new wires for all three directly to battery, etc. Personally, I’ve checked with him and he does think it’s a good idea to put a fuse in the main power feed; I use 20A.
And a thought; your brown wire to the reg/rec is from switched power isn’t it ? Otherwise the whole thing will stay powered up when you key off and walk away. That’ll leak your battery charge away while it’s standing. I’m sure you’ve done that, but just putting it out there.

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3

I have an electrex rectifier / regulator on my Cali 3 and have connected the brown wire direct to the battery. This doesn’t seem to cause a battery drain. This wire tells the unit the state of the battery voltage and decides if it needs to push volts into the battery or not so is quite important to have a good connection.

This is a good guide to Guzzi charging system, but having a combined rectifier/regulator, you have removed the majoity of the components.

Another place for info is the Gutsibits shed, there’s a couple of useful articles for you in there. Bosch combined regrec wiring and RR451 fiting instructions,

https://www.gutsibits.co.uk/pr/TheShed/techdocs.php

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4

Hi Andy,
Appreciate your reply and comments.
The symptom was a flat battery 2 days or even 1 day after a ride.
Good point about the earthing.
My Electrex reg/rec is earthed directly to the battery (as Electrex recommend) as is the power.
The main earth cable from the battery goes directly through the battery tray and bolts onto the gearbox casing. Both ends of the earth cable look good, clean and what I can see of the cable braiding shows no corrosion.
Brown is going from the Electrex reg/rec through the 6 way connector to the field coil (DF). Orange from the Electrex reg/rec goes through the 6 way connector to the battery indicator lamp and ignition switch.

5

Do you know which model the Electrex unit is as they have diferent wiring set ups. I received this from Electrex concerning my unit
“RR451 has a voltage sense wire which is the brown one. This is connected to a switch live so that when you turn the ignition on the brown wire has 12volts to the regulator/rectifier. If you have no voltage due to bad connection in the switch or connectors, the unit will overcharge.”

6

Hi Don,
Many thanks. I didn’t know about that page on the Gutsibits website so thanks for that.

I have the RR45 fitting instructions. I was going to do the bulb test described but since Electrex offered to test their reg/rec for me and they’re not far from me I took that option. Helpful and knowledgeable team there…

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7

Have you done this test yet as the Rotor needs to be ‘excited’ before you will get anything out of the Alternator. Put 12v across the brushes and then run the engine and you should get upwards of 30v AC.

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8

Hi Nik,
Thanks for your message.
I’ve just finished running the tests.

With yellows from reg/rec still connected to the stator, black connected to the brushes , I disconnected brown at DF on the brushes.

Before starting, the battery was at 12.74 volts.

Engine started, I ran a wire directly to positive at the battery and immediately heard the revs drop slightly.

Decided to check at the battery first and sure enough, 12.45V at 1200 rpm rising with revs to 15.25V at 2500 rpm.

Reconnected everything back to normal and restarted the engine. 10.74V at 1200rpm, not increasing with revs.

So stator and rotor appear to be good.
I’ll recheck the continuity of the brown wire back to the 6 way block but this was good when I checked continuity before.

9

Just out of interest, I ran Electrex’s troubleshooting tip for their reg/rec.

Disconnecting black and brown from the brushes, I used a 55W headlight bulb from my car and connected it to battery positive and to the brown wire which connects at DF on the stator.

With the engine running, this should light the bulb but it didn’t work.

Electrex have tested this reg/rec ant it’s performing to spec. When installed on my bike, for some reason I’m not getting current via brown to the field coil.

10

I assume you have seen this sheet about installing the unit.

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11

I had an RR45, but didn’t have enough confidence in it to put it on in the end. (Intead I ended up using an electronic regulator intended for BMW, and keeping the stock rectifier, which was perfectly OK.)

I bench-tested it, and one of my issues with it was it flatly refused to light the charge lamp (or equivalent 1.2W bulb, 2.2W bulb, etc.), because the currrent is too low to light the bulb.

There is a chip inside the RR45 and I got the datasheet for it. The charge light connection goes direct to a current source in the chip, meaning it can have any Voltage on it, but there must be some for it to detect that the igntion is switched on. It’s supposed to be 140 mA or somesuch, but I was only getting 30 mA or something like that, whatever it was, it was not going to light the dash bulb. 30 mA is also too high for an LED. An LED with a dropper resistor to limit its current to a safe maximum, plus another resistor in parallel to get the 30 mA, possibly, but it suddenly starts getting very complicated… I was even looking at making some sort of transistor switch circuit to light the bulb…

It could be just connected to an ignition switched source directly and that’s what I was going to do as the simplest option, but would mean no working charge light.

I also discovered that when the ignition is turned on (so this input is high), the chip immediately sends 4 Amps into the rotor winding, before the engine has even been started. This is the part I didn’t like; if battery was a bit weak the last thing you want is the equivalent of a halogen headlamp bulb wasting the battery while you’re trying to start it.

The chip includes an input to detect alternator AC to prevent this (so that the rotor isn’t energised until the engine is ‘seen’ to be running), but in the RR45 it isn’t implemented for some reason, the AC detect input is wired direct to battery connection. This could easily be done by simply using one of the 3 alternator inputs, and I couldn’t see why not. It all seemed a bit of a bodge, or not thoroughly thought out, hence I was not overly convinced and abandoned it.

Tests you can do - put a multimeter across the rotor terminals (brushes), turn ignition on and you should get battery Voltage (or near enough) showing across the brushes. If not, the chip is not turning on.

If so next thing to try is connect the charge light wire (orange?) direct to an ignition switched point (i.e. bypass the dash bulb), and see if that make the chip turn on.

??? :+1:

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12

Unfortunately this doesn’t make sense, because as I said the brown wire output is battery positive to the rotor, if the chip is working, and so there will be no Voltage between it and actual battery positive. :thinking:

However if that’s what’s happening, then the chip appears to be working. But do the test for Voltage across the brushes to be sure.

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13

If the chip does not turn off there will be a constant 4 Amps drain to the rotor

(Another aspect that made me nervous about it)

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14

Hello Don,
Thanks. Yes I have that document and RR45 is the reg/rec that I have.

15

Hello MIke,
Thanks for all information on the work you’ve done on this.
Yes, the instructions mentioned that the RR45 reg/rec needs to sense a current of at least 120ma or it won’t start up. The standard 1.2W bulb will only provide 100mA so they recommend either replacing with a 2W bulb (if you want the warning light) or a piece of wire in place of the bulb.
Thank you for the test suggestions. I will do this tomorrow and report back.
Thanks again,
Nigel

16

Hi Mike,

With everything connected up, I tested for 12V at the brushes and it was 0V.

I removed the charge warning capless bulb in the instrument cluster and put a small jumper wire across the connectors. 12.5V at the brushes!

This bulb is working and 1.8W (instead of the standard 1.2W) which should draw 150mA, above the 120mA threshold Electrex say the RR45 requires.

BTW I cleaned the bulb holder contacts and spade connectors and swapped the bulb holder over, just in case, with 0V still at the brushes. Perhaps the bulb has degraded below it’s Wattage rating.

I will go back to Electrex for comment.

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17

Or, trying to include a panel bulb simply does not work. OK so we know that if orange is battery Volts, there is output to the rotor. Alrighty then! So it basically should work.

Addendum (EDIT): if you got a multimeter that can measure mA, you could insert it into the orange wire and measure what the actual control current is. Maybe like mine it’s not what the instructions say it should be.

I remembered a few minutes before this - re my issue with power on the rotor as soon as the ignition is switched on - I was actually considering have a separate switch to delay the regulator working until the engine is started, but then you have to remember to turn it on. (After you’ve remembered to turn it off for starting the engine.)

So there might have been a further idea to have some sort of additional electronic circuit to detect engine running, which would then send out 12V on the orange wire. Like I said, it was all getting too complicated! :smile:

18

I replaced the battery indicator 1.8W bulb with a 2.3W one from Halfords (product number 284).

Ignition switch on and 12V at the stator!

Started the bike, and had 12.84V at idle and 14.05V at 2500 rpm.

According to the spec, 1.8W should have been enough to turn the RR45 on. It was working before so perhaps the bulb’s resistance increased with age?

No reply from Electrex yet.

Thanks very much to everyone here who helped. Much appreciated.

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19

Fab, so you got it all working including the charge light? Which is more than I could manage :+1::grin:

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20

It is thank you Mike! :smile::+1:t2:

Electrex’s reply was that, yes the 1.8W bulb could have degraded enough not to draw enough current. :thinking:

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