Jonathan Kay

Quoting Paul Deslandes: I've been following the thread but not quite understood what was going on. If the bulb has zero volts on one end and 12 on the other (at the same time) it should light up, unless its blown or has a diode in series. Simon: Apart from the pulley and the earth strap and the regulator we really need to sort this issue about the bulb. There are two reasons for this. At the moment you're trying to debug a fault but can't be certain that the test equipment is OK. And once it seems to be working you won't know if it's charging properly or not until it's flat again. I'd still recommend you measure voltage from point to point, not through the fuse box or any wiring. Then I'd try the bulb assembly and wiring the other way round. Then I'd take that bulb assembly and wiring and try them (both ways round) in a test rig that has nothing to do with anything on your car. Jonathan

Quoting batteredoldsupersport: The alternator voltage will never rise above that of battery positive, as they are directly connected and as soon as the alternator spins up it raises battery +ve along with alternator +ve. The diode in the circuit is a new one on me though. If the alternator is charging the battery there must be a PD or the electrons wouldn't know which way to go. But I'm sure you're right in that will be very small because of the low impedance of the connecting wires. Jonathan

Welcome back Paul. I was hoping for someone who knew more... Does that circuit usually/ often contain diodes? I can see why they would in order to stop the bulb lighting up when the alternator output voltage goes above the battery live... but I was getting there from first principles. Jonathan

Here's the bit I don't understand... if you have 12V PD between battery positive and alternator terminal with the engine off why doesn't the bulb light up when connected in the same way? Some thoughts: You're not testing between exactly the same points in the circuit and there is a fault in the wiring that is different between the two tests. Your bulb and wiring are directional! Could it be an LED, or is there a diode somewhere. Could you try the bulb etc the other way round? Probably easiest to test this directly to a battery. Jonathan

You're way beyond with me the Denso alternator. But it sounds to me as if you're reading all voltages with reference to chassis earth, and that's why you're expressing them as paired values, and why you mention the dash. I suggest you do that test again with point to point measurements with no wires or earth involved. I don't understand why the bulb isn't lighting. Have you connected a battery across the wires leading to the bulb holder so that you can test those wires, the bulb-holder and the bulb all at once? Jonathan

I have a CSI Airflow for the 7 and an AccuMate for the Vespa. Both work fine, but I've never used them on bigger batteries. Jonathan

Can you connect your voltmeter to mimic the bulb exactly as BOSS describes? Forget about earth. What voltage do you get between the battery positive terminal (not just a wire attached to it) and the bulb feed from the alternator (ditto), firstly when the engine isn't running, then when it is running fast? Jonathan

That's the explanation of how ignition lights work... but are you sure your bulb is OK? Jonathan

I think what most people do is: * Use the cigar lighter plug on the end of the charger * Wire a cigar lighter socket directly to the battery with an appropriate in-line fuse This lets you use the charger on other vehicles, gives you a socket for map lights, inspection lights, sat nav devices, 'phone chargers, etc, and bypasses any other wiring problems. Jonathan

Fred: Was your ignition light on all that time, before you changed the alternator speed? Jonathan Edited by - Jonathan Kay on 8 Dec 2011 13:02:53

Plus check the ignition lamp bulb asap. Jonathan

I'd clean and inspect all the contacts from the battery to the starter. Jonathan

New battery and 14V when running... High resistance path as Paul suggested. The voltage is OK but can the connections handle enough current for the starter to turn the engine? Bad battery connections or earth strap? What exactly happens when you try and start... with a voltmeter in place (or the lights on)? Jonathan

Smallest that will do the task. Jonathan

Hope you've found a solution... Jonathan

I had a Ford Popular 103E which was kept in a shed at school. Unlicensed but only used in the school grounds. Fabric roof... because of post-war steel shortage? (If so it's related to Land Rovers!) But the wipers were operated by inlet manifold vacuum... much posher than manual. Jonathan

Motion sensor sounds good, but would it be too difficult/ expensive to achieve? How about replacing the switch with a mechanical timer switch and installing a battery backup light (replacement or next to the existing light) to avoid the plunge into darkness? (Backup light would need appropriate rating for bathroom.) Jonathan

Interesting question. Quick thoughts: I assume the switched feed is a single wire which later splits to the light and fan but you can't get at the bits separately... Why would anyone notice the indicator if they don't notice the light? Is it a wall switch or a ceiling pull? Would it meet your needs if the fan turned off after a set time but the lights stayed on? How about a mechanical timer switch to replace the switch? Disadvantage would be the plunge into darkness... but it would turn everything off. Jonathan

Quoting SiCrad: I'm a Honda chap at heart Keep the Honda, lose the BEC... how about an S2000? How many have ever been converted to this? Jonathan Edited by - Jonathan Kay on 27 Nov 2011 18:23:35

Very happy with my Titon 4 point. They made the strap tightening the way I wanted: away from the buckle. I bought mine from Prima Recommended. Jonathan Edited by - Jonathan Kay on 24 Nov 2011 20:21:07

Thanks. I'm getting out of my area of knowledge, and wondered whether all of that could be done by a regulated supply with two modes, or whether it required more logic control to do it. I use a couple of these little conditioning chargers on my 7 (PVR25) and my Vespa all the time they are in the garage and they seem to work OK. Jonathan

AccuMate Info AccuMate’s advanced 4-step charging program: (6V values in brackets) STEP1: Boost – Constant current charging of 1.2A up to 14.3V (7.15V) Yellow CHARGE LED on STEP2: Absorption – Voltage held at 14.3V (7.1V) until current drops below 200mA Yellow CHARGE LED on STEP3: Maintenance – Float voltage held at 13.5V (6.7V) for ideal long-term battery care Green MAINTAIN LED on STEP4: Interactive standby – Active only once a battery has reached step 3: Monitors if current exceeds 200mA or voltage drops below 13.2V and cycles between step 2 and 3 to prevent the battery from losing any charge due to permanently connected devices such as an alarm or parasitic drain caused by aged or faulty vehicle wiring. With interactive standby your battery will always be ready to start your vehicle. Jonathan

I have just received an email from Amazon UK about lots of discounts on CTEK chargers. (I hate it when sites "know" what I've been looking at elsewhere.) Jonathan

Agreed: my money would be on the bulb-holder (assumptions as above). Jonathan

Quoting oldbuffer: Wasn't he in Police Squad and Naked Gun That's someone different, surely Jonathan