Battery charge

[StuBYD]

Last week when taking my Series 1 EType out out noted that the higher the revs the more charge was being put into the battery - according to the amp meter. On occasions the needle was almost 3/4 the way up. However on using a test metre at the battery the maximum input even at high revs was about 14.2 volts. Could this be a defective voltage regulator?

[Heuer]

If your car has an alternator the ammeter is pretty useless anyway but what you are seeing is normal. If the voltage to the battery is no more than 14.2v then the regulator is working OK.

[StuBYD]

David,
Thanks for speedy response and note your comments. However previously amp metre performed OK with needle always hovering just in the Charge sector. Why should this change?
Regards,
Stewart

[christopher storey]

Stewart : the ammeter registers the current flow, and not the voltage of the output. The whole purpose of the regulator in relation to current control ( and this applies both to the DC dynamo and the AC alternator ) is to bring the battery up to optimum charge as quickly as possible. Thus, if the battery is part discharged either by disuse for several weeks, or by a prolonged period of cold start usage ( 15 seconds churning is easily discernible) the regulator will allow a high current flow for several minutes, gradually tapering off to just a trickle . The other purpose of the regulator is to control the peak voltage of the output as batteries do not take kindly to excessive voltage which in this context means much over 14.5 volts ( they tend to boil off the water element of the electrolyte and suffer buckled plates) .

Just as a postscript, one thing I have noticed is that the Lucas 4TR regulator is rather susceptible to underbonnet temperatures , and in hot weather my ammeter tends to have a flickering needle rather a lot particularly if the car is stationary

[StuBYD]

Chris, Many thanks for your detailed response. I was away for about five weeks prior to taking the car out and for a month prior to that it had had little use. Possible therefore that battery was low. However the run I took it out on was about thirty miles and I assume this should have been enough to restore the charge. I am taking the car out again tomorrow so will see if there is any change to the charge level.
Regards,
Stewart

[christopher storey]

Stewart : in 30 miles I would have expected that the current would normally have reached the trickle stage, but there are a considerable number of variables which can affect it ; not all current outflows are registered on the ammeter on E type circuits, ( for reasons I have never fully understood) and if you have a significant current draw - e.g. heater fan or radiator fan ( or both) - there may have been a correspondingly greater charge shown to compensate . This is particularly so if you have a modern fan eg Coolkat where the current draw is sometimes as much as 30 amps . Alternatively, if your battery is ageing and developing higher internal resistance, or if the electrolyte is low, again this may influence the apparent rate of charge. It needs to be remembered that the 4.2 E type had one of the earliest alternator and rectifier setups employed in the UK , and the control setup is far from sophisticated by modern standards , and thus the setup has a tendency to be somewhat erratic. If your battery started the car after a 4 week layup without difficulty, I doubt whether there is much wrong with it ( Edit : since writing this I have realised that you have not said whether you are 3.8 with dynamo, or 4.2 with Alt ) . Most of what I have said applies to both, but the CVC control unit on dynamo equipped cars is much more adjustable than the 4TR alternator control)

[StuBYD]

Dave,
Once again many thanks and for the record it has an alternator. Am taking it out today and will see how it performs. Do have a Kenlowe fan installed and following a run it does tend to run on for quite some time. On the outing referred to I stopped at a pub for lunch and the fan must have run on for at least 10 minutes. Perhaps I should turn the temperature setting up a bit?
Regards,
Stewart

[1954Etype]

Dave,
Once again many thanks and for the record it has an alternator. Am taking it out today and will see how it performs. Do have a Kenlowe fan installed and following a run it does tend to run on for quite some time. On the outing referred to I stopped at a pub for lunch and the fan must have run on for at least 10 minutes. Perhaps I should turn the temperature setting up a bit?
Regards,
Stewart

Stewart, I would say that if your battery is in good condition it would appear you don't have a problem. When I had an ammeter, it took a long run for the needle to sit in the middle and then flick occassionally when the fuel pump clicked. Re running your fan when you switch off; what is the perceived wisdom on this one? I have a coolkat fan which goes off when I switch off the ignition and have never had a problem. Is there a good argument that saysI should rewire mine?

[daverawle]

Stewart, I would say that if your battery is in good condition it would appear you don't have a problem. When I had an ammeter, it took a long run for the needle to sit in the middle and then flick occassionally when the fuel pump clicked. Re running your fan when you switch off; what is the perceived wisdom on this one? I have a coolkat fan which goes off when I switch off the ignition and have never had a problem. Is there a good argument that saysI should rewire mine?

Angus,
I've wired my fan separate from the ignition switch so it runs on like Stewart's. Three reason I think it's a good idea:
The ignition switch doesn't handle large loads very well and modern fans draw high current.
I don't like electronics sitting in a high heat environment; the fan blows cold air onto the dizzy and alternator.
Some re-painted bonnets blister around the exhaust side louvers so it may help there.

Dave

[Heuer]

My Kenlowe fan is wired to go off with the ignition and I have never had a problem even after running in temperatures of 40c. I don't like leaving the car with any electrics running as you could come back to a flat battery which kind of takes a shine off your day.

[daverawle]

My Kenlowe fan is wired to go off with the ignition and I have never had a problem even after running in temperatures of 40c. I don't like leaving the car with any electrics running as you could come back to a flat battery which kind of takes a shine off your day.

David, I know what you mean about leaving things running but the fan starts/stops periodically over a 10 minute period if the car is very hot - that is around 1 Amp/Hr of consumption and should have no effect on a serviceable 40 Amp/Hr battery. If I were running the fan from the ignition switch I would do it via a relay as the switches get hot due to cheap or worn contacts - probably the reason the headlamps aren't wired through it. Comments refer to an alternator equipped car, if it has a dynamo then don't run anyting without the engine running

Dave

[Heuer]

All Kenlowe's operate via a relay so the ignition switch should not be a problem. CMC insisted on re-wiring the fan through its own dedicated 60A fuse as they reckon at start-up the Kenlowe can easily exceed the in dash fuse limits and could also melt the standard fuse carrier.

White bit of plastic is the fuse cover. This is a mod which really needs to be done for any after-market fan equipped car.

[StuBYD]

Hi Dave,
Had no problems today. Only on one occasion did the ammeter reading rise, but for the rest of the run of about 140 miles it remained in the centre or showed only a very slight charge. Think your rational regarding the battery not having been much used and the high current being drawn by the Kenlowe fan could have been the cause. Have adjusted the temperature setting to prevent fan running on for what I think is an exraordinary amount of time, and will now play around with this in order to get the right compromise. Have noted comments of others and may well consider installing a seperate fuse.
Once again many thanks for your support.
Regards,
Stewart

[S12+2]

Glad to hear your problems are resolved. Can I suggest you look at the thread regarding changing the ammeter for a voltmeter. I have just carried out this mod on my S1 4.2 and found a suitable voltmeter on E Bay for under a tenner. It was easy to fit using the photos & instructions on the thread and gives a much more useful reading.

Best wishes
Nick