Tried to start the car (S2 elan)last night and ignition light was on, fuel pump working etc. Tried to crank the engine but was unable to generate enough power to turn it over.
This AM checked the voltage (11.7), ran a set of jumper cables to the car from my jeep and it started right up. I removed the jumpers and after a couple of minutes I shut the engine and re-started without the jump. I gather from this I had enough juice to start a warm enging but not enought to turn over the cold one. I currentlu have the battery on a charger.
I want to get to the root cause of this.
Some driving history for this year.
Replaced the front harness this winter. Battery was out of the vehicle all winter, plenty of power to start the car after the harness job was done. I drive 1-3 days per week for oughly 1/2 h twice on those days.
Voltage across battery at 1000 rpm is 11.7 should this be higher?
Is this likely a generator (has not been fitted for an alternator) issue?
i am about to dig out the workshop manual but would like to get your insight in parallel.
To be honest, I’d anticipate problems with that sort of usage (irregular/short trips) with a dynamo (generator). It will only be putting charge into the battery at higher revs and it is likely that starting the engine is draining almost as much juice as the dynamo will replenish in a half hour drive.
Voltage across battery at 1000rpm is not surprising, if the battery charge is a little low, since at these revs the dynamo probably won’t be giving charge and current is being drawn from the battery to feed the ignition, etc.
It would be worth checking that the regulator is correctly adjusted, though, to control the maximum voltage and cut-in point on the dynamo. The workshop manual gives instructions how to do this, but if you can find an auto electrician with experience of old English cars, it would only take him ten minutes to check and adjust. It wouldn’t do any harm to make sure all the terminals and connections are clean and tight, too, to minimise resistances.
Other than that, you probably need to think about keeping the car connected to a trickle charger when it’s not in use, and/or convert to an alternator.
Suggest you check the battery cable connections at battery & solenoid & solenoid to starter lead as well as engine earth. Check there is no broken strands. My starter motor lead had several broken strands replaced this & off she went the cable run is quite long from boot so when pulling 400 amps for starter the volt drop in the cable can be high unless in good condition. Get battery load tested could be battery past its best & as above would always connect a trickle charger will extend life of battery.
regards
Ian
A Fully charged battery should be 12.6volts, once it has dropped to 12v and under it is unlikely to start your car, measuring the voltage across the battery with the engine running the voltage should show an increase of voltage as the revs rise to a maxium of about 13.8V (depending on temp and battery state)
Even at 1000 rpm it should not be showing a discharge unless you have current consumers switched on (example lights)
The worst thing for a battery is not being used, a trickle charge and an occasional boost will prolong the battery life and the trend now is to use a battery conditioner.
As your battery had reached a low state of charge have it charged and then load tested as per other posts although if it is not chargeing at 1000rpm it sounds like you may have a generator/regulator problem.
Meters can vary a bit, but I like to see 12.5 across the battery. If you can remove the caps, check that the ‘burbling’ is consistent in all the cells while on the charger, a short burst ( 10 min) @ 50 amps will often retard sulfation. Once the battery is fully charged a simple load test can be done with a multimeter, voltage drop with starter engaged should be less than 15%. Hope this helps.
One good thing about having a battery cutoff switch installed is you can turn off the power when you park it, prolonging whatever battery life you DO have. Doesn’t get at the root of your problem, but will help get you home more often.
The voltage does not rise when the engine is revved. I will isolate the generator/dynamo and check to see if it is working.
I was able to get a full charge on the battery overnight so can run it and do some more diagnostics.
I did a quick check online and most of the battery conditioners seem to be sold in the UK. Any recomendations for a US conditioner(want to avoid adapters)
Sorry cant help with U.S. conditioners.
I am not sure which regulator you have, the later RB 340 three bobbin or the earlier RB 106 two bobbin, here are some links that may help you with your diagnostic but really you are wasting your time as the answer is to fit an alternator, “Lucas the Prince of darkness” takes no prisoners ponypics.com/spitfire/regulator.html mgoctagoncarclub.com/articles/regulation.htm
You might try Northern Tool or The Battery Zone ( ads at bottom of this page) for a battery minder. Now, a stupid question, I have avoided fitting alternators all these years because mine are +earth( didn’t want to change tachs, etc,), can I use an alternator without changing polarity?
The short answer is no but the Tach can be converted or a later Tach used. All other things will work on negitive earth but be aware if you have a radio it is ground sensitive.
You can buy a shumacher trickle smart charger at wally world for $17.44 It will sllllooooowwwlllllyyy charge your battery then go to float and keep it charged but not overcharged. It has a switch and you can carge 6 or 12v .
Fit the alternator, switch over the tach, and be happy. The dynamo just isn’t up to the job unless everything is right up to snuff. The alternator will keep your battery fully charged while you are driving, even with the lights on at night (and by the way, they’ll be brighter) - a bizarre concept for the Elan driver but there you are!
I have been working at a snails pace (too many competing priorities). Checked the Dynamo and it topped out at about 3 volts so it needs to be replaced.
Question: Why would I not switch to an alternator? The car is not original (cobbled together from 3 elans- frame; body; engine) so it is not a show car.
If you prefer the sound of a starter motor operating at a slow speed declining to silence as opposed to the sound of the engine starting right up.
If you consider the slow operation of the power windows to be a safety feature.
If you prefer single speed wipers (off-off-slow) to two speed wipers.
If you prefer variable speed direction signals (as they slow down with the engine speed).
If you like the added weight of the generator and voltage regulator as opposed to that of an alternator.
The Lucas generator puts out 22 amps. The Lucas alternator found in Europas puts out 35 amps. You’d be hard pressed to find a modern Japanese alternator that puts out less than 45 amps. Two weeks ago, after 165,000 miles, I replaced the original Nippondenso alternator that came from the factory on my Dodge minivan. It puts out 120 amps, the equivalent of 5-1/2 Lucas generators.
You got me there. Didn’t check to make sure Robb had an S3, S4, or Sprint. Well maybe he’ll be so excited to move into the 20th century that he will pull the windows up and down faster by hand!
Thanks for the great advice as always. I was able to get a rebuilt generator for just over $100 and I can install it this week so I will try the dynamo one more time.
I figured it was going to cost me $500-750 (alternator, electronic ignition and tach) and a couple of dedicated days (which for me means several weeks) to convert to the alternator right now. The weather is too nice to leave her in the garage and the original setup was working well for me until the dynamo died.
So for a $100 I can keep driving this fall- seems worth it and I will do the conversion later.