Lotus Elan

Overcharging?

PostPost by: Robbie693 » Mon May 06, 2019 1:51 pm

Hello,

Finally got the Plus 2 out this Easter after fitting the battery which has been off the car and periodically charged with an Optimate maintainer for the winter.

Unfortunately I didn't check the voltage before I fitted it but I noticed it wasn't quite as lively turning over as last year. Anyway, got it started and drove 20 miles or so. When I got to my destination I checked the voltage a couple of hours after turning off and got the surprising reading of 13.8V - with the engine off. The journey back was done with the lights on which is usually guaranteed to drop the voltage a bit and the voltmeter in the car was showing what it always does which is just over 13V lights off, dropping to just about 12.5V lights on.

Car has been sitting for a couple of weeks now and I have just been down to see how the battery is. Before even trying to start the car I got 14V at the battery. Took it out to check the electrolyte level which was fine and re-tested it and it had dropped to 12.5V. Put it on the car but it didn't have enough power to start the engine.

Question is; could this excessive voltage be a symptom of the battery dying or do I have a problem with the Alternator too?

Robbie
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PostPost by: Elanman99 » Mon May 06, 2019 6:28 pm

Have you checked the voltage that your voltmeter is reading correctly, I would check with a different meter just in case.

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PostPost by: Robbie693 » Mon May 06, 2019 11:33 pm

I did, the first reading (on the first journey) was with a different multimeter to the one I used at home today...
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PostPost by: Quart Meg Miles » Thu May 09, 2019 8:05 pm

A properly charged battery would register 13.8V. As it dropped from 14V to 12.5 without any current being drawn I suspect the battery is finished. MIne only last four years and I have always used a charger during the winter to help the dynamo, and lately a proper maintainer. With a new battery the maintainer never kicks in.

I wouldn't put much faith in the dash voltmeter and it is worth putting your voltmeter on the battery while the engine is running to check the alternator. My S130 had a faulty alternator when I bought it, charging at 17V which destroyed the battery after a while.
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PostPost by: Robbie693 » Sun May 12, 2019 11:56 pm

Thanks Meg,

A new battery has just arrived, just need to find time to fit it and do some tests so I can confirm

Cheers

Robbie
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PostPost by: Robbie693 » Wed May 29, 2019 9:05 am

Update....

New battery arrived, lugged it the 1/2 mile down to the garage and fitted it and the car started instantly! Which was surprising as it hadn't ran for a fortnight.

Checked the output from the alternator and it's 13.9V and the battery was showing 14V at 1000rpm so this seems ok. I did notice before starting however there is a bit of a voltage drop between the positive battery terminal and the boot mounted isolator switch, 0.2V on the 12 inches of cable and 0.1V across the switch itself so I will be replacing these (the cable strands are starting to break up so not surprising).

Anyway, after this I moved on to a compression check which I've been trying to get to do for ages, unfortunately the battery started to run out of go before I'd even pumped up enough pressure on the second cylinder, which I thought was odd...

So I humped the battery back home to charge it.

Now I need to start the car to give it a bath for the bi-annual valuation and guess what? Click from the solenoid but nothing else! Pushing the car in gear is easy so a few taps on the starter gets me a faint whirr before the clicking returns. Bugger, left the multimeter at home. Headlights stay bright when I turn the key, motor is still tight to the bell housing and the wire is on and clean connections. So I think the starter is fried (remember I said it was sluggish before I bought a battery) and I think the compression tests pushed it over the edge, apparently they can get hot quite quickly.

As I only recently replaced the end plate (another one cracked) I am gong to use another starter I have spare and swap the plate and bendix over to make a whole one temporarily but I see a new, pre-engaged, one coming along soon. Once I decide which one to buy.

Current shortlist is WOSP or one of the Powerlites available from Paul Matty. Brise seems extraordinarily expensive. Anyone know what make is the one Sue Miller sells?

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