Good battery and alternator but no charge

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Re: Good battery and alternator but no charge

Postby elnaught » Sun 15.04.2018, 22:03

Update, I have now replaced the alternator (new one has a lifetime guarantee!) I did not get to the bottom of the issue with the old one, cleaned the brushes etc but no difference, was taking up a ramp so just fitted a new one.

The battery conditioner I was using was made by maypole, I'd don't think it cost much, think I had better invest in a better smart charger, any recommendations?
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Re: Good battery and alternator but no charge

Postby Saltire » Sun 15.04.2018, 22:30

elnaught wrote:The battery conditioner I was using was made by maypole, I'd don't think it cost much, think I had better invest in a better smart charger, any recommendations?


I’ve always used either Ctek or (occasionally) Optimate, on a variety of cars over 40 years and never had any problems with them.
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Re: Good battery and alternator but no charge

Postby B_land » Thu 26.04.2018, 18:08

Sorry to hijack this thread....but I have a query regarding my elans alternator. I have noticed some interference through the radio which is affected by engine revs, I've tested the battery at 12.4v and the alternator is putting out 14.3v DC at the battery but there is also 30.4v AC. I'm no expert but thought that there should be no AC volts? Has something failed and should I replace the alternator?

Thanks
EG S2
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Re: Good battery and alternator but no charge

Postby Rambo » Thu 26.04.2018, 18:34

That sounds right up Geoff's, Lotusflasheman Phil's or Simon P's street ;-)

I'm sure one of them will come up with an answer and a possible solution to your quandry
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Re: Good battery and alternator but no charge

Postby Elanlover » Thu 26.04.2018, 19:37

There's lots of reasons why you can get that whining noise in your radio when the engine revs higher. One of the main reasons is a ground line shared with other functions. Running a dedicated ground from the head unit back to the battery can cure it. If you google for it you'll probably find all the other reasons too.
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Re: Good battery and alternator but no charge

Postby peteoddcar » Thu 26.04.2018, 20:19

Hi B-Land,
Can you help to define the issue in more detail please.
1. You mention radio - is the interference there on media play too? ( CD, Bluetooth etc)
2. What make model is the unit?
3. Is there an external amplifier ?
4. With radio off station, volume loud, switch Ignition on with engine not running, switch wipers, blower, flash headlamps.What interference noise do you hear
5. If answer to 1 is just radio then what aerial is fitted ?
Last edited by peteoddcar on Thu 26.04.2018, 21:50, edited 1 time in total.
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Re: Good battery and alternator but no charge

Postby B_land » Thu 26.04.2018, 21:10

peteoddcar wrote:Hi B-Land,
Can you help to define the issue in more detail please.
1. You mention radio - is the interference there on media play too? ( CD, Bluetooth etc)
2. What make model is the unit?
3. Is there an external amplifier ?
4. With radio off station, volume loud, switch Ignition on with engine not running, switch wipers, blower, flash headlamps.What interference noise do you hear
5. If answer to 1 is just radio then what aerial is fitted ?


Thanks for the reply
Ok to answer
1 yes interference on CD play
2 pioneer deh-x8600bt
3 there is an amplifier in the system (came with car)
4 with high volume there is high interference but doesn't seem to change when load is applied
5 not just radio
EG S2
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Re: Good battery and alternator but no charge

Postby lotusflasherman » Thu 26.04.2018, 22:25

B_land wrote:Sorry to hijack this thread....but I have a query regarding my elans alternator. I have noticed some interference through the radio which is affected by engine revs, I've tested the battery at 12.4v and the alternator is putting out 14.3v DC at the battery but there is also 30.4v AC. I'm no expert but thought that there should be no AC volts? Has something failed and should I replace the alternator?

Thanks


No, don't replace the alternator, 14.3V DC is just what you need. Unless you measured it with an oscilloscope, I wouldn't worry about it.. :lol:

If you measure DC with any multimeter set to AC you will get a reading but it's totally meaningless. Take the measurement again with the engine not running and you'll probably get about 25V AC from just the battery. It's all to do with how we express sinusoidal AC voltage as a Root Mean Square value to be equivalent to a DC voltage so the multimeter when set to AC is calibrated to expect a voltage that goes up and down and you're giving it a constant voltage so it over-reads..

... and if your alternator was putting 30.4V AC into the battery I don't think it would last long before there was a big bang behind your back :burnout:
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Re: Good battery and alternator but no charge

Postby peteoddcar » Thu 26.04.2018, 22:39

Hi
Assuming it’s wired correctly and tidy.
Always been there or just started?
If just started then it’s possibly a diode failure in the alternator, it may still charge but with reduced current output.

Try this
Drop head unit out
Disconnect aerial - check again
Is it a whine whirr or a super fast machine gun noise?

In the meantime

Check amplifier grounds and power feed ideally directly from battery ensure that the case is grounded


As built the alternator should have had a 3 (?) micro farad suppression capacitor between B+ and ground - this can help, but it’s a pain to fit one with the alternator in situ.
Ensure the battery terminals are clean and tight. Also Battery neg junction box near battery - engine neg strap cable, battery neg to chassis in boot.
Check b+ at the binding post and alternator all clean and tight maxi fuse box

The fix to add a cable from audio chassis suggested is a good one and may well fix it, wire the amp ground in the same way as the cause is likely to be a ground loop.

At Lotus I was responsible for Audio on the M100 back in the day, but with the glass fibre construction and a separate chassis the are so many variables.
Blaupunkt, Sony and Clarion Head units (back in the day) were found to perform best in Lotus, interference wise.
I have an Alpine in my car and it’s got very slight alternator whine (but I would never hear it whilst driving.)

There several grounding straps - for bonnet, aerial, coil pack etc.the bonnet should be lined with foil which is grounded to the chassis.
From memory this is quite important but mainly for radio reception

Hope that gives you some ideas/ things to check.
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