Pop Quiz - Alternator producing less than 13-14 volts
Discussion
Just a quick one.
My old man is on his way to France this afternoon in the wedge; we replaced the alternator last night as the old one was on the way out. Needed to make some slight mods to the new one as it had a smaller shaft, but not biggie.
After fitting it last night, we started it up and the battery light went out. Happy days. Now the voltmeter was showing just over 11v on the gauge, but we assumed this was the current level the battery had. Pretty sure we're wrong now.
Just had a phone call and the old man has broken down; seems the car has no juice left and the fuel pump has cut out. He is just waiting on the RAC.
So, assuming the belt is tight (which is was) and the pulley is tight (also checked), then what else could cause the car to run out of power? The alternator is brand new, so I can't see that being the problem (although will get RAC to run a voltmeter across it).
Is there anything else that could cause this? All the cables were re-attached properly and it also had a new battery last week.
I'll update as more comes through.
My old man is on his way to France this afternoon in the wedge; we replaced the alternator last night as the old one was on the way out. Needed to make some slight mods to the new one as it had a smaller shaft, but not biggie.
After fitting it last night, we started it up and the battery light went out. Happy days. Now the voltmeter was showing just over 11v on the gauge, but we assumed this was the current level the battery had. Pretty sure we're wrong now.
Just had a phone call and the old man has broken down; seems the car has no juice left and the fuel pump has cut out. He is just waiting on the RAC.
So, assuming the belt is tight (which is was) and the pulley is tight (also checked), then what else could cause the car to run out of power? The alternator is brand new, so I can't see that being the problem (although will get RAC to run a voltmeter across it).
Is there anything else that could cause this? All the cables were re-attached properly and it also had a new battery last week.
I'll update as more comes through.
When you fitted the new alternator, did you put a volt meter across battery terminals with the engine running?. It should have read around 14v. If not, then the alternator is not charging battery and hence battery will soon drain. You say the red light went out when engine started. That indicates the battery is being charged. The ignition light should come on when ignition is switched on and go off when engine starts, then come on when engine is switched off, with the ignition on.
Also. If all the above is good, then you may have a different problem. Earthing, wiring, connections, starter motor and it's connections etc. I hope that helps.
Tony. TCB.
Also. If all the above is good, then you may have a different problem. Earthing, wiring, connections, starter motor and it's connections etc. I hope that helps.
Tony. TCB.
Whoa, just take a step back a moment....
Is the alternator REALLY producing only 11 volts, or is that what the gauge says. A dodgy connection/earth can easily account for a couple of volts. It could be a faulty alternator, but it could also be something else. Check the main wiring points are clean and tight (engine earth, alternator and starter motor).
Check output AT THE ALTERNATOR. Then check output at the battery.
Are you sure battery is OK - a faulty cell can drag down the voltage too, and the charge light won't always come on. Leave battery for 30 mins or so, then check it's voltage is over 12 volts - if it's more like 10, then it could be battery is at fault.
Does charge light come on initially ? Has bulb blown ? Sounds stupid, but seen people make that mistake - battery won't charge on some alternator designs unless bulb is OK.
er... can't think of anything else just now.....
Is the alternator REALLY producing only 11 volts, or is that what the gauge says. A dodgy connection/earth can easily account for a couple of volts. It could be a faulty alternator, but it could also be something else. Check the main wiring points are clean and tight (engine earth, alternator and starter motor).
Check output AT THE ALTERNATOR. Then check output at the battery.
Are you sure battery is OK - a faulty cell can drag down the voltage too, and the charge light won't always come on. Leave battery for 30 mins or so, then check it's voltage is over 12 volts - if it's more like 10, then it could be battery is at fault.
Does charge light come on initially ? Has bulb blown ? Sounds stupid, but seen people make that mistake - battery won't charge on some alternator designs unless bulb is OK.
er... can't think of anything else just now.....
Cheers guys
Battery light came on with ignition and then went out when the engine was running. Stupidly, we didn't run a voltmeter across the terminals as it was late and we were in a rush.
Alternator was a OEM replacement listed as suitable for Rover V8 engines, specifically mentioning TVRs, Morgans, Rovers etc. The new alternator looks like a far higher quality unit than the original. Don't know the exact price, but I don' think it was cheap.
Battery is brand new, so I'd be surprised if the cells were dead.
RAC guy is pretty convinced the alternator is dodgy. I'm not there, but I assume he ran a voltmeter across the terminals to check.
Never have been able to suss out the voltmeter gauge.
Wiring should be fine. The car has been stripped and rebuilt over the years and the wiring is all immaculate and well laid out. Could be a loose connection, but I tightened everything up that I disconnected (4 cables) so I don't think the problem is there.
Battery light came on with ignition and then went out when the engine was running. Stupidly, we didn't run a voltmeter across the terminals as it was late and we were in a rush.
Alternator was a OEM replacement listed as suitable for Rover V8 engines, specifically mentioning TVRs, Morgans, Rovers etc. The new alternator looks like a far higher quality unit than the original. Don't know the exact price, but I don' think it was cheap.
Battery is brand new, so I'd be surprised if the cells were dead.
RAC guy is pretty convinced the alternator is dodgy. I'm not there, but I assume he ran a voltmeter across the terminals to check.
Never have been able to suss out the voltmeter gauge.
Wiring should be fine. The car has been stripped and rebuilt over the years and the wiring is all immaculate and well laid out. Could be a loose connection, but I tightened everything up that I disconnected (4 cables) so I don't think the problem is there.
Just to close this one off; alternator confirmed as duff. Apparently it is the diodes that are faulty.
The unit was bought off a reputable Ebay trader, cost circa £80. So not a cheap knock off.
Having a replacement fitted now, so he still has time to make the ferry.
Nothing like a bit of TVR related drama just before a road trip
The unit was bought off a reputable Ebay trader, cost circa £80. So not a cheap knock off.
Having a replacement fitted now, so he still has time to make the ferry.
Nothing like a bit of TVR related drama just before a road trip
yeah good news.
FYI the 400SX can show 11V on the internal gauge and this is with 13+V at the battery - it depends what ancillaries are running - fan at full blast drops it 2V.
I bought my alternator for £57 and it was perfect - 70A too I think. Cheap doesn't necessarily mean s
te. Expensive is no guarantee of quality.
FYI the 400SX can show 11V on the internal gauge and this is with 13+V at the battery - it depends what ancillaries are running - fan at full blast drops it 2V.
I bought my alternator for £57 and it was perfect - 70A too I think. Cheap doesn't necessarily mean s
te. Expensive is no guarantee of quality.Gassing Station | Wedges | Top of Page | What's New | My Stuff