BMF
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| posted on 29/7/07 at 05:51 PM |
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Why does it run better without the battery??
Got an XE running dizzy and coil with a pair of 45's, but today when out today it back fired and then stalled and wouldn't start.
Realised the battery is crap, but also when running and I remove the negative, it runs better!
Any ideas?
On a similar vain, is it worth replacing the old cavalier coil for one of the high performance jobs?
Cheers, ben
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BenB
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| posted on 29/7/07 at 06:06 PM |
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The alternator will be robbing bhp to charge the battery... If you disconnect the battery the alternator will consume virtually zero BHP. After a
while the battery should be fully charged and the power goes back to normal. If your batter is knackered, however, it'll be on full charge all
the time....
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rusty nuts
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| posted on 29/7/07 at 06:11 PM |
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Running an engine with the alternator disconnect could damage the alternator. When you fit a new battery check the charging rate .Suspect the reason
it runs better disconnected is as BenB suggests
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BMF
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| posted on 29/7/07 at 06:25 PM |
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So basically it is because the battery is buggered then?
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owelly
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| posted on 29/7/07 at 08:40 PM |
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I would concur about the knackered battery but I don't understand why running with no battery would wreck the alternator. If there is no power
feeding the excitation, then surely the alternator is just a spinning bundle of nothingness??
http://www.ppcmag.co.uk
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RazMan
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| posted on 29/7/07 at 09:57 PM |
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Disconnecting the battery while running the engine is likely to damage the alternator and even sensitive electrics like the ecu or electronic dash -
you might even blow bulbs. The battery acts like a smoothing filter, taking the spikes out of the supply.
Owelly - I think the alternator would supply its own excitation while running anyway.
Ben - It sounds like your battery is fubar and the power is probably being converted to heat. Best get it replaced asap.
[Edited on 29-7-07 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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MikeRJ
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| posted on 29/7/07 at 11:09 PM |
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quote:
Originally posted by RazMan
Disconnecting the battery while running the engine is likely to damage the alternator and even sensitive electrics like the ecu or electronic dash -
you might even blow bulbs. The battery acts like a smoothing filter, taking the spikes out of the supply.
You get a situation known as "load dump". Due to the finite bandwidth of the voltage regulation, removing a heavy load from an alternator
can cause voltage spikes several times the normal level, e.g. 50volts or more. Although automotve electronics are usualy built to survive this,
it's a very bad idea to induce these spikes deliberately.
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