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Old 24th November 2019, 20:00   #11
Comfortably Numb
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Also, if your battery gets down to 11.7 volts, do not be tempted to recharge it by driving it after jump starting it off another car or battery; 14+ volts and a high current output over a long period may boil off the acid in the battery. Best to put it on a smart trickle charger overnight, or leave it idling with a low current (amperes) output.
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Old 24th November 2019, 20:01   #12
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I put it on a charger. It took 12 hours to charge.
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Old 24th November 2019, 20:07   #13
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Quote:
Originally Posted by Comfortably Numb View Post
12.7V is a more than adequate starting voltage, damage is likely to occur if it is regularly allowed to discharge to around 12.2V or less, and it is also likely to present starting problems at such a low voltage, and discharge the battery further, into the damagingly low realms where sulphating of the plates is rapid. If your brand new battery is discharging from 12.7v to 11.7v in a week, you definitely have a leak and this could be down to one or more of the diodes in the voltage regulator failing. The alternator will tend to give out a high voltage long after it should have reduced, as it is pushing power into both the battery, and the leak, rather like pumping water into a tank with a hole in. When you switch off the supply, your briefly full battery continues to leak back through the diodes. When you leave your car after you have been for a drive, try disconnecting the wires from the alternator. If the battery remains fully charged, you have isolated the problem. If it continues to discharge, then it isn't the alternator!
More to the above post.--

The battery voltage is monitored by the voltage regulator in the alternator. It is set to give around 14 to 14.5 volts with a charged battery.

Think about switching on any of the cars electrical components. All of them could be considered as LEAKS.

However with all these things on and the engine at a fast tick-over the voltage will still read around 14 volts at the battery terminals even though lots of CURRENT is being used.---


Here endeth the sermon.-------

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Old 24th November 2019, 20:10   #14
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AGM battery is a good choice - they can survive deep cycle discharge much better than standard LA. Colvert, you are quite right of course, but best not to induce higher rates of sulphating in the first place.
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Old 24th November 2019, 20:10   #15
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I agree with the last bit but disconnecting the alternator isn't too easy.----------------
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Old 24th November 2019, 20:18   #16
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For info. I bought an AGM battery this time round. Apparently it doesn't suffer as much when the voltage does drop down too much.
Very good idea.--Don't forget though, that a Glass Mat battery takes longer to charge than a standard lead acid battery.


Leave that plug in a wee bit longer.---
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Old 24th November 2019, 21:21   #17
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So. Is there a way of testing my alternators regulater? Or do I renew it, just in case.

Last edited by pletevl; 25th November 2019 at 13:21..
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Old 25th November 2019, 11:10   #18
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https://www.google.com/search?q=how+...Z1fAPn8GKwA834
This you tube video is very thorough and knowledgeable. PS AGM batteries are QUICKER to recharge than L/A. Good luck.
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Old 25th November 2019, 17:50   #19
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So. Is there a way of testing my alternators regulater? Or do I renew it, just in case.
Yes.---If the voltage at the battery terminals is around 14 volts ( tickover. ) the regulator is just fine.
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Old 25th November 2019, 17:55   #20
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Quote:
Originally Posted by Comfortably Numb View Post
https://www.google.com/search?q=how+...Z1fAPn8GKwA834
This you tube video is very thorough and knowledgeable. PS AGM batteries are QUICKER to recharge than L/A. Good luck.
I must have a look at that.---My motorbike has an AGM battery and I was sure I Read that it takes longer to charge than lead acid.---



PS. I am unfortunate that I have always had this need to know.---
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