Mud-club

Vehicle & Technical => Range Rover => Topic started by: zulublue on February 21, 2007, 21:54:46

Title: Voltage
Post by: zulublue on February 21, 2007, 21:54:46

What voltage should I get on the battery when on tickover? when everthing is switched off even the engine it reads 12.44 but when running it shows 12.20, I thought it should be somewhere around 13.6v.

Answers please.

Title: Voltage
Post by: Range Rover Blues on February 22, 2007, 13:03:51

A lead-acid battery should be charged at no more than 14.3 volts, the internal regulator should ensure this is the case.

12.4 sounds a little low but don't worry.  Turn off the engine, the voltage you see straight away is called surface charge, the voltage will subside to around 12 volts in a few minutes, depending on the condition of the battery.

Once you have established the baselilne voltage for your battery, taking into account how accurate your meter is, then start the engine again.

Does the reading go up or not?  If not and you have nothing switched on then you may have a problem.  Rev the engine, does it go up.  If not the alternator is toast.  If it does how far up does it go.

Now, let the engine idle and switch everything on, headlights, heated screens, blower.  Check the voltage agian at idle and at about 2-3,000 revs.

tell me what you get.

Title: Voltage
Post by: zulublue on February 22, 2007, 20:13:46

Cheers RRB, I will double check tomorrow.

When i started the engine the other day the meter dropped by 0.2 of a volt.

I am running these, only have 1 fitted untill tomorrow.

Title: Voltage
Post by: mark.yellow.series.3 on February 22, 2007, 21:31:39

12.44vdc on the battery when the engine is off is a normal reading, however the voltage should increase when the engine is running, so, in your case if it reads 12.20vdc with the engine running it means your alternator is not charging. :(

Title: Voltage
Post by: zulublue on February 23, 2007, 18:25:33

Ok now sorted, must have been a poor connection, tested 12.5 before I touched, started her up, on low tickover it went to 12.2, I think the cold start is not working that well, so I revved her to about 3000rmp for a minute and let her idle, holding about 1000 rpm now reading 14.4V so I am happy with that.
Added the other battery today an linked them across, they both leveled well and the the same thing happened, low on tickover ok once she hits 1000 rpm.

put all the lights on about 500w the heater heated screen wipers cig lighter as held at 13.4v :lol:

Title: Voltage
Post by: Range Rover Blues on February 24, 2007, 11:38:41

Yeap. alternator sounds fine, just watch out for that 0.2volt drop as it means at idle your battery is going flat, very slowly.

Title: Voltage
Post by: zulublue on February 24, 2007, 11:57:51

will do, but once she has warmed up and been revved a bit she is back to 14v

Title: Voltage
Post by: Range Rover Blues on February 24, 2007, 12:19:05

Ah, alternators need reving to get them to 'self-excite'.