Battery Voltage

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12th February 2016, 10:16 AM
DiscoMick

Quote:

Originally Posted by Road Stone

Hi Folks,

Returned from my lightning trip to Brisbane. Now with Multi Meter!

First up, car has sat for 10 days unused. Started on the button, I was stupid and did not take a reading first!

After a short run, the MM indicates battery at 12.8v. I started the car and it showed 13.7v.

From the helpful advice already given, this appears to be okay.

I'm going to monitor over the next few days and see what happens. I go away again next week for 11 days so WILL check on my return.

Prices have gone up in Brisbane!!

Cheers, Jerry

As I understand electrickery, 12.8 is a fully charged battery so that's good. The 13.7 after starting would have been the amount of power the alternator was pushing around the system and that's also a good number. My Defender sits on 13.9-14.0.
15th February 2016, 06:54 PM
Road Stone

So just and update:

After 10 days of sitting doing nothing, the wife elected not to use it whilst I was away, I took the battery reading before starting it.

MM read 12.4v which I guess is not bad?

On starting, it got a reading after a couple of minutes of just over 14v.

No I'm wondering if my alternator is on it way out!!

Cheers, Jerry
15th February 2016, 08:12 PM
Aaron IIA

All sounds good there.

Aaron
16th February 2016, 06:02 AM
drivesafe

The reading depends on where you sourced it and were you driving at the time.

I would have expected around 14.5+v for some time, while driving, and then settling back to around 13.8 to 14v, but this would be after at least 30 minutes of driving.

Except for the last of the L322s, their initial voltage boost will last for exactly 30 minutes and then settle back to the normal operating voltage, and the boost voltage can go as high as 14.9.

What year model is your RR?
16th February 2016, 10:57 AM
DiscoMick

14 volts sounds normal to me, as others have said.
16th February 2016, 07:32 PM
Road Stone

Quote:

Originally Posted by drivesafe

The reading depends on where you sourced it and were you driving at the time.

I would have expected around 14.5+v for some time, while driving, and then settling back to around 13.8 to 14v, but this would be after at least 30 minutes of driving.

Except for the last of the L322s, their initial voltage boost will last for exactly 30 minutes and then settle back to the normal operating voltage, and the boost voltage can go as high as 14.9.

What year model is your RR?

Thanks Guys,

Its a 2007 TDV8.

Yes Drivesafe, you are correct. On start up 14.4v and then after a while it drops to 13.5v these readings taken from my diagnostics machine (Hawkeye).

I took the multi meter readings from both the jump start point and direct from the battery terminals both read exactly the same.

I have decided to buy a recon alternator and keep here as a spare. Given where I am if something did happen I wont be off the road for a month! $400 for a 150amp 2 year warranty, valid here too believe it or not so feel its wise.

Cheers, Jerry
16th February 2016, 08:30 PM
drivesafe

Those voltages are fine and it sounds like it is running OK.

BTW, they are fun ( NOT ) to change.
17th February 2016, 03:59 PM
DiscoMick

Quote:

Originally Posted by Road Stone

Thanks Guys,

Its a 2007 TDV8.

Yes Drivesafe, you are correct. On start up 14.4v and then after a while it drops to 13.5v these readings taken from my diagnostics machine (Hawkeye).

I took the multi meter readings from both the jump start point and direct from the battery terminals both read exactly the same.

I have decided to buy a recon alternator and keep here as a spare. Given where I am if something did happen I wont be off the road for a month! $400 for a 150amp 2 year warranty, valid here too believe it or not so feel its wise.

Cheers, Jerry

I assume your TDV8 has a 'smart' alternator which is designed to vary the output depending on the demand i.e. raises it to start and recover the charge used for starting, then drops it depending on the load on the system, so that's normal.
My Defender isn't that smart - it just makes the same all the time.
17th February 2016, 05:16 PM
bsperka

Quote:

Originally Posted by DiscoMick

I assume your TDV8 has a 'smart' alternator which is designed to vary the output depending on the demand i.e. raises it to start and recover the charge used for starting, then drops it depending on the load on the system, so that's normal.
My Defender isn't that smart - it just makes the same all the time.

Btw: typically "smarter" than that. Won't charge at idle ( unless battery voltage indicates required), charges when decelerating, won't charge if high engine output required etc .
22nd February 2016, 03:35 PM
Road Stone

Quote:

Originally Posted by DiscoMick

I assume your TDV8 has a 'smart' alternator which is designed to vary the output depending on the demand i.e. raises it to start and recover the charge used for starting, then drops it depending on the load on the system, so that's normal.
My Defender isn't that smart - it just makes the same all the time.

I have no idea if its smart or not! Hope so, smarter than me anyway. As long as it charges when in remote areas I don't care LoL!

I'm heading on safari mid week in the remote Western part of Uganda/DRC boarder so heres hoping!

Cheers, Jerry

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