Some Ampere tests on 2006 RX350 Battery

[BachelorDays]

I don't use my cars regularly, at times parking them for long periods.  So I'm always conscious of the Battery condition and drain.  In addition, long waits in places such as the Channel Tunnel with the engine switched off and some accessories working always need one eye on the Battery for a re-start.

I realise the hybrids gang here isn't worried about cranking amps, but I've noticed that causes another false condition - a Battery that has had it and would indicate this as a slow cranking engine instead silently reaches levels low enough to give erratic results and sudden no-starts.  You guys really need a handle on the volts your Battery is dishing out.  I use a voltage meter that you can plug into the lighter socket (they are only £3-4 on net) .  On ACC it'll give you a good indication.  Good to know every once in a while in the morning with the winter coming in now.

Back to 12V Battery usage - I normally address potential issues here by installing a larger Battery and evaluating usage of accessories.  In this Lexus there isn't space for a larger Battery so the 70Ah will have to do.  As for usage, getting a clamp meter on the wires around the Battery proved quite difficult.  I did manage the clamp around the negative leads with the display just visible - so ready to go!

It sits at under 50mA when unlocked with nothing on.  The key in ACC position takes a chunky 5.8A.  Switch off the display screen and it drops by about 0.7A.  Putting the CD player on, volume at 15, adds about 0.4A.  Put the volume up to 25 and it goes up to 0.6A (The Mark Levinson system with its umpteen speakers does take its toll).  Leave the driver's door open and that adds almost 6A.

So if the Battery is in good condition and you've waited an hour at the tunnel and then another 40 mins in the train you'll probably use no more than 13A.  Not a problem.  Just don't wait with the door ajar.  Double this (given a delay/ early arrival) and a struggling Battery... Probably best to crank up the engine half way for 15-20 mins.

Hope this is useful.  It would be great if someone could corroborate these figures.

Cheers

 

[Britprius]

Your figures are as I would expect for a non hybrid. With a hybrid the ACC position takes more current almost double in fact, and in general have smaller batteries fitted "only 45 AH"

The 50ma idle may not at first seem much, but works out at 1.2 AH over 24 hours or 8.4 AH over a week. It does then become obvious why some hybrids have problems after a few weeks of inactivity.

I have found that mobility batteries of the same dimensions of the OEM batteries can have up to 50% higher AH capacity. The only downside being different terminal types.

John.

[BachelorDays]

22 hours ago, Britprius said:

Your figures are as I would expect for a non hybrid. With a hybrid the ACC position takes more current almost double in fact, and in general have smaller batteries fitted "only 45 AH"

The 50ma idle may not at first seem much, but works out at 1.2 AH over 24 hours or 8.4 AH over a week. It does then become obvious why some hybrids have problems after a few weeks of inactivity.

I have found that mobility batteries of the same dimensions of the OEM batteries can have up to 50% higher AH capacity. The only downside being different terminal types.

John.

12Ah on ACC standby!  Wow.  Whatever is it doing?  So the advice must be to stay in Ready whenever you are in the hybrid?

I don't leave a Battery connected on a car I'm leaving parked for over 3 weeks - too many electronics.

[Herbie]

For more than 30 years I've only ever driven automatics and as you probably know, you can't push/bump-start a car with an auto box so I've always kept a very beefy set of jump leads in the boot. However, the Law of Sod being what it is, you could almost guarantee that there would be no one else around to provide a jump start when needed, so I invested in one of these little rascals.

I've not needed to use it yet but it's been in the boot for over a year and is still 75% charged, so I know it holds its charge well and will be ready if I ever do need it.

52 minutes ago, BachelorDays said:

12Ah on ACC standby!  Wow.  Whatever is it doing?  So the advice must be to stay in Ready whenever you are in the hybrid?

Yes. We often park up on a seafront/promenade somewhere and if the weather is too bad to go for a walk we'll just sit in the car for two or three hours watching the sea and watching the world go by. However, we are both big music fans and so will have the radio/other media playing all the time. If the car is in READY then the ICE will fire up as and when necessary to keep the traction Battery charged up but if you don't, the radio will shut down after a while and a message on the multi-function display informs you that it's been turned off to conserve Battery power.

[Britprius]

1 hour ago, BachelorDays said:

12Ah on ACC standby!  Wow.  Whatever is it doing?  So the advice must be to stay in Ready whenever you are in the hybrid?

I don't leave a battery connected on a car I'm leaving parked for over 3 weeks - too many electronics.

One of the extra items is an electric pump that pumps coolant from the engine to the heater. This is required even when the car is being driven because the engine may not be running, and therefore the normal engine cooling pump will not be circulating the hot coolant to the heater to heat the cabin.

John.

[BachelorDays]

On 10/14/2018 at 5:34 PM, Britprius said:

One of the extra items is an electric pump that pumps coolant from the engine to the heater. This is required even when the car is being driven because the engine may not be running, and therefore the normal engine cooling pump will not be circulating the hot coolant to the heater to heat the cabin.

John.

I'd've thought that would be the case once On/Ready is selected.  Normal cars don't have the pump running on ACC.  Oh well..

Cheers

[BachelorDays]

On 10/14/2018 at 4:46 PM, Herbie said:

For more than 30 years I've only ever driven automatics and as you probably know, you can't push/bump-start a car with an auto box so I've always kept a very beefy set of jump leads in the boot. However, the Law of Sod being what it is, you could almost guarantee that there would be no one else around to provide a jump start when needed, so I invested in one of these little rascals.

I've not needed to use it yet but it's been in the boot for over a year and is still 75% charged, so I know it holds its charge well and will be ready if I ever do need it.

Yes. We often park up on a seafront/promenade somewhere and if the weather is too bad to go for a walk we'll just sit in the car for two or three hours watching the sea and watching the world go by. However, we are both big music fans and so will have the radio/other media playing all the time. If the car is in READY then the ICE will fire up as and when necessary to keep the traction battery charged up but if you don't, the radio will shut down after a while and a message on the multi-function display informs you that it's been turned off to conserve battery power.

That is a useful device - and excellent for a hybrid.  I don't know how these things fare on cranking when it's -5C outside and the 3.5L V6 has been parked for a couple of days, although I imagine they would always do the trick on a still-warm engine.

[Delphius1]

I'm a bit paranoid about the Battery state on cars that have so many electrical toys, especially as the wife tends to keep the seat heater on constantly (why do women do that?). But because the car is so dependent on the Battery being in good condition and the fact there are so many toys to drain it even on an RX300, I installed this little doohickey.

Two hi-current USB ports and a digital voltmeter all in one. It need some slight adjustment of the switch position with a file, but I'm sure will be invaluble over the winter. Keeps the mobile charged as well and turned out to be a pretty tidy setup:

 

The Battery is a bit healthier now, that was after a few days of mucking about with the lights on and the engine not running. Back up to 12.6v with the engine off now.

[Herbie]

If anyone doesn't fancy taking a file to the dash, this may be a better alternative if you don't smoke. It's a direct replacement for the cig lighter socket.