Battery drain?

Scribe · February 27, 2021

Went to start the car today for its weekly shopping trip (and foot down on the dual carriageway) and the Battery wasn't even flat - it was completely dead. Everything was fine a week ago, and the car has started throughout the coldest winter weather, but today there were no lights, nothing. Battery is less than two years old. I'm wondering whether there's a Battery drain. Any ideas what and how to check? My first thought was the boot light staying on, so I could take out the bulb when I've charged the Battery. Any suggestions appreciated.

Malc · February 27, 2021

Did you get her going eventually ?

alternator all ok ?

Malc

Scribe · February 27, 2021

Hi Malc. I'm going to wait till tomorrow to disconnect the Battery and charge it. Car has been running fine, with no electrical oddities, and in the past the Battery has never gone completely flat - just too flat to turn the engine over to start. And the new Battery cured that anyway.

ambermarine · February 28, 2021

This sounds like a cell as gone in the Battery ,not unusual in cold weather which tends to seek out weak cells if a couple of plates touch the Battery is shorted and self drains ,if the acid in the Battery is weak it can freeze and buckle the plates.

If it is possible keep the Battery on a maintenance charger which should help to prevent these type of spikes.

Scribe · February 28, 2021

The Battery is a Yuasa with a 5-year guarantee. It's now on charge so we'll see what happens. When disconnecting it I noticed that the negative lead wasn't fitting as tightly onto the terminal as it should, and I wondered if the problem was simply a poor connection. But after tightening it up there was still no power, hence the charger is now on. If this doesn't work, presumably I can take the Battery back to Halfords and get it tested (and possibly replaced)? It has been very cold but the car is kept in a garage.

plexus914 · February 28, 2021

Regarding Battery drain - should be under 50mA - on a 97 model its 24.8mA:

Before you measure any rest current your car has to get into "sleep mode". Keep in mind that in order for the car
to sleep at all it must be off and nothing can be "touched" (no opening of the trunk or doors, no pressing any buttons
on the key fob etc.) If something is touched the timer starts all over again. How long it takes for it "to go to sleep"
I am not quite sure, but 30 minutes should be enough and rest current should be under 0,05Amps (50mA). For comparison
20 minutes after arming the anti theft deterrent system my 1997 LS400 has a rest current of 18 - 28mA.
(before 20min it is about 40-50mA).
Alarm went off at about 11,82Volts.
Battery should be charged when less than 12,4Volts (75%).

Procedure of how I did it and got a reading of 24.8mA:

- Turn ignition off and pull the key

- Open engine bonnet and close its lock with a screwdriver

- Close all doors

- leave the Battery connected and arm the anti theft deterrent system either by key or by key fob.....and check
security lamp if it works

- to be sure leave the car alone for about 30 - 60 minutes (I went back to the car after about one hour)

- go back to the car's Battery and measure rest current without interrupting the current.

Before disconnecting the Battery put the pair of test leads (black one/-)to the negative Battery terminal and
the other (red one/+/amps or mA) to the negative terminal clamp.......now disconnect carefully terminal and clamp.

Scribe · February 28, 2021

Thanks for taking the trouble to supply all that info. Does 'normal' drain (under 50Ma) result from the security system? I notice that the red light on the dashboard flashes continuously even when the car's unlocked, so I guess this system operates permanently.

Tinonline · February 28, 2021

The red light does flash permanently so that’s fine. Lexus are not known for draining batteries as a rule where components fail to shut down and cause the dreaded drain.

A light won’t pull that much juice if left on but a faulty earth would.

I’m not trusting the Battery so checking that is the first step. Then the alternator.

Herbie · March 1, 2021

5 hours ago, Scribe said:

Thanks for taking the trouble to supply all that info. Does 'normal' drain (under 50Ma) result from the security system? I notice that the red light on the dashboard flashes continuously even when the car's unlocked, so I guess this system operates permanently.

The alarm, the immobiliser, the clock, the radio presets/memory, seat and steering wheel memory will all consume power when the car is parked up. This is called the quiescent current draw. Batteries will also naturally self-discharge, even when sat on a shelf and not connected to anything.

Scribe · March 3, 2021

Update: returned the Battery to Halfords, who don't have a replacement in stock and can't order one - they just arrive when they arrive. They checked mine and said it was fine anyway, but offered to keep it on charge to double-check. Apparently they can tell whether a cell is faulty even though the charge stays high.

When I went to collect it today the young man who served me had the sense to check it again first, and he discovered it wasn't holding its charge as it should. Would I like my money back or wait until a new one appears from somewhere? My mechanic says he can get me one, so I got my money back. If nothing else, I've had 18 months of free Battery power. Hopefully the new one will sort everything.

Bluesman · March 3, 2021

25 minutes ago, Scribe said:

Update: returned the battery to Halfords, who don't have a replacement in stock and can't order one - they just arrive when they arrive. They checked mine and said it was fine anyway, but offered to keep it on charge to double-check. Apparently they can tell whether a cell is faulty even though the charge stays high.

When I went to collect it today the young man who served me had the sense to check it again first, and he discovered it wasn't holding its charge as it should. Would I like my money back or wait until a new one appears from somewhere? My mechanic says he can get me one, so I got my money back. If nothing else, I've had 18 months of free battery power. Hopefully the new one will sort everything.

Are you leaving your phone switched on all night while its parked up, I had the same problem a few years back and it was because of leaving the phone switched on.

Herbie · March 3, 2021

5 minutes ago, Bluesman said:

Are you leaving your phone switched on all night while its parked up, I had the same problem a few years back and it was because of leaving the phone switched on.

So how does that work then?

The phone may be on but if the car is off then there's nothing for the phone to interact with, ie, no Bluetooth, wifi or anything else for the phone to have a connection with.

NemesisUK · March 3, 2021

The car may be off/locked but the phone sub-system may remain active whilst the phone is within range? Something similar in the two Mercs I had.

Bluesman · March 4, 2021

On 3/3/2021 at 6:38 PM, Herbie said:

So how does that work then?

The phone may be on but if the car is off then there's nothing for the phone to interact with, ie, no Bluetooth, wifi or anything else for the phone to have a connection with.

All I can say is that the phone left in the on position in the cradle will drain the Battery. Once I took the phone off the cradle problem with drained Battery stopped and its never been a problem since.

Scribe · March 5, 2021

That makes sense, but I've never used the phone cradle in the car. At one point I thought about removing it, then decided to leave it for the sake of 'originality'.

BigBoomer · March 5, 2021

If you suspect the boot light is staying on, start recording video with the selfie camera on your smartphone, put it in the boot, close the boot.
On playback you will soon see if the boot light goes out when the boot is closed.
A 5Watt boot light will draw 400mA and will flatten a 70Ah Battery completely in just over a week.
You won't be able to start the car after just 2-4 days depending on Battery age and condition.

If you only ever make short runs, they are often not enough to recharge the power you use starting the engine, so over time the Battery progressively gets lower.
You need to be driving for at least 15 miles (just sitting on tick-over is not good enough) to recharge what is used starting the engine.

Scribe · March 13, 2021

Took me a while to sort out a new Battery, but I've just put it on. Positive terminal connected first, and as soon as the negative one made contact there was the sound of clicking coming from somewhere inside the car, so I knew we had power again. This didn't happen when I reconnected the old Battery after charging, so it seems like it really was knackered. Followed George's suggestion and recorded the boot closing and opening from inside, and the light goes on and off as it should. I'm going to wait till tomorrow to check the car starts okay.

Las Palmas · March 13, 2021

Good luck with new Battery.

Of the many reasons to like Lexus: cars more than 20 years are still going strong.

One here for sale for 2600 Euro has more than 300000km on it.

Quality is quality.

royoftherovers · March 13, 2021

11 minutes ago, Las Palmas said:

Good luck with new battery.

Of the many reasons to like Lexus: cars more than 20 years are still going strong.

One here for sale for 2600 Euro has more than 300000km on it.

Quality is quality.

That is as maybe John, but it is only 186,000 miles !

My Merc is on 247,000 miles. Old quality is quality.

Herbie · March 13, 2021

On 3/4/2021 at 7:16 PM, Bluesman said:

All I can say is that the phone left in the on position in the cradle will drain the battery. Once I took the phone off the cradle problem with drained battery stopped and its never been a problem since.

Aha, right, I get it now. It was connected electrically so the car was powering the cradle and the phone in it, but not interacting with it in a Bluetooth/call/music sort of way.

MLW · March 27, 2021

Had a big drain down on my 430 recently. Had a brake fluid change and wanted to check they had done it correctly. Opened the bonnet and accidently opened the boot. The latches are close. Two days later the Battery was really really dead.....nothing. I also could not close the boot.

Had to disconnect the Battery from the car and charge it. It look days on a trickle charger, but then all OK. The boot then closed when electrical power was sorted out.

Malc · March 28, 2021

22 hours ago, MLW said:

The boot then closed when electrical power was sorted out.

modern cars can sure have too much silly technology ........ closing the boot manually............ can't often need super technological electronic assistance ( for most people ) :unsure:

That's where our old fashioned, low tech but super doopa Ls400s come into their own I guess

Malc

Tulpen · March 28, 2021

2 hours ago, Malc said:

modern cars can sure have too much silly technology ........ closing the boot manually............ can't often need super technological electronic assistance ( for most people )

That's where our old fashioned, low tech but super doopa Ls400s come into their own I guess

Malc

And those TV remotes.......what a waste of time.......too much silly technology! 😁

Malc · March 28, 2021

OMG ............ your Ls460 has a TV .......... with remote ?

Malc

BigBoomer · March 29, 2021

17 hours ago, Malc said:

modern cars can sure have too much silly technology ........ closing the boot manually............ can't often need super technological electronic assistance ( for most people )

That's where our old fashioned, low tech but super doopa Ls400s come into their own I guess

Malc

Now don't start off a 400 vs 430 war.
You know you're gonna lose that one.
Way more 400 threads on here than 430 threads but then they are older and less capable. :boxing: 🤣