Flat Battery

[stericker]

Hi all. Whenever I go away for a few days (maybe a week) the Battery (Lexus- two years old) is flat when I return, although I am

careful to turn everything off.

I am concerned about the alarm going off as the Battery runs down. Is there a way of securing the car (LS400 '99) without the alarm

or is it best to disconnect the Battery ? If the Battery is disconnected for a week what electrics might I lose ? I do not seem to have

a radio code. Because the radio is built in perhaps it doesnot need a code.

Thank you in advance for any advice.

[brendangeorge]

Hi all. Whenever I go away for a few days (maybe a week) the battery (Lexus- two years old) is flat when I return, although I am

careful to turn everything off.

I am concerned about the alarm going off as the battery runs down. Is there a way of securing the car (LS400 '99) without the alarm

or is it best to disconnect the battery ? If the battery is disconnected for a week what electrics might I lose ? I do not seem to have

a radio code. Because the radio is built in perhaps it doesnot need a code.

Thank you in advance for any advice.

Hi Anthony

There is no radio code so you don't have to worry about that. The car

will drain the Battery if sat for a few days because of all the electronics - so

the best thing is to leave it connected to a Battery charger that has a float

charge function. CTEK are good and I use one. You can also put your

charger on a timer that runs it for say two hours a day - it is vital that you

do not over-charge the Battery or the water in the electrolyte will electrolyse

and the hydrogen and oxygen generated will be vented and could be a fire risk -

if you cause a spark when disconnecting the charger – also your Battery has

then had it because you have no way to refill it with water. The possible

venting of gas is why you are told to disconnect the Battery before charging but

this does not help if you do not remove it to another room –

just ventilate your garage and you will be fine.

Some people sell Battery tenders that will provide the float charge function

– I think this is just another (American?) name for a float charger.

If you do not have a garage and cannot use the charger method there are

solar solutions available (assuming the sun shines).

It sounds as if you are thinking about removing the Battery from the car and

charging it separately while you are away – while all the hand books say you

should do this – I do not believe it is necessary and I never do – note this

comment does not mean I accept any liability for you blowing anything or

yourself up because I know nothing J

I hope this helps.

Good luck

Bren

[stericker]

Many thanks Bren. Good to know about the radio code. I have a Battery booster pack (always fully charged)

so I was thinking of just disconnecting the negative (correct ?) and reconnecting on my return and using the

booster pack. Does that make sense ?

[brendangeorge]

Many thanks Bren. Good to know about the radio code. I have a Battery booster pack (always fully charged)

so I was thinking of just disconnecting the negative (correct ?) and reconnecting on my return and using the

booster pack. Does that make sense ?

Hi Anthony

What you are suggesting will work but I would caution against it. You car Battery is not designed to be discharged (flattened) to do so regularly will shorten its life. Car batteries are designed to provide a lot of current for a short time (during cranking) and not to be discharged deeply - depth of discharge and number of charge discharge cycles determine the Battery life. This is why float charging should be used when not using your car for a period of time. Also you will still need to charge your Battery - unless you drive long distances - after you let if go flat.

If you keep it in a garage and can float charge it (CTEK charges are £30 to £50 on ebay) and your Battery could last 6 years vs a new Battery £100 (with a 3 year guarrantee. You can easily kill a Battery in 1 to 2 years.

Modern cars can be a pain because they are full of electronics (I am an electrical and electronics engineer :))

Cheers

Bren

[cruisermark]

the Mark 4 satnav/radio/cd can have a code if it has been set by the previous owner - you can find this out by going into the settings menu - but the fact you have had flat Battery and haven't mentioned any problems with the stereo means the there is no code set

[ambermarine]

Sorry Brendanorange if I contradict you I have a 98 Mark4 and it as a radio code in fact it not only controls the radio but the satnav also .

It seeems that when I bought my spare centre console with Screen and Audio The reason It was cheap was the code had been lost .There is a thread on the forum that instructs the retreval of the code by pressing various buttons and indicator stork.

I would check your users handbook before dissconecting the Battery Anthony.

I too use a smart charger as the security system flattens the Battery and cannot be switched off.

It took a while to find one that did'nt pack in after a couple of week The trick is to buy an heavy duty unit the 600ma units are not up to the job they cannot keep up with the recharge cycle as the Security system burns a fair bit of juice.

I ended up buying the type of charger that are used on golf carts the output being 1 amp.

[brendangeorge]

the Mark 4 satnav/radio/cd can have a code if it has been set by the previous owner - you can find this out by going into the settings menu - but the fact you have had flat battery and haven't mentioned any problems with the stereo means the there is no code set

Amazing Mark - I had two MK4s and did not know there was a code function. It would be really annoying to go to the trouble of knicking a Lexus stero etc and then finding out it needed a code. I don't think the 430 has a code but what would I know I have only owned it for 11 years :)

Cheers

Bren

[brendangeorge]

Sorry Brendanorange if I contradict you I have a 98 Mark4 and it as a radio code in fact it not only controls the radio but the satnav also .

It seeems that when I bought my spare centre console with Screen and Audio The reason It was cheap was the code had been lost .There is a thread on the forum that instructs the retreval of the code by pressing various buttons and indicator stork.

I would check your users handbook before dissconecting the battery Anthony.

I too use a smart charger as the security system flattens the battery and cannot be switched off.

No sweat Amber - as can be seen from my reply to Mark I had two of the beasts and did not know about the code function. It does seem a redundant feature - especially when there is a crack available.

Cheers

Bren

PS does the anybody know if the 430 has a code function for the stereo/sat nav?

[cruisermark]

oh yes - one guy found out the hard and long way but got there in the end

http://evansweb.info/2007/04/18/forty-two-seventy

Not too sure wether the LS430 has one to be honest

[39buss]

On the LS400 MK3 (and,I believe, the MK1&2)the radio code is the last digits of the VIN number. Does this not apply to the newer models.

[Bluesman]

Took me 3 years to find a hidden tray for valuables under the passenger seat. Mike

[soundchaser100]

Took me 3 years to find a hidden tray for valuables under the passenger seat. Mike

Oh.... is that what that is.... by the way there should be a window sticker to warn would be thieves that the radio is coded.

Paul

[Bluesman]

Took me 3 years to find a hidden tray for valuables under the passenger seat. Mike

Oh.... is that what that is.... by the way there should be a window sticker to warn would be thieves that the radio is coded.

Paul

I'll have a look for that tomorrow. Mike

[brendangeorge]

Took me 3 years to find a hidden tray for valuables under the passenger seat. Mike

Oh.... is that what that is.... by the way there should be a window sticker to warn would be thieves that the radio is coded.

Paul

I'll have a look for that tomorrow. Mike

You may want to include a link on how to remove the radio - when they see it takes more than 30 secs they will p%ss off and rob somebody else.

Bren

[Chris Skelton]

If you keep the car in a garage, why set the alarm?

I found that, if I used the key to lock the car -not the Plip - then the Alarm wasn't set and the Battery didn't drain as fast. (Ser 4)

The Trickle charge things usually plug into a Cig socket. But when the car is switched off, so is the socket?

I fancied a Solar one once, but never got one because of this.

DO people steal Lexus?

[eurotrotter]

Hello Brendan,

I have the same problem,no garage and go away with work for 2/3 weeks,i have just put on Saturday a new 95amp Battery so i thought i would go down the solar panel route,I went Maplins to get one the guy asked what is the drain ampage ? because pointless to get 1.5 amp charger if its losing 2amps, so he said check with Lexus, so this afternoon did just that but the service guy and 2 techs didn't know. So the big question is do you or anyone on here know the answer ???

Regards,

Alan

[soundchaser100]

Hello Brendan,

I have the same problem,no garage and go away with work for 2/3 weeks,i have just put on Saturday a new 95amp battery so i thought i would go down the solar panel route,I went Maplins to get one the guy asked what is the drain ampage ? because pointless to get 1.5 amp charger if its losing 2amps, so he said check with Lexus, so this afternoon did just that but the service guy and 2 techs didn't know. So the big question is do you or anyone on here know the answer ???

Regards,

Alan

Get hold of a multimeter, set it to show current (amps), then disconnect the live of your Battery. Put the multimeter in series with the Battery terminal and the live (red) lead to the car circuitry. Lock the doors and the meter will show you how much current is being drawn by the cars electrics.

Paul

[ManicMark]

Get a solar charger & a couple of crocodile clips to connect direct to the Battery should do the trick.

[brendangeorge]

Hello Brendan,

I have the same problem,no garage and go away with work for 2/3 weeks,i have just put on Saturday a new 95amp battery so i thought i would go down the solar panel route,I went Maplins to get one the guy asked what is the drain ampage ? because pointless to get 1.5 amp charger if its losing 2amps, so he said check with Lexus, so this afternoon did just that but the service guy and 2 techs didn't know. So the big question is do you or anyone on here know the answer ???

Regards,

Alan

Hi Alan

I will try and check but it may be the weekend before I can - I don't think it will be anything like 2 amps - with the ignition on if I remember it draws 6 amps. If you go the solar route you will need to cable it on to the Battery (with an in-line fuse etc),

Cheers

Bren

[ambermarine]

The draw on the Battery is there wether the car is locked manually by the key or electronically by the fob .When the key is taken from the ignition the imobilisor sets in and it this that drains the Battery.The Mark 4 I bought last year had been fitted with a dash switch that was wired from the Battery through the cig/lighter plug so a solar panel could be used on the car without need of the ignition turned on for cig/lighter plug circuit.

I took it out as I don't like these indeterminable additions and how effective or detrimental they could be to the integrity of the car's wiring system.

As I have already posted, a 1 amp output smart charger as proved adequate connected direct to the Battery.

[eurotrotter]

Thanx guys iv'e gone down the solar panel route and crok clips, so as they say watch this space.

Alan

[Bluesbreaker]

Ambermarine

I agree with your comments, regarding what I would term "add ons" to what I would consider, a pretty sophisticated electronic system in the LS, (or any other Lexus, for that matter), call me old-fashioned, the thought of tinkering with it fills

[Bluesbreaker]

Pressed the wrong button..........

.....fills me with dread, I'd rather leave it well alone,-but then car-electronics intimidate the hell out of me, unlike the mechanical side.

[Parrot of Doom]

I've left my mk4 for longer than a week and it's started without any trouble. I'd check your Battery isn't on its last legs.

[brendangeorge]

The draw on the battery is there wether the car is locked manually by the key or electronically by the fob .When the key is taken from the ignition the imobilisor sets in and it this that drains the battery.The Mark 4 I bought last year had been fitted with a dash switch that was wired from the battery through the cig/lighter plug so a solar panel could be used on the car without need of the ignition turned on for cig/lighter plug circuit.

I took it out as I don't like these indeterminable additions and how effective or detrimental they could be to the integrity of the car's wiring system.

As I have already posted, a 1 amp output smart charger as proved adequate connected direct to the battery.

Having a bit of fun measuring the drain on my Battery

I just had a look at the current drawn from my 430's Battery. It has

been parked over-night after 160 miles yesterday. I used a clamp-on

ammeter on the -VE cable.

Ignition switch off 1.1 amps

Ignition switch to accessories 5.5 amps

Ignition on 17.5 amps

7.5 - 8 amps when running (charging the battery)

Not an exhaustive test but it seems to suggest you will need a float charger

that supplies around 1amp (which is nuts) and more importantly my 70 amp hour

Battery will only last for 70 hours if the car draws 1 amp while sat still -

also nuts. This means the ignition off number I measured is wrong - the

others look OK. From some digging around I saw the maximum permitted

drain is 200mA (I need to substantiate this) and 45 mA is reasonable but I need

to investigate more. It takes up to an hour for all the cars systems to

shut down and having the bonnet open (unless you wire round the bonnet open

switch) they never will which is why my ignition off number is wrong. So

I need to investigate more. If the car draws 100mA while sat still then

my 70Ah Battery will last for a month until flat - however the day before it

goes flat don't count on it starting your car. In the past I have had no

probs after two weeks with a decent Battery - after airport parking or holidays

etc.

From looking about there are plenty of bits and pieces, on the car, that

could fail and keep running after you switch off so if you have a decent

Battery and can't leave the car stood for two weeks it needs looking at

If anybody does connect a solar charger directly to their Battery they must

put a fuse in - note must not should - because a shorted charged car Battery

could deliver 400 Amps. Also a regulator of some kind would be a good

idea but if you have one of those 4 or 5 watt jobs it is hard to see how in

England you could over charge the Battery. In fact a solar charger is

likely to be ineffective because we never get any sun shine :)

Bren