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The car started fine and before moving off I received an incoming phone call linked by BT to the car.
I stopped the engine but kept the phone link live using key position one.
Call lasted 8-10 minutes
Turn off ignition
Try to restart
Dead - does not even try to turn the engine
Attach small battery booster
Car starts as if it had a brand new fully charged battery
Suspects are battery and alternator BUT I do not understand how the car can change from a perfect, strong start to zero using only 10 minutes in key position 1. Then an instant start using a battery booster. There can be nothing such as a security system intervention etc because the car is perfect with the booster.
Hence my thoughts are that the battery has "some" power but that the voltage is depleted below a specific level. Does anyone have anything to share that might throw some light on this? I WILL get battery and alternator tested. Quick home test suggests they are OK.
I have a SType Jag. They are notorious for needing the battery at almost 12V at all times. If the voltage falls below ?11.5? the car will start but there will be error codes to clear. Anything like that with the Lexus?
What is the battery voltage with the engine off? Sounds like a classic battery post and terminal problem to me both should be meticulously cleaned don't assume they are clean. Also post a few pictures of the battery.
LeX2K - I think you may be spot on. Yesterday I left the battery on charge for a full day. I disconnected it to test the voltage just after charge and a day with nothing attached. I noticed that the earth terminal came off WAY too easily so I think we have found the fault. I'll go ahead and let the battery sit for a day to see if the voltage drops.
As for the age of the battery - I do not know. We have only had the car for 6 months. The previous owner said the battery was fairly new.
Since the signs and symptoms are 100% compatible with a loose terminal - going from full started motor to zero in a few minutes then reconnecting again when I attach the portable booster.
Thanks for your help. I'll update in a couple of days with voltage info.
It has been on charge overnight and the voltage is 13V. However the battery condition "bubble window" maybe black. Shine an LED on it and there is a glimmer of green. After 3 hours voltage is 12.4V
The Battery date code is KT0E12. I think that means made in May 2012 - so getting old.
Those terminals are in poor shape. Soak them in baking soda and water for awhile, then clean them with a maroon Scotch-Brite pad. Never, ever use the wire style battery post cleaners they remove way too much material and don't do a good job either. Also clean the battery posts with the Scotch-Brite pad. If that doesn't work then the battery is toast. 12.4 volts with a charger on it is no good either the charger is not working or the battery is not taking a charge.
Ideally replace the positive battery terminal with OEM and clean the terminals that bolt to it.
Yes - I wanted to isolate the battery to see what will happen if left for a day or two. Will it fall in voltage? Will it behave perfectly and hold charge?
Maybe someone has already stripped some "meat" off that post!
Brian
Could be. If the negative terminal still doesn't tighten down remove the nut and bolt (will be hard at the end of the threads, bolt is peened) and bend the ends of the terminal so it can close more.
My terminals also look like this. I bought new bolts from Amazon but if you get new terminals I think they will come with the bolt. [edit: Remembered, the ones I got from Amazon did not fit.]
I have had trouble with the battery, even after replacing it, but my problem is more related to only driving once a week or two. I did have a problem after replacing the battery with it dwindling way too fast and that turned out to be because we had not tightened the bolts enough.
I did clean mine up with baking soda, but the rust came back. I think I need to replace the more difficult one (the negative) to change. Does this require a crimping tool? Something I can learn from Youtube or better to add to the mechanic's list?
Last edited by Luv07RX350; 01-03-22 at 09:24 PM.
Reason: incorrect
Yes - I wanted to isolate the battery to see what will happen if left for a day or two. Will it fall in voltage? Will it behave perfectly and hold charge?
Brian
Generally if you disconnect a battery, it will hold the same charge for quite a while. Immediately after driving, it will have some surface charge that will drop over the next few hours. A new battery might show 12.6 or 12.7 after
after driving and then drop to 12.5ish after a few hours. If it drops to 11 within a day, then you likely have a damaged cell that will not hold charge. Doesn't sound like that is the situation. But if the max is 12.4 that battery has lost some capacity due to sulfation.
For all who may still be following this thread you may be interested to know it was solved.
NEW BATTERY!
What threw me was the fact that most of the time the battery tested OK.
Held charge and voltage for days
then it would start, travel 30 miles and go "dead" when trying to start.
Start car, drive 50 yards and goes "dead"
etc etc. Nothing consistent.
It seems there was an intermittent fault. We all know they are the worst!!
Regards
Brian ..... Whose next job is to sort out the air suspension. Yesterday it turned itself off and I cannot get it back. Jumps up and down like a jack Rabbit!
12-27-21, 07:22 AM
RX300 2005 Battery Problems Maybe
12.7 Volts
