charging problem or not

[para999]

 i have a 2021 UX 250H fsport with very low mileage for the year. owing to the fact on occasions my car stands for a while unused and i have to use a boost pack to start it. i have a question about the slave Battery. i know where its located in the car and the procedure for using a boost pack to start it via the adapter in the fuse box.

my question is how do i know the slave Battery is being charged from the engine once the car is started and also the state of the Battery at any one time, there is no way of telling, as when driving the pictograph shows when the hybrid Battery is charging but not the slave Battery.

i need to point out that i am unable to park my car near to my front door to allow trickle charging and to remove and reconnect the slave would be a right pain.

[Moleman]

2 minutes ago, para999 said:

 i have a 2021 UX 250H fsport with very low mileage for the year. owing to the fact on occasions my car stands for a while unused and i have to use a boost pack to start it. i have a question about the slave battery. i know where its located in the car and the procedure for using a boost pack to start it via the adapter in the fuse box.

my question is how do i know the slave battery is being charged from the engine once the car is started and also the state of the battery at any one time, there is no way of telling, as when driving the pictograph shows when the hybrid battery is charging but not the slave battery.

i need to point out that i am unable to park my car near to my front door to allow trickle charging and to remove and reconnect the slave would be a right pain.

As far as I am aware, the answer is no, there is no way of telling the state of the start Battery (from within the car). Other third party equipment can be added to measure this.

If you are not using the car at least weekly, Lexus recommend running the car in park for at least one hour, to ensure the start Battery is charged. During this time the hybrid Battery will charge the start Battery.

If you cannot trickle charge, then the car needs to be used as described above as minimum.

[para999]

1 minute ago, Moleman said:

As far as I am aware, the answer is no, there is no way of telling the state of the start battery (from within the car). Other third party equipment can be added to measure this.

If you are not using the car at least weekly, Lexus recommend running the car in park for at least one hour, to ensure the start battery is charged. During this time the hybrid battery will charge the start battery.

If you cannot trickle charge, then the car needs to be used as described above as minimum.

thanks for your reply i have owned 3 lexus's in the past this being the fourth and this is the first time i have heard of and been told about this lexus recommendation. doing what they suggest would be a bit difficult for me for reasons i won't go into, but at least i know now.

[royoftherovers]

1 hour ago, para999 said:

thanks for your reply i have owned 3 lexus's in the past this being the fourth and this is the first time i have heard of and been told about this lexus recommendation. doing what they suggest would be a bit difficult for me for reasons i won't go into, but at least i know now.

Had 3 Lexus and not read any of the Handbooks, Para ?

[royoftherovers]

1 hour ago, Moleman said:

As far as I am aware, the answer is no, there is no way of telling the state of the start battery (from within the car). Other third party equipment can be added to measure this.

If you are not using the car at least weekly, Lexus recommend running the car in park for at least one hour, to ensure the start battery is charged. During this time the hybrid battery will charge the start battery.

If you cannot trickle charge, then the car needs to be used as described above as minimum.

The car not entering the READY state might be an indicator Maurice ?

[RXtoNX]

1 hour ago, Moleman said:

 

If you are not using the car at least weekly, Lexus recommend running the car in park for at least one hour, to ensure the start battery is charged. During this time the hybrid battery will charge the start battery.

 

So in effect Lexus are saying that their cars are not suitable if you plan to leave them at an airport for 2 weeks whilst you go on vacation?

Really 🤔, not in my experience🙄

[Herbie]

1 hour ago, RXtoNX said:

So in effect Lexus are saying that their cars are not suitable if you plan to leave them at an airport for 2 weeks whilst you go on vacation?

Really 🤔, not in my experience🙄

 

3 hours ago, para999 said:

thanks for your reply i have owned 3 lexus's in the past this being the fourth and this is the first time i have heard of and been told about this lexus recommendation.

@para999 - maybe a hybrid is not the car for your useage pattern if you can't or don't use it enough.

The problem is that it isn't a problem. It's not a fault as such; there's nothing wrong so there's nothing to fix. If anything, it can only be classed as a design problem that probably shouldn't have made it off the drawing board. For whatever reason, Toyota/Lexus decided to fit low capacity 12V batteries and we have to live with the consequences.

First thing to say is that every time the Battery goes into a deep discharge then it sustains slight damage and a small amount of capacity is lost. In other words, when you first buy it the charger will cut out at 100% full. After a few deep discharges it may cut out at 80% full because the Battery can't accept any more charge.

Secondly, you can make a very rough calculation as to how long it will hold charge, but a lot of it is guesswork.

As an example, we'll say that we have a brand new and fully charged Battery of 50Ah capacity. That means that it can supply 50A for one hour, or 25A for two hours and so on.

All cars have a quiescent current drain when they aren't being used, which is to keep such things as the alarm, the radio presets, the seat memories and so on, alive. As a general rule of thumb, around 50mA (0.05A) is considered to be normal.

So, 50Ah divided by 0.05A = 1,000 hours from fully charged to fully discharged. That's 41.6 days or 5.94 weeks.

However, in reality, your Battery will not be brand new and fully charged and also, for the purposes of starting the car, it won't be able to do that well before it reaches full discharge. This means that you won't get anywhere near the 1,000 hours/41.6 days/5.94 weeks before it becomes useless.

 

[para999]

3 hours ago, royoftherovers said:

Had 3 Lexus and not read any of the Handbooks, Para ?

were you born being sarcastic or is it something you have grown into. i wouldn't be asking if i had looked and couldn't find it ! also i have only recently retired so not come across this situation before as the car was used regularly. is that ok with you. don't bother replying as your replies are meaningless to my question.

 

 

[para999]

1 hour ago, Herbie said:

 

@para999 - maybe a hybrid is not the car for your useage pattern if you can't or don't use it enough.

The problem is that it isn't a problem. It's not a fault as such; there's nothing wrong so there's nothing to fix. If anything, it can only be classed as a design problem that probably shouldn't have made it off the drawing board. For whatever reason, Toyota/Lexus decided to fit low capacity 12V batteries and we have to live with the consequences.

First thing to say is that every time the battery goes into a deep discharge then it sustains slight damage and a small amount of capacity is lost. In other words, when you first buy it the charger will cut out at 100% full. After a few deep discharges it may cut out at 80% full because the battery can't accept any more charge.

Secondly, you can make a very rough calculation as to how long it will hold charge, but a lot of it is guesswork.

As an example, we'll say that we have a brand new and fully charged battery of 50Ah capacity. That means that it can supply 50A for one hour, or 25A for two hours and so on.

All cars have a quiescent current drain when they aren't being used, which is to keep such things as the alarm, the radio presets, the seat memories and so on, alive. As a general rule of thumb, around 50mA (0.05A) is considered to be normal.

So, 50Ah divided by 0.05A = 1,000 hours from fully charged to fully discharged. That's 41.6 days or 5.94 weeks.

However, in reality, your battery will not be brand new and fully charged and also, for the purposes of starting the car, it won't be able to do that well before it reaches full discharge. This means that you won't get anywhere near the 1,000 hours/41.6 days/5.94 weeks before it becomes useless.

 

thanks for your reply but i have recently retired and as the car was used daily before this point i had never come across this situation before.

as for changing my car just because i am not using it as much as i did before. having only just finished paying for it and not in the position to afford to change it,i wont be changing it.

having worked for the AA for 10 years before retiring i have not come across this situation before either. this is the reason i was asking advice.

[Herbie]

1 hour ago, para999 said:

thanks for your reply but i have recently retired and as the car was used daily before this point i had never come across this situation before.

as for changing my car just because i am not using it as much as i did before. having only just finished paying for it and not in the position to afford to change it,i wont be changing it.

having worked for the AA for 10 years before retiring i have not come across this situation before either. this is the reason i was asking advice.

That's fine, no worries, but now that you know the cause you only really have two choices and that's either to use the car more or to run it for an hour when stationary and in Park.* Of course, the main problem with the latter is that you have to stay close by or even in the car (read a newspaper or whatever) or someone could drive away in it. I do the same when I'm defrosting snow/ice but I leave my big old steering wheel lock in place so that I can go back in the house.

*I suppose a third choice is just to continue on as you are and keep jump starting it.

[Moleman]

5 hours ago, royoftherovers said:

The car not entering the READY state might be an indicator Maurice ?

Okay John, I will give you that one.

[tedd]

Something like this might help to give advance warning. 
Battery Monitor, 12V Car Battery Monitor Tester BM2 Device Leisure Battery Tester Compatible with Android iOS and Ipad with Bluetooth 4.0 and Above https://amzn.eu/d/8lj9pPI

 

gives a decent view of the state of charge via an app. 

[Moleman]

5 minutes ago, Moleman said:

Okay John, I will give you that one.

But at that point too late.

[ColinBarber]

7 hours ago, para999 said:

my question is how do i know the slave battery is being charged from the engine once the car is started and also the state of the battery at any one time, there is no way of telling, as when driving the pictograph shows when the hybrid battery is charging but not the slave battery.

It's no different from any other vehicle in that you don't truly know your Battery is being charged. All you know is the 12v system is being fed 14+v from the alternator, or DC-DC converter in the case of a hybrid, which will extinguish the Battery warning light. In the case of the UX you would get the following warning if the 12v line was low and therefore not charging the battery:

 

Unfortunately the UX doesn't have the Battery Guard feature as part of the Connected Services which all the other models from around 2020 onwards have. This gives you a reading of the 12v Battery from the mobile app and gives an alert if low.

The Bluetooth Battery monitor suggested by Ted above is only way to get that functionality, although your phone needs to be near the car to receive the signal.

[LenT]

5 hours ago, para999 said:

having worked for the AA for 10 years before retiring i have not come across this situation before either. 

You don’t say in what capacity you worked for the AA, but I believe they sell a couple of solar panel chargers.  As a conventional trickle charger is not practical, is it possible that one of these - or some other brand - might produce enough to keep the small capacity Battery charged?

[para999]

just want to reply to say.the reason i asked the question in the first place as having not come across this situation before i was thinking somebody may have come across this problem before and maybe had a solution like fitting a larger capacity Battery or some other shortcut. that is the idea of a forum to share experiences which i have found very useful on other forums when i have owned different makes of car.thankyou to all those that have come up with sensible suggestions. will leave it there.no more replies.

 

 

[para999]

will the mods now close this thread thanks

[hieronymous]

Threads like this one are valuable for any Lexus owner new to hybrids, not just the OP.

I also recommend the BM2, see @tedd's post above - on my IS300h, Kona EV and house generator. The Bluetooth range is limited to about 10m, but I can easily check all 3 over morning coffee with the phone app.

Regular (daily) checking is the answer to small Battery issues, and the BM2 is a great solution. In a decade of hybrid/EV ownership, I've never been caught out...

[ALAW]

6 hours ago, Herbie said:

That's fine, no worries, but now that you know the cause you only really have two choices and that's either to use the car more or to run it for an hour when stationary and in Park.* Of course, the main problem with the latter is that you have to stay close by or even in the car (read a newspaper or whatever) or someone could drive away in it. I do the same when I'm defrosting snow/ice but I leave my big old steering wheel lock in place so that I can go back in the house.

*I suppose a third choice is just to continue on as you are and keep jump starting it.

Herbie i was going to start a thread similar. I have a bit of 12v Battery anxiety. My UX will be left at the airport for 10 days on my return will the car start. Unlike Para i do drive practically every day and about once a week it will have an hours run. Someone above reckons it should be ok. What you reckon. 

[stepppy]

My local Toyota dealer sells a solar trickle charger for just this purpose. I think it was around £90.  They have flyers for them on all the waiting room tables. 
 

I am fortunate that my car is garaged, so can use my smart charger every now and then, but the solar charger may be a good option. 

[Herbie]

12 hours ago, ALAW said:

Herbie i was going to start a thread similar. I have a bit of 12v battery anxiety. My UX will be left at the airport for 10 days on my return will the car start. Unlike Para i do drive practically every day and about once a week it will have an hours run. Someone above reckons it should be ok. What you reckon. 

In theory it should be fine Brent, but the caveat is that I don't know the current state of your Battery so I can't guarantee it.

To remove all anxiety and give peace of mind I always carry a unit similar to this one. Never had to use it on my own car yet but it's started at least a dozen others and works first time, every time.

[Herbie]

@tedd does that Battery monitor just work as a basic voltage meter or does it work as a load tester and stress the Battery?

I was just idly thinking that if it's the former and it only shows the standing voltage, then it's thirty quid for a single-trick pony that does nothing else. Of course, it may well be brilliant at that one thing that it does and that's fair enough, but if anyone's interested, there may be an alternative to that.

For just an extra fiver (admittedly plus £60/year for the SIM) the Rewire DB2 Tracker shows Battery voltage along with a whole host of other things, as well as tracking the car and monitoring other parameters. This screendump is from my desktop PC but there are Android and apple apps for use on phones and tablets.

[Las Palmas]

On 1/17/2023 at 10:55 AM, para999 said:

my question is how do i know the slave battery is being charged from the engine once the car is started and also the state of the battery at any one time, there is no way of telling, as when driving the pictograph shows when the hybrid battery is charging but not the slave battery.

Instead of running the car in park, I would drive around and enjoy the car an hour or 2 weekly. Just do not need that as using it almost every day. I believe the little 12V Battery is handled well by the computer in the car and charged enough if used regularly. Have once been away a week and no problems starting and yearly service is supposed to keep an eye on things and inform if something is not OK. If they do - ???

[para999]

47 minutes ago, Herbie said:

@tedd does that battery monitor just work as a basic voltage meter or does it work as a load tester and stress the battery?

I was just idly thinking that if it's the former and it only shows the standing voltage, then it's thirty quid for a single-trick pony that does nothing else. Of course, it may well be brilliant at that one thing that it does and that's fair enough, but if anyone's interested, there may be an alternative to that.

For just an extra fiver (admittedly plus £60/year for the SIM) the Rewire DB2 Tracker shows battery voltage along with a whole host of other things, as well as tracking the car and monitoring other parameters. This screendump is from my desktop PC but there are Android and Apple apps for use on phones and tablets.

can i just say i have been using a jump pack but the problem is that once you put it on the alarm goes off and will not stop until there is a certain amount of charge to be able to press the lock and unlock button for the doors. that is owing to the fact that i have to use the emergency key to open the doors in the first place. this takes time of course and i don't think the neighbours would appreciate me doing that too often.i have decided to go for the bm2 which is on offer at £20. worth a go.

[tedd]

1 hour ago, Herbie said:

@tedd does that battery monitor just work as a basic voltage meter or does it work as a load tester and stress the battery?

It monitors Battery voltage both in the short term and longer term so you can see any discharge over a period of time. The ‘strange’ readings from yesterday were because I was washing the car with doors/windows open and closed, and moving the car in and out of the sun. 
Yes, it’s a bit of a one trick pony as it does have tests for cranking voltage and charging but the cranking voltage is a waste of time on a hybrid, and the charge test is pretty obvious if you look at it with the ignition on. 
Works well for me though as I can get a reading from the front room/bedroom. 
For me, the only ‘proper’ way to test a Battery is with a high rate discharge tester on a fully charged Battery - which I have. I also have a Foxwell Battery tester which injects an ac current into the Battery to test the impedence. Not as accurate imho, but can give a reasonable guide to the general condition of the Battery 👍🏻👍🏻