Charging 12V Battery in the Lexus UX

[AL100]

I have a CTEK charger which I used with my previous car, a BMW, to keep the Battery topped up.  The BMW had the Battery in the boot, like the UX, and charging terminals under the bonnet which I could use to connect the CTEK charger and trickle charge the Battery.  The Lexus has a connector under the bonnet for jump starting and I have seen a video of somebody connecting a CTEK charger to that.  However, there is nothing in the manual to say whether this terminal can be used to trickle charge the Battery.  I would be grateful for any advice; initially my dealer said I could do this but then said he wasn't sure as Lexus Customer Services said they didn't think I could do it as the manual didn't say you could.  All very confusing and not very helpful.  Does anybody have a definitive answer on this?

[NemesisUK]

Personally, I would connect directly to the Battery in the boot. 

[ALAW]

AL100 I was concerned about the 12v Battery going flat the salesman at the dealer said as long as the car is driven it shouldnt be a problem. The Battery can be charged but be careful and the same if you want a jumpstart. There are two parts in the manual that discuss the 12v Battery i think the one that would help you starts on page 543 hope this helps.

Brent

 

[royoftherovers]

Good helpful post Brent. Handbooks can be a very useful source of invaluable information.

[ColinBarber]

7 hours ago, ALAW said:

AL100 I was concerned about the 12v battery going flat the salesman at the dealer said as long as the car is driven it shouldnt be a problem. The battery can be charged but be careful and the same if you want a jumpstart. There are two parts in the manual that discuss the 12v battery i think the one that would help you starts on page 543 hope this helps.

Brent

 

The problem is that the manual doesn't explicitly state the jump point can be used for charging, just to get the vehicle started in an 'emergency' situation. Elsewhere in the manual it states that the Battery should be disconnected from the vehicle before charging which means the jump terminal isn't going to work.

In reality the jump point is a direct connection to the 12v aux Battery (albeit via a 100+ Amp fuse) as this is the main connection to the vehicle's fuse box where all the 12v connections are fed from.

Personally I would use the jump point in the engine bay if I were to use a trickle charger as you can get the leads out of the vehicle without pressing again a seal and damaging it as with the boot hatch. But I wouldn't use a charger without an inline fuse as close to the +ve Battery terminal as possible. It is quite poor that the CTEK doesn't have this given that it is supposedly a quality product and that is capable of indefinite trickle charging - although very easy to fit one. You don't want a rodent chewing at the charging cables and shorting them together, effectively shorting your Battery.

[NemesisUK]

15 minutes ago, ColinBarber said:

Personally I would use the jump point in the engine bay if I were to use a trickle charger as you can get the leads out of the vehicle without pressing again a seal and damaging it as with the boot hatch. But I wouldn't use a charger without an inline fuse as close to the +ve battery terminal as possible. It is quite poor that the CTEK doesn't have this given that it is supposedly a quality product and that is capable of indefinite trickle charging - although very easy to fit one. You don't want a rodent chewing at the charging cables and shorting them together, effectively shorting your battery.

Just checked my CTEK charger direct connection kit and it does have an inline fuse in the +ve lead about 5cm from the Battery terminal eyelet.

Not sure if the boot seals on my CLS55 would be that different from those on a Lexus but I trailed the mains cable from the CTEK through the closed boot seal without issue for approx 4yrs.

[AL100]

Thank you for all the helpful advice.  I will check my CTEK charger for an inline fuse and if it has one I'll try using the jump point in the engine bay; otherwise I'll see if I can feed the cables out through the hatch and connect directly to the Battery. 

[Soham]

Hello everyone, 

I am new owner of UX and due to COVID, car is not driven much since the first lockdown started. I already have called AA 4 x times now due to flat 12v Battery. Can someone advice how do I charge 12v Battery in the boot and what kind of charger should I buy please.
sorry I am new to this type of issue and not a knowledgeable person in this area. 
thank you for your support in advance. 

[NemesisUK]

Get the CTEK 5 MXS maintenance charger (available from amazon ~£60)  and connect directly to the 12v Battery in the boot.

[royoftherovers]

18 minutes ago, NemesisUK said:

Get the CTEK 5 MXS maintenance charger (available from Amazon ~£60)  and connect directly to the 12v battery in the boot.

If you have a convenient 13amp power supply, or

just sit in the car, start it up,then read the Handbook for 30mins  each 5/6 days whilst it charges itself. It will switch itself on and off during this time,so just read on !

Or buy one of these  https://www.amazon.co.uk/NOCO-GB20-UltraSafe-Lithium-Gasoline/dp/B015TKPT1A/ref=sxin_8_sxwds-deals-bau?crid=3BDRLD20VFU44&cv_ct_cx=jump+starter+power+pack&dchild=1&keywords=jump+starter+power+pack&pd_rd_i=B015TKPT1A&pd_rd_r=0eeee464-d6fa-422d-a1d0-b2d8aed62e00&pd_rd_w=kkk6V&pd_rd_wg=8lC2O&pf_rd_p=14202638-f5d7-4aaf-a990-7819aeac1d41&pf_rd_r=GFK9R2E3B1D0E9HQV1N9&psc=1&qid=1604772232&sprefix=jump+start%2Caps%2C228&sr=1-2-52097d59-f253-4553-be63-55323b14096b

[AL100]

Hi Soham,

I have a CTEK 5 MXS charger and following the advice I was given above I have been charging my UX by connecting directly to the Battery in the boot.  That seems to work just fine and I haven't had any issues.  I fold the rear seats down, connect the charger and pass the cable out via the rear side door window.  I do have the luxury of leaving the car in my garage while I am charging the Battery so it is quite secure.  I may try using the jump starting terminal under the bonnet next time - as recommended by Colin Barber. 

[Soham]

Oh thank you very much. Your advice is really appreciated. 

[Artyone63]

Why won't the Lexus Technical Department just clarify once and for all if it is acceptable to use an 'Intelligent Trickle Charger' to keep the 12V Battery topped up during extended periods of the car not being used.

[Navnan2]

Not got my UX yet but is there any implied issue with this type of vehicle with infrequent use compared to a non-hybrid? I can see me having periods of time where its idle because I have more than one vehicle. The UX may not be used for a week or more on a regular basis. I never had problems with my petrol Insignias i had previously so just wondeing?

[EvilRacer329]

My guess? It would mean officially sanctioning customer go and dig up their Battery and connect stuff to it. If a customer dropped a screwdriver across the terminals, mis-wired a charger, or simply used a dodgy or broken charger and caused damage to themselves or their car, Lexus' endorsement of the procedure would be seized on by lawyers. Sadly anything customer-facing has to be designed with the lowest-common-denominator in mind, and there'd always be some idiot that would get it wrong and sue them.

Nick

[EvilRacer329]

I think you'll be fine Navnan - I also don't use my car for weeks on end sometimes. The hybrid Battery pack never lets itself discharge below 30% as far as I've been able to spot, and the 12v Battery isn't under any more of a parasitic draw than it is in any other car. If anything, the hybrid system is probably better at keeping the 12v Battery healthy, and as there's no traditional starter motor, the 12v Battery never has to do much in the way of heavy lifting. Its just there to power up the computers and bring the hybrid system online, and you could do that with a Battery a quarter of the size.

Nick

[Herbie]

I speak not as a Lexus technician or design engineer, nor in any official capacity whatsoever, but rather as a fully qualified, time-served electrician who, since completing my apprenticeship in 1978, has worked mostly in the maintenance and installation fields of both domestic and industrial electrics; spent most of my working career as a telephone engineer (cable jointer) on BT; and latterly self-employed doing computer repairs and bespoke builds, and whose hobbies include amateur radio (callsign G7IFM).

In other words, most of my life has been spent dealing with electrical and electronics systems.

I mean no disrespect to anyone but I really do think that a lot of people get hung up on this and overthink it to the nth degree, whereas it's really very simple.

12 Volts DC is 12 Volts DC in the UK, the USA, India, China and so on.

12 Volts DC is 12 Volts DC both at the back of the car (if the Battery is in the boot) and also at the front of the car if you want to utilise the dedicated jump start post.

12 Volts DC is 12 Volts DC whether it comes from the car Battery or a Battery charger, or a trickle charger, or the car's own alternator or DC/DC converter.

Trickle chargers can be connected to the Battery whilst it is still connected to the car. The clue is in the name, ie, trickle charger. It only supplies enough current to overcome the quiescent current draw of things like the clock, the radio presets, the alarm etc., and also the self-discharge rate of the Battery. Add all that up and it comes to far less than the Battery itself can supply so, in and of itself, a trickle charger cannot do any harm unless - and this is very important - it goes faulty in some way.

I would imagine that most, if not all trickle chargers, will have some sort of fail-safe mechanism to avoid any damage either to itself or to the car, but if something goes wrong I can take no responsibility - you do this at your own risk.

Just sayin'

[royoftherovers]

Thanks Herbie.

So as long as we buy wisely something that has the official kitemark or accreditation and is recognised professionally as something that is excellent at what it is designed for e.g. Cetek or similar ?

We should ignore relatively cheap equipment (s) which appear to offer value for money?

A bit like crossing the road really---i.e. look both ways!

[Navnan2]

1 hour ago, EvilRacer329 said:

I think you'll be fine Navnan - I also don't use my car for weeks on end sometimes. The hybrid battery pack never lets itself discharge below 30% as far as I've been able to spot, and the 12v battery isn't under any more of a parasitic draw than it is in any other car. If anything, the hybrid system is probably better at keeping the 12v battery healthy, and as there's no traditional starter motor, the 12v battery never has to do much in the way of heavy lifting. Its just there to power up the computers and bring the hybrid system online, and you could do that with a battery a quarter of the size.

Nick

Hi Nick, thanks for your feedback on this, very reassuring. Regards my delivery the Durban Highway has just exited the Suez canal into the Med and is due in to Livorno Italy on the 15th. So slowly getting closer!

[Herbie]

49 minutes ago, royoftherovers said:

So as long as we buy wisely something that has the official kitemark or accreditation and is recognised professionally as something that is excellent at what it is designed for e.g. Cetek or similar ?

We should ignore relatively cheap equipment (s) which appear to offer value for money?

I'm not really sure to be honest, John.

For instance, there's lots of stuff (not just talking about Battery chargers) out there without a kite mark or accreditation but it's very good and reliable.

Maybe the source could be as important as the item itself. We have a shop here in Preston that sells batteries for cars, trucks, golf carts, and mobility scooters amongst other things, and they also sell chargers. They are a great business to deal with and they've been trading for a long time, so I would be happy buying any item that they sell because I know they don't sell bad stuff. Is everything in there kite marked or accredited? I doubt it, but I'd still buy from them.

Like anything else from cookers to cars, TVs to fridges and beyond, you do the research and then 'you pays your money and you takes your chance', as the saying goes.

[royoftherovers]

Ok Herbie, I understand where you are coming from.Perhaps I was trying to be too simplistic?

"Exercise due diligence and be cautious" might have been more appropriate

[Herbie]

45 minutes ago, royoftherovers said:

Ok Herbie, I understand where you are coming from.Perhaps I was trying to be too simplistic?

"Exercise due diligence and be cautious" might have been more appropriate

Haha, yes, just got my mind on other things at the moment - having a patio awning fitted but it's not a straightforward job, so I'm just watching my mate working wonders 😊

[EvilRacer329]

Those of us who ride motorcycles are all-too familiar with Battery tenders. The big brands are Optimate and Oxford, both of whom do versions for car batteries and should be perfectly safe to hook up for months on end.

No idea what a 'Kite Mark' is, though... 🙂

Nick

[royoftherovers]

10 minutes ago, EvilRacer329 said:

Those of us who ride motorcycles are all-too familiar with battery tenders. The big brands are Optimate and Oxford, both of whom do versions for car batteries and should be perfectly safe to hook up for months on end.

No idea what a 'Kite Mark' is, though... 🙂

Nick

Thanks Nick.

A Kite mark is   https://www.google.com/search?q=kite+mark&oq=kite+mark&aqs=chrome..69i57.7625j0j7&sourceid=chrome&ie=UTF-8

[EvilRacer329]

Yup, I deserved that. 😄

It looks familiar, but I don't know that I've seen it recently. You learn something new every day!

Nick