12v Battery Monitor and Jump Starter pack (RX450h+)

TonyLexus · September 13

Any views and opinions please on...

(1) a 12v Battery monitor (something like this one https://www.ebay.co.uk/itm/295644935211), so charge can be monitored on the mobile phone

(2) recommending a jump starter power pack, specifically one for the Lexus RX450h+ (one of these maybe, https://www.amazon.co.uk/car-jump-start/s?k=car+jump+start)

Just for peace of mind....

Many thanks in advance!

ColinBarber · September 13

Both are fine. Just be aware that the Battery monitor works via Bluetooth to your phone, so you need to stand near the vehicle to get a reading.

Any booster will do, you don't need a high capacity one for the 450h+ - personally I like Noco products but those cheaper Chinese boosters work fine (aside from a concern about lithium ion Battery packs and safety - I'd store it at 80% capacity rather than 100%).

TonyLexus · September 13

Thanks Colin. Is any particular current required (they vary enormously) and any concern with a sudden charge, from power pack, of larger current than required? Excuse my ignorance here!

ColinBarber · September 13

1 hour ago, TonyLexus said:

Thanks Colin. Is any particular current required (they vary enormously) and any concern with a sudden charge, from power pack, of larger current than required? Excuse my ignorance here!

No, because the hybrid system doesn't start the petrol engine from the 12v system (it uses the hybrid battery). Therefore the 12v power pack really only needs enough power for the on-board computers (something like 20 amps) so the smallest one will do. You can use a larger capacity pack without issue, the car will only draw what it requires independent on what the pack could provide.

The only advice I give people is to purchase a pack with enough capacity for use with other cars in the household, or for helping a neighbour etc. e.g. if you wife has a large diesel car then get something that can support its requirement.

TonyLexus · September 13

TonyLexus · September 18

Took the Lexus to the dealership yesterday (for unrelated work). Showed them the Ancel Battery monitor and asked them to fit it whilst I was there. They would, but said also that the monitor running all the time would, in itself, be a drain on the 12v Battery, however slight. It would be my decision if I wanted them to go ahead and fit it. I've reserved decision on that at the moment...

As for the jump starter, they said they use them all the time, for cars that may have not been started for some weeks.

GSLV6 · September 19

Or just keep your Battery charged when car's not in use with something like a CTEK Battery conditioner?

TonyLexus · September 21

Thanks Paul. I think I'll get a Battery jump starter anyway, could come in handy elsewhere....

Thank you for replies!

Lexusjim · September 21

Tony

The drain on the Battery from a Battery monitor is very small.....somewhere in the region of 1.5mA.....providing you check it regularly, (once a week.?) I think it is a useful addition.

With luck, someone from the forum may give you the maths in relation to how long it will take to affect the Battery.

PeterI · September 21

I've been reading this thread over on the US forums and I'm wondering if we've been seeing the same thing in the UK

https://www.clublexus.com/forums/rx-5th-gen-2023-present/1019997-dead-12v-battery-incident-merged-threads.html

Sounds like a lot of this is keys / phone apps waking up the cars communication modules, but one thing I noticed is if you're going to use the "official" lexus grounding point you'll need longer leads.

Lexusjim · September 24

Excellent (and long) thread....looks to me like the problem is worse in the US..

TonyLexus · September 26

Colin wrote: ''....personally I like Noco products but those cheaper Chinese boosters work fine''

The Noco jump starters are made in China (!)

I bought the Noco GB40 which has somewhat short leads, which are fine for connecting direct to the Battery terminals, but where is the closest earth to the charging fuse that's under the bonnet? I'm told that some (all?) of the bolts close to the fusebox should not be used as they could cause serious damage (= fry?) the management system. The owners handbook does show an earth, for connecting the negative cable, about it's a metre or so away, at the other side of the car.

Herbie · September 26

54 minutes ago, TonyLexus said:

but where is the closest earth to the charging fuse that's under the bonnet? I'm told that some (all?) of the bolts close to the fusebox should not be used as they could cause serious damage (= fry?) the management system.

I'm afraid that that is just absolute codswallop (the board won't let me use the phrase I really want to :laugh: )

The negative Battery post is connected directly to the car body by means of a thick wire and a couple of braided earthing straps. This means that the entire body and any* clean, unpainted, screw, nut, bolt, bracket etc., whether that be at the front, back, top or bottom of the car, right next to or as far as possible from the fusebox, is a suitable point to use as a negative connection.

No harm will come to any of the car's ECUs or electronics unless you reverse the polarity of the leads. Even then, the small booster packs have inbuilt reverse polarity protection and should stop anything bad from happening.

I write this as a time-served, qualified electrician who, after the factory closed down went on to spend the vast majority of my working life as a telephone engineer and latterly, after a back injury, went self-employed as a computer repair technician. I'm also a licenced radio ham, callsign G7IFM. I tell you this not to be obnoxious or anything but just to make the point that I've been in the electrical/electronic field for more than 40 years and that I do have a bit of an inkling as to how these things work :thumbsup:

*The only thing to be wary of is that there will be some self-tappers around that only screw into plastic, which is obviously no good for this purpose; anything that screws into metal will be good to go.

Tom, · September 26

Well said Herbs - 73 G3OLB

TonyLexus · September 26

Hi Herbie

I know as much about electrics and electronics as I do about astrophysics (= zero), so bear with my ignorance. I found the following, which have been lifted from the North American 'Club Lexus' forum which didn’t help with my concern, on where to actually clamp the negative.

Please watch particularly the video which talks of other bolts not being suitable for use as earth:

(1) Quote:

Just tried my charger for first time and seems to work. I used the exposed bolt head just to the left of the positive terminal as per image. Regards-I HAVE NOW LEARNED THAT THIS BOLT IS NOT TO BE USED AS THE GROUND AS YOU CAN FRY YOUR ELECONTRICS.

(2) Quote:

Also, the service tech warned me about connecting the negative cable to the first bare metal bolt next to the positive terminal while boosting. According to him you can fry the electronics in your car by doing so. Lexus engineers really dropped the ball on this one. First they gave us a faulty Battery that keeps dying on you. Then they put the negative and positive terminals three feet away from each other so no conventional booster cables can reach them. If this wasn't enough, they put an exposed bolt head right next to the positive terminal that will fry your electronics if used.

(3) Quote:

Thanks for this information, I have been using the bolt for trickle charging my Battery, I will now stop doing this as I had no idea that I could fry the electronics! Here is a link that explains this bolt.

Regards

Tony

ColinBarber · September 26

7 hours ago, TonyLexus said:

Colin wrote: ''....personally I like Noco products but those cheaper Chinese boosters work fine''

The Noco jump starters are made in China (!)

I should clarify. Lot's of things are made in China, and that isn't necessarily a bad thing at all, but there is a difference between a well engineered product designed from a large established company with warranty and support staff available vs a unknown product that has been designed by an unknown source which dozens of unheard of companies brand with no real ability to get support or warranty and with little confidence that the safety standard logos printed on the product indicate that it has been designed and tested to meet those standards.

ColinBarber · September 26

2 hours ago, TonyLexus said:

Just tried my charger for first time and seems to work. I used the exposed bolt head just to the left of the positive terminal as per image. Regards-I HAVE NOW LEARNED THAT THIS BOLT IS NOT TO BE USED AS THE GROUND AS YOU CAN FRY YOUR ELECONTRICS.

That possibly isn't a great ground as the it looks like that bolt goes into plastic and/or is possibly using the ECU body and therefore the wiring connections to it rather than the vehicle body. Not sure it will fry anything but there are better connection points.

In that video the two possibilities are shown as arrows (assuming there is a nice non-painted metal bolt behind the bracket on the right).

This is a LHD vehicle so you may have to find another bolt that is going directly into the body. Avoid the bolts holding the suspension strut though, as they might not have a good electrical connection because of paint and the rubber mount used on the strut.