Battery

[Russell Wheeler]

Sure this will have been covered but could not find anything obvious. I have just been bequeathed an RX400h (2006), and when I got it the Battery was completely flat. I have disconnected the Battery and when you leave it and check, it holds charge. When connected to the car it only seems to last a couple of weeks before going dead. Do these cars suffer from a parasitic drain ?  - I can see that the Battery is far too small,   - Is there a replacement Battery that holds more power ? - It seems to only need to "boot" the computer system before the hybrid batteries take over.

[Herbie]

Hi Russell and welcome to the club.

You are quite correct, the batteries are quite small but that's how the cars are designed and there's nothing wrong or any problem with anything.

A conventional car has a starter motor that will draw more than 300A when it's cranking the engine so the Battery has to be fairly big and beefy to cope with that.

Our hybrids don't have starter motors as such and it only takes less than 20A to boot the computers, pressurise the brakes and get the hybrid system into READY mode, which is the equivalent of a conventional car having been started and just sitting there idling.

This benefits the manufacturers in a couple of ways:

1. The Battery can be much smaller in both physical size and capacity so there's a cost saving there
2. Smaller Battery weighs less, which helps keep the overall weight of the car down, which helps to keep emissions down to the ever-lowering limits set by various governments

To us as the owners of an individual car it doesn't make much difference, but when you scale it up to hundreds of thousands of cars, you begin to see the logic in their decision.

The only downside to us is that small batteries will go flat quicker than a larger one would, so we just have to either use the car more or if you don't actually want to move it, Toyota's advice during the lockdown is to have it in READY mode and 'Park' for about 60 minutes per week while you sit in it reading the paper or whatever.

As I said above this is the way the cars are designed, so quite a few of us on here carry one of these jump start battery packs or something similar in the car 'just in case' and they're well worth it for the peace of mind alone - they really do work superbly well. I decided to make a 'comfort' jump start point in the cabin so that if the weather was bad when I needed to do it, at least I'd be dry 😊

 

 

[Russell Wheeler]

Guess this would work then   - https://www.ebay.co.uk/itm/153977637146?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

At the moment I am sorting out some body damage, it can't be doing the Battery good to completely discharge it.

[Herbie]

13 hours ago, Russell Wheeler said:

Guess this would work then   - https://www.ebay.co.uk/itm/153977637146?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

At the moment I am sorting out some body damage, it can't be doing the battery good to completely discharge it.

Yes, it would do the job.

However, if you're a helpful sort of a person then I'd encourage you to get a bigger one with more capacity, closer to what I linked to above. You should never use a hybrid to jump start a conventional car (and the jury's out as to whether it's even alright to jump another hybrid) so if anyone was stranded and asked you for help, you would have to say no unless you had a bigger Battery pack.

I know I just wouldn't feel right if I had to refuse so I purposely got a much bigger one than I needed. Rather that than have it on my conscience that I turned someone away, but hey, that's just me - always been a soft touch

[PCM]

As... Herbie, my wife has discovered.

RX 450h goes 'dead' quicker than my old RX300.

She had to call Mr.AA, who arrived and thought it was my car with the issue, as they sit next to each other...

[Barry14UK]

Maybe be late but better than never, you should not allow a car Battery, especially one of the AGM (Absorbed Glass Matt)  Valve Regulated Lead Acid (VRLA) type fitted to later RX models with Battery in boot to go flat as this can seriously reduce the life of these small but expensive batteries. Another way to keep them adequately charged is to use a smart trickle charger with an amp rate not exceeding  5. and the most appropriate mode selected.  The most mentioned model is the CTEK 5 but of course there are many others. Using a higher powered charger can lead to gassing and blow out through the Battery vent, again shortening it's life.  The capacity of the Battery is small and needs to be checked every couple of weeks if car is not otherwise charged.  When it needs replacing the same type should be installed, usually only available through Lexus dealers.  The get out of jail solution Herbs suggests is a good emergency  solution but means Battery has been allowed to discharge too much but may still work but with a shortened life.

[Herbie]

3 hours ago, PCM said:

As... Herbie, my wife has discovered.

RX 450h goes 'dead' quicker than my old RX300.

I'm not surprised Piers. It's almost three years since we traded in our RX300 but if I remember correctly the Battery on that was about 75Ah capacity, whereas the Battery on my RX450h is about 45Ah.

[Zotto]

26 minutes ago, Herbie said:

I'm not surprised Piers. It's almost three years since we traded in our RX300 but if I remember correctly the battery on that was about 75Ah capacity, whereas the battery on my RX450h is about 45Ah.

AFAIK on my RX 12V Battery is 70 Ah... 

 

[Thackeray]

From what I've read on the internet, another reason the designers might have chosen to use an AGM Battery is that it tolerates deep cycling better than standard flooded lead acid batteries. That seems to mean that although the capacity might be smaller (45Ah instead of, say, 70) it can be run down more deeply without shortening its life than would be possible with a standard flooded lead acid.

This website says, "AGM offers a depth-of-discharge of 80 percent; the flooded, on the other hand, is specified at 50 percent DoD to attain the same cycle life."

I've no idea if that's correct. Maybe someone who knows about batteries can confirm whether this is right. (Just because it's on the internet doesn't mean it's true!)

[Herbie]

16 minutes ago, Zotto said:

AFAIK on my RX 12V battery is 70 Ah...

I was wrong earlier - mine is 51Ah:

[Barry14UK]

Yes 51Ah on mine too.  As I remember, the 45Ah is on the Prius.  Alternative suitable 45 Ah deep cycle batteries are available in the UK for the Prius but interestingly have a label saying the 5 year guarantee is void if the Battery falls below a specified  level, note on top of Battery. https://www.ebay.co.uk/i/25408899742

Unfortunately, the UK stockist will not stock the 50Ah version with the correct terminal layout unless we can order 200 units for our 3Gen RX.

If Lugi is correct that the 4Gen RX450h has a 70Ah Battery, he may be able to use the 75Ah version of the above 45Ah Battery which is at least stocked in the UK  when a replacement is required for his car if available where he is  Unfortunately, it is too long for the provided boot location in the 3rd Gen RX otherwise a 50% increase in capacity would be great.  https://www.ebay.co.uk/i/254370212679?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=254370212679&targetid=1000009159107&device=c&mktype=pla&googleloc=1006709&poi=&campaignid=10199418955&mkgroupid=101401893585&rlsatarget=pla-1000009159107&abcId=1145984&merchantid=7449214&gclid=CjwKCAiA2O39BRBjEiwApB2Ikka35jDV4OBcADrIC1XZOVXYuHrnTMLcPzsmPbaRsc5zuoJGGRXMRRoCZCUQAvD_BwE

[MrChemist]

On 11/23/2020 at 12:08 PM, Thackeray said:

From what I've read on the internet, another reason the designers might have chosen to use an AGM battery is that it tolerates deep cycling better than standard flooded lead acid batteries. That seems to mean that although the capacity might be smaller (45Ah instead of, say, 70) it can be run down more deeply without shortening its life than would be possible with a standard flooded lead acid.

This website says, "AGM offers a depth-of-discharge of 80 percent; the flooded, on the other hand, is specified at 50 percent DoD to attain the same cycle life."

I've no idea if that's correct. Maybe someone who knows about batteries can confirm whether this is right. (Just because it's on the internet doesn't mean it's true!)

My wife and I had Covid in March 2020, the car sat for over 2 weeks as my son brought us shopping.  The (original) Battery was down to 8V when I couldn't start the car, after a couple of hours (on my new Halfords charger) it was back to 13V and the car started, but it was down to 6V four days later and needed a day to fully charge (chargers are quoted at a maximum charge rate, mine is 6A, but they never just give full current for long, it's time that really helps.)

I had the dealer test the Battery at the service yesterday, but they reckon it's still OK (gave it an overnight charge first). It was also fine when I left the car in Southampton for 10 days last year, while we went on a cruise, but the 4-hour journey down there would have helped that. All credit to Lexus Sheffield for not picking the low-hanging fruit "You need a new one", but they know they can afford to wait, I have air suspension. 

Hope this helps someone.

[Farnham Dave]

On 11/22/2020 at 9:40 PM, Russell Wheeler said:

Guess this would work then   - https://www.ebay.co.uk/itm/153977637146?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

At the moment I am sorting out some body damage, it can't be doing the battery good to completely discharge it.

I bought an emergency jump starter recently (a little bigger than that one), and it works pretty well. Basically a rechargeable usb power pack, but with 12v clamps for car starting, too. Would link to it, but can't find where I bought it from.

My car's getting left for days or weeks at a time, and it drains the Battery regularly (I suspect that the Battery has now had it). So I've bought this Battery isolator switch: https://www.amazon.co.uk/dp/B019XQRHBG?ref=ppx_pop_mob_ap_share

FItting went smooth enough. I'm going to try the car tomorrow, and then at increasing intervals after that to see if it's stopped the drain. Updates to follow.

Yes, I could get into trouble for driving around for the sake of it (not that any one else seems worried about that!), but I'm buggered if I'm going to miss my vaccine spot because of a non starting car. 

[Herbie]

30 minutes ago, Farnham Dave said:

FItting went smooth enough. I'm going to try the car tomorrow, and then at increasing intervals after that to see if it's stopped the drain. Updates to follow

If it's been fitted correctly then yes, it will have stopped the drain - but it will also stop everything else too.

Every time you switch it back on you'll have to reset the windows, sunroof, radio, clock etc., and, of course, while it's off the alarm and immobiliser will be off too. These things are really meant for situations where you may be putting the car into storage for months on end.

[Madsod]

Hi Russell,

Sorry to hear you having problems with the small Battery fitted to the RX400H, when I had mine and following advice I found on this forum, I purchased an AA solar panel which comes complete with an OBD connector that allows you to plug the panel in to OBD connector mounted just under the dashboard on the drivers side.

it provides a constant trickle charge to the Battery and has a built in safety protection for the Battery to prevent overcharging. I used to rest mine inside my sunroof cover and the cable is long enough reach the OBD connector. I found it very effective when parked up regularly at an airport for 2-3 weeks and it never let me down, in fact I still use it now on my 450H due to lack of car usage during the  current pandemic.

You can find them on the internet at varying prices for around £25 -£45 and I think it provides a good alternative to a booster pack by preventing a flat Battery happening in the first place. (Subject to getting daylight of course)

hope that helps.

Regards

Kev

[elche286]

7 hours ago, Madsod said:

Hi Russell,

Sorry to hear you having problems with the small battery fitted to the RX400H, when I had mine and following advice I found on this forum, I purchased an AA solar panel which comes complete with an OBD connector that allows you to plug the panel in to OBD connector mounted just under the dashboard on the drivers side.

it provides a constant trickle charge to the battery and has a built in safety protection for the battery to prevent overcharging. I used to rest mine inside my sunroof cover and the cable is long enough reach the OBD connector. I found it very effective when parked up regularly at an airport for 2-3 weeks and it never let me down, in fact I still use it now on my 450H due to lack of car usage during the  current pandemic.

You can find them on the internet at varying prices for around £25 -£45 and I think it provides a good alternative to a booster pack by preventing a flat battery happening in the first place. (Subject to getting daylight of course)

hope that helps.

Regards

Kev

Bought the same. So far (finger crossed) 4 years (+'x' yrs before I bought it) the 12V Battery is going strong.

 

This is is mine:

 

[ColinBarber]

As the 400h has its Battery in the engine bay it gets dirty and subject to moisture. Definitely worth cleaning it every year to stop a resistive path being formed across the top of the Battery and adding to the drain. You can measure how bad it is with a voltmeter - I think I read over 1 volt once on my old 400h.

 

[Farnham Dave]

On 1/21/2021 at 4:54 PM, Herbie said:

If it's been fitted correctly then yes, it will have stopped the drain - but it will also stop everything else too.

Every time you switch it back on you'll have to reset the windows, sunroof, radio, clock etc., and, of course, while it's off the alarm and immobiliser will be off too. These things are really meant for situations where you may be putting the car into storage for months on end.

I'm aware of these as issues. Car is in for service at the moment. Looks like it's the ignition barrel and/or driver's courtesy light switch that's contributing to problems. Also, might be a problem with the ECU, but that's for another thread

[Russell Wheeler]

Had the car a couple of years now, and learnt to live with the Battery problem. Between April and October, a solar panel keeps enough charge in the Battery to not worry about things. In the winter, I use a Battery disconnect switch. The car lasts about a week if left with the Battery connected in winter. Any longer than that and you risk it not starting. I also carry a jump pack, so have not been stranded at all. It only gets used every few weeks for long journeys, I have a small hatchback for local running. Obviously my use of the car is not really compatible with how it was designed to be used.