2018 Hybrid 12v battery woes

[Adi8v]

I've had my rav4 hybrid in at the dealers twice over the last month as we have that scenario where it won't go in to ready every now and then. I can "jump" it from the terminals under the bonnet and then it will work fine. I've also been using a CTEK to make sure it is charged but it seems to die very quickly.

Anyway, yesterday they performed a Battery test using their Midtronics. It came back saying the Battery was good and gave a 'state of charge' of 12.68v.

Got the car back today and about 10 mins after I got in from a quick trip to the supermarket down the road I thought i'd stick my meter on and see what it says. So, with the car turned off, I opened the boot to get to the Battery and put my meter on it; 12.2v. Sounds a bit low doesn't it?

Then I turned the car on (ready) and measured again; 14.6v. That sounds ok from what i've read.

Then turned it off again. 12.7v that then dropped gradually over a few minutes back to 12.2v.

Then I did one more test where I put the meter such that I could see it with the boot closed. Closed everything, locked it and put the key back in the house; 12.2v again.

Does anyone with more battery related knowledge than me think that those measurements sound right?

Thanks.

[IanML]

It is pretty in conclusive trying to base a diagnosis purely on the voltage.  As suggested in the other post on this issue, you need to measure the current being drawn with a clamp meter.  That will show if there is a fault which manifests itself in an inappropriate current drain, which you can then then track down by removing fuses one-by-one.

[Adi8v]

Ok. Does anyone know which fuses are relevant to the 12v Battery?

[IanML]

All the fuses in the normal fusebox carry supply from the 12V Battery to services.  They should be listed in the Owners Manual with an illustration.

There are usually separate (i.e. not in the fusebox) fuses in yellow which protect the airbag system, and in orange for the high-voltage traction system.  Do not touch those.

You should do the fuse removals with the car switched off, whilst monitoring the current draw from the 12V Battery.  If there is no reduction of the draw when a fuse is removed, replace it.  When the draw significantly reduces, the last fuse you removed is connected to the service which is causing the excessive draw.

[ernieb]

I wish I had a manual that listed all the fuses. ☹️

[philip42h]

14 hours ago, Adi8v said:

I've had my rav4 hybrid in at the dealers twice over the last month as we have that scenario where it won't go in to ready every now and then. I can "jump" it from the terminals under the bonnet and then it will work fine. I've also been using a CTEK to make sure it is charged but it seems to die very quickly.

Anyway, yesterday they performed a battery test using their Midtronics. It came back saying the battery was good and gave a 'state of charge' of 12.68v.

Got the car back today and about 10 mins after I got in from a quick trip to the supermarket down the road I thought i'd stick my meter on and see what it says. So, with the car turned off, I opened the boot to get to the battery and put my meter on it; 12.2v. Sounds a bit low doesn't it?

Then I turned the car on (ready) and measured again; 14.6v. That sounds ok from what i've read.

Then turned it off again. 12.7v that then dropped gradually over a few minutes back to 12.2v.

Then I did one more test where I put the meter such that I could see it with the boot closed. Closed everything, locked it and put the key back in the house; 12.2v again.

Does anyone with more battery related knowledge than me think that those measurements sound right?

Thanks.

I don't claim any specific Battery related knowledge but your measurements sound fine and tell me precisely nothing about the fault ... 😉

• 12.2v seems a perfectly good resting voltage for a 12v Battery
• 14.6v seems a perfectly good charge voltage from an alternator or, in this case, from a feed from your traction Battery in Ready mode
• When you switch off, the charge voltage should drop away rapidly and I could well imagine a capacitor in the system discharging from 12.7v over a couple of minutes

You really need to measure the battery voltage when the car won't start - but there again it's probably going to be down around 11.5v (or something like that) indicating that the battery needs charging.

You may have a charge drain, over and above the car's electronic systems, in which case you should first look at anything added as an extra / accessory beyond the car's original spec.

It might also be helpful to measure the battery voltage morning and evening over several days when the car isn't otherwise being used - which may be impossible but ...

Failing that, just replace the battery with the biggest capacity battery that you can find that fits the spec for the car. While three years is really a pretty rubbish lifetime for a battery, the auxiliary batteries fitted to our hybrids are relatively low capacity and 'reasonably' cheap to replace ...

[ernieb]

Philip some good points as usual and totally agree about the HEV/PHEV AGM type batteries and having seen a few topics also with Battery issues I’d decided that if I had any issue I suspected was related to the 12v Battery and the car was around the three year mark  then I’d more than likely swap it out as the first line of action. This seems to be a topic that crops up not just with Toyota cars and Battery manufacturers seem to quote 3 to 5 years maybe longer if we’ll maintained (?). One of the critical things seems to not let the battery discharge to lower than 50% on a regular basis. I guess if the car is used regularly then that should not be an issue but if it was parked up on a regular basis or short winter trips then maybe that could be a potential weakness.

whatever, battery issues are a real pain and problematic to sort out.

[flash22]

The cells have reduced capacity, a dip in voltage will make the electronics freak out the cold snaps over the last month will kill a weak Battery + add in lockdown it will kill it off even quicker, If it's an AGM Battery it will be a deep cycle type these have very different characteristics compared to a lead acid, and the testing methodology is different they require a low (current <4a) and slow charge what can take 48 hours, a resting AGM should read 12.5 -12.8v at 75% charge, full charged 12.8 - 13.4 - typical charging voltages are 14.6 to 14.8, but can pull up to 16v if the cells are <20% charge

New Battery time

[roadster-rav]

Yes the figures are normal but indicate the Battery was at that time in a lowish state of charge. If you charge it fully with a good quality external charger it would probably take around 12 hours at an average of three amps to get close to fully charged. If you then read the voltage after it has stood for a few hours a good Battery would still read around 12.6 volts but if its reaching end of life it could drop back to 12.2 quite quickly even if there is very little drain. When a Battery reaches that state it can either be immediately replaced or it can be charged every few weeks to extend its life until its finally killed off at some indeterminate time in the future. If you want your new battery to last much longer then fully charge it when new and check it once per month and charge if necessary. Alternatively you can use a charger with a maintenance mode which remains plugged in whenever the car is not in daily use and this will consume at least 5 to 10 watts from your mains supply.

It is important to realize that, although in-car charging commences as soon as ready mode is on, the battery still requires many hours of charging to restore it from a near exhausted state because several factors affect the rate of charge provided by the cars electronic controls and the charge current will probably be far less than 10 amps once an initial recovery period brings the voltage up to the safe maximum. So it is the amount of time that the car is run which affects battery life rather than the distance covered or the speed ( which can even be zero as long as its in ready mode).

[Adi8v]

Thanks everyone for your input. The car has been stood since I posted this on Wednesday so pretty much 2 days without use. The Battery now reads 12.0v. This is after being fully charged by the dealer on Monday/Tuesday.

Wondering whether just to swap it for a new one to rule out it being a Battery on its way out. Any suggestions where best to source one besides the dealer?

Anything to look out for when swapping over or just unhook old and put in new?

Thanks.

[ernieb]

Adrian, time for a new Battery me thinks. 

[Catlover]

22 minutes ago, Adi8v said:

Thanks everyone for your input. The car has been stood since I posted this on Wednesday so pretty much 2 days without use. The battery now reads 12.0v. This is after being fully charged by the dealer on Monday/Tuesday.

Wondering whether just to swap it for a new one to rule out it being a battery on its way out. Any suggestions where best to source one besides the dealer?

Anything to look out for when swapping over or just unhook old and put in new?

Thanks.

Check out dealer prices, very often tyres and batteries they can be competitive. Personal experience.

[flash22]

If it's an AGM type' it is Yuasa or main dealer/eBay (oem is Yuasa) £120-150

[Roger_N]

I take it the dealer has refused to change it under waeeanty?

 

I think that’s what I would be pushing for 3 years is not long for a 12v Battery .

[Adi8v]

I suggested they changed it under warranty  but they said as they had done their midtronics test on the Battery and it came back as “good” they wouldn’t cover the cost of a new one.

[Roger_N]

Then approach it from the other way, the car is not starting intermittently so there is a fault, book it in and make sure they can give you a loan car. If they still say they can’t find an issue contact Toyota customer services and let them know the issue.

It may just be that the Battery spec needs changing as it is failing to soon, if you just change the Battery yourself and except the cost then thing won’t  change but if that’s what you want to do it fair enough but I would take the old one and get an independent test done on it, that way if it is faulty you could ask for a refund on the old Battery from the dealer.

[IanML]

At the risk of being repetitive, it is easy to assume that a Battery which loses voltage as described is on the way out, and it may well be true in this case, but placed against the test using professional equipment, it may well be wrong.  You have not eliminated the possibility that the car is drawing excessive current when off - if it is, it will do the same to a new Battery.  

Open the bonnet, close everything else, switch everything off, wait ten minutes and then put a clamp meter on one of the Battery cables, and read the current.  It is so easy and quick, no disconnections required.

[Roy124]

I think, and hope, that the near total lock down last year, and a probable lack of knowledge on Battery care at that time, knackered many batteries. 

Hopefully, with normal usage most batteries will not fail early. It will be interesting to see if mid 2020 cars, and those with new batteries since last year, also have issues. 

[roadster-rav]

8 minutes ago, IanML said:

At the risk of being repetitive, it is easy to assume that a battery which loses voltage as described is on the way out, and it may well be true in this case, but placed against the test using professional equipment, it may well be wrong.  You have not eliminated the possibility that the car is drawing excessive current when off - if it is, it will do the same to a new battery.  

Open the bonnet, close everything else, switch everything off, wait ten minutes and then put a clamp meter on one of the battery cables, and read the current.  It is so easy and quick, no disconnections required.

A properly equipped auto-electrician would certainly be able to do this but non-contact meters capable of accurately read down to milliamps are not cheap. 

[IanML]

31 minutes ago, roadster-rav said:

A properly equipped auto-electrician would certainly be able to do this but non-contact meters capable of accurately read down to milliamps are not cheap. 

Mine was about £25.  The offerings currently at that price may say ac/dc, but when you look closely, they do not do dc current.  This is much like mine, but is "reassuringly expensive" at £36.  Still, how many batteries you didn't need would you rather buy?

[Talshia]

This is from our overseas cousins.....

https://www.motorbiscuit.com/are-2019-and-2020-toyota-rav4-hybrids-suffering-battery-issues/

maybe of help / interest / or just a red herring !

I use a cetek charger to keep my car batteries topped up in these covid lockdown times.

Keep safe

Paul

[philip42h]

44 minutes ago, IanML said:

At the risk of being repetitive, it is easy to assume that a battery which loses voltage as described is on the way out, and it may well be true in this case, but placed against the test using professional equipment, it may well be wrong.  You have not eliminated the possibility that the car is drawing excessive current when off - if it is, it will do the same to a new battery.  

Open the bonnet, close everything else, switch everything off, wait ten minutes and then put a clamp meter on one of the battery cables, and read the current.  It is so easy and quick, no disconnections required.

A picky point, but on the RAV 4.4 hybrid the "auxiliary Battery is located in the cargo area. It is concealed by a plastic resin cover in the rear quarter panel well". The same is true for the 4.5. So the suggestion should read - "open the tailgate" ... 😉 ... and then he will need to switch off the interior lights before testing.

And then I agree - it remains at least possible that there is an excessive drain that will (eventually) need to be found - particularly as the Battery has been tested "OK". But there is a current drain by design to keep some electric on when the car is otherwise off and I, for one, have know idea what the design drain is supposed to be. And it is a 2018 car so fatigue and corrosion are relatively unlikely to be the cause of an unexpected short. It is certainly worth considering any accessories that have been added post production - e.g. dash cams hardwired and always on or anything else of that sort?

[ernieb]

Philip, it's certainly a similar location to the PHEV, boot RH side when you look in.

[IanML]

I don't know the car, but, imho, anything in excess of 20mA should raise eyebrows.  I'm used to seeing up to 5mA, perhaps 8 on the outside.

If you consider a 40Ah Battery, not new, say 75% SOH so still serviceable, and assume failure to start at 15% SOC, that gives 25.5Ah to play with, so at 20mA drain, it will last for 53 days. 

40x0.75x(1.0-0.15)/0.02/24=53.125

You can manipulate the figures to form your own judgement.

[philip42h]

28 minutes ago, IanML said:

I don't know the car, but, imho, anything in excess of 20mA should raise eyebrows.  I'm used to seeing up to 5mA, perhaps 8 on the outside.

If you consider a 40Ah battery, not new, say 75% SOH so still serviceable, and assume failure to start at 15% SOC, that gives 25.5Ah to play with, so at 20mA drain, it will last for 53 days. 

40x0.75x(1.0-0.15)/0.02/24=53.125

You can manipulate the figures to form your own judgement.

That seems certainly in the right ball-park.

There's a pinned thread at the top of the forum giving a link to Toyota's recommendations in respect of the hybrid auxiliary Battery. They suggest that if the car is in Ready mode for an aggregate hour a week (moving or not) the auxiliary Battery will remain happily topped-up and the owner should have no concerns. If a hybrid owner were to leave they car idle for a month they probably shouldn't be surprised if it doesn't start without assistance - whether that 'month' is three weeks or six is anyone's guess.

I've assumed that the OP is aware of all this (but I guess one shouldn't assume anything) and note that they haven't (yet) given a profile of use for the car ...

I don't have the kit or I'd measure the resting drain on mine. Maybe someone else does / can?