Yaris Hybrid 12 volt auxiliary battery

[Kingsway]

I've had some problem finding out what Battery is best to fit to my 'new' 2014 Yaris Hybrid  - most Battery suppliers offer a 054 flooded lead acid Battery as a replacement

This morning I took out the back seat to get easy access to the top of the battery and have discovered that the original battery is a  Yuasa Auxiliary AGM HJ-S34B20L-A GS Battery

It's had a good overnight charge, and is now looking a lot healthier than before!  (SOC 100%  SOH 100%!) 

One thing does puzzle me.  When I first used my battery tester I connected it to the 'jump start terminal' in the fuse box (engine compartment rear right) Which I'd assume is connected directly to the battery). But  I got a different reading than when I connect directly to either the battery terminals, or the end of the white cable in the fusebox! 

The battery is now reading about 12.5 volts, but still drops fairly quickly towards  12v under the load of the headlights.   Is this normal?? 

 Yuasa appear to offer a 3 year guarantee on this battery - but aren't AGM's supposed to be much more long-lasting than 'normal' batteries?   Given the cost of the Yuasa battery (£167.00 upwards, depending on the supplier)  You'd hope it would last two or three times longer than a much cheaper conventional battery? 

Has anyone had to change the 12v battery after only 3 years?  (47000 miles in my case)

 

TIA!

[Anthony Poli]

Since the Battery is smaller than a traditional car Battery and so will drain quickly under loads like headlights. The charging rate is also lower.
Ideally you shouldn’t leave things like headlights on without the ready light.


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[Kingsway]

I know what you mean, Anthony but, actually not all that small!   -  I have two little Daihatsu Charades I use in my business - one manual, one automatic - with exactly the same size Battery, for starting as well as all other loads.

Here's the actual  spec:    (Interesting to see the recommended charge rate - if the car is set to charge it that slowly, I can see why the voltage might easily get too  low if the car is seldom used)

Yuasa HJ-S34B20L-A - Auxilliary, Backup & Specialist Batteries

Performance
Voltage 12V
Capacity (20-hour) 35Ah
Cold Cranking Amps (EN1) 272A
Dimensions
Length 197mm
Width 129mm
Height 227mm

>>    Recommended Charge Rate 2A    <<

Weights & Measures
Mean Weight with Acid 10.5kg
Dry Weight -
Acid Volume -

Container Features
Case Type B20 JIS AGM
Hold Down N
State of Charge Indicator -
Handles Y
End Venting Y
Semi-Traction Features Y
Lid Type VRLA
Technology
Flame Arrestor Y
Technology Ca/Ca VRLA
Separator AGM
VDA Roll Over Test -
Vibration V1 (30Hz/3g/2hr)

 

 

[Anthony Poli]

I left a cheap obd dongle plugged in over a weekend and had a discharged Battery on the Monday morning. After recharging the Battery in the house it’s been fine since.

My mother’s Yaris hybrid is only used once a week and clocks up 30 miles. That’s enough to keep the Battery charged.


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[Mike J.]

Slightly off topic, but what is the precise method for removing the rear seat lower panels, in particular the plastic rivet/clips? Is it just brute force or is a special tool needed?

[Anthony Poli]

I am after the information, I gave up trying as I didn’t want break anything.


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[Kingsway]

I haven't actually done it yet  but,  apparently, it is just a matter of pushing the centre button  inwards firmly using a blunt tool - fingers won't work - then pulling the clips out.

I think you might only need to do this to actually remove the Battery. To access the terminals, I just pulled the seat up sharply, and removed the entire lower seat base.

 

 

 

[Anthony Poli]

Thanks. Just wanted to be prepared, in case I need to clean the traction Battery fan.


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[Kingsway]

I've no doubt it's over-kill, but I bought one of these :   https://www.amazon.co.uk/gp/product/B074SFBT8K/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I'm also fitting LED interior lamps, so much less chance of running too flat!

 

[Anthony Poli]

Let us know how you get on with that and if it keeps your Battery topped up. small enough to fit on the Parcel shelf.

[Devon Aygo]

If the Battery is failing, have you had it looked at by Toyota as a 2014 Yaris would have a 5 year warranty and if it is faulty then it would be replaced under warranty. Also Toyota offer a fixed Price of £100 supplied and fitted for the 12v Battery with a 3 year warranty.

 

[CPN]

7 hours ago, Kingsway said:

I've no doubt it's over-kill, but I bought one of these :   https://www.amazon.co.uk/gp/product/B074SFBT8K/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I'm also fitting LED interior lamps, so much less chance of running too flat!

 

You'd have been better off ordering one of these Richard as it plugs into the OBDII socket directly and works really well...

https://www.amazon.co.uk/gp/product/B00AC1LLQY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

[CPN]

7 hours ago, Anthony Poli said:

Let us know how you get on with that and if it keeps your battery topped up. small enough to fit on the Parcel shelf.

They work much better on top of the dashboard under the windscreen...

[Mick F]

16 hours ago, Mike J. said:

Slightly off topic, but what is the precise method for removing the rear seat lower panels, in particular the plastic rivet/clips? Is it just brute force or is a special tool needed?

The buttons have a button in the centre.  You press them and they click inwards.  Then use a fingernail or a small screwdriver to pull out the whole button.  Veery easy to get out .............. but a devil of a job to get back it.

Read my thread on removing the seat as part of the rear seatbelts issue.  I describe how you lift out the rear seat and how to get the buttons back in on the lower panels.

Good luck!

Mick.

 

[Kingsway]

22 hours ago, Devon Aygo said:

If the battery is failing, have you had it looked at by Toyota as a 2014 Yaris would have a 5 year warranty and if it is faulty then it would be replaced under warranty. Also Toyota offer a fixed Price of £100 supplied and fitted for the 12v battery with a 3 year warranty.

 

Yup - but I don't want to get charged for wasting their time, if it isn't faulty.  After about 18 hours of slow charging at home , it is looking a great deal healthier!  My Battery analyser recons it's state of health is now  95%   I think it had been standing at the dealer for a while, and had been slowly losing charge.  Any Battery that is not in constant use is likely to get a bit low, I reckon, and the occasional run will not be enough to do it justice.  That's why I'm keen to have a little solar panel connected permanently  to always keep it up to scratch.   (I still plan to give it a bit of an equilisation charge once or twice a year)

BTW There is a very interesting thread on ecomodders.com  - with a conventional car, you can sometimes get 5 % to 10% better economy by disconnecting the alternator, and running the car from a big deep-discharge Battery you charge up at home. They were talking about the idea of trying to do something similar with a Prius.   They also mention that your MPG figure is likely to drop noticeably once the 12v auxiliary battery starts to fail. Too much energy being wasted in unsuccessfully trying to charge it....

[Kingsway]

16 hours ago, CPN said:

You'd have been better off ordering one of these Richard as it plugs into the OBDII socket directly and works really well...

https://www.amazon.co.uk/gp/product/B00AC1LLQY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Not so convenient for me, though.  I want to have it  on the back parcel shelf, and permanently connected to the Battery that's only a few feet away under the back seat.  You can even use the rubber suckers to mount it on the window if you like!

 

[Kingsway]

I found this  article, which may be of interest!   http://prius.ecrostech.com/original/Owning/Undriven.htm

 

[Anthony Poli]

I found this  article, which may be of interest!   http://prius.ecrostech.com/original/Owning/Undriven.htm
 

That article might be helpful to some, the same advice is in the owners manual.

I heard of people going away for a month or more and finding the 12v going flat. Or like myself, I left something connected and discharged it over a weekend.

The more dangerous situation is running out of fuel and discharging the hybrid Battery. Which people do, which usually ends up a costly mistake.


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[Kingsway]

On 11/12/2017 at 12:53 AM, Kingsway said:

I found this  article, which may be of interest!   http://prius.ecrostech.com/original/Owning/Undriven.htm

 

A customer of mine has a Prius which was left standing too long. I don't know the details, but she claims ithad to be towed by the dealer who kept it for two days and the bill was £500!

[Heidfirst]

but how much of that is for the towing charge?

[Mick F]

Question regarding the aux Battery.

How is it trickle charged during use?  Is it charged directly from the traction Battery, or only when the EV motor is generating?

Thank, Mick.

[Anthony Poli]

Question regarding the aux battery.
How is it trickle charged during use?  Is it charged directly from the traction battery, or only when the EV motor is generating?
Thank, Mick.

It is charged via the dc to dc converter from the traction Battery whilst the car is in ready mode. So it starts charging as soon as you are ready to go.

For my Battery, the max charge current is 4 amps, but I suspect the charge current to be below that, to prolong the life of the Battery.


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[Mick F]

Thanks!  

[Mick F]

Next (hypothetical) question.

Say the traction Battery was full and in good condition .................. If the aux Battery was flat due to leaving the lights on overnight, can the car be started the next morning?

 

Mick.

[Kingsway]

18 minutes ago, Mick F said:

Next (hypothetical) question.

Say the traction battery was full and in good condition .................. If the aux battery was flat due to leaving the lights on overnight, can the car be started the next morning?

 

Mick.

Nope - the car can do nothing without the 12v supply.  However, I wonder if the 12v Battery might recover a little once you take away the load....  It doesn't have to supply a huge current, like a conventional car Battery, so you might just get lucky?