12v battery maintenance, issues, etc.

[Roy124]

Rear Seat Cushion removal.  I want to lift the rea seat cushion on the Yaris Cross.  I saw an explanation in the forum but can't find it, what is the process?

[Cyker]

You basically have to give it a short sharp yank (oo err) from under the front edge of the bench, and it should just come up (matron!).

The trick is tugging in the right places (...), as it'll be easier the closer you pull to the fastener - They're roughly 1 third and 2 thirds along the seat, but if someone has the picture that'll make it easier to locate by eye.

 

[RickyC]

Relating to who says "I you don't plan to use the car every day, it could be better a classic ICE powered car instead of a full hybrid like a Yaris".  An equivalent ICE powered car of the same segent is usually supplied with a 45Ah Battery. I agree that it's capacity is about 10 Ah more than the one of the Yaris but at every start a traditional ICE car requires 100-150 A for the stater motor and not just 50/60 A like a Hybrid Toyota.   

I expect that a lot of owners of standard ICE cars use the car once a week maybe for short trips like it happens for some hybrid car users.  But I'm not reading a lot of complaints of dead batteries after leaving the car in garage for a week or two. 

The DC-DC converter of a Yaris should behave like a traditional car alternator ( with the plus that a DC-DC can charge the Battery also when ICE is off and charge current is not dependant from ICE rotation speed ).  So why Yaris Battery is so critical to low usage?   

Is DC-DC supplying a lower charging current than an alternator?

Starting form a same initial charge level, and leaving the car

• in Ready for 30 minutes
• charge the battery with a CTEK ( or a similar charger ) for the 30 minutes

will move the battery to the same charge level ?

[Dala]

1 hour ago, Roy124 said:

I fitted a battery monitor a couple of days ago and it is early days to draw any firm conclusions.  However on first data, after a short run yesterday the voltage was 12.77v dropping to 12.51v at midnight - half a volt in 24 hours.

However from midnight to 1000 today the loss was just 0.07v or about 0.17v per day.  At that rate it would take about 6 days to drop to 11.4v assuming a linear drain.

The next week will see regular usage so not sure when I will have a longer no use preiod.

can you show some graphs ?
temperature and voltage

[Cyker]

50 minutes ago, RickyC said:

Relating to who says "I you don't plan to use the car every day, it could be better a classic ICE powered car instead of a full hybrid like a Yaris".  An equivalent ICE powered car of the same segent is usually supplied with a 45Ah battery. I agree that it's capacity is about 10 Ah more than the one of the Yaris but at every start a traditional ICE car requires 100-150 A for the stater motor and not just 50/60 A like a Hybrid Toyota.   

I expect that a lot of owners of standard ICE cars use the car once a week maybe for short trips like it happens for some hybrid car users.  But I'm not reading a lot of complaints of dead batteries after leaving the car in garage for a week or two. 

The DC-DC converter of a Yaris should behave like a traditional car alternator ( with the plus that a DC-DC can charge the battery also when ICE is off and charge current is not dependant from ICE rotation speed ).  So why Yaris battery is so critical to low usage?   

Is DC-DC supplying a lower charging current than an alternator?

Starting form a same initial charge level, and leaving the car

• in Ready for 30 minutes
• charge the battery with a CTEK ( or a similar charger ) for the 30 minutes

will move the battery to the same charge level ?

I think that is partly the issue - the DC-DC converter doesn't behave anything like an alternator.

The alternator delivers a fixed charging voltage and the current is either determined by engine rpm or regulated by changing the load on the engine.

The DC-DC, from what I understand, just delivers a fixed charging current.

My theory on why the hybrids are more prone to it, is an alternator can deliver a lot of current very quickly as it can put as much load on the engine as it wants to generate electricity, and it has a tendency to keep the Battery fully charged while the engine is running.

OTOH, because the DC-DC can only deliver a fixed and lower level of current, it needs much more time to recharge the Battery, esp. as it has to also power all the car's 12v systems within its fixed current limit. Also, the DC-DC converter will shut down on occasion and leave the 12v Battery to power everything in the car on its own (Either to save energy or because it's using a cyclic-charge rather than a float-charge scheme).

The fact that you can jump-start another car just by revving the alternator to 2000+rpm, whereas the DC-DC system can't do it at all, would suggest a massive difference in current capacity.

I figured if they could up the DC-DC system's capacity that would help a lot.

The only trouble with this theory is I've read things that say car alternators generally generate about 60 amps, and the DC-DC system is supposedly capable of delivering 120 amps (Fused to 100A) which, if true, throws all of what I just theorized out the window, and makes the 12 battery drain issues make even less sense! 

[Roy124]

Dala, not yet.  I have only a day of so of graph.  Very similar to yours in parts though the start sequence is cleaner, the voltage drop over time looks as if it might be greater but the slow deterioration is to a higher level than yours.

Just find the information is fascinating.

[Roy124]

1 hour ago, RickyC said:

 ....at every start a traditional ICE car requires 100-150 A for the stater motor and not just 50/60 A like a Hybrid Toyota.   

... 

The DC-DC converter of a Yaris should behave like a traditional car alternator ( with the plus that a DC-DC can charge the battery also when ICE is off and charge current is not dependant from ICE rotation speed ).  So why Yaris battery is so critical to low usage?   

Is DC-DC supplying a lower charging current than an alternator?

I think you have answered the question.  I think a serviceable alternator can recharge the Battery much more quickly than the the DC-DC.  The latter will provide a more gentle current.

My old on-off charger (I bought it for my Dad in 1964) could bang in 5Ah and then you manually switched it to 1-2 Ah.  Simple maths, 5x4 followed by 20x2, job done. 🙂

It eventually died ( the charger not the battery) and the Ring replacement worked in a similar fashion but did nothing for the Corolla.

*That 1960s charger was probably a simple stepdown transformer, metal box, white metal case, and lots of ventilation holes.

[anchorman]

1 hour ago, Roy124 said:

Rear Seat Cushion removal.  I want to lift the rea seat cushion on the Yaris Cross.  I saw an explanation in the forum but can't find it, what is the process?

I've pointed out the clip Roy.  Slide your hands in from each side and pull!

[anchorman]

Regarding fitting a bigger Battery, I reckon it’s cheaper and more convenient to just carry a cheap jump pack.  Dead easy to hook it up at the front if you need to.  You’d have to take Toyota’s advice before fitting a bigger Battery - is the DC to DC converter up to it?  Maybe Devon Aygo knows?

[TonyHSD]

Not sure it’s a good idea to fit a larger Battery as replacement of a smaller one. The inverter or alternator has their specs as per the requirements of the exact car and going too large probably will also kill the Battery, just in a longer run, in 3 years instead of a 2. If you charge the Battery with external charger solar or mains powered the original battery will last you the longest. 👍

[anchorman]

1 minute ago, TonyHSD said:

Not sure it’s a good idea to fit a larger battery as replacement of a smaller one. The inverter or alternator has their specs as per the requirements of the exact car and going too large probably will also kill the battery, just in a longer run, in 3 years instead of a 2. If you charge the battery with external charger solar or mains powered the original are battery will last you the longest. 👍

No alternator Tony 😉

[TonyHSD]

6 minutes ago, anchorman said:

No alternator Tony 😉

Of course 👍 

I meant for non hybrid cars 👌

[Cyker]

Because the DC-DC converter is self-limited, I don't think a bigger capacity Battery would affect it much, just take even longer to reach 100% capacity from low (If it is charging at a fixed current like I'm theorizing!)

It's not like unregulated systems where you'd get a bigger inrush current that is out of spec and makes fun popping sounds happen in other parts of the car  (I learned the hard way this is why the correct value of current limiting resistor is very important and you can't e.g. just add more capacitors without checking how it affects things like that...     )

 

[TonyHSD]

I have measured a couple of times the inverter supply voltage in ready mode and always been 14.7v but once showed 15.1v. Don’t know much about it but it works fine and keeps my 12 years old Battery alive. 

[Cyker]

In an ideal world, the voltage should be held steady at the correct charging voltage for the 12v Battery, and only the current change, but it's trickier to measure current - Normally ammeters need to be connected in-line (Which means things need to be unplugged), unlike voltmeters which go in parallel (So nothing needs unplugging).

[Max_Headroom]

Quote

Sometimes the car has started fine even when the battery was as low as 11.1V after we haven't used it for a few days.

Do the hybrids allow you to see the charge state of the 12v Battery on the dash somewhere or do you have to use a tester? 

[Roy124]

Max, no. You would need a tester or monitor. 

You remind me, some cars used to have proper instrumentation such as ammeters and oil pressure gauges. 

On my Triumph 1300 I added a reversing light, voltmeter and oil pressure gauge.  Today we just have warning lights. 

Given that Toyotas are basically computers with a motor and wheels there is no reason why they can't send Battery status to MyT. 

[Max_Headroom]

This could be the answer to our prayers - 

 

 

[Max_Headroom]

This could be the answer - 

 

 

[anchorman]

8 minutes ago, Max_Headroom said:

This could be the answer to our prayers - 

 

 

It depends if it draws current when the car is switched off.

[Graham47]

21 minutes ago, Max_Headroom said:

This could be the answer to our prayers - 

Does it prevent flattening of the Battery ??

[Max_Headroom]

 

 

Quote

Does it prevent flattening of the battery ??

Obviously not but you already know that don't you. 

Some members have put their own Battery monitor on the car the big plus about this one is you can check it on your phone without opening the car, if you don't drive often it'll warn you when its getting to a point where you need to do something about it. 

[Max_Headroom]

9 hours ago, anchorman said:

It depends if it draws current when the car is switched off.

Try watching the video that is covered. 🙄

[anchorman]

40 minutes ago, Max_Headroom said:

Try watching the video that is covered. 🙄

“You don’t have to worry about it drawing power too much” doesn’t answer the question 🙄

[Hibird]

I have a modest solar panel set up (House not car) which includes a bluetooth Battery monitor which I did connect to the car for a while over the life of this thread

The biggest plus is you can monitor the Battery in a stabilzed state (no need to open doors etc) fom a distance, mine worked ok up to around 4 meters from indoors. That unit consumes an average of less than 2ma so would take around 450 days to drag a fully charged Battery down to a 50% charge level if it was the only load.