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Low traction battery indicator..........


Lawnmowerman
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Yesterday, I travelled 14 miles for shopping then a further 18 miles (still had a further 17 miles to travel) by which time the car switched from EV to HEV. Battery indicator at that point straddling blue & green as expected.

However, after about a mile (or two) I glanced at the Battery indicator meter and was concerned to see it sitting about 1/8th of an inch above zero! Initial worry was there was a fault but pressed on. After about another mile or two of it staying there it started to recover to the point between blue and green.

Now, this may have happened before as it isn't an instrument that I check very often. Naturally a concern was if I terminated my journey with the meter so low (without noticing) would it restart the car?

Anyone else had this happen?

 

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8 minutes ago, Lawnmowerman said:

Yesterday, I travelled 14 miles for shopping then a further 18 miles (still had a further 17 miles to travel) by which time the car switched from EV to HEV. Battery indicator at that point straddling blue & green as expected.

However, after about a mile (or two) I glanced at the battery indicator meter and was concerned to see it sitting about 1/8th of an inch above zero! Initial worry was there was a fault but pressed on. After about another mile or two of it staying there it started to recover to the point between blue and green.

Now, this may have happened before as it isn't an instrument that I check very often. Naturally a concern was if I terminated my journey with the meter so low (without noticing) would it restart the car?

Anyone else had this happen?

 

Like any PHEV, the Battery indication it shows you isn't real, the car keeps 10 to 20% capacity in reserve always, zero on the Battery reading is zero of the Battery capacity available to you to use, don't worry, it won't let you use the reserve.

Has to keep the reserve for starting the engine (and often for a burst of emergency acceleration too). The 12v battery will be small and just used for powering up the electronics, there is no regular starter motor.

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William, I’ve noticed that occasionally that when the car switches into HEV mode it has a tendency to ‘drain’ the traction  battery towards the zero rather than it hover at the 30% mark (green/blue). The only explanation I’ve come up with, pure guess, is that the system for Battery integrity drains the Battery and then does a recharge. I’ve noticed that the recharge to the 30% mark seems pretty fast.

Most of the time it keeps the Battery around the 30% mark.

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3 hours ago, Catlover said:

I presume the PHEV has a12v battery. Isn't that what “starts” the car.?

No, it's the traction Battery that is used for starting - it has a 12v Battery that powers up all the systems to allow the traction Battery do it's thing (as I understand it).

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3 hours ago, Rav Rob said:

Like any PHEV, the battery indication it shows you isn't real, the car keeps 10 to 20% capacity in reserve always, zero on the battery reading is zero of the battery capacity available to you to use, don't worry, it won't let you use the reserve.

Has to keep the reserve for starting the engine (and often for a burst of emergency acceleration too). The 12v battery will be small and just used for powering up the electronics, there is no regular starter motor.

Thanks Rob, I knew the traction Battery starts the vehicle (and that it doesn't have a 'regular' starter motor). But my concern was that with the traction Battery monitor so low it may have had a fault and thus rendered starting impossible.

The following post from Ernie seems to answer my query.

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1 hour ago, ernieb said:

William, I’ve noticed that occasionally that when the car switches into HEV mode it has a tendency to ‘drain’ the traction  battery towards the zero rather than it hover at the 30% mark (green/blue). The only explanation I’ve come up with, pure guess, is that the system for battery integrity drains the battery and then does a recharge. I’ve noticed that the recharge to the 30% mark seems pretty fast.

Most of the time it keeps the battery around the 30% mark.

Thanks Ernie, that is reassuring that I am not the only one to experience this.

Your 'guess' may seem correct - certainly plausible.

Thanks.

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1 hour ago, ernieb said:

William, I’ve noticed that occasionally that when the car switches into HEV mode it has a tendency to ‘drain’ the traction  battery towards the zero rather than it hover at the 30% mark (green/blue). The only explanation I’ve come up with, pure guess, is that the system for battery integrity drains the battery and then does a recharge. I’ve noticed that the recharge to the 30% mark seems pretty fast.

Most of the time it keeps the battery around the 30% mark.

Could it be that the drain is caused by starting the ICE? 

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5 minutes ago, IanML said:

Could it be that the drain is caused by starting the ICE? 

Never (to my knowledge) happened before. And, when starting the ICE from cold with no EV available (i.e. 30% traction Battery available) it has started the engine with no discernible effect on the traction Battery capacity.

Thanks.

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1 hour ago, Lawnmowerman said:

No, it's the traction battery that is used for starting - it has a 12v battery that powers up all the systems to allow the traction battery do it's thing (as I understand it).

Take the 12v Battery away and will the car start.? I wouldn’t think so, that’s why with so many flat 12v batteries the rescue companies get many calls? The 12v is an important part of the system, as is the hybrid Battery. Team work.

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As Joe says the 12v Battery is needed to energise the accessory and control systems needed to run the car including starting the system, in the Ready mode the traction Battery will charge the 12v Battery. But without the 12v battery you’d not be able to get into the car in the normal way.

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I had the Outlander PHEV for 5 years 120,000m.  It had about a 12kwh Battery, only let you use 10kwh of that. Never ever had issue starting ICE no matter how drained it showed. Enjoy your lovely PHEV  (Bl@@dy Toyota and their too-late price drops or I would in one by now too)

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2 hours ago, Lawnmowerman said:

Never (to my knowledge) happened before. And, when starting the ICE from cold with no EV available (i.e. 30% traction battery available) it has started the engine with no discernible effect on the traction battery capacity.

Thanks.

OK, theory No2:  The ICE is initially lightly loaded, until it warms up.  During that period, the traction Battery is called upon to shoulder more of the load.  More pronounced in colder weather, obviously.

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Ian, my experience is once the ICE has kicked in it’s running and working just the same way a normal ICE only car would if started and driven off. If it kicks in say on the motorway and the traction Battery is down to 30% then it’s working hard to propel the car. The energy flow screen shows the ICE driving the front wheels. 

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1 hour ago, IanML said:

OK, theory No2:  The ICE is initially lightly loaded, until it warms up.  During that period, the traction battery is called upon to shoulder more of the load.  More pronounced in colder weather, obviously.

Well obviously I don't know hence the thread - but - I think you're way off there Ian, way off 🤪

But keep the theories coming 👍

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The way I understood how the PHEVs worked is almost like they have 2 batteries - One big one that holds the lion's share of the charge for EV-mode, and a smaller one for the hybrid part.

This was actually the case in the original Prius PHEV, and was why you couldn't charge the second Battery up from just driving around, only from the plugging it in, so it would always hover around the low charge part of the Battery meter unless you plugged it in.

I think the newer PHEVs just have one big Battery, but this capacity split is still in place, so once the 'EV' part of the battery runs out, you're just hovering around the hybrid-part of the battery, and it'll drain and charge as you drive like it does in the normal hybrids, but because that battery gauge shows the full usable capacity of the battery and the hybrid part is just a small part at the bottom, it'll look like it's almost out, when that's actually just the hybrid part of the battery.

Does that sound plausible??

My Mk4 has a tiny 0.7kW battery and it uses less than half of that in normal driving, so it doesn't take much to run in hybrid mode (And get ~75mpg :tongue:) - Compare with the RAV4 PHEV's battery which is, what, 18kW, so 20x bigger :laugh: ? So I reckon it's normal and fine!

 

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7 hours ago, ernieb said:

William, I’ve noticed that occasionally that when the car switches into HEV mode it has a tendency to ‘drain’ the traction  battery towards the zero rather than it hover at the 30% mark (green/blue). The only explanation I’ve come up with, pure guess, is that the system for battery integrity drains the battery and then does a recharge. I’ve noticed that the recharge to the 30% mark seems pretty fast.

Most of the time it keeps the battery around the 30% mark.

So, the PHEV has an 18.1 kWh Battery. By the time you've got down to the 30% mark you'll have 5-6 kWh left. It's taken you 30-40 miles to burn through the first 12 kWh in EV mode. There's just no way that you could burn through (or replace) the next 5kWh in a couple of miles or so. There must be something anomalous going on with the display ... I think ...

(The HEV manages just fine with a 1.6 kWh Battery!)

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9 hours ago, philip42h said:

So, the PHEV has an 18.1 kWh battery. By the time you've got down to the 30% mark you'll have 5-6 kWh left. It's taken you 30-40 miles to burn through the first 12 kWh in EV mode. There's just no way that you could burn through (or replace) the next 5kWh in a couple of miles or so. There must be something anomalous going on with the display ... I think ...

(The HEV manages just fine with a 1.6 kWh battery!)

The first 70% of the traction Battery gives you the full EV range so average 45/50 miles depending on season. In my experience the cut in point for the HEV mode is not necessarily the same point on the energy meter as William has said it’s not particularly accurate and pretty compressed. I’ve seen it cut in whilst still in the blue and then again when it’s well into the green. The EV range display also has a strange feature, sometimes it drops to ‘0’ (zero) the the HEV mode kicks in then sometimes displays ‘- - - ‘ (three bars) and keeps running in EV even when I’d have expected it to have switched to HEV mode. The energy monitor now drains down towards the actual zero point. Whilst the HEV model runs fine with its smaller Battery the PHEV reserves more of a larger traction Battery so that the full spec, power, acceleration etc., can still be achieved.

To get an accurate view of what’s going on you’d need to connect an OBD monitor. William’s observation’s are similar to mine, not anything to be concerned about just an interesting observation.

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Paid close attention today when visiting daughter. Car was due to go into HEV mode within about a mile of destination so 5 miles out I selected charge hold (didn't want engine kicking in potentially a few hundred yards from destination and switching off an un-warmed engine). 

When going home the car ran in EV mode for 5 miles and then HEV mode kicked in with Battery indicator in the expected position. However, on this occasion meter did not drop at all and stayed at the transition point. So, all's well.

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