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I would think so but only if your engine cranking battery is kaput.
 

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I don't understand the point. Trickle charging the traction battery (244 volts, good luck finding a 244v trickle charger) is pointless since it only gets you a mile or two on its own anyway. Trickle charging the 12v battery, which only starts up the computer systems when the car starts, is useless as well. Unless of course it is so dead it can't power up the computers which would prevent the car from starting, in which case yes you can.
The engine itself starts from one of the electric motors running off the traction battery.
 

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I guess that's a no. Thanks. New to the hybrids
 

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As I understand it, the type of battery which Toyota uses in the hybrid for traction power is a lifetime component with essentially zero discharge rate when not being used. It is not a lead/acid type of battery which can self-discharge over time. This is from a Green Car Reports article:

"Toyota told us that the engineers consider the NiMH batteries in Prius and other Toyota hybrids to be a life-of-the-car component. It could be several owners and hundreds of thousands of miles down the line before the pack requires replacement, at which point the car itself may well be past its prime."

In other words, if I were an owner I wouldn't worry about the traction battery.
 

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As I understand it, the type of battery which Toyota uses in the hybrid for traction power is a lifetime component with essentially zero discharge rate when not being used. It is not a lead/acid type of battery which can self-discharge over time. This is from a Green Car Reports article:

"Toyota told us that the engineers consider the NiMH batteries in Prius and other Toyota hybrids to be a life-of-the-car component. It could be several owners and hundreds of thousands of miles down the line before the pack requires replacement, at which point the car itself may well be past its prime."

In other words, if I were an owner I wouldn't worry about the traction battery.
I was amazed recently after going on a 7 day trip. Parked car at airport outside in snow and came back to a still totally topped up traction battery. I figured there would be a bit of discharge or even fully discharged battery. Especially since it's getting below 0 degrees these days. But nope, full bars. Soon to see how it does in the -35 degree temps unfortunately. :eek:
 

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Starting with a full traction battery really improves fuel economy according to my observations.. Id like to have this somehow :)


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I don't understand the point. Trickle charging the traction battery (244 volts, good luck finding a 244v trickle charger) is pointless since it only gets you a mile or two on its own anyway. Trickle charging the 12v battery, which only starts up the computer systems when the car starts, is useless as well. Unless of course it is so dead it can't power up the computers which would prevent the car from starting, in which case yes you can.
The engine itself starts from one of the electric motors running off the traction battery.

Question. In the unfortunate event where the 12 volt battery is discharge to a level that does not allow it to start up the computer system, could the trickle charger be connected to the + terminal in the engine compartment, the one in the large fuse box? This would be much easier than connecting directly to the 12 v battery in the rear compartment.
 

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Question. In the unfortunate event where the 12 volt battery is discharge to a level that does not allow it to start up the computer system, could the trickle charger be connected to the + terminal in the engine compartment, the one in the large fuse box? This would be much easier than connecting directly to the 12 v battery in the rear compartment.
trickle chargers by definition are more maintaining charge level over long period of storage, so they only put out a small amount of amps (just enough to top up the battery)

if the battery was dead, I would use a regular charger
 

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Question. In the unfortunate event where the 12 volt battery is discharge to a level that does not allow it to start up the computer system, could the trickle charger be connected to the + terminal in the engine compartment, the one in the large fuse box? This would be much easier than connecting directly to the 12 v battery in the rear compartment.
You're talking about a "jump start", which is covered in the manual, and its what that connect point is for. There's wouldn't be any point in trying to charge it in that scenario. Just jump it. You only need 12v and a few amps of current for a split second.
 

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Starting with a full traction battery really improves fuel economy according to my observations.. Id like to have this somehow :)
That's a false assumption. A full traction battery is ultimately (always) achieved by burning fuel. Doesn't matter whether you did that on the previous drive or this one, its still gasoline converted to electricity.

This is not a perpetual motion machine, and you can't trick it into being one.
 

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That's a false assumption. A full traction battery is ultimately (always) achieved by burning fuel. Doesn't matter whether you did that on the previous drive or this one, its still gasoline converted to electricity.

This is not a perpetual motion machine, and you can't trick it into being one.


If you start with a full battery the since start fuel economy is much better after 10 miles given eveything else constant.

Remember I'm talking about charging the battery from the grid.


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If you read the manual, it states to recharge the 12V battery with the engine, if it won't start it needs to be jumped, it does not mention charging the battery with an external charger. I would only do so after removing or disconnecting the 12V battery, then recharging it with a low amp charger, it's only rated at 355AH, about the same as my lawn mower's battery!
 

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If you start with a full battery the since start fuel economy is much better after 10 miles given eveything else constant.

Remember I'm talking about charging the battery from the grid.
Which, as has been stated, is not possible. If you want a plug-in HV, that's what you should buy.

And I'll say again that your assumption about better economy starting with a full battery is false.
 

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If you read the manual, it states to recharge the 12V battery with the engine, if it won't start it needs to be jumped, it does not mention charging the battery with an external charger. I would only do so after removing or disconnecting the 12V battery, then recharging it with a low amp charger, it's only rated at 355AH, about the same as my lawn mower's battery!
Where did you ever find that totally-incorrect amp-hour figure?

The 12 volt battery is (in most Toyota hybrids) either a 32 or 40 amp-hour AGM (sealed lead-acid) battery and only runs the 12 volt systems to activate the car. Once the traction battery is connected to the inverter/converter part of the hybrid system (the two distinct clunks heard during power-up), the 12 volt system is run by the inverter/converter and recharges the battery. The inverter/converter system provides approximately 100-120 amps to run the 12 volt accessories and recharge the 12 volt battery. The traction battery, of course, is also charged/discharged by the inverter/converter by using the motor/generator(s) as a generator. During braking, MG2 and MG3 provide regenerative braking while MG1 always provides power to run MG2 and MG3 as well as recharge the traction battery when the ICE is running.
 

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The battery is marked CCA 355A which I believed to be cold cranking amps, my memory slipped a bit, it's not AH. :doh: My Craftsman mower battery is rated about the same CCA which is less than half what a normal 12V car battery is rated for comparison.
 

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Which, as has been stated, is not possible. If you want a plug-in HV, that's what you should buy.

And I'll say again that your assumption about better economy starting with a full battery is false.


Read again what I wrote and check it.

The battery helps out quite abit for the current trip, when you start the hybrid system and the [READY] lights up one of the fuel computers (Since Start) is resetted.


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The battery is marked CCA 355A which I believed to be cold cranking amps, my memory slipped a bit, it's not AH. :doh: My Craftsman mower battery is rated about the same CCA which is less than half what a normal 12V car battery is rated for comparison.
CCA has nothing to do with our hybrids. The 12 volt battery does not crank the engine - the traction battery spins MG-1 to start the engine. So Cold Cranking Amps has no value to us. The 12 volt battery in my 2016 Rav4 hybrid (XLE) is a Yuasa 40 AH AGM battery. Although there is a CCA value printed on it, it has no meaningful value in the hybrid vehicle. All you need to do with the 12 volt battery is to power the lights and computers during the startup sequence. Once the pre-charge contactor and main contactor have connected the traction battery to the inverter/converter the traction battery takes over running the vehicle's electronics and starting the ICE. So there's no value at all to that CCA capacity - it's extra info that we don't need. The main value we DO need is the AH capacity (which is 40 Amp-Hours).
 

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You're talking about a "jump start", which is covered in the manual, and its what that connect point is for. There's wouldn't be any point in trying to charge it in that scenario. Just jump it. You only need 12v and a few amps of current for a split second.

Yes, I know that is covered in the manual but charging the 12 v battery is also covered in the manual. It only addresses charging the battery from the battery location in the rear of the vehicle and also states that recharging the 12v battery should only be a slow charge (5A or less) or the battery could explode if charged at a quicker rate.
So, if one can jump start the 12v battery from the engine compartment, is it feasible to charge the battery from this location? That was my original question.
 

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Yes, of course you can charge the 12 volt battery from the engine compartment. The length of heavy wire between the under-hood connector and the battery terminal will limit the charge capacity but you already know it needs to be a slower charge than what a jump-starting connection to another vehicle might provide. The safest approach is to connect jumper cables with both vehicles powered-off. This way the voltage difference between the other vehicle and your hybrid will be minimized and thus the current between the two kept to a minimum. Once the hybrid vehicle has completed its startup sequence and closed the contactors between the traction battery and inverter/converter the other vehicle may be disconnected. Normal operation and battery charging will be taken over by the hybrid power system and will get you home or to the service department at Toyota where the reason for the depleted 12 volt battery can be found and corrected.
 
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