What will happen

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Alex800st

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If both batteries are discharged and you have no access to L1/L2 charger?
Say you can use jumper cables for 12v battery, but will it help - Clarity will not be able to start the engine off 12v, am I correct? And she will not be able to charge the main battery - she needs the engine for that?
 
I don’t see any reason why HV or HV Charge couldn’t be activated once the car powered up from a jumper battery, unless of course, you’ve also run out of gas.
 
Say gas is there but I do not see a way where the main battery will get a charge - Clarity does not have 12v starter motor therefore the engine can not be started to start charging the main battery.
 
Most if not all hybrids (at least the common Toyota and Honda systems) do need the HV battery to have enough charge to be able to start the engine, and often to provide some of the power for acceleration. The car is designed to leave a significant margin, both for long term battery health and to ensure it can start the engine. In the Clarity, at 0 EV miles remaining point where the engine starts there's still 10-20% left.

The manual does say that the HV battery drains over time and not to let it drain "too much" or you might not be able to start the car. They also suggest charging at least every 3 months when not in use, but that's as much to protect the long term battery health. It is quite possible that if you let it drain too much (likely many months of sitting) it might need to be towed to a dealer to fix, but I don't think that's something to worry about in normal usage.

Many of the cases of poor performance seem to be related to irresponsible dealers letting the cars sit on their lot for months and months without keeping them charged such that the HV battery is well below that normal cushion (yes, they're irresponsible -- they are supposed to know the requirements of the cars they sell and handle them accordingly).
 
Interesting. The reason I started to worry about that scenario is that I gave my previous car Honda Civic Hybrid 2014 to my kid. Yesterday she forgot to switch off a light and discharged 12v battery. After a jump car came back to life, but I was thinking - what if after recharging 12v battery traction battery did not have enough juice to start the engine - and on a normal hybrid there is no way to charge it again. What would happen then.
 
Alex800st said:
Interesting. The reason I started to worry about that scenario is that I gave my previous car Honda Civic Hybrid 2014 to my kid. Yesterday she forgot to switch off a light and discharged 12v battery. After a jump car came back to life, but I was thinking - what if after recharging 12v battery traction battery did not have enough juice to start the engine - and on a normal hybrid there is no way to charge it again. What would happen then.
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Hah; my daughter had a dead batter in my (she calls it "her") 2007 Civic after listening to the radio for a long time in the school parking lot in "On" (not started) mode. She got to learn how to jump-start a car and not to do that again, so was a good thing!

The short answer is: Don't worry about it, because the car simply won't let the traction battery get anywhere near low enough for that to occur; it will automatically start the engine to charge it well before that point. And when the car is off (or any mode other than "Ready to drive"), the HV battery is completely and totally disconnected by relay (for safety reasons), so isn't susceptible to leaving lights on etc. If it did get low enough, correct that you'd need probably need to tow the car, but that just isn't going to happen normally.

There are other threads on this where people drained their 12V battery because they thought the HV battery was being used, but it is not used in either accessory (one press of the power button without brake) or "On" mode (two presses without brake) even though the fan can run. Only in "Ready" (power button with brake) is the HV battery engaged, and if you sit in that mode the engine will eventually come on when the HV battery gets low.
 
This discussion would prove sound judgement for a Clarity driver who keeps a L1 evse in the lower trunk compartment of the car. :)
 
I’d have to agree with the great minds that believe the traction battery will not be depleted to a level where the engine would be unable to be started.

Whatever the low SOC voltage may be at, 10% or even 0%, it appears to be sufficient to start the engine. There have been many reports of dealers leaving the cars to sit for months with depleted batteries. I’m not sure how they all were started, but I’d imagine a 12V jump got the party going.

Stickware has driven more than 120K miles, most of those without ever charging the traction battery. I parked the car in the garage, unplugged, in mid-March with a fully charged battery and returned in mid-September to a car with a fully charged battery. Only the 12V battery was dead.

Personally, I think the traction battery could be discharged to 0-10%, left to sit for 6-12 months and the car would power up with a 12V jump and the ICE would fire up on command.
 
I just did a simple test with voltmeter on that hybrid civic - and indeed 12v battery get charged all the time when the car is in “ready” mode, regardless of the engine running or not.
It also means that when the traction battery passes away for good, she will not become a regular non-hybrid civic, but dead lifeless body.

And i highly doubt that if i bring that car in a dealership with discharged traction battery Unable to start they will be able to recharge it.
 
Alex800st said:
I just did a simple test with voltmeter on that hybrid civic - and indeed 12v battery get charged all the time when the car is in “ready” mode, regardless of the engine running or not.
It also means that when the traction battery passes away for good, she will not become a regular non-hybrid civic, but dead lifeless body.

And i highly doubt that if i bring that car in a dealership with discharged traction battery Unable to start they will be able to recharge it.
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Last year I took my gen-1 Honda Insight into my dealer's service department to have them verify the IMA battery was kaput. I had used a battery charger on the 12-Volt battery to enable me to get to the dealership. I mistakenly assumed I would have enough 12-Volt power to get home after I declined to have them replace the IMA battery. Just as I hit the expressway exit a mile from home, my Insight died. I pulled off onto the grass next to the exit, had my wife come get me, went home, got tools, went back, took out the 12-Volt battery, went home, charged the battery during dinner, went back, re-installed the charged battery, drove home, ordered a Bumblebee battery, and installed that battery when it arrived a week later. Thanks to YouTube, it was easier than I expected, I saved a thousand dollars, and I got a battery known to have all-new cells. Honda just calls their more expensive IMA batteries "reconditioned" so you don't know if they changed only the battery sticks that didn't pass their test.

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There have been people who have installed an alternator in their IMA battery-less Insights to make them usable.
 
Thank you! Very useful, now I know how much it will cost me to replace traction battery in my old civic.
Question: i am confused how you were able to start the car by just replacing 12v battery? Insight has 12v starter motor unlike civic?
 
Alex800st said:
Thank you! Very useful, now I know how much it will cost me to replace traction battery in my old civic.
Question: i am confused how you were able to start the car by just replacing 12v battery? Insight has 12v starter motor unlike civic?
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Yes, the gen-1 Insight has a starter motor, but it uses the traction motor to start the engine on all but the coldest days. I was always surprised on those days because instead of an instant start, I heard the "chug-chug-chug" starter motor sound regular car owners are so used to hearing.
 
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