Dead Battery (for starting the car)

Sandroad said:
If you didn’t leave anything on and the 12v battery died in 5 days, you need a new 12v battery. It was likely damaged (sulphated) by the dealer leaving it discharged on the lot for a long time. However, I’m concerned that you write the battery went from completely charged to 0%. There is no indicator for the 12v battery, so how did you know it had a full charge? The 12v battery by itself does very little in the car. It just energizes the relay to bring the big battery on-line when you push start and it keeps a few small things on while the car is off. Power flows through it for some uses while the car is running, but the electricity for those uses originates elsewhere. IMHO, the 12v battery in our cars would be a good application for a deep cycle battery. Good luck with the dealer. Don’t put up with having to deal with a frequent dead 12v battery.
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Doesn't the 12-volt battery run every piece of electronics, all the lighting, and all the accessories except for the heater and A/C (and those fans use 12 volts, too, right?)?
 
insightman said:
Doesn't the 12-volt battery run every piece of electronics, all the lighting, and all the accessories except for the heater and A/C (and those fans use 12 volts, too, right?)?
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The 12v battery is in the system that runs all those things, so technically yes. But, the electricity comes from the dc-dc converter that originates in the hybrid battery and/or the generator. The 12v battery would only last a few minutes if it had to run all the 12v devices without an "external" source of power.
 
This is very interesting and I've always wondered how the 12 v battery gets charged considering there is no alternator nor even any fan belt when I take a look under the hood. So if I'm understanding the discussion, the big battery is charging the 12 v battery via the dc-dc converter so in essence the big battery powers everything 12v in the car via the dc-dc converter and the 12v will always be 100% charged when ignition is turned off? I'm learning something from this forum all the time.
 
As a side note, though we call it a “12V” system and battery, during the few times I actually measured the voltages on circuits when the car was fully on they were about 14.3V.

I think I remember, but can’t completely be sure, that when the car was off (so same circuit was powered by 12V battery) it dropped to 12V.

I assume the dc-dc converter, when on, holds the system at 14.3 V and thereby charges back the “12V” battery in this way. There may be other reasons.
 
Claire Green said:
This is very interesting and I've always wondered how the 12 v battery gets charged considering there is no alternator nor even any fan belt when I take a look under the hood. So if I'm understanding the discussion, the big battery is charging the 12 v battery via the dc-dc converter so in essence the big battery powers everything 12v in the car via the dc-dc converter and the 12v will always be 100% charged when ignition is turned off? I'm learning something from this forum all the time.
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Poster @Hi.Ho.Silver used an inverter connected to his Clarity PHEV's 12-volt battery to power parts of his home after Hurricane Michael. @KentuckyKen then asked, "Did you have to turn the car on to have the 17kW hv battery keep the 12v battery full to do this..." and @Hi.Ho.Silver replied, "Yes, the car has to be on in the ready to drive mode to provide power to the 12v battery."
 
KentuckyKen said:
White woman’s dealer blow smoke where great light in sky not shine. He heap bad dealer. No trust him.

The Clarity’s 12 v battery is rated at 310 CCA and the Fit’s battery at 340 CCA so it’s only 10% less. His argument is meaningless and he’s just trying to brush you off and not have to deal with it.
The dealer is cautioned by Honda to keep both the 12v and 17 kW traction battery charged to prevent permanent damage. Evidently many are not doing this. The dealer is mandated by Honda to check the Amp Hr of the 17 kW battery and to perfom a Check of the 12v battery.
Here is how they are supposed to check the 12 v battery (taken from Honda’s PDI doc):

5. Check the 12-Volt Battery To ensure long battery life and that the customer gets a fully charged battery, you must check it at these times:
 When the vehicle first arrives at the dealership
 During the PDI (if done at a later date)
 At regular intervals (if stored)
 Just before vehicle delivery
Test the battery with the ED-18 battery tester following S/B 88-023,
Battery Testing and Replacement.
If the ED-18 does not show GOOD BATTERY, charge the battery with the GR8 battery diagnostic station.
Write down the GOOD BATTERY 10-digit code in the PDI and Final Delivery Checklist booklet.
During the PDI, write down the code in the “Under Hood - Engine Cold” section.
Then, at vehicle delivery, test the battery again, charge if needed, and write down the new code in the “Final Inspection (At Delivery)” section. NOTE: Make sure the ED-18 has the latest software installed before using it.

Your battery should not have run down in less than a week with the car off. Either there is a problem with the car charging or the battery is weak and cant hold a charge.
If I were you, I would demand your dealer show you both the PDI and the print out from his checking the 12v battery (which they should have done at least once) if you did not get them at delivery. And have them test your battery now to see if it passes. Mine tested at 346 CCA and 12.46v at 73 F at Delivery.
If they can’t produce the PDI and a test print out, then I would demand they replace your battery because they did not follow Honda’s guidelines and damaged it.
And remember, you can have warranty work performed at any Honda dealer.
Let us know what you find out after testing the battery.

Here’s what the test looks like.
View attachment 1896
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@KentuckyKen is your key fob red or is that a silicone cover?
 
jorgie393 said:
As a side note, though we call it a “12V” system and battery, during the few times I actually measured the voltages on circuits when the car was fully on they were about 14.3V.

I think I remember, but can’t completely be sure, that when the car was off (so same circuit was powered by 12V battery) it dropped to 12V.

I assume the dc-dc converter, when on, holds the system at 14.3 V and thereby charges back the “12V” battery in this way. There may be other reasons.
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ALL automotive and power sport charging systems charge at greater than 12 volts. If you ever check across the battery terminal with a VOM on a running car, you should see 13.5-14.5 volts at idle on a healthy charging system.

Because of the voltage drop in the system, most of the components only “see” or have available to them around 12v depending on the vehicle.

-Skip


Sent from my iPhone using Tapatalk
 
Vezz66 said:
@KentuckyKen is your key fob red or is that a silicone cover?
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It’s actually a purple silicone cover. It was a freebie from my dealer. I think the brand is The Jacket. Fits perfectly but doesn’t cover the chrome at top where the key ring is. I have it in my spare fob and use a Lexus leather cover on the fob I pocket (another freebie, boy am I cheap!) that keeps the chrome top from being scratched.
 
I accidentally left my lights on and drained the 12v battery overnight. When I went to my car in the morning the dome lights wouldn’t go on and the car wouldn’t start. I connected a jumper cable to the car just like I would do for any other car and was able to start the car and charge up the 12v. Does anyone know a way to “jump” the car from the 17kw battery? That one still had a full charge but a couldn’t use it to get the car started. I guess it’s good that it was protected from my stupidity that caused the 12v to drain.
 
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RickSE said:
I accidentally left my lights on and drained the 12v battery overnight. When I went to my car in the morning the dome lights wouldn’t go on and the car wouldn’t start. I connected a jumper cable to the car just live I would do for any other car and was able to start the car and charge up the 12v. Does anyone know a way to “jump” the car from the 17kw battery? That one still had a full charge but a couldn’t use it to get the car started. I guess it’s good that it was protected from my stupidity that caused the 12v to drain.
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So apparently it means that the 17kw battery does not keep the 12v battery charged up when the car isn't on? Reason I ask: when leaving the car for a few weeks in the garage should I have my battery tender on the 12v battery?

Sent from my SM-G955U using Inside EVs mobile app
 
@Hi.Ho.Silver reported that when he used his 12-volt battery as a home power source during Hurricane Michael, he had to leave his Clarity ON to get the big battery to keep the small one charged. Some posters have speculated that it's possible the Clarity can send a small charge to the 12-volt battery without the car being ON, but probably not enough current to offset the drain from the LED headlights (didn't you get an audible warning?). The car's substantial 12-volt battery should easily retain its charge a couple of weeks without a trickle charger.
 
insightman said:
@Hi.Ho.Silver reported that when he used his 12-volt battery as a home power source during Hurricane Michael, he had to leave his Clarity ON to get the big battery to keep the small one charged. Some posters have speculated that it's possible the Clarity can send a small charge to the 12-volt battery without the car being ON, but probably not enough current to offset the drain from the LED headlights (didn't you get an audible warning?). The car's substantial 12-volt battery should easily retain its charge a couple of weeks without a trickle charger.
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Do you see any downside with having the 12v trickle charged (because of the PHEV system)? I'm going to be down south during the depths of (zero degree F temps) winter. Can't find any info if the fact the car is a PHEV if would change charging like an ICE car.

Sent from my SM-G955U using Inside EVs mobile app
 
Richard_arch74 said:
Do you see any downside with having the 12v trickle charged (because of the PHEV system)? I'm going to be down south during the depths of (zero degree F temps) winter. Can't find any info if the fact the car is a PHEV if would change charging like an ICE car.

Sent from my SM-G955U using Inside EVs mobile app
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Other than a lightning strike, I don't believe there would be any problems associated with using a trickle charger, but smarter members of this forum may believe otherwise.
 
Based on posts and my checking the battery, I think the verdict is still out as to exactly what happens to the 12v battery when the car is off.
Immediately after driving, I measure the voltage around 13 v, and 12 hours after charging (not turned on) around 12.5v. I left the car garaged for 11 days turned off and it measures 12.1v.
We need more observations on this to figure it out. If the Clarity treats the 12v battery like a regular gasmobile does and just lets it sit there, then it’s going to eventually run down since most all modern cars have a parasitic drain when off. The question is, if that’s the case (and that’s a big if) will it sense the low voltage and at some point charge it if the HV battery is not below some threshold?? Does having it plugged to an EVSE make any difference in this behavior?? I don’t think we know for sure yet. I await the more expert among us for enlightenment.

At my present level of understanding, I would use a trickle charger or battery minder if I was going to let the car sit for more than 2 weeks (maybe less if very cold?).
 
KentuckyKen said:
Based on posts and my checking the battery, I think the verdict is still out as to exactly what happens to the 12v battery when the car is off.
Immediately after driving, I measure the voltage around 13 v, and 12 hours after charging (not turned on) around 12.5v. I left the car garaged for 11 days turned off and it measures 12.1v.
We need more observations on this to figure it out. If the Clarity treats the 12v battery like a regular gasmobile does and just lets it sit there, then it’s going to eventually run down since most all modern cars have a parasitic drain when off. The question is, if that’s the case (and that’s a big if) will it sense the low voltage and at some point charge it if the HV battery is not below some threshold?? Does having it plugged to an EVSE make any difference in this behavior?? I don’t think we know for sure yet. I await the more expert among us for enlightenment.

At my present level of understanding, I would use a trickle charger or battery minder if I was going to let the car sit for more than 2 weeks (maybe less if very cold?).
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I can tell you that leaving the lights on all night resulted in a dead battery that had to be jump started. :-).
 
No. It wasn’t plugged in. Not sure I want to test this again with the plug in - but I’ll think about it!
 
RickSE said:
No. It wasn’t plugged in. Not sure I want to test this again with the plug in - but I’ll think about it!
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I hear you! I’ve already tested the HGDA (Honda garage door avoidance system) and it didn’t work. Don’t want to test it again. I did accidentally test the water tightness of the key fob and it made it through a wash and extra rinse cycle, but I’m not testing that again either. LOL at myself.
 
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