Just got my 2015 Accord Hybrid yesterday. Read through the manual. Slightly confused on the issue of jump starting the vehicle.
- Page 10 The high voltage battery charges the 12-V battery
-Page 11 states the generator starts the engine and it is part of the high voltage system.
- Page 528- This is where I am confused. If the engine wont start, how does charging up the 12V battery help?

 

I did some reading and I think the answer is a bidirectional DC-DC converter. With a dead system -jumping the 12v battery the 12 volts is converted by the DC-DC converter to 260 volts which then can provide power to turn the generator to start the gas engine. Sounds reasonable?

 

So the new Accord Hybrid doesn't have a 'Backup' traditional starter?? The Civic Hybrids have a backup starter. If the high voltage battery is low, you can actually hear the backup starter which uses the 12V battery.

 

I'd bed a nut there's a backup starter, and that's why it helps. Though I can't say vman doesn't have it right.

 

There's not a backup starter. The dc-dc converter only works one way, the 12v battery does not charge the high voltage battery. What jumping the 12v battery off does is enable the electronics to work so that the high voltage battery can be used to start the engine in the normal way, using the motor/generator hooked directly to the crankshaft. If the 12v battery dies there is no power to run the computers, so the command to start the engine using the high voltage system cannot be issued.

 

Even with a backup starter, that's the same setup as the HCH1/HCH2/G1 Insight. You can have a banging strong IMA battery, but a low 12V won't energize the electronics to allow use of the IMA battery to start.

 

I find it very hard to believe that there is not a backup starter (without a factory installed way to plug in the large battery for trickle charge - recovery scheme). So if this is true, unlike 99% of the cars in existence, there is no way to jump start the HAH if the large battery is depleted. You would need to jump start the large battery since we are assuming the 12V battery cannot start the vehicle in any way other than providing control voltages. I will have to look at the service manual. There has to be a procedure if the large battery is depleted. I guess the chances of this are very low, but I could see a scenario of long storage where the large battery could get low.

 

Anyone had a chance to investigate this on a lift (or just looking around under the hood)?

Remember this hybrid power train is COMPLETELY different than the earlier Civic, Insight, etc Honda hybrids. This is an entirely different design from the earlier IMA setups. Those used the HV battery + electric motor to supplement engine power. This new Accord Hybrid is a SERIES hybrid.

A good overview is this writeup by Car and Driver.
http://www.caranddriver.com/features...stem-tech-dept
www (dot) caranddriver (dot) com /features/explaining-the-honda-accords-shrewdly-designed-new-hybrid-system-tech-dept

I can believe there might not be a standard starter. The way the series hybrid works the HV electric motor basically IS a starter. There really wouldn't be any reason to have an additional 20 pounds plus wiring for a usually worthless piece of equipment. The ONLY time a traditional starter would be used would be in an event when the HV battery was 100% depleted, which should never happen.

The car seems to never let the HV battery go below two bars. Thus, approximately 15-20% of HV battery power is saved as a reserve. Being a Lithium Ion battery it should provide just as much voltage & amperage in that remaining SOC down to 0%, so the only way you should ever have an HV battery pack so depleted that it cannot start the ICE is if you leave the car sitting for months on end and the HV battery self-discharged to 0%.

I don't have my manual on hand, but does Honda have any instructions for putting the new hybrid Accord into long-term storage that addresses this?

That said, I also don't see why the DC-DC charger would be one-way only. It should be possible with electronic controls that the DC-DC charger could recharge the HV battery pack from a fully charged 13.5+v standard 12v lead-acid battery.

I do wish Honda had an engineer who'd frequent forums such as this an offer information. The Yahoo forums section for the EU2000 generator has one such employee who can answer questions, provide links to recall info, etc. That person also takes feedback from the forums back to engineering. I do know the power accessories/generators division is completely different from the Honda automobiles division but again, just wish someone from Honda with the knowledge/connections could help inform the community of owners about our new hybrid Accords.

We love our 2015 Accord hybrid Touring and expect to keep it as long as we kept our last Accord. We bought our 2003 Accord new from the dealer and kept it 12 years before we got this new 2015 Accord. There was a wealth of internet knowledge and commentary on that generation of Accord. Over time I'm sure we'll build a knowledge base, but so far there's a lot of confusion over how (EXACTLY) our new cars work.

 

Yes we need to find out the following:

if the large battery either gets depleted fully, OR the battery goes bad when you are out somewhere, can the 12V battery save us by providing enough juice to the inverter (in reverse) to start the generator(large starter).

I have a feeling Honda has it handled somehow. We just need confirmation!

Note: the Civic Hybrids can also run even if you completely remove the IMA battery.

Can the HAH run without large battery? I'm guessing that it COULD but the Gas engine would have to run the entire time, revving high enough to provide generation of electric current 'On the fly'.

This would be a good question to answer also, because there's nothing worse than a car that has a good ICE engine but cannot drive because of a battery issue.

 

For the current generation of HAH, the unequivocal answer to point 1 is NO. The 2 motor hybrid has to have electrical continuity through the traction battery in order to function - an open circuit or significant under-voltage will render the drivetrain non-functional. The 12 volt is required to boot/keep alive the ECU, which runs the whole show.

The 2 motor hybrid uses the main traction motor as the sole source for low-speed propulsion - the ICE is turning the 2nd motor to provide the current, along with the traction battery. The ICE works to provide direct torque to the driven wheels only at cruise speed when the clutch engages it, and it remains engaged only at cruise - significant torque demand gets it back into providing current for the main electrical motor.

IMA was an add-on and could function as a slowed-down ICE-only car. The 2 motor hybrid system has to have the electrical side mostly functional for the car to move.

The C&D article has a good write-up on how the various components work and relate.