While you are gone... I WILL TAKE IT FOR A SPIN !!!

 

Unfortunately, a 12V system alone is not a guarantee of a successful boost. As you indicated it is all about "cranking amps". The 12V subsystem on the HCH-II sits right at the borderline of adequacy for the car, and as such, is not a good platform to boost another non-hybrid at all.

In fact, there have been DC-DC module "early" failures reported and in most of those cases a boost of a car had taken place. The problem is aggravated even more in colder weather especially when the HCH-II boosts another car as its own battery is barely enough to start the engine on three crank cycles.

Personally, I will never consider boosting another vehicle unless its cranking requirements are as low as that of the HCH-II. As a good rule of thumb, the battery in the non-starting car must have a similar or lower cranking rating as the one in my HCH's.

For those who are a little unsure about this, please contact your service technician for specifics.

Cheers;

MSantos

 

So MSantos, what you are saying is that hybrids should be able to boost other hybrids, but not most regular cars?

 

Pretty much.

I don't know what the cranking resistance offered by a non-starting FEH in a cold day is but, I am pretty certain that it is much higher that of many smaller ICE's (sub 1.8L). So, would I consider the boosting of a FEH a safe thing to do? Certainly not.

The HCH-II has one of the most "friction free" engines in the world, cranking it in a cold day is already a challenge and the 12V battery is an even match for it. Anything else out there may require far higher cranking current (12V batt+DC-DC) than what the HCH-II can sustain.
So boosting an Insight or HCH-1 is OK (I never tried a cold Prius, but I may just for giggles do it one day). Boosting anything else (Hybrid or not) may be a challenge most of us are better off not taking.


Cheers;

MSantos

 

MSantos:
That makes sense to me, but I wonder why the AAA guy said that hybrids can't boost other hybrids. It seems like they would be able to boost other hybrids easier than conventional cars. I guess he was misinformed. I know it is possible (maybe not recommended, but possible) to boost an SUV off an HCHII.

 

A few months ago, my '03 HCH's battery died, and I easily jump-started it with my '07 Prius, following the owner's manual's instructions.
You might need to allow a few minutes for the boosting car to charge the dead battery a little before trying to start it.

 

I have a question. I read a post on another forum that said that a "jump pac" should not be used to jump-start a hybrid. The reason had to do with the larger amount of amps provided by the jump pac. Does anyone have any info on that?

 

A jump pack like this one...



... will not cause any damage to a Toyota or Honda hybrid - provided that the only thing wrong with the hybrid is a depleted 12V battery. If there is a failure that caused the 12V battery depletion in the first place then it could be very bad to attempt a jump start with such high currents.

Some things make a lot of sense when we define them in the appropriate context don't they?

Cheers;

MSantos

 

MSantos, if anyone else was saying this, I'd say they're out to lunch (that AAA guy *definitely* is) -- since it's you, I'm inclined to think I'm missing something, so let me put this as questions:

- You seem to be talking about "cold cranking amps" with the HCH 12V battery, but in a jump start, aren't CCA's pretty much irrelevant? The jumping vehicle is running, so power is taken not off the battery (at least, not alone) but off the whole electrical system, which is a nominal 14.4v and max amperage is whatever the alternator puts out *plus* the battery's reserve amperage. (It's often suggested that the jumping vehicle rev its engine slightly off idle to ensure the voltage stays up as the dead vehicle's electrical load hits.) So, how does your explanation account for that?

- What *is* the HCH's nominal voltage for electrical subsystems when the system's on? Whether it's 12V, 14.4V (the universal standard for alternators), or something else, it's obviously "artificially" rectified from the current (154V?) coming off the IMA generator. So, do you know what that's set at?

- How in world with a mega battery dumping power into the total car electrical system (the HCH has no alternator because the IMA system generates all electricity for running all systems and charging the 12V and traction batteries) could the HCH run short of power for jumping another vehicle?

- Why do Honda owners manuals for the HCH not offer stern warnings about what the HCH can and can't jump start? If I recall correctly, the manual -- like the manual for every car I've ever seen -- says that jump starting someone else's car with yours is very risky and might damage your vehicle and you really ought to let some other guy do it. But I don't recall any more specific or dire warnings than normal, and I remember looking pretty closely because I was explicitly curious about this as a new owner.


In short, would you be willing to say more on this all? According to what you're saying, some of my assumptions must be off or I must pretty seriously misunderstand the HCH's electrical system -- which I would like not to do.

cheers --
doug

 

Good questions DougD;


Not at all... Even if we have the HCH running, the HCH 12V battery is hardly able to start the foreign car on its own. The extra demand for current will have to be provided by the DC-DC module. This momentary demand for current from the DC-DC has been identified as a potential reason for its early (premature) failure. The problem is aggravated even further in colder weather as the DC-DC will avoid getting the power it needs from the battery pack. What can help the boosting HCH is to rev the engine past 3000 RPM while providing the boost.

Anyway, what has happened is that the HCH's will run the risk of suffering a "crash" and behave erratically right after a stressful boosting attempt. These types of crashes occur when the voltage drops too far below 12V (even if momentarily) and some people do not notice them until sometime later. Fortunately these types of crashes can be easily resolved with a simple "12V power-off" reset.
In the more extreme cases, a damaged DC-DC is not so easily fixed and will likely require a replacement.

The nominal operation voltage level is at ~12.6V. The charging level is ~13.7V.
The 13.7V level is provided by the DC-DC module as a "step down" from the battery pack voltage. If the current demanded by the boosted vehicle is too high the HCH voltage may drop too far and "may get seriously hurt" in the process.


Cheers;

MSantos