Power System Error + Check Engine Light + Sudden Battery Charge Drop

You’re assuming that because the car has battery A and battery B, wired in parallel, that it is capable of operating with one of the batteries in isolation. Do we know this to be the case?

From your descriptions, it appears that the car is recognizing a dead battery. With a dead battery the engine acts as a generator to provide electricity to the motor since no electricity is available from the battery. The exception is Engine Drive Mode, but if you’re goosing the throttle, EDM is unlikely to engage. While the engine may seem to be “over-revving” to some, it is not. It is simply working to provide ~60hp.

With a healthy battery, the engine would attempt to maintain SOC while in HV Mode. With a defective battery, I can only speculate as to whether or not the car would allow charging to occur. You have mentioned charging the battery. In some cases a defective battery will appear to accept a charge, but it will be unable to hold a charge. This could be what you are experiencing when you see a half charged battery gauge drop to empty while demanding power.

A possible workaround would be to “charge” the battery and operate exclusively in HV. No guarantee on that idea. If you believe the car is unsafe, I’d advise that you request a loaner car from the dealer.

This is interesting, if correct, as it would allow Honda a means to escape the 8-10 year battery warranty.

 

The warranty for any Honda replacement part is one year, or the remainder of the original warranty for that component, whichever is longer. If you have to have a steering component replaced after six months, the replacement would be warranted for the remaining 2½ years of the original warranty. If that same component is replaced after four years, then it gets a one-year warranty. The replacement battery will be warranted for the balance of the eight or ten years from the car's original sale date that the original battery warranty is good for.

 

Just FYI, I watched a PHEV Clarity battery tear down before and each of the battery arrays have completely separate sets of relays (total of 4) which surprised and elated the salvage person tearing it down because they are expensive and heavy components, and he couldn't think of a reason to duplicate them. So the smart reason would be so that each array could operate independently, which if true would make the clarity quite unique.

Of course it all depends on the software running the relays.

 

You should also have the 12v battery tested as well if it hasn’t been replaced yet. Not saying that is the cause of this but it will definitely amplify issues seen. Honda hybrids get really angry with low 12v batteries.

 

Thanks for that. Was it the guy at AZ Lithium, by any chance?

We do know that pressing the brake pedal and power button sends a 12V signal which activates the high voltage system. Also, the emergency response protocols shows that pressing and holding the power button for 3 seconds deactivates the high voltage system. We also know that the voltages of battery A and B can be measured separately. Those measurements would need to be taken on the battery side of a relay. Those may be the only functions of the relays.

What we don’t know is if one relay can isolate one half of a defective battery bank. I agree, it would be a nifty feature. The car should be able to operate somewhat normally with an 8.5kWh battery. Perhaps battery power would be halved to 60.5hp?

Up to this point, however, the descriptions from descolado are consistent with those of a Clarity with a depleted HV battery.

 

I don't remember who it was, there seems to be several now if people want to take a look on youtube.

I don't see why technically it is not possible to just run with a single string. And yes, it would have to run at half the battery power output due to not only the battery capacity but also the power throughput of the wiring (and relays!). But there are a lot of strange choices honda has made regarding how the PHEV operates (i.e. starting the engine for engine brake when battery is near full instead of just friction braking). There is still however the engine that can supplement the power up to the power you need.

From what I understand (i may be wrong), the battery is actually from the ford fusion PHEV x2 which is why there is two strings. the need for two sets of relays just might be a legacy effect from it and they don't actually program it for an ability to have the strings activated independently.

 

Not necessarily. I’d like to believe that the wires running from 2 sets of batteries wired in parallel would be capable of handling the voltage and current from one set of those batteries.

The short lived Clarity BEV had 3 sets of 8.5kWh batteries. It’s probably feasible to parallel 4 or more such batteries. It’s simply a way to increase capacity while maintaining the same nominal voltage of the pack.

 

Well, the relays, which are only designed to handle one set of batteries and it's associated wiring probably are not. Especially considering there is a 'safe' amount of current that can be drawn from batteries of a certain capacity. This is why the leaf, gains more motor power every time the battery gets larger. The electric motor actually is the same motor (at least up to the year I bought my clarity). And, for instance, why you can't draw 100kw out of a prius battery (or charge them at a high rate for that matter... filling a bucket with a firehose comes to mind). They are most likely rated and limited to half the power of the full set of batteries if it ever let you just run with one string. But I would imagine that if that did happen the gas engine would kick in to provide additional power to compensate. All conjecture.. just would be nice if it had that feature.

Also, all the cars that I had researched up to when I got my clarity only had one set of battery relays (as far as I know) it is really a duplication that is unnecessary. They simply wire the batteries up in parallel before the power relays. It is the cheaper simpler solution. Not saying that honda likes cheap simple.

 

In any situation below 45mph, the gas engine acts as a generator. It can reportedly generate an amount of electricity that will produce 60hp. The battery pack can produce up to 121hp. With depleted batteries, you’ve essentially got a 60hp vehicle.

The car will draw power from depleted batteries (2 bars or 0 EV range, by my definition of depleted). The engine/generator will also attempt to maintain some degree of charge in the batteries while simultaneously attempting to meet the demands of a driver who presses the accelerator pedal to the floor in a desperate to propel the car forward.

There are a few theories on the whereabouts of the horses between 60 and 103, the rating of the engine. Regardless of their location, the car will not make 181hp or 212hp with depleted batteries.

 

Get the 12v that was stored FULLY charged before putting it in the car to get it the best chance. EVs seem to treat the 12v batteries poorly pointlessly. Glad everything is fixed and you have it back.

 

By any chance did the dealer provide you with a measurement of the capacity for the new battery? Or, better yet, a full printed report which includes individual cell voltages?

 

Sorry, I just now saw this post, and wasn't able to respond in time for your deadline...

As discussed in the thread, Torque will not work for this because it has a limited buffer size. You must use Car Scanner. Car Scanner has adopted our PID's so no manual creation of PID's is required... You simply choose your vehicle to be the Clarity and it will just work from there.

In any event, I'm glad to hear that you ae back on the road again. Although you have missed the opportunity to capture the parameters of a bad battery, perhaps you would still like to try this on the new one (particularly if you didn't receive any kind of printout from the dealer).