[Armin]

Friends,

I found something curious over the weekend and think it might have a big impact:

Turning on the headlights makes the car charge the IMA battery more aggressively!

This seems counterintuitive at first and I don't quite understand the reasoning behind it. It's almost like turning on the A/C. However, the lights use significantly less power so there should be no noticable mpg hit. Don't forget to turn them off when parked or in idle-stop for longer periods.

When I turn the lights on, charging starts within 10 - 30 seconds and stops immediately when I turn the light back off. If the car was charging already, turning the light on makes the charge current go up 1.0 to 1.5 Amps! This works both for forced charging and hidden charging (forced charging without green bars lit). It works for most levels of battery charge, except when full (19 or 20 bars).


To all those who suffer from recals, never get their SoC gauge to read full, or have other battery problems: Try driving around with the lights on at all times and see if you notice a change!

No, I'm not drunk and it's not a late April fools joke.

 

[Armin]

not quite

Since the transformer that steps the 144 volt power down to the charging voltage for the 12 volt system has one fixed step-down ratio, that means that the control system would want the 144 volt system topped off in order to provide that power to the 12 volt system.

Sorry, Will, but I think you are a little off. The DC-DC converter that provides 12V power is not a transformer at all. And it does not have a fixed conversion ratio. (This wouldn't work, since the NiMH battery's voltage varies between 120V and 180V during driving!)

The DC-DC really provides very well regulated constant 13.9V output. Also, the charge current that I measured and talked about in my earlier email is the current going into the 144V battery. This should not be affected by current drains in the 12V system, since those are usually supplied by the IMA motor/generator while the engine is running. Also, the effect is opposite what it would be, if it was just the current supplying the load. (it would be a discharge on the battery, or reduced charge current).

No the only way to explain the symptom is that there must be a software feature that says "when there is x load on the 12V system, increase charging the 144V system." For whatever reason.

 

[Armin]

back on topic

This thread went a little OT, but to come back on topic:

I confirmed that any load on the 12V system (lights, rear-window-defogger, fan, ...) has the same effect of charging the 144V battery more aggressively.

It does keep the SoC of my 144V battery almost always at 18-19 bars again. Before I turned the light on, it was frequently going to about half and recalibrating.

I'll have to wait and watch a little to see if my recals really get fewer.

 

[Armin]

Aaron,

one of the pecularities of the "recal" problem is that it only affects some cars.

We have tried very hard in the past in both yahoo groups to link it to something in driving style, environmental conditions, gas quality, driver weight, ... etc. without success. It is entirely random. Just because you don't see it doesn't mean it's not there.

Consider yourself lucky!