Inverter HIGH voltage shutdown

[brulaz]

This is a new one to me.

Simple plug-in 400W inverter my wife uses in the car to charge/run her computer. Has worked fine over the last 9 months. But just recently during the cold spell, it complained and refused to work.

I assumed it was a low voltage issue, what with the age of the car's battery and the low temperatures, and started looking for a new battery. But then decided to RTFM and, whaddya-know, the error indication was for "High Voltage Shutdown". Hunh?

Turns out the inverter doesn't like anything much over 15V and the chevy cruze's alternator can put out 15.5V when at 90% duty cycle (http://www.cruzetalk.com/forum/17-off-topic-discussion/1339-chevy-cruze-regulates-voltage-boost-fuel...).

Since it was very cold, we were running the heater fan and occasionally the electric defoggers so a 90% duty cycle on the alternator makes sense, although I haven't measured the V myself.

[Germania]

Then again what's the inverter operating limits+- 10%. More to think about.

[GordonThree]

The cars alternator has no idea what's plugged into the cigarette lighter. It's worried about voltage at the battery, the ecu, fuel injectors, ignition packs, etc.

[brulaz]

ScottG wrote:

...
My much older RAM will happily sit a little over 15V when it's cold here.

Ah, good to know.
So you would have the same problem I'm having.

Have never heard of such high alternator V's before.

So maybe just an unexpected inverter issue (15V limit).
Nothing to do with the car.

[brulaz]

GordonThree wrote:
Stop by Wally world and pickup a China special 12v accessory extension cord. The light weight wires should drop some voltage for you.

Trouble is: the inverter refuses to even startup, before plugging any loads in. Little or no V drop from the get-go with no loads.

And even if I did add a separate load inline and increase the V drop, I wonder if the car's computer wouldn't attempt to increase the alternator's duty cycle (>90%?) and V output to compensate?

I'll monitor the V's tomorrow and try to get a better handle on what's happening.

Another thought is that maybe the car's battery is weak and not taking a charge, so the alternator is trying harder with higher Vs.

A New Year's puzzle, if nothing else.

[ScottG]

brulaz wrote:
Good points. Apparently battery temp is also used in the chevy's control circuits to set alternator voltage.

Previous Link wrote:
This is accomplished by using knowledge of the battery state-of-charge and temperature to set the charging voltage to an optimum battery voltage level for recharging without detriment to battery life.

Compared to my newer RAM, this 2011 Cruze seems to have a much more sophisticated charging algorithm. The RAM just sits at 14.3-14.5V all the time AFAIK. But I've never had it down to really low temps. It's currently vacationing in Florida.

I suspect your RAM is smarter than that. My much older RAM will happily sit a little over 15V when it's cold here.

[GordonThree]

Stop by Wally world and pickup a China special 12v accessory extension cord. The light weight wires should drop some voltage for you.

[brulaz]

Good points. Apparently battery temp is also used in the chevy's control circuits to set alternator voltage.

Previous Link wrote:
This is accomplished by using knowledge of the battery state-of-charge and temperature to set the charging voltage to an optimum battery voltage level for recharging without detriment to battery life.

Compared to my newer RAM, this 2011 Cruze seems to have a much more sophisticated charging algorithm. The RAM just sits at 14.3-14.5V all the time AFAIK. But I've never had it down to really low temps. It's currently vacationing in Florida.

[hedge]

It can also happen with chargers with temperature compensation as they'll raise the charge voltage when it's cold. I know with my solar charge controller with temp compensation I'll see over 16v charging when it's real cold.

[BFL13]

You can get that with temperature compensated solar too. 14.8v at 77F is 15.2v at 35F so you can be over the inverter's limit in the afternoon if your batteries reach Vabs.

Then you have to figure out a way to knock down your battery voltage long enough to get the inverter to start-which will then bring the voltage down more while it is running.

Another good reason to have a switch to turn off the solar (on the PV side of the controller)