I think the ScanGauge killed my 12V battery

Hmm. I have had a SGII since Dec. No problem with the battery. My SG does not come on until I power up. Interesting problem.

 

Not sure if this is what's happening to you, but I thought I'd throw it out. On the Gen2 the Prius goes into what I've termed "suicide" mode when the battery voltage drops below a certain voltage. In this mode a bunch of the vehicles control electronics power up and start happily chatting to each other (a simplification of course, but sufficient for this description).

I call it "suicide" mode because when these electronics come online it of course causes the battery to deplete significantly faster because they draw lots of power while on. Now I don't know how Scan-Gauge wakes up, but if it's based on communication traffic (which is likely given people's claims that if you open the doors in the Prius it may not shut off--opening and closing doors causes brief communication chatter) then that may be what happened--once the car enters suicide mode it will never exit it until the battery is charged back up.

This could be indicative of a poor capacity 12v battery (eg: one that doesn't hold much charge and thus the energy it stored up on the long trip was simply wasted). You'll need some sort of 12v battery charger (capable of outputting more than 2A @12v to overcome the "suicide" mode current draw) to charge it back up and see if the battery itself is going bad...

Hope this helps some.
Andrew

 

My ScanGauge II came on when I opened the driver's door and went back to sleep when I shut the door. I tried it a couple of more times, both driver's door and hatch, but it wouldn't come on at all until I went to the Ready mode so there must be some kind of time delay. I couldn't do anything to make it come on and stay on unless the car was in Ready.

I checked the ScanGauge manual and I didn't find anything about current draw but I think it must be really low. I can't imagine it draws enough to drain a 12 Volt battery in a few days even if it did stay on unless the ScanGauge had a short in it. I don't think your ScanGauge is the culprit.

Be aware there are some suspicions that some of our cars were unknowingly equipped with defective 12 Volt batteries at the factory. Don't know if your car has an alarm system but they are suspect also.

 

The scangauge un-sleeps on supply voltage changes. This is
documented in its manual. Sometimes the little delta from opening
the door [which also powers up the brake system and sometimes runs
the pump] is enough; sometimes it takes the charging system coming
on and bumping the rail up to 14V to do it. Or, of course, if you
hit the button. It goes to sleep when engine RPM stays at 0 long
enough, or in "hybrid" mode when it can no longer *read* engine
RPM [zero or otherwise] from an ECU. Sleep mode is a tiny trickle
of current, so if the display isn't live it's not the SG that's
draining your battery.
.
_H*

 

OK that explains what I observed then, when I opened the door the first time the brake booster charged the system and that's what woke it up. When I went back a few minutes later and opened doors again the booster pump did not run and there was not a sufficient Voltage bump to wake it up again.

 

When I opened up my door this afternoon on the way home, the SG didn't come to life until after I powered up. It had been sitting all day too. Guess my SG is not sensitive.

 

macman408: Curious to know if you had continued trouble with SG draining the battery. Thanks.

 

No problems with my ScanGauge and battery drainage. It is one of the best investments made on the Prius.

DBCassidy

 

Good to here.

 

yes, scangauge can kill your 12V battery, straight from the manual i had the same problem, where my 12v battery died because of this event

"Set the Sleep Event
By default, the ScanGauge will shut down when it sees 0 RPM. This may not be the desired setting if your vehicle is a Hybrid, which will report 0 RPM when the vehicle
is stopped. When you select HYBRID in the fuel type
(TYPE) parameter in the Basic Setup procedure (see page 11), ScanGauge will automatically set the Sleep Event parameter to NO COM.
When using ScanGauge with the Sleep Event parameter set to NO COM, there is a small risk that the vehicle’s ECU and ScanGauge will stay on and drain the battery. You must be sure the ScanGauge goes to sleep properly when the engine is turned off. "

 

Yes, I've had the ScanGauge turn on occasionally when I open the hatch or rear door after I close the drivers door. When I leave my car at the airport for an extended time I now unplug the ScanGauge just to be safe. If it's in the garage for the evening I look to see if a rear hatch or back door opening caused it to turn on. This has happened on my 2004 and on my 2007 Prius. It's somewhat random and unpredictable. I love the ScanGauge, but it does have this quirk on the Prius.

 

Doesn't happen with mine! Used Scangauge for two years now and no battery probs.

 

no scangauge problems
have it set to hybrid and com. not rpm because then it will shutdown on 0 rpm and its a hybrid so that happens a lot ;-)

 

Thanks for info as it explains why the display of my Scan Gauge II was still lit when I went out for a walk and saw it lighting up the car late one night. Clearly the electroluminescent display could draw enough current over weekly timespans to make a difference in battery charge, especially if it was chatting with the ECU and thus causing the ECU to also use more energy.

 

Mine turns on and turns off like it supposed to.

Left it plugged in for 2 weeks undrivened, no battery drain.

DBCassidy

 

Not likely ... I have scangauge and I always open the trunk AFTER I stopped the engine and get my stuff out ...

As a matter of fact the scangauge is in the second Prius nothing like this happened ... scangauge uses way less power then dome light.

Of course YOUR scangaguge could be faulty. The odbc port is always powered so does the scangauge. There are many user here with scangauge nothing like this was reported.

 

I realize this is an old thread, so my apols. for the resurrection if apols. are appropriate. I have a 2009 Gen II Prius, and noticed recently that the ScanGauge came on after I switched off the power, and opened the passenger door. It has happened a couple of times, but each time the SG has switched off after about 30 secs or so, and I've not noticed any problems with the 12V battery being flat after an extended period. - Wil