Interesting, maybe, Scangauge power use

[booster]

We had kind of an odd dead starting battery in our 07 Roadtrek 190P the last week.


The van had been sitting for over month, but that is not unusual as it will go way longer than that with the gp27 starting battery.



I had done some wiring in of a couple of accessory sockets on the dash a couple of weeks ago, so the starting battery power was shut off and then turned back on after the wiring. Maybe a week after the wiring, I tried to test a GPS in the accessory outlet and it wouldn't run. Checked the battery at 6.0v, so pretty much dead dead. I charged it and did recondition cycles with the Ctek charger and then check voltage periodically. It was losing over .1v per day, with nothing turned on. Put an ammeter on it and it was pulling a constant 1.3 amps with occasional drops to near no amps for a second or two and then back to 1.3. I have checked it several times in the past and it was always under 0.04amps. I pulled fuses and found about 1/2 of the power going to the radio and the other half to IP, which I think is instrument panel.



Long story shorter, after messing with the radio and about everything else I could find, I unplugged the Scangauge and the the amps dropped by half, and then a timer cycled off the other half, right down to the .035 amps I usually would see. Plug the Scangauge back in and the situation would repeat. We have had a Scangauge for years, although this one is only a couple of years old, and never have seen this before.


Lots more testing of different power on/off stuff, key position, you name it, and I think I know how to prevent the problem, but not certain over time.



I found that if I removed the starting battery power from the van, and then turned it back on, the Scangauge would go in to a continuous loop of trying to connect to the computers, not being able to, stopping trying for a second, and then start all over again. It continued even after the Scangauge display timed out the backlight, essentially forever.


The fix, if it continues to work that way, is to make sure to turn on the ignition to the run position after reconnecting the battery. The Scangauge will connect to the computers and have the normal screen and the extra power will reduce a bit. Turn off the key and the door and radio timers run for a bit and then the power drops to the .035amps and stays there from then on.


I think the same thing would happen when you just plug in the Scangauge, so would also want to turn on the key after you do, until it connects.


I will be sending Scangauge an email question to see what they say, but it certainly does seem to be something to be aware of because you can kill a battery in just a few days.

[Nic7320]

It sounds like you might have a defective ScanGauge, or there's some sort of problem with your OBDII port. I leave mine in place when the vehicle is idle for months and the battery is fine.

But the ScanGauge shouldn't even get power from your OBDII port with the ignition off. That's really odd.

Another item that may drain your battery are USB ports. Unfortunately, they still have some current drain even when nothing is plugged in, especially the ones with LEDs.

A small solar panel on your starting battery might be the easiest way to solve your problem. It will keep the battery charged and your vehicle will always be ready to go.

[booster]

Originally Posted by Nic7320

It sounds like you might have a defective ScanGauge, or there's some sort of problem with your OBDII port. I leave mine in place when the vehicle is idle for months and the battery is fine.

But the ScanGauge shouldn't even get power from your OBDII port with the ignition off. That's really odd.

Another item that may drain your battery are USB ports. Unfortunately, they still have some current drain even when nothing is plugged in, especially the ones with LEDs.

A solar panel might be the easiest way to solve your problem. It will keep the battery charged and your vehicle will always be ready to go.

We have solar and 440ah of batteries that we can connect to starting system, so that isn't an issue. The fact that Scanguage does this is what is mystifying. I think the 5v power stays on to the OBDII port, as it is on the same circuit as the accessory outlet from the OEM. The Scangauge may not draw any power, but seeing the 5v, may be need to keep it connected, as they would want to make sure it tried to reconnect if you moved it to another vehicle.


I am going to pull the older Scanguage that used to be in the van out of my old Buick and see if that does the same thing, as we never saw this in quite a few years of using it, although it is also very likely that the engine would have been run at essentially every Scangauge plug in or battery disconnect.



Hopefully, the Scangauge folks will be of some help also.


I know it is not any other drain, as with the Scangauge disconnected I go right back to the low drain we have always seen for a decade. We also get the exact same low drain with Scangauge plugged in after it connects to the van computer and then the key is shut off.


In the reviews for Scangauges online, there did always seem to be a small minority of people that said they were junk because they killed their batteries, so maybe they really did have issues like this.

[booster]

I did some looking on the Scangauge site, and there are indications that this may be a normal function for the units. Not good, but normal.


The instructions tell you to have the key in the "run" position when you plug the unit in, or turn it on right after you plug in and wait for it to connect to the computers before turning off the key.


In the frequently asked questions, one of the is what to do if the unit just continually says "connecting" without finishing. One of the answers was to turn on the key to run position until it connects, then turn it off.


No mention of power use, but that is there during the connection period as I have seen it come and go as stated.


The fact that the Scangauge can continually try to connect even with the key off, and that is normal behavior, would indicate that the Scangauge and the OBDII port are powered with the key off.


I am sure the circumstances of causing the power drain are kind of rare, as it is not a normal thing to disconnect the battery or the Scangauge and then reconnect it without turning on the key to test for power or to start the engine. It would be more likely for anyone moving the Scangauge from vehicle to vehicle often.

[GeorgeRa]

Not completely related to your issue but it was my experience with the ScanGauge E. I had it plugged into my Opel Astra. Killed the battery to the level of not accepting charging and killed the CPU. Towed to the Opel dealer and $1K later my car had a new CPU and a battery. Service folks never had this type of problem and felt strongly it had to be the ScanGauge. I never figured out if the issue was OBDII compatibility in EU or just a defective unit but didn’t want to test it in US so the unit ended in the garbage.

[markopolo]

That's great info Booster - thanks for posting about it. I've seen my Scangauge wake up many times when doing other electrical stuff. I bet it went into the trying to connect mode you discovered.

My rigs tend to be plugged in and on a float charge or on solar either of which couples house and chassis batteries so the extra current draw went noticed.

I will pay more attention when moving it between the three vehicles I use it on and make sure to put the key in the run position when installing.

I also have a Bluetooth OBDII device that goes into a sleep mode after a period of time. The fact that the sleep mode feature exists would pretty much confirm that the OBDII port is continually powered.

[booster]

Originally Posted by GeorgeRa

Not completely related to your issue but it was my experience with the ScanGauge E. I had it plugged into my Opel Astra. Killed the battery to the level of not accepting charging and killed the CPU. Towed to the Opel dealer and $1K later my car had a new CPU and a battery. Service folks never had this type of problem and felt strongly it had to be the ScanGauge. I never figured out if the issue was OBDII compatibility in EU or just a defective unit but didn’t want to test it in US so the unit ended in the garbage.

Interesting. If the FAQ for the Scangauge on their site, in the area I mentioned earlier about trying to connect but never getting there, one of the other solutions was to check the setting for the vehicle coding system. If the Scangauge and vehicle aren't on the same system, it will never connect and give the same issue I had, it appears. Here is what they say about the connecting int he FAQ section, and there a lot of different systems, especially when you get away from the major vehicle manufacturers. Sounds like that might have been what happened to you.

ScanGauge never stops saying “Connecting…”First – be sure the key is in the RUN position, and/or start engine.
If that does not solve the problem, then the ECU may not responding properly. You may need to manually set, or “Force”, the operating MODE of your ScanGauge. Please refer to the user manual for your ScanGauge for information on how to access the MODE setting screen. Once you are ready to set the mode, you can try the following settings:
FORD Products: PWM or CANSF
GM Products: VPW , ISO or CANSF
Chrysler Products: ISO, VPW or CANSF
Volvo Products: ISO, CANSF or CANLF
Others: ISO, KWPS, KWPF, CANSF, CANLF, CANSS or CANLS
Next – confirm your vehicle meets the minimum OBDII, OBD2 or EOBD compatibility requirements. Click the following link if your vehicle is 1995 or older, or click this link if your vehicle 1996 or newer.

[booster]

I just went out and tested our older Scangauge that I have in my 96 Roadmaster, and it does exactly the same thing. Plug it in with the key off and it will try to connect forever it appears. Turn on the key and it is connected within seconds.

[cruising7388]

Originally Posted by booster

I just went out and tested our older Scangauge that I have in my 96 Roadmaster, and it does exactly the same thing. Plug it in with the key off and it will try to connect forever it appears. Turn on the key and it is connected within seconds.

I have a Scangauge that I've never installed but it appears from the instructions that the unit does not have a manual controlled on-off switch. Is that correct?

[booster]

Originally Posted by cruising7388

I have a Scangauge that I've never installed but it appears from the instructions that the unit does not have a manual controlled on-off switch. Is that correct?

That is correct.

[cruising7388]

Originally Posted by booster

I did some looking on the Scangauge site, and there are indications that this may be a normal function for the units. Not good, but normal.


The instructions tell you to have the key in the "run" position when you plug the unit in, or turn it on right after you plug in and wait for it to connect to the computers before turning off the key.


In the frequently asked questions, one of the is what to do if the unit just continually says "connecting" without finishing. One of the answers was to turn on the key to run position until it connects, then turn it off.


No mention of power use, but that is there during the connection period as I have seen it come and go as stated.


The fact that the Scangauge can continually try to connect even with the key off, and that is normal behavior, would indicate that the Scangauge and the OBDII port are powered with the key off.


I am sure the circumstances of causing the power drain are kind of rare, as it is not a normal thing to disconnect the battery or the Scangauge and then reconnect it without turning on the key to test for power or to start the engine. It would be more likely for anyone moving the Scangauge from vehicle to vehicle often.

I think it's remarkable that it's taken this many years to fully understand the anecdotal reports of engine battery failure. There is no way to describe this issue other than as a serious design flaw. Us pilgrims out here might be oblivious to the innards of the OBD II port but surely Scangauge should have determined during the design phase that the OBDII port power feed was fed directly from the battery.

It would normally be easy for the unit to be designed to power down after X number of unsuccessful connect attempts but because the unit has no internal power, it would be unable to subsequently reboot from shutdown. But since OBD II is always hot, a manual on-off switch would resolve that.

After some period, the display shuts off presumably to reduce power draw but ironically all this does is aggravate the condition since it appears to the owner that the unit is powered down..

The manual describes the problem as a failure to connect but it doesn't make clear that this condition can bring the battery to its knees.

[markopolo]

Originally Posted by booster

.................................. I am sure the circumstances of causing the power drain are kind of rare, as it is not a normal thing to disconnect the battery or the Scangauge and then reconnect it without turning on the key to test for power or to start the engine. It would be more likely for anyone moving the Scangauge from vehicle to vehicle often..................

As Booster noted, the abnormal power drain would be or should be a very rare event and easily prevented by following the installation instructions.

I just have to remember to turn the key to the run position after moving the Scangauge to another vehicle if I'm not going to drive it soon.

As cruising7388 noted, a manual on/off switch would be a solution but drivers would likely to forget to turn it off. Lots of vehicles have multiple drivers. It's probably not a bad idea to unplug the unit if storing the vehicle over winter for example.

[WJones]

The OBDII port to the Scangauge is definitely powered 100% of the time. Easy to check. When the engine is off and the Scangauge is sleeping, wake it up with the button on the lower right corner. It will turn back on and read the battery voltage live.
Good to know, Booster. I guess few people have this problem because when you install it initially you will normally turn the engine on to try it.

[booster]

Originally Posted by WJones

. I guess few people have this problem because when you install it initially you will normally turn the engine on to try it.

I totally agree. I think the most likely time for it to happen would be like I did it. Over the winter you need to put in an accessory or clean the battery terminals so you disconnect the battery to do that work. When done you reconnect the battery with no reason to think about the Scangauge at all. You can even charge the battery repeated times and it doesn't ever connect, so you don't know until you go to start the van.

[Luv2Go]

The interesting thing is the scangauge designers have the info they need to resolve this. They measure and report the battery voltage regardless of key position, I've seen it change with the key off so I know that they are not getting it from the ECU. They could easily add an algorithm to keep the search process from happening with low battery voltage.

[booster]

Or they could just limit the time it will try to connect and if it goes to long set a code and shut it off. Display the code the next time it the key is activated.

[cruising7388]

Originally Posted by booster

I totally agree. I think the most likely time for it to happen would be like I did it. Over the winter you need to put in an accessory or clean the battery terminals so you disconnect the battery to do that work. When done you reconnect the battery with no reason to think about the Scangauge at all. You can even charge the battery repeated times and it doesn't ever connect, so you don't know until you go to start the van.

The problem isn't so much that this condition can occur as much as if it occurs, with a blanked display, there is no discernible symptom to alert you until long after the battery has been totally trashed.

[booster]

Originally Posted by cruising7388

The problem isn't so much that this condition can occur as much as if it occurs, with a blanked display, there is no discernible symptom to alert you until long after the battery has been totally trashed.

Yep, and even if the screen did show the fault, you might miss it if you just had the battery unhooked to clean terminals or do a bit of wiring.

[WJones]

OK, so this happened when you disconnected the battery. I wonder if it could happen when, for some reason, the engine battery is completely discharged. Let's say someone leaves the lights on and when he realizes it, simply puts the battery on a charger until it says it's fully charged. He unplugs the charger and discovers after a few days that it's discharged again. Next step: "I'm getting a new battery because this one must be shot."
At what voltage does the Scangauge react this way?

[cruising7388]

Originally Posted by markopolo

As cruising7388 noted, a manual on/off switch would be a solution but drivers would likely to forget to turn it off. Lots of vehicles have multiple drivers. It's probably not a bad idea to unplug the unit if storing the vehicle over winter for example.

If the battery is disconnected. the unit obviously shuts down. So far so good. The problem develops when the battery is reconnected, because the unit as designed is hard wired to power up. But with a manual switch interfaced, when the battery is reconnected, the unit would remain off until it is manually powered up which would both prevent a battery discharge plus making it practical to implement a timeout shutdown after a number of unsuccessful attempts to connect.

There are currently OBD II readers that are wireless and use a module plugged into the port that talks to your I phone or Android eliminating at least one cable from the cable clutter from a GPS, cellphone etc. that festoons our dashboard. It would be nice to see this that wireless feature available on the Scangauge.

Someone aboard indicated that a USB power consumes power even if nothing is plugged into it. Is this correct?