So I have been struggling with small batteries for a while now, I am on my second one in 18 months. The first one from AMS, which was a rebranded Odyssey, went out on me in only 9 months. I charged it out of the car and it would only last 3-4 days just sitting before the car would not turn over (without an OpenPort). I was working at the time so it wasn't uncommon for it to not show it's ugly face unless a holiday weekend or vacation came around. So I purchased a Battery Tender and ordered a new small battery.

I purchased a real Odyssey PC680-P and the car has been just fine for 5 months. I think it even sat at Evolution Dynamics for 12 days or so and cranked like a champ. I drive the car maybe once every few weeks or at autocrosses. I have not left the OpenPort plugged in for more than a day or so, actually since having this new battery I only plug it in at autocrosses to log my runs then remove it at home.

More than 3 times now, I have left the OpenPort plugged in while the car sat in the garage and more than 3 times now after 3-5 days the battery is COMPLETELY drained, so much so I have to remove the battery harnesses to get the battery to take a charge. I tried 2 times already leaving the car sitting in the garage for up to 14 days without cranking it and it has started just fine without the OpenPort plugged in. Needless to say, I am glad I figured it out but I really didn't think the OpenPort required enough current to drain the battery in just 4-5 days. I do realize it is additional load on the battery over what the ECU, alarm, etc. put on the battery.

So I guess the moral of the story is, if you are going to let your car sit for extended periods of time and you have a small battery kit, don't leave your OpenPort plugged in while you are away!

 

very interesting! good to know the cable draws current even with the car off.

 

Yeah, I always noticed the LED's blinking on the device, I just thought it was the LED's drawing current, which would only be a few milliamps...

I tried finding the rated current for the OpenPort in both the car off/on conditions but no luck so far.

 

it would be easy to check with a ammeter. just cut the power wire in the obd connector

 

I have an OBD extender cable I don't use and a Fluke/Tektronix system, I may just do that.

 

Someone on the other forums brought up they had the same issue with leaving a CAN bus breakout box plugged in on their work truck and stated having the device plugged in may have been keeping something on the ECU alive. They had the same issue with the battery going dead so they canned the idea. That makes more sense, I just don't see the electronics on the OpenPort draining even nearly as much as the alarm system and keyless entry.

 

I dont have the same problem you do, but having a series 1 AEM, the car needs a little more time to crank, and in winter I'am always afraid it would leave me stranded. Plus the problem with the pole connection breaking, so out with the mini, in with the Optima.

 

I have seen the same issue with a small battery and the Tactrix cable left plugged in. It completely drains the battery in a day or two. Without the Tactrix cable plugged in I can go for at least a week without draining the battery.

 

Never had that issues with the PC680, but mine eventually died a few weeks ago due to sitting in freezing temps. I did a ton of research and eventually went with a DEKA EXT30L battery. Its slight larger than the PC680 and has double the CCA. Have had my car sat for an entire week, and it starts right up. I started a thread i nthe show and shine section about it to let people know. Check those out!