How important to do this ?CaC
- Thread starter Jim K
- Start date
On newer cars, you lose more than your radio settings and clock. Throttle body and transmission adaptions, power window and sunroof auto functions just off the top of my head, not to mention emissions monitor settings which can take hundreds of miles to complete. None are huge issues but if you don't have to go through them by a simple connection, why not.
Some cars like newer Ford's you have to reset the battery monitoring system, either you have to have a scan tool or you have to find what combination of pedals and buttons will trigger the reset.
I wouldn't do this unless necessary, if the positive wire terminal touches the bodywork anywhere during the change, you'll have a short and some fuses blown. Unless there's a short protection in that obd-plug
You could use the battery from a 12V cordless tool.
The way I've seen it done was to use something hooked up to the lighter plug with the ignition turned (but not started). Not quite sure how that would work with newer cars with keyless start. That can be done with some jump starters, as well as some of the starting aids that are supposed to charge up the battery through the lighter plug.
JHZR2
Staff member
I’d look for a different/better spot to keep things charged. And use a fuse. That battery can put some good short circuit current and I’d hate to think what it would do through the wires connected from the OBD II port to who knows where.
Maybe I’m wrong and that’s a heavy wire but I have my doubts.
Maybe I’m wrong and that’s a heavy wire but I have my doubts.
Why does backfeeding power make me squeamish
Especially into an OBD 2 port that is connected to every computer in your car.
because the OBD port has a live feed? you're not putting the power on the canbus that's connected to everything... the main battery is also connected to everything btw..
One would assume that car manufacturers figured people would change the battery by just disconnecting the two cables and popping in new battery. And people would leave a light on a drain the battery to dead.
I think important stuff is retained in flash memory. Other not really important stuff will just be relearned.
I do not think having the ECM re-learn things every few years is a bad thing.
I think important stuff is retained in flash memory. Other not really important stuff will just be relearned.
I do not think having the ECM re-learn things every few years is a bad thing.
$5 memory saver. It uses a 9 volt and plugs into the lighter socket. As long as you use a fresh 9 volt battery and don't take too long to swap out the new battery. Probably won't work on more upscale vehicles ( complex procedure)but on a regular DD it will suffice.
I used this to change a battery in an Audi Q3 last weekend:
https://www.amazon.com/gp/product/B01M7PDFLJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I used it with a motorcycle battery. Worked perfectly!
https://www.amazon.com/gp/product/B01M7PDFLJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I used it with a motorcycle battery. Worked perfectly!
Richard , I have that already to. My only issue is I don`t have any batterys around to hook that up . That is why I bought the one that hooks to a 9 volt battery. So I have both OBD2 connectors , but a battery change should not be anytime soon . My current battery is not to old.
