Battery change memory savers

[kb27]

Originally Posted By: HorseThief
Originally Posted By: Danh
Originally Posted By: HorseThief
depends on the vehicle and you have to be careful. ODB ports are only spec'd for 4 amps officially, but it depends on what fuse they're running off. Interior lights, auto lamps/DRL, fancy radio head units and the like can draw quite a bit of power

You have to plug it in and keep the doors closed to ensure the vehicle won't draw too much power. If you accidentally open the door with the battery disconnected, there's a small chance you could blow a fuse and have to go hunting for it.

Typically, when I have the time or it's important to not lose settings like security codes, I will use a small 12V SLA battery with test leads to battery lugs or fuse panel under the hood.

With proper precautions taken, they're very convenient to have around and if it has a 2 pin sae connector, it can be used with a bunch of different battery maintainers and low amperage chargers.

Some of the Noco chargers have a 12V 3-5A maintain/supply mode that works well for this.


Just to be sure I understand, you'd rather use essentially a spare 12V lead-acid battery with jumper cables attached to the positive and negative battery cables than going through the OBDII port? Thanks.


No - I would love to go through the ODB port, it's just that I won't do it with a customer standing by. I don't want them opening a door or turning anything on (and no - people don't listen when you tell them not to do something) On my own vehicle, that's a different story.

Otherwise, I should clarify - not jumper cables, jumper wires or test leads. 18-16AWG wire with large alligator clips. Aside from GM vehicles where the power distribution panel is mounted on the battery cover, it works well and stays out of the way.


I'm always looking for a place to connect the backup battery that stays out of the way, when I'm changing battery.
Fuse panel seems like a good idea, provided there's lug to clamp on and it stays secure during the change process.

 

[Danh]

Just as an update, I did make the battery change using a memory saver attached to the OBDII port. The memory saver power source was a spare 12v car battery. I exchanged my CRV's small 51R battery for a larger 24F, which required a bit more fitment time than usual, but all electronic memory seems to have been preserved.

As others have pointed out, the key with an OBDII memory saver seems to be keeping current demands to an absolute minimum while the only power is through the OBD port as its power-carrying capacity is limited. Just to be sure demands were minimal I did not open car doors during this time, left the car unlocked (theft-deterrent system), turned off Bluetooth on my phone (because who knows?) and kept my keyless ignition fob far away.

 

[Silverado12]

Maybe I'm missing something but I've always just swapped batteries making sure everything is shut off inside the car. Never had any issues, but yes, sometimes I have to do the presets depending on the car and my clock resets itself the first time it senses my phone on the bluetooth.

 

[Danh]

Originally Posted By: Silverado12
Maybe I'm missing something but I've always just swapped batteries making sure everything is shut off inside the car. Never had any issues, but yes, sometimes I have to do the presets depending on the car and my clock resets itself the first time it senses my phone on the bluetooth.


That's been my prior experience, too. But with the proliferation of electronics in the current/future vehicles I thought this was a reasonable thing to do. And as it turns out, pretty easy.