A memory saver for your car battery is a connector with a small battery. It has just enough voltage and current to keep all of your car's computer memory alive while you change the main battery. The connector plugs into the car's cigarette lighter, or the OBDII connector.

While looking for a memory saver I have a few options. The best for me is a separate battery charger and OBDII port adapter. The chargers within my price range so far all seem to have a 16v DC output. If I use one of these and send 16 volts through my OBDII port can I cause damage? I know that some cars have 15 volts going through pin 16 there but what about 16 volts? I don't want to buy a separate dedicated memory saver; the 9 volt battery ones are too fragile and the good ones are too expensive and I would still have to buy a jump starter.

  • Why not just re-enter the radio code? As it seems you have so many conditions for a memory saver that none will be good enough.
    – Solar Mike
    Aug 20 '21 at 7:05
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    @solarmike How did you make the leap to “radio code” from the specific wording of this issue? I have no clue what this person is talking about and how that relates to this question forum.
    – zipzit
    Aug 20 '21 at 16:39
  • @zipzit ask the OP for details.
    – Solar Mike
    Aug 20 '21 at 16:41
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    Make, model, year? What memory are you trying to save? If you are considering using a charger connected to the OBD II port, irreparable damage may occur to the body control module. If you're trying to retain memory in ecm, pcm, bcm and radio, perhaps one method to consider would be the unswitched cigarette lighter or auxiliary power socket, All memory in modules total less than 50 milliamps to power them. An inexpensive 2-3 amp (no more) trickle charger plugged into the cigarette/aux socket will feed power to all modules with memory.
    – F Dryer
    Aug 20 '21 at 19:42
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    @zipzit - I disagree. The question is whether too much voltage can damage the system ... that seems very on point to me. Aug 20 '21 at 19:46

The memory saver provides keep alive power to electronic modules when car is off and the vehicle battery is replaced.

Lots of modules in the vehicle use volatile memory. Volatile memory is computer storage that only maintains its data while the device is powered. Lots of modules can be affected. Powertrain Control Module (recent history of starts, trouble codes, etc..) Body Modules / Audio / Infotainment modules.(radio station settings, body & lamp & electric seat selections, bluetooth & phone settings...) And it certainly would be convenient to keep that stuff whole.

Reminder, virtually all of those modules with volatile memory are using 5v (and in some cases 3.5v) dc voltage. Included in each module is a voltage converter that reduces 12v (vehicle nominal) down to the appropriate level. And the hint here is, the 9v old skool radio battery system will totally work to keep the memory active for up to two hours while you replace your vehicle battery.

9v battery adapter

Its unclear on the discussion on the 16 volt stuff. Pin #16 on an Onboard Diagnostic (OBDII) is connected directly to battery hot wire. There is nothing else there. Its a straight connection. Please check your wiring diagram to confirm.

If you are asking if an automotive battery charger is designed for 16v is correct, I doubt it. Its possible, but I really doubt it. Remember for your 12v (nominal) system, normal battery chargers charge at 13.6 to 13.8v dc (float charge). A fast charge typically goes to 14.4vdc. A fully charged battery typically sits at 12.7vdc.

Now its certainly possible that someone is using a laptop type charger to power a small "memory saver" keep alive module (and internally they are regulating the incoming voltage down to 12.7 or so). That keep alive module is plugged in to either the cigarette lighter or the OBDII connector. Note when you do this be really carefull when you disconnect the battery so the positive cable NEVER touches vehicle ground. It's not really clear on where you are going here.

The chargers within my price range so far all seem to have a 16v DC output.

I'd like to see the details of that device. If so, it sounds like that device is not designed for 12v automotive use. Peak voltage spike to 16v, okay. 16v output steady state, no go.

And for anybody interested in how automotive modules protect internals from power supply issues, here is a nice technical overview document.

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