Trick To Prevent Loss of Settings When Changing Your Battery

[DonB]

With all the recent talk about batteries, storage and maintainers; I changed my battery Saturday with a new Interstate AGM. The main issue I dreaded was resetting all the multitude of settings in the C6. Then I had a brainstorm.

Enlisting the help of my trusty Crapsman battery charger, I connected my Red (+positive) battery charger clip to the output post (Red 12 volt) on the alternator and the Black charger clip to the mounting bolt of the alternator for the (-) ground. Set the charger to LOW or 2amp. Then plugged in the charger and turned it on.

Now you can remove the battery cables from the battery without loosing the 12v. for the system memory. Be careful NOT to touch the positive battery cable to ground because it's live. Once the battery cables are back on tight, FIRST, TURN OFF the battery charger and then remove the leads from the alternator. You don't want any current arcs at the alternator. At the battery the ground cable comes off first and goes back on last.

You see there are diodes in the alternator that basically turn the alternating current the alternator produces into DC to charge the battery and operate everything. These same diodes prevent the power from the battery charger from back-feeding into the alternator and causing any damage.

Works like a Charm! VIOLA! (And, Yes,..I did figure this out myself.)

 

[LLC5]

With all the recent talk about batteries, storage and maintainers; I changed my battery Saturday with a new Interstate AGM. The main issue I dreaded was resetting all the multitude of settings in the C6. Then I had a brainstorm.

Enlisting the help of my trusty Crapsman battery charger, I connected my Red (+positive) battery charger clip to the output post (Red 12 volt) on the alternator and the Black charger clip to the mounting bolt of the alternator for the (-) ground. Set the charger to LOW or 2amp. Then plugged in the charger and turned it on.

Now you can remove the battery cables from the battery without loosing the 12v. for the system memory. Be careful NOT to touch the positive battery cable to ground because it's live. Once the battery cables are back on tight, FIRST, TURN OFF the battery charger and then remove the leads from the alternator. You don't want any current arcs at the alternator. At the battery the ground cable comes off first and goes back on last.

You see there are diodes in the alternator that basically turn the alternating current the alternator produces into DC to charge the battery and operate everything. These same diodes prevent the power from the battery charger from back-feeding into the alternator and causing any damage.

Works like a Charm! VIOLA! (And, Yes,..I did figure this out myself.)

This is very flawed, do not do this.

First of all, having a 120V sourced 2A charger on your battery cables and then removing them from the battery allows the charger to possibly send spike voltages and corresponding current into the computers and modules and damage them. Do not run a battery charger open circuit (no battery load, except for the electronics in the vehicle) and then allow it to power your vehicle electronics, I would say that you are very lucky that nothing was damaged.

 

[Hib Halverson]

"LLC5" is right.

DO NOT use the above procedure. You risk damage to the electrical system.

Not only do you risk damage from voltage spikes but the output of a "Crapsman" or other brand of charger is not 12v DC. It's more likely a pulsating DC which also can damage certain electrical components when the storage battery is removed from the circuit.

 

[DonB]

You are entitled to your opinion, But enough with the gloom and doom. You can even use a KNOWN GOOD 12v battery in place of the charger "on LOW.' It IS necessary to disconnect and reconnect the battery and charger cables EXACTLY as I explained to avoid any possibility of a Spike. This procedure caused NO MORE of a SPIKE than replacing the battery normally.
I have been in the BIZ for 40 years with GM and MOPAR and we have done this on many occasions. Without any problems.

 

[Hib Halverson]

You are entitled to your opinion, But enough with the gloom and doom. You can even use a KNOWN GOOD 12v battery in place of the charger "on LOW.' It IS necessary to disconnect and reconnect the battery and charger cables EXACTLY as I explained to avoid any possibility of a Spike. This procedure caused NO MORE of a SPIKE than replacing the battery normally.
I have been in the BIZ for 40 years with GM and MOPAR and we have done this on many occasions. Without any problems.

Please, cite the section in the 2005 Corvette Service Manual which advises technicians to connect battery chargers to the B+ connections in the abscence of a storage battery.

Also, tell us what "settings" are lost when the battery is disconnected from the vehicle.

 

[DonB]

First of all, I said what I did was a "trick" or "shortcut" to avoid loosing all the settings in the car. I NEVER said the FSM recommended it. So don't put words in my mouth. As with most car mechanical & electrical tricks and shortcuts, they are acquired in the field doing years of real work. NOT pecking away at a keyboard, belittling everything a guy says because it isn't on page xxx of the FSM.
Secondly "The Settings," I'm referring to would be all the memory settings for the radio. I have a Pioneer that has a bunch of them. Plus also the memory for each driver(or FOB) associated with the seats, mirrors, column, entry/exit, lighting, Vats to name just a few off the top of my head. Also the engine,drive train and other associated management systems settings it learns as you drive the car.

So I guess, O.K. Here!

DISCLAIMER: Should you NOT be familiar with your car's electrical system, Automotive DC electrical, can Not follow precise instructions and/or do NOT trust your own ABILITY;
DO NOT ATTEMPT THIS PROCEDURE.

 

[LLC5]

You are entitled to your opinion, But enough with the gloom and doom. You can even use a KNOWN GOOD 12v battery in place of the charger "on LOW.' It IS necessary to disconnect and reconnect the battery and charger cables EXACTLY as I explained to avoid any possibility of a Spike. This procedure caused NO MORE of a SPIKE than replacing the battery normally.
I have been in the BIZ for 40 years with GM and MOPAR and we have done this on many occasions. Without any problems.

Your second sentence is how it should be done, usually with a good jumper battery, and NOT with a battery charger of any kind, even a .25A battery maintainer. And it's not just an opinion it's a fact, computers and modules can be damaged with an open circuit battery charger attached. Period.

You state that you have been in the BIZ for 40 years with GM and Mopar, which of their factory training center classes instructed you to perform this procedure?

 

[DonB]

Now you're just being facetious......None.

 

[LLC5]

Now you're just being facetious......None.

No, actually I wasn't.

There is always an outside chance that a instructor would teach that procedure, it would be wrong but not impossible. I have been to enough training classes to know.

 

[DonB]

I understand that jumping off another battery would have been the preferred method. That actually is the way we have always done it. Using a jumper pack(battery) or the like. But in all honesty,..I got lazy and didn't feel like jockeying all the cars around because my jumper pack was stone dead. Plus the right side of the Vette, where the battery is, was against the garage wall. Sometimes you just "Luck-out." Just to be clear though, the charger was at 2amps and I was ready to swap the battery. Hold down was off and cables were loose. Couldn't have been more than a minute.....(Yes, I know,"It only takes a second.") I'd never attempt it with any more amps than that. Like the 50amp booster! The thing would "still" be smokin'. LOL!

I wonder if a 9v battery would be sufficient to sustain the memory for a minute? Actually a small back-up battery, like those used with some alarm systems could work. It isn't a bad idea to have one on board, wired into the system. Like a small lawn tractor battery. Hmmmm; Food for thought! Now where to put it?

After all, that's how a lot of Vettes get stolen. They pop(puncture) the battery through the fender(or vent) and after the acid drains out, it's dead and the VATS won't work. In my C4 I have a stainless box around the battery because it's easy to pop the battery through the left side fender vent. A friend of mine(former Vette owner) with a towing company told me that one. I'm thinking about designing one for the C6, but the c6's battery is farther in board and the hood latch mechanism protects it a bit from the outside. The c4's is right up against the lower fender panel.

Later, thanks for the input.

 

[LLC5]

I understand that jumping off another battery would have been the preferred method. That actually is the way we have always done it. Using a jumper pack(battery) or the like. But in all honesty,..I got lazy and didn't feel like jockeying all the cars around because my jumper pack was stone dead. Plus the right side of the Vette, where the battery is, was against the garage wall. Sometimes you just "Luck-out." Just to be clear though, the charger was at 2amps and I was ready to swap the battery. Hold down was off and cables were loose. Couldn't have been more than a minute.....(Yes, I know,"It only takes a second.") I'd never attempt it with any more amps than that. Like the 50amp booster! The thing would "still" be smokin'. LOL!

I wonder if a 9v battery would be sufficient to sustain the memory for a minute? Actually a small back-up battery, like those used with some alarm systems could work. It isn't a bad idea to have one on board, wired into the system. Like a small lawn tractor battery. Hmmmm; Food for thought! Now where to put it?

Let's just say that the risk certainly does not out weigh the gain in this situation. Glad that it worked out for you this time.


We have a battery source that plugs into the OBD 2 connector that saves the memory for vehicle electronics. I have had 9V batteries fail to save the memory on some vehicles, so I would not recommend it especially on later vehicles. Trying a 9V source won't hurt anything, it may just fail to preserve memory in the electronics.

 

[vett boy]

I don't know why people get paranoid about disconnecting a battery .All you have to do is re-index your windows and re-set your clock ,the car does the rest when you drive it .