Preserve settings with a battery maintainer?

Messages
2,147
Location
Chicago, IL
I don't have a fancy battery maintainer, but I do have a small jump box. What I do it just connect the ground to somewhere on the body and clip the positive to the positive battery terminal. Then I unscrew the terminals and remove the old battery. Put in the new battery (all while hoping the positive clip doesn't get unclipped) and you're good to go. If you have small alligator clip test leads, it makes it a little easier to maneuver than the big jump box clamps. I don't know if I would use a big battery charger to do it (I don't know how well regulated they are on small loads), but if I had a small battery tender type charger, I would go for it. Same method.
 
Messages
486
Location
Los Angeles, CA
Yes it can, in addition to the battery clips. If yours came with a cigarette lighter adapter, use that. In most cars you probably have to put the key in the ignition or just turn it once to 'on' so that the cigarette 'port' is on.
 
Messages
2,408
Location
CA
Depends on the specific device. Most "smart" battery maintainers are trying to monitor voltage, so if the voltage goes to 0 then the device goes to error mode and may stop providing charge. "Dumb" battery chargers might give you better success. If you're getting a device just to do this: You don't want a charger. What you want is just another battery that you can hook up like a heart surgery bypass. There are "emergency jumpstarter/airpump/flashlight" units that basically have an extra 12v battery in it. They also sell simplified versions that plugs into your cigarette lighter, but whether those will work may also depend on your wiring. You can also just jumper to another car. That being said, just get better at putting all your settings back in.
 
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Messages
36,475
Location
ME
I use this bad boy hooked up to a former Power Wheels 12V lead acid battery. The flaw of this is if you short the battery leads you blow a 10 amp fuse for the OBDII or the radio, cigar lighter etc and the spark will be so small you may not even know.
 

Quattro Pete

Thread starter
Messages
40,743
Location
Great Lakes
Originally Posted By: raytseng
Most "smart" battery maintainers are trying to monitor voltage, so if the voltage goes to 0 then the device goes to error mode and may stop providing charge.
Yeah, that's what I'm worried about. I've got the Battery Minder 2012, and I think it's too smart for this to work. But I also have a smaller Battery Tender Jr... wonder if that one is dumb enough.
 

Quattro Pete

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40,743
Location
Great Lakes
So the guy at the automotive dept at Walmart tells me to just change the battery while the car is running to solve the settings problem. He says that's how they change batteries on cars. Is that really safe to do? Something tells me it's probably not a good idea on most modern cars...
 
Messages
987
Location
Alberta
Please don't try to change the battery with the car running. Alternators are exactly that...alternating current, half wave rectified and use the battery for ripple stabilization. Your electronics in the vehicle are going to be VERY unhappy with half wave rectified waveforms. Battery chargers and tenders are often the same thing...transformed AC line voltage and will do the same thing to your electronics: damage them. As suggested above, get a small 12V battery and alligator clips or even booster cables attached to another vehicle's battery (that is NOT running) and clipped to the terminals on the vehicle having its battery changed. Be very careful not to touch any other metal parts with the live battery and all will be fine.
 
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11,660
Location
NorthEast
even the 9v battery will work; as a matter of fact, some of the store sold contraption named "memory saver" are like that. Obviously, you have to make that absolutely no electrical circuits are on when you remove the battery (except the memory). better memory saver devices back feed 12V through OBD-II port. Once again, same precautions apply; otherwise you might blow the OBD-II circuit.
 

Quattro Pete

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Messages
40,743
Location
Great Lakes
Originally Posted By: Vikas
even the 9v battery will work; as a matter of fact, some of the store sold contraption named "memory saver" are like that.
Yup... just noticed the other Walmart near me has them for $4.50, including the battery. Will give it a try.
 
Messages
5,104
Location
Pittsburgh,PA U.S.A.
Originally Posted By: tcp71
Please don't try to change the battery with the car running. Alternators are exactly that...alternating current, half wave rectified and use the battery for ripple stabilization. Your electronics in the vehicle are going to be VERY unhappy with half wave rectified waveforms. Battery chargers and tenders are often the same thing...transformed AC line voltage and will do the same thing to your electronics: damage them. As suggested above, get a small 12V battery and alligator clips or even booster cables attached to another vehicle's battery (that is NOT running) and clipped to the terminals on the vehicle having its battery changed. Be very careful not to touch any other metal parts with the live battery and all will be fine.
Actually alternators in vehicles are three phase, with a three phase full wave rectifier. Practically as smooth as DC from a battery.
 
Messages
5,104
Location
Pittsburgh,PA U.S.A.
If you are going to use something like a small 9 volt battery with a diode installed to allow the 9 volt battery to supply power when the vehicles 12 volt battery is disconnected. The smart place to attach it to the vehicles electric system is the cigarette lighter, because it would get in the way and will end up being disconnected when you are working on the vehicles battery connection during disconnecting the vehicles battery.
 
Messages
5,722
Location
Charlotte, NC
Originally Posted By: tcp71
Please don't try to change the battery with the car running. Alternators are exactly that...alternating current, half wave rectified and use the battery for ripple stabilization. Your electronics in the vehicle are going to be VERY unhappy with half wave rectified waveforms. Battery chargers and tenders are often the same thing...transformed AC line voltage and will do the same thing to your electronics: damage them.
Wow! Alternators sure work differently on Canadia... In the U.S. alternators have full wave 3 phase rectifiers. The ripple is very small. grin2 OTOH: Given the level of electronics in modern cars, I would hesitate to knowingly disconnect a battery with the engine running. Like someone else said, I'd just reprogram the radio. But that's just me... YMMV Wayne JimPghPA beat me to it.
 
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Quattro Pete

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40,743
Location
Great Lakes
Originally Posted By: raytseng
man, i'd just reprogram my radio to save $4.50
There's more stuff on this car that'd need reprogramming. Some things can't be reprogrammed at all, like all time avg. MPG for example... but that's just my OCD kicking in. smile
 
Messages
11,660
Location
NorthEast
I don't think 9V battery even shorted can go over 10A, so you are safe as far as risk to the vehicle is concerned with that contraption. As I said before, just make sure every single thing is off when you turn the key in the ACC position with the gizmo in the power outlet.
 
Messages
162
Location
Singapore
I change batteries for a living everyday. I've tried many different ways of backing up settings. 1. Use a small 9V battery maintainer plugged into the dc socket - Many cars does not connect that socket when the ignition is off, so you have to turn it on. Some cars have optitron display which can't be turned off, and that drain the 9V battery flat, once you pull the terminal off the main battery. 2. Clip a spare battery at the terminals - You're sure to knock it off while working the battery or the clips slide off and you lose everything. 3. Hook up a small 12V 7AH SLA battery at the dc socket - Turn ignition to on, before changing battery. This will fix no. 1 problem, but make sure to fuse it not more than 15A. 4. Certain cars like Merc or BMW has separate jump points. You can clip a small jump starter (lithium-ion type) on these points and this will work too.
 

Quattro Pete

Thread starter
Messages
40,743
Location
Great Lakes
Thankfully this car does not require the key to be in ACC position for the cigarette lighter socket to work. I just need to wait a bit after I shut the doors so that all the cabin lights eventually go off before I disconnect the old battery.
 
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