Might the fuse box charge terminal have some surge protection? (edited)

....

or is it a non-event if i have my battery code?

also, on many cars, i find that if i change the battery with the disconnection period less than, say 2 minutes, all is fine.

I know its a non-event on my 2004 (in fact the radio is locked to the CAN-buss, not a code anyway). Just wondering on the 2000.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

charging the battery to prevent having to enter the battery code and reset the window limits and recalibrate the e-gas system.

Additionally the trip odometer gets reset along with the clock.

Last the DME loses its adaptation values and has to reconstruct these. No biggie but just something to be aware of.

Oh in newer models the steering wheel angle sensor can display an error message along with other system controllers like the stability management system as these controllers are sensitive to low/loss of power. The techs tell me the errors will go away on their own after the car is driven a few times.

Sounds like its a "nice to do", but wont do any harm to lose those values every 5 years.

The only hurdle is that i'd need to go to radio shack and make myself a cord with alligators on one end and a lighter plug on the other, and 20" of wire int he middle. Just more to do. but i may!

I've been through those re-learnings on the red car 6-7 times in the last few months as it came back together.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Not that I think so, but just wondering if there's anything electronically fragile that can be affected by the battery being out of the circuit and a separate charge, small as it might be, coming through the lighter.

But don't try to put any real amps through the lighter circuit if you want the wires not to fry. No starting or high speed charging. Maintainers don't put out a lot of juice which is why they are OK.

Ok. I was considering if the charging circuit would get "confused" somehow; not "seeing" a battery, but having a current come in from another origin.
For years I've used a Sears charger maintainer that puts out 2 Amps maximum at a nominal 12 Volts. The dealer gave me a Charge-O-Mat, which has definitely been compatible with any Porsche up until now, but as it puts out 3-something Amps, and the Wiki article on AGMs says they can't take more than 2.7, I got a bit concerned. Later I found more substantive information that allayed this worry. VRLA/AGM batteries are lead-acid types, btw.
[www.powerstream.com]
[www.busconversions.com]

he only draw that should be placed on that little circuit is the parasitic draw of the car and the keep current for the various electronics nannies

Its service life should be that to rapidly swap the batteries. Say, 2 min. I suspect that one maybe should really disconnect the original and seconds later plug int he maintainer, since there will be a differential from dead-ish to live batteries, even no-load.
Grant

Grant

gee-lenahan-at-gee-mail-dot-com



Edited 1 time(s). Last edit at 02/12/2013 02:46PM by grant. (view changes)

First, this is what many dealers nd pros do. They plug in 12V

Second, i would plug the 2nd battery in first.

Third, DC does not on its own provide a spike. Its DC. The only spike would be the delta between battery voltage 1 and 2.

If #1 is connected when #2 is connected, they both act as giant capacitors and no surge should occur.

If there is a significant voltage delta between the two, it will blow the fuse or melt the (small) wire connecting the two vehicles. My lighter is on a 5 or 10 amp fuse (60 or 120 watts)

Any faulty logic here?

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

by the end i concluded (convinced myself) that if the car's battery is well and truly dead, and one connects it to a healthy 12V battery in another car, there will be a (12-dead)V voltage drop across what appears to be a dead short ( a battery or capacity can seem that way) and smoke the wire or fuse, just as Mike noted... although he was referring to cranking the sucker.....

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Quote
grant
Sounds like its a "nice to do", but wont do any harm to lose those values every 5 years.

The only hurdle is that i'd need to go to radio shack and make myself a cord with alligators on one end and a lighter plug on the other, and 20" of wire int he middle. Just more to do. but i may!

I've been through those re-learnings on the red car 6-7 times in the last few months as it came back together.

Grant

When you power down the car's electrical system then power it up again this is a good time for some component to fail. There is some kind of stress/shock/surge that occurs when the system is powered and this is when things can go bad. Kind of like old incandescent bulbs. They always seemed to fail when one flipped the light switch on. Once on they seem to be ok. (There's a light bulb in a firehouse in Fremont CA that has been on now for decades. Some kind of a world record of light bulb longevity. It never gets shut off.

Anyhow, but maintaining power you avoid the surge that occurs from powering the circuit.



Edited 1 time(s). Last edit at 02/12/2013 11:55PM by MarcW. (view changes)

..that the way to overcome the problem of battery-differential (if i hook a 10.5V dying battery to a new 12V battery via the lighter) is to put a 10 ohm resistor in series. For normal draw the drop will be insignificant. But it will prevent a surge, since the worst case scenarios is, say 12-8v = 4V/10 ohm = 400mA

Given that the normal draw is likely well under 100mA, the voltage drop should be less than 1.2V

Any bad assumptions here? This way i can connect them before removal, eliminating any "break before make" loss of power.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

That's where a dead battery is supposed/recommended to be charged from anyway.



Edited 1 time(s). Last edit at 02/13/2013 11:13AM by Laz. (view changes)

Quote
grant
..that the way to overcome the problem of battery-differential (if i hook a 10.5V dying battery to a new 12V battery via the lighter) is to put a 10 ohm resistor in series. For normal draw the drop will be insignificant. But it will prevent a surge, since the worst case scenarios is, say 12-8v = 4V/10 ohm = 400mA

Given that the normal draw is likely well under 100mA, the voltage drop should be less than 1.2V

Any bad assumptions here? This way i can connect them before removal, eliminating any "break before make" loss of power.

Grant

assumptions regarding what you plan to do. Whether your assumptions are good, bad, or somewhere in between I can't say.

If you can leave the power on leave it on. If you need to disconnect the battery but do not need the power off then bring in some kind of back up power, shop 12V power. I watch the techs do this all the time before they disconnect power. If you are going to work on something, a circuit that can't have power to the car then disconnect the power completely.

Then it is fine to disconnect the battery to charge it.

The car may run a little rough when you reconnect the battery since the adaptive fuel map will get reset but it's really no big deal.

You can also charge the battery with it still connected.

Its a total non-event. The windows need to be run down and up, the radio code was not needed, and the motor took a trip around the block to re-adapt (thereby maybe starting clean anyway).

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

the owners manual for your car for the instructions.

Generally the instructions are: IIRC lower the window with the down button. When fully down release the button. Then press and hold the raise button and continue to hold it 5 seconds after the window is fully raised. Release. Repeat for other window.

If the car has e-Gas this must be re-calibrated. Do not touch the gas pedal during this process. With ignition off turn the ignition to on. Do not continue turning to engine start. Wait 60 seconds. Turn the ignition to off. Wait 10 seconds. Then start engine.

The DME will rebuild its adaptation values as you drive the car.

The partial-down stops work. The open/close works. The one touch works.

No issues whatsoever.

Running very smooth.

Very soft compared with "my" car.
(kinda nice on the road!)

I'll do the recalibrate, but is it effective no that the car's been used for a bunch of short trips?

Grant

Grant

gee-lenahan-at-gee-mail-dot-com



Edited 1 time(s). Last edit at 02/15/2013 04:15PM by grant. (view changes)

When I changed the battery in my 02 Boxster I bought one of those 9 volt things you pug into the lighter socket and changed out the battery. Every worked just fine. I've used it on other vehicles with same results. I think this is a safe way to change out batteries and not do any hard or lose anything.

[www.amazon.com]



Edited 1 time(s). Last edit at 02/15/2013 06:38PM by Laz. (view changes)

Quote
Laz
[www.amazon.com]

Yes

My 2004 must have been disconnected 15 times while i played with seats (to protect from an airbag alarm)

This one now, twice.

Grant

Grant

gee-lenahan-at-gee-mail-dot-com

Quote
grant
The partial-down stops work. The open/close works. The one touch works.

No issues whatsoever.

Running very smooth.

Very soft compared with "my" car.
(kinda nice on the road!)

I'll do the recalibrate, but is it effective no that the car's been used for a bunch of short trips?

Grant

the battery in the 996 I just did the window reset operation and the e-Gas calibration operation first thing after getting into the car.When I work on cars I have no desire to blaze a new trail regarding these things but simply follow the instructions from the owners manual or factory manual if I have it.