Disconnecting the battery

[KillerHERTZ]

Ian's getting down with the kids like Richard Madeley:

 

[Ian B Walker]

Been on the acid as well Ian?

Ian's getting down with the kids like Richard Madeley:

Having had a really cr@p week and tonight a 1/3 bottle of malt ( not something that is a regular occurrence I hasten to add) I felt like belonging to the modern world

 

[stevesey]

It's only Monday! I hope the rest of the week improves.

 

[Ian B Walker]

Oh it will :bannana:. Daughter released from Hospital, Work coming out of my ears and a very rare car to work on. Drools with anticipation :bannana::bannana:

 

[tony2311]

So disconnect negative first, and reconnect negative last.

How about thoughts regarding damage to SAM, ECU, etc - as this is what would concern me most?

So its confirm -ve off first and on last, what about damage to sam, ecu etc you hear on here during jump start etc?

 

[Number_Cruncher]

If I were designing a tool to do this job, this is what I would do;

One way to avoid damage from spikes is to connect a decently large sized capacitor with a variable series resistor; one terminal to the battery +ve, and the other to a good earth.

When you remove the -ve terminal from the battery, with the variable resistor set to a low value, the capacitor then temporarily supplies any circuits which are placing any demand on the battery, so, you get no spark from the terminal, and the capacitor gracefully discharges through the series resistor.

The reverse process is a bit more involved. Charge up the capacitor directly across the battery, then disconnect, setting the series resitor to a high value, and then connect capacitor +ve to battery +ve, -ve to a good earth, gradually turn down the series resistor (effectively turning up the voltage supplied to the car), and then re-connect the -ve battery terminal before the capacitor has discharged significantly.

I don't know if that's what's inside this box of tricks;

ebay.co.uk item:260429406919

but, I suspect it is, and it looks to have some indicators on the side indicating its state of charge.

 

[bennesspipers]

Negative first, recon negative last. If done the other way, you run serious risk of frying electronics, EXPENSIVE !

 

[lynall]

Neg first and last, i have removed stacks of batteries over the years and always try to do the above, but in some circumstances thats not possible and whatevers nearest first comes off due to access problems.



Lynall

 

[Number_Cruncher]

>>Neg first and last

Yes, I fully agree.

The reason is purely safety. It has absolutely nothing to do with protecting electronics.

The sparks which occur as you disconnect and re-connect happen whichever way round you do it, and these sparks represent electrical supply spikes which can damage electronics. There are tools to reduce the disruptive spikes in the supply as I described above, but, very few people actually use them.

To re-iterate, Neg first and last is the right way to do it, for safet reasons, but that won't protect your electronics.

 

[normanr]

If I were designing a tool to do this job, this is what I would do;

One way to avoid damage from spikes is to connect a decently large sized capacitor with a variable series resistor; one terminal to the battery +ve, and the other to a good earth.

When you remove the -ve terminal from the battery, with the variable resistor set to a low value, the capacitor then temporarily supplies any circuits which are placing any demand on the battery, so, you get no spark from the terminal, and the capacitor gracefully discharges through the series resistor.

The reverse process is a bit more involved. Charge up the capacitor directly across the battery, then disconnect, setting the series resitor to a high value, and then connect capacitor +ve to battery +ve, -ve to a good earth, gradually turn down the series resistor (effectively turning up the voltage supplied to the car), and then re-connect the -ve battery terminal before the capacitor has discharged significantly.

I don't know if that's what's inside this box of tricks;

ebay.co.uk item:260429406919

but, I suspect it is, and it looks to have some indicators on the side indicating its state of charge.

Just bought one of these as it is such a good price it would not be worth the time and money to make it (Yeh I know don't be lazy):bannana: