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| Thread ID: 101562 | 2009-07-19 08:35:00 | Jumpstart question for newer cars | Nomad (952) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 792956 | 2009-07-19 10:55:00 | I was just mentioning the 2V. Dunno what it was. The AA guy said he battery is fine and the alternator was doing 14. The interior light was left on for 36hours while it was parked. Are there any DIY test one could do to see if one really need a new battery? |
Nomad (952) | ||
| 792957 | 2009-07-19 11:47:00 | In my other life in 1985 I took at trip up to Auckland to repair some video game monitors amongst other things, whilst in the workshop one day a mechanic came in asking if we could look at/repair about 12 or 15 pcb's taken out of cars that had been jump started with 24volts on the wharf after they had been loaded off the ship. lol. | zqwerty (97) | ||
| 792958 | 2009-07-19 20:31:00 | It's not really a problem for the vehicle that's RECEIVING the jump-start, as the battery will act as a giant sink to help remove any spikes and transients to it's own system like a giant sponge . It's the GIVING vehicle that's at risk . When the starter motor is activated, there are a lot of spikes and dirty voltage EMF and REMF that can destroy the ECM/TCM/VCM or BCM (take your pick - some new vehicles have multiple computers all requiring clean and purified voltage) on the car providing the jump . That battery that went below voltage (seriously below!) is not trustworthy any more and will let you down in the near future . |
SurferJoe46 (51) | ||
| 792959 | 2009-07-20 01:48:00 | It's not really a problem for the vehicle that's RECEIVING the jump-start, as the battery will act as a giant sink to help remove any spikes and transients to it's own system like a giant sponge . It's the GIVING vehicle that's at risk . When the starter motor is activated, there are a lot of spikes and dirty voltage EMF and REMF that can destroy the ECM/TCM/VCM or BCM (take your pick - some new vehicles have multiple computers all requiring clean and purified voltage) on the car providing the jump . That battery that went below voltage (seriously below!) is not trustworthy any more and will let you down in the near future . So then why doesn't the starter motor of a car do this to the car itself? The ECM must be running while the starter motor is cranking so why does it not blow up the computer in car it's in? I can't see a difference between the starter motor, which is wired straight to the battery, and that of the car being jumped . |
george12 (7) | ||
| 792960 | 2009-07-20 02:07:00 | So then why doesn't the starter motor of a car do this to the car itself? The ECM must be running while the starter motor is cranking so why does it not blow up the computer in car it's in? I can't see a difference between the starter motor, which is wired straight to the battery, and that of the car being jumped . In "CRANK-MODE" the vehicle being started is in a partial bypass condition with only the most important devices and systems running . Injection is in binary or paired firing (limp-back mode or ie: CEL-ON condition) and as such it is not as susceptible to spikes and transients . That's just the way it is . It doesn't matter whether you "see it" or not - it's not a good idea to surge the provider's vehicle with the starter on the jumped vehicle's stray electrical spikes . You can only poke bears with sticks if you can afford to or you somehow get away with it . Cadillac warns, as does most manufacturers with digital motors in the systems that have infinite speed control (ie: wipers, heating/cooling fans, CD players, etc) that they can be damaged by these stray spikes and peaks over designed-in limits . Suggested is to completely disconnect the provider's battery from the electrical system in the provider's car, then after the jumped vehicle is running, reset all the programmable devices that lost their KAM (let's NOT go into THAT again!) Even Korean 4-wheeled fecal matter have a lot of digital systems and sub-systems now, so it's not just a luxury car scenario any more . But go ahead and just stick with 1920s Hupmobile and DeSoto policies and just keep paying for ignorance when it knocks at your window . Unfortunately I am retired and cannot gloat if you keep these self-destructive policies, but remember this: "you cannot make me mad by slapping me in the face with money" . You might get away with it or you might not . |
SurferJoe46 (51) | ||
| 792961 | 2009-07-20 02:13:00 | What I do is hook up the cars, start the good car run for about 5 minutes to get the battery voltage up then start the the sick car run for few minutes then disconnect. Cant see how you could get a spike if both batteries are about 14 volts. If you want hassles you try and jump start a vehicle with a series parallel switch this a heavy relay which when you turn the key hooks the 12 volt batteries together to make 24 volts for the starer motor then when you let the key go it goes back to 12 volts. Only way to jump to use 2 12 volt batteries and 2 sets of jumper leads. |
prefect (6291) | ||
| 792962 | 2009-07-20 02:33:00 | Would it not be easier to disconnect the "giving" car battery on the giving vehicle, then connect the receiving vehicle onto the "giving" car battery and start it to avoid any risks? Or is that not viable? | SKT174 (1319) | ||
| 792963 | 2009-07-20 04:01:00 | Would it not be easier to disconnect the "giving" car battery on the giving vehicle, then connect the receiving vehicle onto the "giving" car battery and start it to avoid any risks? Or is that not viable? That's what I said: Suggested is to completely disconnect the provider's battery from the electrical system in the provider's car, then after the jumped vehicle is running, reset all the programmable devices that lost their KAM (let's NOT go into THAT again!) |
SurferJoe46 (51) | ||
| 792964 | 2009-07-20 09:02:00 | In "CRANK-MODE" the vehicle being started is in a partial bypass condition with only the most important devices and systems running . Injection is in binary or paired firing (limp-back mode or ie: CEL-ON condition) and as such it is not as susceptible to spikes and transients . That's just the way it is . It doesn't matter whether you "see it" or not - it's not a good idea to surge the provider's vehicle with the starter on the jumped vehicle's stray electrical spikes . You can only poke bears with sticks if you can afford to or you somehow get away with it . Cadillac warns, as does most manufacturers with digital motors in the systems that have infinite speed control (ie: wipers, heating/cooling fans, CD players, etc) that they can be damaged by these stray spikes and peaks over designed-in limits . Suggested is to completely disconnect the provider's battery from the electrical system in the provider's car, then after the jumped vehicle is running, reset all the programmable devices that lost their KAM (let's NOT go into THAT again!) Even Korean 4-wheeled fecal matter have a lot of digital systems and sub-systems now, so it's not just a luxury car scenario any more . But go ahead and just stick with 1920s Hupmobile and DeSoto policies and just keep paying for ignorance when it knocks at your window . Unfortunately I am retired and cannot gloat if you keep these self-destructive policies, but remember this: "you cannot make me mad by slapping me in the face with money" . You might get away with it or you might not . Relax, I didn't say I disagreed with you, I said I had no idea why you shouldn't do it and wanted someone to explain, which you have done nicely . What then is wrong with just using "computer protecting" jumper leads? |
george12 (7) | ||
| 792965 | 2009-07-20 10:11:00 | Personally (in 30+ years of mechanicing), I've seen only three vehicles "killed" by jump-starting, and in each case it was because of being connected BACKWARDS (positive to negative, negative to positive) by the owner. :crying Most automotive electronics are fairly robust and reliable as long as you're careful, advisable to use com-proof jumper leads (of a decent amp rating, dont use any of those thin/poxy things you'd get from Supercheap), they have a smoothing circuit built-in. Nothing would prevent total meltdown if you do this though :horrified Only way to jump to use 2 12 volt batteries and 2 sets of jumper leads. |
feersumendjinn (64) | ||
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