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      11-21-2016, 12:00 PM   #1
FamilyManTrackSedan
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Keep battery alive with another car while flash tuning?

I can't seem to find this specific question via search. Anyone know if, while flash tuning with mhd, instead of using a charger, I can use another running car and jumper cables to keep my battery from dying? Good/bad idea? What would be the step-by-step for that?

Edit: Also if I do buy a charger, how many amps should it be capable of/is the car pulling, while doing such a thing?

Last edited by FamilyManTrackSedan; 11-21-2016 at 12:24 PM.
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      11-21-2016, 12:33 PM   #2
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Quote:
Originally Posted by FamilyManTrackSedan View Post
I can't seem to find this specific question via search. Anyone know if, while flash tuning with mhd, instead of using a charger, I can use another running car and jumper cables to keep my battery from dying? Good/bad idea? What would be the step-by-step for that?

Edit: Also if I do buy a charger, how many amps should it be capable of/is the car pulling, while doing such a thing?
I did that except the other car was not running. I just attached the jumper cables to the other battery.

I was concerned about over charging.

It worked.

Oh yes, I made sure to turn off lights, turn off A/C, and I also pulled the fuel pump fuse.

ECU backup took about 50 minutes.
1st flash took about 45 minutes I think.

So I had to do them on 2 separate days (backup first).

Last edited by lordbmw; 11-21-2016 at 12:44 PM.
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      11-21-2016, 12:42 PM   #3
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A friend just handed me this thing: https://www.amazon.com/Schumacher-IP.../dp/B000ZIMK82

I'm now wondering if this is NOT the same as a battery tender, it doesn't seem to be a thing you keep plugged into the wall while using it, or if it won't overcharge my battery.
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      11-21-2016, 12:47 PM   #4
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Quote:
Originally Posted by FamilyManTrackSedan View Post
A friend just handed me this thing: https://www.amazon.com/Schumacher-IP.../dp/B000ZIMK82

I'm now wondering if this is NOT the same as a battery tender, it doesn't seem to be a thing you keep plugged into the wall while using it, or if it won't overcharge my battery.
Looks like a battery jumper. I don't know if those things are designed for long continuous use (45 mins+). Typically battery jumpers are only used for jumping (30 seconds max).
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      11-21-2016, 01:34 PM   #5
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A charger will cost you all of $40 bucks and be VERY useful for the rest of your life. Yes you can do it the way you are saying but just spend the cash. It's small money and not worth the risk of something going wrong like a cable falling off causing damage.
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      11-21-2016, 02:52 PM   #6
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A charger will cost you all of $40 bucks and be VERY useful for the rest of your life. Yes you can do it the way you are saying but just spend the cash. It's small money and not worth the risk of something going wrong like a cable falling off causing damage.
The problem with a charger is that it typically requires access to an electrical outlet.

That was my problem. My parking lot has no electrical outlet at all. A Tesla car would be absolutely worthless to me right now.
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      11-21-2016, 03:02 PM   #7
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Quote:
Originally Posted by Torgus View Post
A charger will cost you all of $40 bucks and be VERY useful for the rest of your life. Yes you can do it the way you are saying but just spend the cash. It's small money and not worth the risk of something going wrong like a cable falling off causing damage.
Good advice. $45 gets me a well-reviewed 3.5A charger; that enough?

Anyone know how many amps are drawn during flashing?
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      11-21-2016, 03:10 PM   #8
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Quote:
Originally Posted by lordbmw View Post
The problem with a charger is that it typically requires access to an electrical outlet.

That was my problem. My parking lot has no electrical outlet at all. A Tesla car would be absolutely worthless to me right now.
For safety reasons I would flash at a location where you have access to AC and a charger, like a friends house, parents, etc. I get where you are coming from but I would only hook to another battery if it was my only option to get the car running and movable. Best of luck.
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      11-21-2016, 03:14 PM   #9
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Quote:
Originally Posted by Torgus View Post
For safety reasons I would flash at a location where you have access to AC and a charger, like a friends house, parents, etc. I get where you are coming from but I would only hook to another battery if it was my only option to get the car running and movable. Best of luck.
Yup, that option was not available to me. I almost contemplated renting an electrical generator, lol
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      11-21-2016, 03:22 PM   #10
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Works just fine. I've had friends do that while I remotely flashed them haha
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      11-21-2016, 03:27 PM   #11
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Originally Posted by Welcome to NBA Jam View Post
Works just fine. I've had friends do that while I remotely flashed them haha
god I can't read your name without hearing the announcer's voice.
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      11-21-2016, 03:28 PM   #12
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It will work, just be mindful your halfing the amps when you connect the battery like that. I would just turn off as much accessories as possible on both cars in order to minimize the load on the alternator.
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      11-21-2016, 04:03 PM   #13
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Still no knowledge on how many amps i'm drawing while flashing, lights off, fuel pump fuse out, etc??
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      11-21-2016, 04:34 PM   #14
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Quote:
Originally Posted by FamilyManTrackSedan
Still no knowledge on how many amps i'm drawing while flashing, lights off, fuel pump fuse out, etc??
I don't know off the top of my head, it'll be a good amount of calculating if I were to figure it out lol. Going by the knowledge that the car your using has the same accessories as the one you need powered, turning off the unneeded ones should be a good amount below the max output.

I'm not an electrical engineer yet, still in school for it, so this shouldn't be taken as a definite solution.
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      11-21-2016, 05:15 PM   #15
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It's my understanding that you'll have the best luck with an automatic charger that responds to the current draw. The main thing that draws power is the fuel pump running while the flash goes so if you pull the fuel pump fuse then you significantly reduce the electrical draw while flashing.

Black & Decker and Stanley sell the same automatic chargers with different branding in 15 and 25 amp versions.

15 amp - Stanley / Black & Decker
25 amp - Stanley / Black & Decker

You should probably be fine with one of the 15 amp ones, even if you don't pull the fuel pump fuse. You can spend a little extra for the 25 amp ones if you want. The automatic feature should keep them from over-charging the car.

The Stanley versions are a bit cheaper, at least on Amazon the 15 amp Stanley is $46 vs. $60 for the same thing branded as Black & Decker. But just look at them, it's the same charger.



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      11-21-2016, 05:16 PM   #16
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you just slap a meter on the battery cable to find out. well the meters we have at work at least

I never pull the fuse and just use mine on it's 10A setting.
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      11-21-2016, 08:40 PM   #17
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this should do it. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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      11-22-2016, 04:11 AM   #18
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Hooking to another car's battery, assuming it's in good condition, should be perfectly fine.
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      11-22-2016, 08:43 AM   #19
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Hooking to another car's battery, assuming it's in good condition, should be perfectly fine.
This.

It's fine to connect to another battery. It's simply a parallel connection, and will provide the extra amperage needed.

I've done 45 minute flashes with no charger. Adding a 5-10A charger or jumping from another battery for extra capacity is PLENTY.........
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      11-22-2016, 08:45 AM   #20
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Quote:
Originally Posted by Wrecker335d View Post
It will work, just be mindful your halfing the amps when you connect the battery like that.
Actually, you are doubling the capacity (Amp hours) of the circuit.....

Parallel = Double capacity (AMP hours) (Voltage stays the same)
Series = Doubles voltage, capacity remains the same.
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      11-22-2016, 08:51 AM   #21
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Quote:
Originally Posted by Cory S
Quote:
Originally Posted by Wrecker335d View Post
It will work, just be mindful your halfing the amps when you connect the battery like that.
Actually, you are doubling the capacity (Amp hours) of the circuit.....

Parallel = Double capacity (AMP hours) (Voltage stays the same)
Series = Doubles voltage, capacity remains the same.
No, reread the law. Voltage is additive in series and amperes are constant. In parallel voltage is constant and amperes are divided.
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      11-22-2016, 08:53 AM   #22
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Quote:
Originally Posted by FamilyManTrackSedan View Post
I can't seem to find this specific question via search. Anyone know if, while flash tuning with mhd, instead of using a charger, I can use another running car and jumper cables to keep my battery from dying? Good/bad idea? What would be the step-by-step for that?

Edit: Also if I do buy a charger, how many amps should it be capable of/is the car pulling, while doing such a thing?
I have heard 70 amps, which likely requires a 20 amp receptacle at the other end. I over-researched this topic back when I was doing the ABS pump, unnecessarily. I was just afraid of the car losing power in the middle of the ABL bleed, does that mean I start the entire bleed over.

It seems that units that provide clean power @ 70 amp are in the $500 ballpark. The idea is that if the car starts drawing 70 amps, the voltage is a steady 13.8V. If you buy a $70 walmart charger that does 100 or 200 amps, as the car draws 70 amps, the voltage spikes up to 16 and electronics could be damaged. That's what I found through my research. People who have the money buy the right stuff. But, I had also identified that the power supplies for RVs are in fact identical, and cost a fraction of the price, and do provide clean power.

What tipped me off to the power supplies used in the coding world, was watching the YouTube doing the ABS pump, I did not know what he had hooked up to his car at the time...
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