I connected one side of the coil to a battery negative terminal and the positive via an amp meter.
(1) 1.5 ohm internal resistance Bosch Red 25KV oil filled coil uses only 600 milliamps
(2) (suppose to be 3 ohm) but ohm meter state 4 ohm Bosch Blue oil filled 18KV coil uses 3.8 Amps
(3) (suppose to be 3 ohm) but ohm meter state 4.5 ohm Bosch epoxy filled 18KV uses 3 Amps
(4) Original 40 years old coil with ohm metered 5 ohm oil filled uses 2.5 Amps
I wonder if there are any higher spark/current out put in relationship to higher current consumption?
Why do some coil requires minimal amps?
- Piledriver
- Moderator
- Posts: 22518
- Joined: Sat Feb 16, 2002 12:01 am
Re: Why do some coil requires minimal amps?
(1) is almost certainly broken.
The rest probably have internal ballast resistors.
Here's a VERY nice set of public domain basic electronics training/reference
(AFAIK the US Navy still uses these)
http://electriciantraining.tpub.com/
The rest probably have internal ballast resistors.
Here's a VERY nice set of public domain basic electronics training/reference
(AFAIK the US Navy still uses these)
http://electriciantraining.tpub.com/
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
- Dale M.
- Posts: 1673
- Joined: Mon Oct 05, 2009 8:09 am
Re: Why do some coil requires minimal amps?
Ditto..... its all about "ohms law".....Piledriver wrote:(1) is almost certainly broken.
The rest probably have internal ballast resistors.
Here's a VERY nice set of public domain basic electronics training/reference
(AFAIK the US Navy still uses these)
http://electriciantraining.tpub.com/
Dale
"Fear The Government That Wants To Take Your Guns" - Thomas Jefferson
1970 "Kellison Sand Piper Roadster"
1970 "Kellison Sand Piper Roadster"
-
- Posts: 1303
- Joined: Mon Sep 13, 2004 12:04 am
Re: Why do some coil requires minimal amps?
Yes, they do have built-in internal ballast resistors but why is it that the measured resistance does match what was specified on the casing? Is that normal? Or that it is not important whether it is 3 ohm or 4.5 ohm.Piledriver wrote:(1) is almost certainly broken.
The rest probably have internal ballast resistors...
-
- Posts: 1303
- Joined: Mon Sep 13, 2004 12:04 am
Re: Why do some coil requires minimal amps?
Ohm's law http://www.bcae1.com/resistrs.htm If a resistor is connected to a battery like shown in the above diagram, there would be less current flow than in the wire alone. How much less current depends on the value of the resistor.
Ohm's law
I=E/R
Which means current flow is equal to the applied voltage divided by the resistance in the circuit.
I=12.6/5
12 volts applied to a 5 ohm resistor
I=2.52 amps
Current flow through the resistor is 2.52 amps.
Ohm's law
I=E/R
Which means current flow is equal to the applied voltage divided by the resistance in the circuit.
I=12.6/5
12 volts applied to a 5 ohm resistor
I=2.52 amps
Current flow through the resistor is 2.52 amps.
- Piledriver
- Moderator
- Posts: 22518
- Joined: Sat Feb 16, 2002 12:01 am
Re: Why do some coil requires minimal amps?
sagaboy wrote:Yes, they do have built-in internal ballast resistors but why is it that the measured resistance does match what was specified on the casing? Is that normal? Or that it is not important whether it is 3 ohm or 4.5 ohm.Piledriver wrote:(1) is almost certainly broken.
The rest probably have internal ballast resistors...
Age/time/heat/vibration/inherent production variations/made in China.
All variables.
Bosch "Red" coils AFAIK do not have internal ballast resistors (this should actually be considererd a feature, as you can get better output from them with a proper dwell-controlling or current limiting driver, and replace a bad ballast resistor if external)
But... based on your measurements, the one you have is a paperweight.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
-
- Posts: 1303
- Joined: Mon Sep 13, 2004 12:04 am
Re: Why do some coil requires minimal amps?
You are correct, the Bosch "Red" coil don't have internal ballast resistors but it is in good running condition as it is in my daily drive. What I did was remove the + battery terminal and connect an amp meter in series then turn the key to "ON" position and it read 600 milliamps--it is possible that the electronic "compuserve" contact point is in the off position--hence low current drain--but based on Ohm's Law--it should be draining at least 9 Amps.Piledriver wrote:sagaboy wrote:Yes, they do have built-in internal ballast resistors but why is it that the measured resistance does match what was specified on the casing? Is that normal? Or that it is not important whether it is 3 ohm or 4.5 ohm.Piledriver wrote:(1) is almost certainly broken.
The rest probably have internal ballast resistors...
Age/time/heat/vibration/inherent production variations/made in China.
All variables.
Bosch "Red" coils AFAIK do not have internal ballast resistors (this should actually be considererd a feature, as you can get better output from them with a proper dwell-controlling or current limiting driver, and replace a bad ballast resistor if external)
But... based on your measurements, the one you have is a paperweight.