SuperDave
Member
Attention shade tree electrical engineers:
I got a chunk of change for my birthday & decided to invest it into Project Turd, my 73 More-Door Newport (called that because it doggy doo brown & it gets crappy gas mileage). I ordered carpet, dead-liner insulation, cables, amplifiers, & speaker wires to complete the sound system I'm making for it. I'll be pushing close to 2000 watts thru 12 speakers (2 dash mounted tweeters, 4 5" midrange door speakers, 4 6x9 woofers on the rear package tray, and a pair of 10" subs in the trunk). I'll also employ tactile transducers in the seats, bass shakers, to supplement the subs for Bass you can Feel. I want my stereo capable of giving you CPR, but I don't want to be arrested or piss off my neighbors doing it.
That much power is sure to make the headlights dim and pulse in time with the music, undesirable. SO, I will be augmenting and fortifying my sound system with a 2 fared capacitor for the amps, a 2nd battery in the trunk (secured inside a marine type battery box), with a battery isolator between the main battery & the second battery. Cables to connect the 2 will be a 4 gauge cable, both positive & negative. Having a negative cable to ground out to besides the chassis ground eliminates lots of noise issues. The isolator has a diode built in, allowing charging current to pass only when the alternator pushes 13v, but blocking discharge thru the main system. This will prevent the stereo from draining the main battery, dimming the headlamps or cause issues with anything electrical.
All that being said, having a 2nd battery in the trunk allows for the possibility of being able to give yourself a jump start when the primary battery fails to crank over that high compression big block that is designed for a muscle car. But rather than drag out the jumper cables & stretch them from the trunk to the hood, why not introduce a solenoid into the circuit, bypassing the isolator and bridging the 2 systems and wiring it to a switch on or under the dash? Plans call for 4 gauge oxygen-free copper cables ($60 for 2 20' lengths!) rated for 500 amps, plenty to provide a boost in cranking amperage. A 3 position toggle switch, up for starter assist (wired thru the crank trigger) so the solenoid only activates when the key is twisted to the crank position, center for off - isolator circuit only connects when the motor is running, and down for full time connection, for "charging" the primary battery or running both batteries simultaneously (in the event the main battery is too pooped to do the job) so I can limp to the auto parts store and buy a new battery.
Sounds good right? Here comes the part where I want to pick your brains: What solenoid do I choose? Initially I thought a standard Ford type fender mounted solenoid should do the trick until I started looking to purchase one. We have your standard garden variety versions (cheap, under $10), heavy duty for high amp pulls, like on a diesel motor, but then there are "Continuous Duty" versions that are set up for long term, low amp draws, rated 300 amps max. The intermittent versions (cheap) can handle 750 amps but only short term usage, I'm not sure if they wouldn't overheat and hang open, "locking" the 2 batteries together. The heavy duty versions can withstand en excess of 1000 amps, but they too are designed for intermittent use. The continuous use versions I see online aren't rated higher than 300 amps max, and the battery I want is a Group 24 battery rated for 600 Cold Cranking Amps, double the rated capacity of the solenoid. So which do I choose? Is there another option? Or do I use 2? One high amp, intermittent use AND a low amp continuous use?
I surrender to the collective wisdom and experience of the forum. Thanks in advance for your reply.
I got a chunk of change for my birthday & decided to invest it into Project Turd, my 73 More-Door Newport (called that because it doggy doo brown & it gets crappy gas mileage). I ordered carpet, dead-liner insulation, cables, amplifiers, & speaker wires to complete the sound system I'm making for it. I'll be pushing close to 2000 watts thru 12 speakers (2 dash mounted tweeters, 4 5" midrange door speakers, 4 6x9 woofers on the rear package tray, and a pair of 10" subs in the trunk). I'll also employ tactile transducers in the seats, bass shakers, to supplement the subs for Bass you can Feel. I want my stereo capable of giving you CPR, but I don't want to be arrested or piss off my neighbors doing it.
That much power is sure to make the headlights dim and pulse in time with the music, undesirable. SO, I will be augmenting and fortifying my sound system with a 2 fared capacitor for the amps, a 2nd battery in the trunk (secured inside a marine type battery box), with a battery isolator between the main battery & the second battery. Cables to connect the 2 will be a 4 gauge cable, both positive & negative. Having a negative cable to ground out to besides the chassis ground eliminates lots of noise issues. The isolator has a diode built in, allowing charging current to pass only when the alternator pushes 13v, but blocking discharge thru the main system. This will prevent the stereo from draining the main battery, dimming the headlamps or cause issues with anything electrical.
All that being said, having a 2nd battery in the trunk allows for the possibility of being able to give yourself a jump start when the primary battery fails to crank over that high compression big block that is designed for a muscle car. But rather than drag out the jumper cables & stretch them from the trunk to the hood, why not introduce a solenoid into the circuit, bypassing the isolator and bridging the 2 systems and wiring it to a switch on or under the dash? Plans call for 4 gauge oxygen-free copper cables ($60 for 2 20' lengths!) rated for 500 amps, plenty to provide a boost in cranking amperage. A 3 position toggle switch, up for starter assist (wired thru the crank trigger) so the solenoid only activates when the key is twisted to the crank position, center for off - isolator circuit only connects when the motor is running, and down for full time connection, for "charging" the primary battery or running both batteries simultaneously (in the event the main battery is too pooped to do the job) so I can limp to the auto parts store and buy a new battery.
Sounds good right? Here comes the part where I want to pick your brains: What solenoid do I choose? Initially I thought a standard Ford type fender mounted solenoid should do the trick until I started looking to purchase one. We have your standard garden variety versions (cheap, under $10), heavy duty for high amp pulls, like on a diesel motor, but then there are "Continuous Duty" versions that are set up for long term, low amp draws, rated 300 amps max. The intermittent versions (cheap) can handle 750 amps but only short term usage, I'm not sure if they wouldn't overheat and hang open, "locking" the 2 batteries together. The heavy duty versions can withstand en excess of 1000 amps, but they too are designed for intermittent use. The continuous use versions I see online aren't rated higher than 300 amps max, and the battery I want is a Group 24 battery rated for 600 Cold Cranking Amps, double the rated capacity of the solenoid. So which do I choose? Is there another option? Or do I use 2? One high amp, intermittent use AND a low amp continuous use?
I surrender to the collective wisdom and experience of the forum. Thanks in advance for your reply.
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