is this a load of monkey diarhea???

[Alexwaves 10+ year member]

hey all i have a question

i am a current student at mobile dynamics in toronto and i we got on the topic of runnin a 2 battery system and the teacher said not to use a isolator because they use up to much current... he said that the avg isolator uses up 0.7 volts because of the interal resistance of the unit... and i took my DMM (digital mult-meter) and he was right the restance and the math worked out too 0.7 volts each side .the unit is pretty much 2 diodes. the diodes use up 0.7 volts each for a total of 1.4 volts. now in the car we only have 13.8 volts from the alt when the car is running... but the battery only puts out 12.6volts so 12.6-1.4 =11.2volts or 13.8-1.4=12.4volt. now most amps are rated at 12.5 or 14.4 volts.... so the teacher then went on to say instead of the isolator we should use a Single Pole Double Throw Relay ( the starter relay the name starts with a S solnide?????) cause a relay does not have any interial restance... does the instructor know what he is talking about?????

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[Prowler573 5,000+ posts]

hey all i have a question i am a current student at mobile dynamics in toronto and i we got on the topic of runnin a 2 battery system and the teacher said not to use a isolator because they use up to much current... he said that the avg isolator uses up 0.7 volts because of the interal resistance of the unit... and i took my DMM (digital mult-meter) and he was right the restance and the math worked out too 0.7 volts each side .the unit is pretty much 2 diodes. the diodes use up 0.7 volts each for a total of 1.4 volts. now in the car we only have 13.8 volts from the alt when the car is running... but the battery only puts out 12.6volts so 12.6-1.4 =11.2volts or 13.8-1.4=12.4volt. now most amps are rated at 12.5 or 14.4 volts.... so the teacher then went on to say instead of the isolator we should use a Single Pole Double Throw Relay ( the starter relay the name starts with a S solnide?????) cause a relay does not have any interial restance... does the instructor know what he is talking about?????

Possibly in your car or whatever car you're specifically taking about...many of us here have 14.5+ charging systems from having high output alternators installed or the stock ones rebuilt to a higher output.

 

[djman37 5,000+ posts]

hey all i have a question i am a current student at mobile dynamics in toronto and i we got on the topic of runnin a 2 battery system and the teacher said not to use a isolator because they use up to much current... he said that the avg isolator uses up 0.7 volts because of the interal resistance of the unit... and i took my DMM (digital mult-meter) and he was right the restance and the math worked out too 0.7 volts each side .the unit is pretty much 2 diodes. the diodes use up 0.7 volts each for a total of 1.4 volts. now in the car we only have 13.8 volts from the alt when the car is running... but the battery only puts out 12.6volts so 12.6-1.4 =11.2volts or 13.8-1.4=12.4volt. now most amps are rated at 12.5 or 14.4 volts.... so the teacher then went on to say instead of the isolator we should use a Single Pole Double Throw Relay ( the starter relay the name starts with a S solnide?????) cause a relay does not have any interial restance... does the instructor know what he is talking about?????

my buddy has a solenoid version. He didn't buy it for the right reason though...he was told if you have two batteries, you need this.

 

[Alexwaves 10+ year member]

solenoid was the word that i was looking for

so is the instructor full or it or???

 

[req 5,000+ posts]

i dunno man. it does not seem like a relay will be able to take that kind of current. must be a beefy *** relay....

 

[stones 10+ year member]

Heres a battery isolator for marine applications that would work for automotive use and claims to have no voltage drops.

http://www.hellroaring.com/simple1.php

 

[djman37 5,000+ posts]

i dunno man. it does not seem like a relay will be able to take that kind of current. must be a beefy *** relay....

it IS. it uses a solenoid to move a big @ss pin to make the connection. His has like 6 or 8 wires going to a remote/status monitor on the dash.

 

[knukonceptz 10+ year member]

Yes, he is right on with the isolator, thay are not good for audio use UNLESS you only care to have the system play off the rear batery for show use (demo'ing the car and such so not to kill the main battery) For SPL use and overall normal use you are better off just adding in the second battery and connecting into the system. This gives you double the reserve capacity (assuming the second battery is equal or greater to the front battery) With an isolator you instead have two systems of the same value (reserve) with less voltage overall.

 

[dbornotdb 10+ year member]

He is absolutly correct.

 

I have and sell 200 amp relays all the time. They aren't nothing like the 30amp relays that you wire into your alarm and stuff. These are beefy and used just for what you were told.