voltage drop after battery isolator

Yes - if 6.8V is not enough to energise the PAC 200. It requires approx 1 Amp at approx 12V (probably above 10V is ok).

thats what i figured. so now i need to find a better 12v lead. right now all i did was tap into the 12v switched wire that goes to the factory amp underneath the passenger seat an ran that back to the hatch then i y adapter it out with one end going to my amp and one end to the isolator.

so after i get a better 12 switched lead then that should energize it enough to send the full 12.7v to my second battery? interesting, how it all works. so becuz it dont have the full 12v(or 10-16v) it does what it can an just so happens it does 10.85v. my sub comes on for a min or less then amp goes int low voltage mode. well now i need to find a new lead an run it this should be fun im guna need more remote wire now.

ogjlbh21 wrote: ...it does what it can....

Which is nothing. If the relay's coil/solenoid does not have enough voltage to pull in the contacts, then the two heavy terminals are not inter-connected. If one is 12.7V and the other 10.85V, then that's because the batteries are 12.7V & 10.85V respectively and they are not interconnected.

i dont understand what that means? are you saying my battery is bad or that i need to fix that 12v switched lead?

i called pac and they told me they dont think its the pac200, they think that my car cannot charge the second battery. now i dont know if i misunderstood this but he then told me all i need to do is fully charge the battery with a battery charger then after that it should work fine and my car will be able to maintain charging it from there. he said i could also get a h.o. alternator an i told him i have a prius and there is no way that i kno of to upgrade it and he told me just to fully charge the second battery an everythign will be fine. so im going to autozone in a little bit. does this sound right to you?

Until you find out what you have, there is little point discussing. You either have a relay like the PAC200, or a voltage-sensing relay/isolator maybe a PAC200 with controller (is it the BC-12 or similar?). A relay is a switch - it is either on or off. If off, there is no connection between the input and output.     Do you hear it click on and off?

i just have the pac200 no bc-12. autozone told me 45-60 mins so im waiting for the battery then i will listen for a click. but my sub wouldnt work at all an the second battey wouldnt work at all either if the pac200 wasnt turning on. so im sure it is turning on. will up date in the next hour.

lol i fell asleep an they closed so i guess i will have to wait til tomoro to get my battery.

Apply 12 volts to the trigger terminal of the pac-200.  If the voltage is not equal on both large terminals, the pac 200 is defective.