voltage drop after battery isolator

i have a kinetik 1400 as my main 12v runs to a pac-200(battery isolator) then runs to a second battery(kinetik 1800) which runs to my jl audio 1000/1. now all grounds have been tested and have a resistance of .3 ohms or less. the main battery voltage settles @ 12.77 on main battery the isolator voltage from the main battery reads the same. the voltage @ the isolator for the second battery reads 10.85, the second battery reads 10.85 and also at the amp it reads 10.85. also would like to mention that at the isolator the 12v switched reads 6.8v(not sure y or if thats normal, its the same 12v switched that connects to the amp. i didnt test the 12v switched that goes to the amp tho but i would guess it also reads 6.8v). now this is all in a prius which doesn't have a alternator like a normal car. so i have 0 gauge everwhere from the main battery throughout all mentioned but i have no way that i know of to do the big three. but with that said i also dont think this voltage drop has anythign to do with the big three i think its somthign to do with the 12v switched at the isolator or somehting wrong with the isolator. i have checked all wiring and grounds and everythign is secure and correct except the voltage at the isolator for the second battery an then on. now my question is if my thinking is correct or not and does anyone else have experience with this? im not by any means experienced with isolators, this is actually my first time working with one. so any and all help is greatly appreciated. also would like to mention that the prius 12v and second 12v as well as the isolator and amp are all in the hatch of the car. please help!!!!

Switch 12v leads and see if reading changes.......could be burnt contact in pac200......could be bad battery.....could be bad connectors on wire...

is the car running to give these readings?

0.3 Ohms or less on grounds? So a 10A load causes a 3V drop? A 100A load is a 30V drop? (IE - your max load will never exceed ~40A??) The PAC 200 is merely a relay so its "input" voltage should be the same as the first/main battery and its output the same as the second (Kinetik) battery. Only when the PAC 200 is energised will the 2 voltages be equal. Are you sure you are energising it? (I assume you have fuses or breakers at each battery and these are ok?)

ok i will try switching the leads tomoro. im also going to check the 12v switched wire at the amp and at the beginning of the wire(in front of car) to see what voltage it reads. i will also bypass the isolator and parallel the batteries to see what the second batteries voltage is. i think the connectors should be fine they were all brand new from jl audio. i took readings with car running and then with car on acc but i dont remember which readings i am going off of i will re do the readings with on and acc just to document exact readings. i too think its something with the pac200.altho i wont rule out the second battery being bad. i will update tomoro night. thanks i also forgot to mention that i have inline circuit breakers( 1 within 12" of main battery, 1 in between the isolator and second battery(only about a 18" line, and 1 within 12" of the second battery) all ring terminals are brand new 1/0g. all wiring is jl 0g. xcept for the remote wire of course that is jl remote wire. also have jl battery terminals on the positive terminals for both batteries. stock terminals for neg on both batteries. also should mention i have a stinger 0g to 4g reducer on the amps power and ground terminals(as the amp only accepts 4g).

Make sure that whatever is turning on (energising) the PAC can supply the ~1A it requires, and that the other side is grounded. Maybe after disconnecting the existing +12V control signal, test with a lead to the primary +12V input.    BUT BE WARNED!! - 10.85V (Open Circuit) on an AGM battery is VERY flat and can indicate a bad battery (if below 11V etc for a considerable time) and could mean a HUGE inrush current when connected to another battery etc. BEWARE of sparks! I'd recommend charging the Kinetik first if it reads below 12V (or even below 12.5V) open circuit and rested.

oooops i didnt mean to submit that... in reply to oldspark. yes .3ohms or less on all grounds. "so 10a load causes a 3v drop?" i understand the voltage drop part but idk where u got a 10a load lol sorry im a newb. same with next question about the 30v and 40a. yes i have read up on the pac200 and thats why i am seeking advice because it was understanding that there would be know voltage drop with the pac200 and it would isolate my batteries. yes i have circuit breakers i noted those in previous post

the 10.85v is a reading at the terminals at the isolator which runs to the second battery then the second battery also reads 10.85 then the amp reads the same. im sure u understand what im saying but im very sorry but i dont understand what u r saying. the pac200 is grounded and the ground is good. idk anythign about the 1a it requires. so disconnent te main 12v then run a lead from the main 12v to whta lol im sorry that dont make sense to me. again im new to this an i guess pretty ignorant. both batteries r brand new an yes i know that dont mean that they might not be bad. im not sure of how to charge the second battery i thought the car battery would charge it? havent seen any sparks altho i did flip the circuit breakers so that it dont keep running liek this. so everythign is dicconected right now via circuit breakers.

If the PAC200's ground is 0.3Ohm, that is ok. But the PAC200 should have 4 terminals = 2 BIG terminals that are to be connected (ie, +12V main battery to secondary battery +12V)... And the 2 terminals to energise it and connect the 2 batteries - ie, +12V and a ground. Correct? The 10A etc referred to grounds for the battery(s) - if they were 0.3 Ohms....    Then the max current they could supply if i=V/R = ~12.7V/0.3R = ~40A.

yes the pac200 has 4 terminals 2 for the batteries (1 from the main battery,1 to the aux battery) one terminal for ground and one for the 12v switched. as for the 10a comment lol i get what you were sayign now altho that is way above me :)

i tested the switchedd 12v(on the isolator) and it only reads 6.8v. thats isnt normal is it? i would think it should be 12v, could that be the problem?