Review on WirthCo 20092 Battery Doctor Isolator by Paul Rose

So far no luck launching this device. I have a 1971 VW Bus and need an extra accessory battery that will not drain the starter battery. Installation was simple and followed very easily. My starter battery is 7 months old. As soon as I connected the ground wire from the auxiliary battery to the frame, the red flashing light turned red as instructed. I start the car, but the blue charging light does not come on. I thought well I'll go and see what happens. I found that my starter battery continued to discharge while the auxiliary battery remained charged. But there was still no blue indicator. Basically it killed my (fairly new) starter battery and I replaced it - found the starter function worked many times. GREAT! New starter battery, as above. Return to square one. I called tech support, "Tim" was very helpful and said the board may be defective and should be sent back. I did and am waiting for a replacement. I hope this works, but the new starter battery probably suffered from frequent discharge. Tech support also mentioned that the device wouldn't work on a positive ground vehicle and suggested this might be my problem. No, VW Bus has a negative ground system. But folks who have a European car with a positive ground system, it won't work. I'll update as soon as I get a replacement but just don't think it will be. work but hope for the best. The instructions say it goes into charge mode when the starter battery voltage is above 13.4V. Well that's probably a problem as even the starter battery reads 12.8V BRAND NEW. Not sure how to increase it to 13.4? Very disappointed, it hasn't worked for me so far and caused a lot of problems along the way. Apparently a lot of people have had good experiences. ****UPDATE**** Batteries, basically the starter battery is dead. Decided to charge it while still in the car. The next morning, to my surprise, the blue LED lit up! It turns out to work fine, I just didn't get the right voltage due to the pre-existing condition of the generator. Alternator wiring has been repaired and this product works as advertised and like a champ!