





🔋 Stay charged, stay unstoppable — power your adventures with confidence!
The WirthCo Battery Doctor 125/150 Amp Battery Isolator is a compact, water-resistant (IP62) electronic device designed to manage dual battery systems in vehicles. It automatically charges an auxiliary battery while isolating the starter battery to prevent drain, supports manual override for jump-starting, and includes surge protection to safeguard modern vehicle electronics. Ideal for marine and automotive use, it delivers up to 150 amps peak amperage, ensuring reliable power management for professional and adventure-ready setups.










| ASIN | B0058SGDFK |
| Amperage | 150 Amps |
| Best Sellers Rank | #220,375 in Automotive ( See Top 100 in Automotive ) #844 in Battery Chargers |
| Brand | WirthCo |
| Customer Reviews | 4.5 4.5 out of 5 stars (820) |
| Date First Available | June 30, 2011 |
| Is Discontinued By Manufacturer | No |
| Item Weight | 15.2 ounces |
| Item model number | 1213.1241 |
| Manufacturer | WirthCo |
| Manufacturer Part Number | 010054200929 |
| Model | Battery Isolator, 125A |
| OEM Part Number | 20092 |
| Product Dimensions | 5.1 x 5.7 x 2.3 inches |
| Voltage | 12 Volts |
N**.
Blue charging light never came on, returning product.
No Luck so far making this device operate. I have a 1971 VW Bus and wanted a aux battery for accessories without draining the starter battery. Installation was easy and followed very easily. I have a 7 month old starter battery. Once I hooked in a ground wire from the aux battery to the frame the red blinking light turned solid red as stated in the instructions. I start the vehicle and the blue charging light never came on. Thought, well I will drive around and see what happens. I found out that my starter battery kept draining while the aux batter remained charged...but still no blue light.Basically it has killed my (fairly new) starter battery and I got it replaced - did find out on numerous occasions that the jumpstart feature works GREAT!!! New starter battery in, same thing exactly as written above. Back to square one. Called tech support, "Tim" was very helpful and said it may be that the circuit board is defective and to return it. I did and waiting on a replacement. I hope it works, but the new starter battery has probably suffered some damage from being discharged frequently. Tech support also mentioned that the unit will not work on a positive grounded vehicle and suggested that may be my issue. No, the VW Bus has a negative ground system....but people who may have a European car that has a positive ground system, this will not work. I will update once I get the replacement, but just don't think it is going to work but hoping for the best. The instructions said it goes into charging mode when the starter battery is above 13.4v....well, that is probably the problem as even the starter battery read 12.8 volts BRAND NEW. Not too sure how to get it up to 13.4? Really disappointed this did not work for me so far and caused a lot of troubles along the way. Looks like many people had a good experience. ****UPDATE**** Batteries, mostly the starter battery was low. Decided to put it on a charger while still in the vehicle. Next morning to my surprise the blue LED light was on! Turns out it is working properly, I was just not getting the proper voltage due to a pre-existing alternator condition. Got the alternator wiring corrected and this product works as described and like a champ!
D**W
Exactly what you need
If you’re running a second battery, I’d highly recommend getting this. You want to hear it, here it goes. This is a smart battery isolator, charger, and jump starter all rolled into 1 palm-sized device. When installed correctly, you can run power into your secondary battery without affecting the main starting battery. The device stays on for less than a minute between shutting off your vehicle and running parallel with your main battery. So there will be a small parasitic draw for balancing both batteries during that minute. This compact device has 3 connection points, main battery, secondary battery, and pre-wired ground. I highly recommend using a fused 4 gauge or higher cable from the main battery with the fuse or breaker fuse closer to the main battery, and a fused same gauge or lower wire out to your accessories from your secondary battery. Following the instructions I realized it wasn’t charging my secondary battery and wondered why. I later found that my main battery was faulting and after charging it for 8 hours didn’t hold a charge past 64%. With that said, it will only charge your secondary battery IF your main battery is charged past 13.4V. Once I got my main battery sorted (new one), everything was working as it should be. FYI, if either your main or secondary battery loses connection, the isolator will shut off by default. I tried to run the isolator in override mode to swap out the main battery without losing power, but found out that it simply shuts itself off. It’s a good thing. I also found out that this thing has a built in voltage spike regulator, similar to a power conditioner. But I wouldn’t consider it to be a conditioner either. Before this, I had an 80A Stinger battery isolator/relay between the main and secondary battery. I also had a 150A fuse breaker between the secondary to my rear fuse box for my accessories that kept tripping only during vehicle startup without any accessories ON. Battery to battery was fine over 80A relay, but the surge of power introduced by the alternator kept tripping my 150A breaker. After installing this, I had my 250W light bar ON running out of the secondary battery without tripping the breaker during startup. So in short, it can detect power spikes and send the correct signals. I highly recommend this if you’re into the whole secondary battery and trying to stay within budget. What’s $53 compared to potentially burning your entire electrical system (undercharging or overcharging) or getting stuck in a remote place without jumper cables. Hopefully this helps you think about what this thing is actually doing and what you’re protecting. I have a truck with a V8 5.0L engine and a stock 150A alternator, and the 125A/150A works for me. V6 and smaller motors with smaller applications can easily use 75A/100A system.
A**S
Great battery isolator
Extremely easy install. Works as advertised. Very happy with this purchase, so far. UPDATE: I've adjusted the 5-star rating to a 3-star rating. Well, the honeymoon is over. LOL. The unit has been installed for a week and it's already acting fritzy. It was really great while it worked, but now long after I have shut the engine off, the blue light continues to burn. I tried pushing the reset button. It didn't work. I had to disconnect the entire unit to get the blue light to go off. When I reconnect it, the red light burns solid, as it should. I turn on the engine, the blue light clicks on. I shut the engine off...the blue light stays on. I've come back hours later to find it still burning. The only way to get it to turn off is to disconnect it. It's seems to be a defective unit. I'll probably be sending it back, unless there is some insight that WirthCo can share with me. The aux battery IS an agm battery, so that might have something to do with it. If this is normal behavior for the isolator when connected to an agm, my apologies. I will correct my rating back to 5-stars. UPDATE FOR THE UPDATE: The blue light will stay on when the AGM battery is completely full, which mine often is, since I wired it to a solar panel,too. When the AGM is slightly depleted, the blue light shuts off about a minute after I shut the ignition off. This is apparently very normal.
J**C
Hasta el momento a funcionado bien, es de buena calidad.
S**I
Good product and useful
R**B
خاص بعزل البطاريه جيدفي العمل
M**.
My previous battery isolator failed. When I looked at replacing it the same make/model I had was only $30 so was definitely cheap & nasty. I bought this WirthCo item based on other reviews. Installation instructions were dead easy. Item worked first go & hasn't missed a beat. Similar devices were much more expensive so this was good value for money.
S**N
I previously used a cole hersee on my last truck.it worked great but required external switches and led. This unit is smaller, cheaper and required no extra switch or light. Seems to work great and is electronic vs solenoid so time will tell Very pleased so far 2020 chev. suburban, install required 2 x 150 Amp breakers plus 30 Amp breaker hard wired to trailer feed. The second battery in the truck powers and recharges my trailer battery and allows effectively endless use as every time we drive the truck it recharges the battery and then we can reconnect to the trailer using extension cable the ability to boost the truck is a nice bonus which saved me on my last truck as the battery aged but this one is still young and the battery isn't dying yet update.. year later 8 camping trips 50,000 kilometers more on the truck and this unit is working great very very pleased
Trustpilot
5 days ago
1 week ago