I bought the 3 bank charger and it made less than a year. The manufacturer replaced it after making me jump through a few hoops. Did not require me to return original. The replacement has lasted several years now. I later upgraded my trolling motor to 36 volts. So I needed a 3 bank for it. And a single for my starter battery. The single made it just a few months and quit charging. The service rep had me try several different things. Which in turn caused my starter battery to boil dry. They then made me take pictures a of the charger and battery. This was a pain since my boat was at Truman lake, some 90 miles away. Several weeks later I finally received the replacement. Several months later the same service tech contacted me and asked me to return the bad unit. I told him that he asked for no return at the time of replacement. So just as with the 3 bank charger the bad one went into the trash. Nothing else was said. Going on 2 seasons this year it’s still working. My conclusion: 2 pro mariner chargers bought on Amazon and 2 bad units. So I have nothing good to say. You make your own conclusion.Please use the following for troubleshooting steps:Tools Required: 1. Large Flathead Screwdriver or coin 2. Diagonal cutters, Metal File or SandpaperTime Required: Approx. 5 minutes1. Disconnect AC power from the charger.2. Confirm all charger cables are connected correctly to batteries.3. Remove the programming cap from the wire end of the charger’s end cap using a screwdriver or a coin.4. Reconnect AC Power. At this point, you should have the following LED’s a. Blue AC power LED b. Green Battery type LED (Gel) c. Red Flashing Analyze/Charge LEDi. If you only see the Blue LED, please contact us, and we will begin the warranty replacement process.5. Disconnect AC power.6. Programming cap alteration:a. Using a metal file or sandpaper, remove approximately half of the material from the unthreaded portion of the programming cap. i. Approximately 1/8th inch of material will be remaining.7. Ensure there is no debris in the programming cap hole, or on the cap itself, and reinstall the programming cap.8. Reconnect AC Power. At this point, you should have the following LED’s a. Blue AC power LED b. Red Battery type LED (Flooded/AGM) c. Red Flashing Analyze/Charge LEDi. If you reencounter the issue, remove more material from the unthreaded portion of the programming cap until the charger is functioning properly.ii. The charger must reset to register the correct position of the programming cap. d. The charger is now functioning properly and will follow the operation outlined in the manual.Please Note: The standard warranty is two years from the purchase date for the original owner. If you would like to send your charger in for evaluation, please don’t hesitate to call us at 1-800-824-0524.Last year Our nitro bass boat was left outside and the 3 bank water proof charger we had on it was submerged in ice water; we had been looking for a new one but every one was 500 plus and there was no way I was allowing that; I jumped on amazon before Father’s Day and found this three bank charger; we didn’t need to purchase any of the extra accessories bc we already had one on our boat before, much to our surprise it fit perfectly in the original holes from our first bank charger and this one during a heavy rainstorm ended up submerged for a few days bc the plug was left it, once again big shock after draining the boat and allowing it to dry we plugged it right in and it still works! No problems what so ever, love this bank charger! It runs two trolling batteries and the master, we can go out for hours and not worry one bit about battery charge! Love it! And under 200.00!This is my second unit in 10 yrs!!! first one went 9 yrs, wow....but i went 3 bank this time and should of done it before. why??? If your using 2 of the banks to charge your 24v electric motor batteries it gives you the third bank for the starter battery, Big plus with the newer main motors. why??? Well with the newer motors if the voltage gets to low the motor won't fire, I mean turn over fine but will not fire at the plugs. I learnt the hard way and took my new motor back to marine i got it and wanted it fixed. It was not the motor, it was the battery!!! It turns over fine but will not fire!!! I went to two things, one i carry power pack to jump start and 2ND 3 bank charger to keep starter battery charged. In Montana you don't want to stay overnite on the shore!!!So far so good but one oddity. Over the previous winter the original 1990 battery charger took out the 3 batteries that it was charging. At the time we thought that it only took out two batteries since, well, they were dead and wouldn't take charge and the third battery would take charge and start the engine. Fast forward to this week and I found the third and final battery had exploded. Big crack right down the middle and crap splashed everywhere. The charger was still trying to charge the exploded battery and didn't have any faults.... Ive replaced the exploded battery and will be watching the batteries very closely. Still dont trust this charger since it does get some negative reviews and it didn't recognize an exploded battery. The risk is that this boat sits all winter in storage so the batteries are left on the charger and cant be checked often. Time will tell... The original charger lasted 26 years and I doubt this one will...Just an update. Amazon replaced the first charger as it quit charging one of the banks. Now the new charger wont kick back on once it shuts off. Some of the batteries power various things throughout the boat (carbon monoxide monitor for example) and over time the batteries will drain. The charger stays in 'maintenance mode' and the batteries die. Unplugging the charger and plugging it back in charges the batteries again. Ive always bought products on amazon that have 70-80% 5 stars but this unit is junk.Product as described. Installed on my pontoon with engine battery and 2 trolling motor batteries. Love that it charges all 3 at once, and diverts to trolling batteries if engine battery is full. Tested in my garage on my batteries after winter storage. Worked perfectly and went into maintenance mode when batteries were topped off. I have a solar charger on my trolling batteries, so this won’t get hard use from me, but will need it when fishing multiple days in a row. With 20 amps, it will charge overnight. Time will tell on longevity. Needed extension to reach engine battery but was available from Promariner/Amazon.I've personally gone thru 2 of these in the span of 2-3 years. Seems like the first one I go from promariner, it lasted a year, then went faulty. Power light would come on, but no power on the charging end. I contacted promariner, and I ended up getting a free replacement no problem. And simply sent the old one back to then with a return label. But here's the thing, the one I got from them to replace the old one did the same thing. Only thing different was I got more than a year out of it. But wasn't covered by warranty. I use this in my boat. Sits onboard where my batteries are. I usually just run a cord to it and plug it in everytime. In the fall time when my boat goes to storage, I take my maintainer back home with the batteries. Unless somewhere between transportation and plugging it in something went wrong, I can't seem to understand how both went faulty the same way. I've since bought a different brand of maintainer as this one to replace is quite costly. When it worked it was great! Kept all my batteries maintained, no problem. Just quite possibly had a few that were a bad batch.The 2018 fishing season is over and the boat has been winterized and put away until the spring. I am happy to report that my ProMariner bank charger worked PERFECTLY all season long and it was so nice to just come home and plug the boat in and not fiddle with battery chargers and clamps anymore. I should have added this to my boat the same year that I bought it! Very happy I went this unit, I highly recommend it. Easy to install, clear instructions and it looks awesome.Bought this to replace my two bank promariner charger which stopped working after half a year. Seems that charger wasn't rated to charge heavy duty 12v 8d marine batteries. Should have bought this 20 amp charger first. My initial 20 amp was the same model and lasted 8 years. Expensive lesson.I rated 1 star because it would not let me submit with no stars!!!!! This is garbage. We bought and installed it in our boat to keep the 3 batteries charged. It stopped working only after1 year. Not worth the money.....