Is the only thing that is wrong is the cooling fan? You can replace the cooling fan. Much better ones are vailable with bearing that will last for years.

Is a 20 amp sufficient for your battery bank?

One thing people, and manufacturers for that matter, don't take into account is the high acceptance rates of AGM batteries. These batts, depending on the brand, can take up to 100% of their Ah rating all the way up into the high 80's in terms of % of charge. Doing this with a 20 amp charger or small alternator that is not temp regulated or current limited by the regulator can burn them out with time.

My guess is that your charger was literally running at full output for periods that it was just not designed for and you kept wearing out the fans. I know of many who use the True Charge without the same issues. AGM's can take LOTS of current so supplying them with a small charger will work it for a long time at or near full output something they just won't put up with for very long.

Check out the Iota line of chargers with the IQ4 feature. If your agm's will take standard wet cell voltages, as many will these days, the Iota's can be bullet proof and a LOT less money. They are built to withstand the rigors of off grid living where banks are often quite deeply discharged.

Contrary to popular belief chargers and alternators do not send or force current into batteries the batteries take or accept the current. If they accept more than the alt or charger can supply it will run at full bore longer than it should.

Wet cells will take about 25% of the Ah rating in bulk phase but AGM's can take up to 100% and for short durations and in-rush as much as 500% of the Ah rating. I have seen many a small alt burned out by AGM's as well as some chargers. Running alts or chargers at max output for longer than they should can really shorten the life span if they are not specifically designed for this, most are not.

Sadly this is a very over looked issued that gets little press..

I concure, the Iota charger is a great value. I just put one of their 45IQ unit in my boat, I am very satisfied with the unit picks up house loads at the dock my old charger did not have enough output to run house loads at the dock and I was drawing down my batteries. The Iota a a good enough value that it allows you to purchase a much higher output charger than competing marine brands. This unit is not a marine unit as it lacks a epoxy coated case, if it is mounted down below away from direct salt air I do not think it is an issue. At the price you can afford to purchase another one in a few years and still be money ahead. Other C36er's have reported no complaints about these units that are primarily sold as chargers for home solar systems.

[QUOTE=Steve Frost;5844]I concure, the Iota charger is a great value. I just put one of their 45IQ unit in my boat, I am very satisfied with the unit picks up house loads at the dock my old charger did not have enough output to run house loads at the dock and I was drawing down my batteries. The Iota a a good enough value that it allows you to purchase a much higher output charger than competing marine brands. This unit is not a marine unit as it lacks a epoxy coated case, if it is mounted down below away from direct salt air I do not think it is an issue. At the price you can afford to purchase another one in a few years and still be money ahead. Other C36er's have reported no complaints about these units that are primarily sold as chargers for home solar systems.[/QUOTE]

Another benefit of the Iota is that it can work as a stand alone 12V power supply. If you are in an area where you remove your batts for the winter the Iota will still give you 12V power while on the hard even with no batteries. The only thing it lacks is the actual marine "ignition protected" certification however they do claim that it can not create any spark so therefore would meet the requirement if they choose to cough up the funds to go for a marine certification. LOTS of "marine" devices do not have conformally coated PC boards and I have not found this to be an issue with the Iota..