Re: Solar battery mantainers- do they help
Obviously the term "maintainer" didn't stick with you. No -- they do not help. Here's the reason. Even a small trolling motor will suck 20 amps or more out of a battery each hour of run time. Since that amount of current (and more) must be pushed back into the battery just to stay even, the panel would need to be a 20 AMP version. Do you know how big a 20 amp solar panel is? Lets just say your boat would have a very substantial roof over its entire length and there would likely be enough overhang that you could rent slip space for a bunch of other boats. The panel manufacturers would like you to think you could power your house with a panel the size of small flat screen TV. Most of the ads for those maintainers don't provide any numbers other than the panel output in MA (milliamps) with are thousanths of an amp (.001 is one thousanth of an amp) or it might be specified in Watts. A 7.5 watt panel will output .6 amps (a little over 1/2 of an amp at full sunlight. That's not enough power to light just one of the tail lights on your boat trailer. Look at that number and then compare it with the 20 amp number I mentioned earlier. Here is the reality. A panel that outputs .6 amps in full sunlight would take 33.3 hours of full sunlight to replace that current. Another way to look at it would be that the batteries would be losing ground at a rate of 19.4 amps per hour with the panel vs 20 amps per hour without it. Now then -- does that make sense to install one these? Of course it is also dark for a good part of every 24 hour period so during those hours the batteries see no charge whatsoever. Now you see why they are called "maintainers". They work well to keep a fully charged battery topped off during storage. They are not capable of charging a deeply discharged battery unless you don't need to use them for several days.
