jfalsone wrote:
Thanks Velera. I received the following from Maine Sail in response to a question about the new system's ability to top off:
Jesse,
It will be a much better fit than what you had as internal regulators are really poor at getting the most current into the bank. That said, a typical deep-cycle flooded lead acid battery will take 6-10+ hours of charging (depends upon battery health) in order to get to a true 100% SoC. The last 4% takes longer than the first 46% if starting at 50% SoC but an external regulator will help you maximize how quickly you can get energy into the bank. What you will gain is accurate voltage sensing, which means longer bulk charging, which means more energy into the bank before the regulator becomes voltage limited. You will also gain the ability to custom set your voltages to the max allowable, to charge based on battery temperature, the ability to limit the load on the belt, the ability to not over-heat the alternator etc., etc...
Since you suggested solar, do you have any suggestions for an adequate system? FWIW, I am at a marina and I have a Statpower True Charge 20+ amp multi stage charger.
I am not entirely understanding what MaineSail is saying. We might have a disagreement here. His videos and comments are generally spot on, but I have had disagreements in the past and maybe this is one of them. A modern "on/off" internal regulator has the advantage of bringing your batteries up to full charge faster than most of the "smart" regulators that taper the charge as it gets closer to fully charged. The downside of internal regulators is that, when you use a lot of your battery capacity (unlike a car where you use a short blast of high amperage, but a miniscule amount of the capacity in the start and the rest of the time the charging system is being continuously supplied by the alternator) batteries that have been slowly and significantly discharged can be heated until they gas a lot and lose their solutions and the alternator can be burned up or have its life significantly shortened by heat in the tiny enclosures we put them in. So "smart" regulators only do "bulk" charging for a limited time period (often with temp sensors attached to the alternator and battery that further limit the charge they deliver) and taper, particularly, the final stages as the acceptance rate of charge goes down as the batteries approach full charge. This creates an penchant "smart" regulators to leave your batteries undercharged. The "on/off" internal regulators might be harder on your batteries and regulators if you are constantly running you batteries down 40 or 50%, but they will bring things to a full charge faster at the risks to your alternator and battery health--just in a brutal way. I am willing to be corrected if there is some Phd in electrical engineering on this matter.
I think you need nothing if you staying in a marina and topping off with a "smart" shore charger. If you were on a mooring, I get by easily with a 65w high quality (shade tolerant) solar panel that can top off my golf cart batteries in a day and keep them there. Not too hard to fit a 100w panel there to give you a cushion. Solar panels of this size need their own controller which is a $15 item. I think most folks would be better off, even in a marina, staying away from all the stray current issues from bringing AC aboard and trying to use solar to top off batteries, but that is just my opinion. Once you are hooked into shore power grounds, I think it is just about impossible to entirely prevent all traces of galvanic corrosion. Isolators help. But I have measure stray current in empty slips. It will find a ground.