Originally Posted by Charliemciver
I bough a pair of Lifeline AGMs for the domestic and Numax Sealed
Marines ones for the rest...
And set to work
I sure wish that folks would ask these questions BEFORE going ahead and buying
stuff. Now that you've made the investment -- in AGMs and sealed batteries -- I guess you'll just have to work with it.
Your questions have been posed and answered and debated ad nausium on this and other Boards. While there's no one "right" answer for everyone, a few things might help you.
1. AGMs and flooded batteries have practically identical charging
profiles. While it's not ideal to connect them together, it can be done will little ill effect.
2. "Sealed" "marine" batteries are generally not to be preferred. They're not real deep-cycle batteries nor are they the best sort of starting batteries for a boat
. But, you're stuck with them for the present.
3. AGMs are indeed meant to be deep-cycled; they can deliver a lot more amperage fast than can flooded batteries.
4. The "ideal" setup involves having a sizeable house battery bank to which ALL onboard charging
sources are connected, including alternator, battery charger
, solar panels
, wind generator
, etc. Then, use either a voltage follower device like the Xantrex EchoCharge or the Balmar
DuoCharge -- or one of many battery combiners to automatically maintain the start battery. You can also maintain a windlass battery the same way, or you can have a separate means of charging. All depends on your setup and your preferences.
5. Golf-cart batteries are often the best bang for the buck (or the pound, in your case). You've already made some battery decisions which obviate this choice for the present, but keep them in mind. They are relatively inexpensive, relatively robust, take a lot of punishment and have a useful life on the order of 5-7 years if treated properly.
6. With a setup such as mentioned in #4 above, you don't need a charger
with multiple outputs nor do you need a splitter on the alternator. You run ALL charging to the house bank, and take excess current
from there to charge the house (and windlass) batteries. These require very little charging....it takes less than 1AH (yes, one amp-hour) to start the typical diesel
. This is replaced very quickly.
7. For a 43-foot family cruising boat
, a house bank of 400-700AH total capacity would be about right. This is the equivalent of four-to-six 6V golf-cart batteries in series/parallel.
8. To take advantage of AGM
charging capabilities you really would need a BIG alternator and external regulator
. Lifeline AGMs can easily take 100% of their amp-hour capacity in charging amps when they're 50% discharged, so 200AH of these AGMs could take 200 amps charging current
easily. Almost no boats are already set up to really take advantage of AGMs....one wonders what the fascination is with them :-) But, again, you're already stuck with them so will have to make the best of it unless you really want to redo your alternator/charging systems.
Don't mean to be overly critical, and perhaps I'm super sensitive about batteries and charging systems because I work with them every day. Some of the most dreaded words I hear from my customers mouths are "I've just bought a new XYZ; could you please come and install it?".
More often than not that means that one has to settle for something less than "ideal"....not what I like to do with my customers.