Re: Battery Reccomendations
Optima, Orbit, and other spiral wound batts are hybrid AGM/gels. They are more sensitive to the charging scheme. If the proper scenario is followed, they perform well but still come out costing more than most other batteries. If you dont have the correct charging profile, the spiral wound batts are dead meat in no time at all. I suggest avoiding them all together.<br /><br />AGMs are where you need to be. Most of what is available to is the
new AGM technology. It is less concerned with the charging profile, goes deep, bounces back, can be charged at extraordinary rates (up to 3-times the batts capacity, i.e. a 100a/hr batt can be charged with 300amps!), can dump more amps for starting applications than a flooded cell starting battery, and they are maintenance free. Oh, and they cost more than a flooded cell, but if maintained, and depending on the charging profile and depth of discharge, can last upwards of 20-years. Not all AGMs last that long, but some are projected to.<br /><br />All batts self-discharge when just sitting. Hence the need for a maintenance charge. Flooded cell batts self-discharge at a rate of just under 2%/month. A batt is considered discharged when it gets for to 90% of its charge, or 10% discharged from full, and in need of charging. This is why flooded cell batts have a 6-mon shelf life. In 6-mons they are 10% discharge just sitter there. AGMs have a much lower rate of self-discharge. They have a 2-year shelf life, i.e. it takes that long to discharged 10% and needing a charge. AGMs do not need to be left on a charger over the winter.<br /><br />If you think the AMGs you have been looking at cost more, take a look at the NorthStar HD Marine battery. Sit down before you check the price. Yeah, they cost more, but they perform like nothing else I have ever seen. That is the only battery I use in my boats now.<br /><br />AGMs have lower internal resistance between the plates. This allows them to dump big amps for starting a motor. Many of the AGMs spec out with higher cranking specs than flooded cell starting batts. All AGMs are deep cycle batts. You are correct, dual-purpose batts excel only within a very narrow application. All AGMs can function as dual-purpose batts, and they do both starting and deep cycling better than a flooded cell designed to just one of those two applications.<br /><br />Back to NorthStar. Their HD Marine batts are based on a telecom AGM batt. They are designed such that a pair of HD Marine batts occupy the same footprint as a single 12v 4D battery. I use the 130a/hr batts, putting two side by side and bridged with the tinned, braided copper strap (each batt comes with the strap) for 24-volts in a 12v (4D) footprint.<br /><br />NorthStar is about 5-years old. It was started with something like $60-million in seed money with the goal of a completely automated battery manfing facility. They succeeded. Every NorthStar batt is perfect, having been made entirely by robotics. When I talked to the distributor last year, not a single HD Marine batt had been returned as defective. Not one!<br /><br />NorthStar also makes a line of AGMs that fit the traditional group-27, 29, 31 footprints. They are sold under the name of Dual-Pro Lightening trolling batts. I believe they are also sold under the distributors own re-branding label. They are ok to cycle down to about 80% discharge when comparing to flooded-cell batts that cycle down to 50% discharge. And the AGMs work perfectly well for starting, too. Look at the numbers. When is the last time you saw a group-27 deep-cycle trolling batt that coughs up 1180 marine cranking amp?!?
<br /><br />
http://www.northstarbattery.com/marine_trolling.php <br /><br />Heres the HD Marine:<br /><br />
http://www.northstarbattery.com/hd_marine.php <br /><br />Heres a website with pix of the HD Marine batts bridged, in a box. That little strap is the tin coated braided copper thingy for bridging batts that comes with ever HD Marine batt. The traditional looking batts at the bottom of the page are (I believe) identical to the NorthStar DualPro Lightening batts.<br /><br />
http://www.boatelectric.com/Energy 1AGM batteries.htm <br /><br />Lastly, I just received the new issue of Powerboat Reports yesterday. Havent read it yet, but in this issue they evaluate the deep-cycle AGM and gel batts. NorthStar was not included. PBR concluded Trojan AGMs were the best bang for the buck of the 700-lbs of batts they tested. If you are interested, Ill read the article and post a synopsis.
