I have 4 blue tops on my boat for the stereo. <BR> <BR>Do I really need a 4 bank smart charger or will a single charger eventually get them all? <BR>What is the benifit to the 4 bank? <BR>My poor alternator works very hard after a few hours of stereo play. I am barely around 11.5-12 volts running when the batteries are low, but it eventually gets back to 13.5 after about 2-3 hours of running. Should I consider an upgrade? <BR> <BR>(Message edited by troyl on August 30, 2007)

If all your blue tops are wired together they would be considered 1 bank. In this case you don't really need a multi bank charger. More important is the output current. For your Optimas I would opt for a 40amp model. I have had great results with the Truecharge 40. It is a multibank charger but you can use it to charge a single bank and still get full output. It also has a setting specifically for gel batteries. They are a little pricey but worth every penny.

Like Scott said, multiple batteries connected together create a "bank". If you have isolated batteries, such as a starting and stereo bank, and you want to charge them both without using a battery switch to connect them together, then you need multiple bank charger. <BR> <BR>As for the output of the battery charger it will all depend on how quickly you want to recharge. If you have the time, slower is better. <BR> <BR>The four optimas will probably combine into around 340 amp-hours. IF they were completely dead, and you wanted to charge them back up in a single night (so you can go back out on Sunday morning), then you would need to get 340 am-hours in 12 hours, which would require a ~28 amp charger. <BR> <BR>If you have all week to charge the batteries back up you will be much better off to get a charger that is 10 to 20 amps instead. <BR> <BR>More important than the amps of the charger is that it be a "multi-stage" inteligent charger. The old fashion dumb chargers taper their charge off significantly so even if they are rated at 30 amps they won't deliver it into anything other than a compleltey dead battery. This will dramatically increase charge time. <BR> <BR>The inteligent multi-stage chargers charge faster and treat the batteries much better. <BR> <BR>Rod

Thats what I wanted to hear. Thanks much. <BR>A 10-20amp will work fine and save me money over the 4 bank. I will get a "smart charger" like the Battery Tender for sure. <BR> <BR>One more?, <BR>Does it matter where the positive and Negative are attached when dealing with 4 batteries? <BR>Same battery....each end....terminal strip...etc.

Scott blue tops are AGM (absorbed glass matt) not gel cells.

Four batteries...I would get a charger that is AGM capable and 20amps at a min.

I have a five battery bank in my boat and I have struggled to find a charger that can bring them back to charge in 12 hours as well as maintain the batteries. <BR> <BR>I bought this 30 amp version from West Marine, and this is the best charger I have ever had. You can select the battery type, temperature and amps. It has a nice internal fan and it regulates the charge based on the needs of the "bank". It is the only one I have found that doesn't overheat during operation. I place my charger on a different battery each time I charge....not sure why, just thought it would be a good idea. This charger is worth the investment. <BR> <BR><a href="http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/232564/377%20710/0/battery%20charger/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710&amp;Ne=0&amp;Ntt=battery%20charger&a mp;Ntk=Primary%20Search&amp;Ntx=mode%20matchallpar tial&amp;Nao=0&amp;Ns=0&amp;keyword=battery%20char ger&amp;isLTokenURL=true&amp;storeNum=9&amp;subdep tNum=544&amp;classNum=683" target="_blank">http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/232564/377%20710/0/battery%20charger/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710&amp;Ne=0&amp;Ntt=battery%20charger&a mp;Ntk=Primary%20Search&amp;Ntx=mode%20matchallpar tial&amp;Nao=0&amp;Ns=0&amp;keyword=battery%20char ger&amp;isLTokenURL=true&amp;storeNum=9&amp;subdep tNum=544&amp;classNum=683</a>

I second the recommendation on the West Marine charger. I bought one a couple of years ago and it works great! <BR> <BR>Rod

Not a marine one but here is the one I use <BR><a href="http://www.samsclub.com/shopping/navigate.do?dest=5&amp;item=190126" target="_blank">http://www.samsclub.com/shopping/navigate.do?dest=5&amp;item=190126</a> <BR>smart charger and 25 amps on high, batt type selectable, probably way cheaper then the west marine one