Battery Know-how

In order for all gadgets and electrical necessities on board to have access to sufficient power resources, batteries are crucial. Ocean Navigator’s January/February 2004 issues has a lengthy article on this topic.
“For the purposes of the average voyager, the quest for reliable, powerful and affordable deep-cycle house and start batteries takes precedence over all other battery interests. Even this considerably narrower category presents a dizzying prospect for the would-be battery purchaser. Available configurations run the gamut from flooded to gel and absorbed glass mat (AGM), from 6-volt traction to dedicated 12-volt marine. How is a cruiser to know what is appropriate for his or her needs?”

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3 Responses

  1. Jeff says:

    I went the AGM (2-8D’s for the house bank and a series 31 for starting) route 4 years ago and after 2 seasons (Maine) had to replace them because the voltage dropped off so quickly after charging. I went with AGM’$ again and now have the same problem. My charging system is a 165A alternator with a Next Step Regulator that I sent in to the manufacturer for the AGM charging mod or a 125A Heart inverter/charger with “AGM” selected on the remote controller. I had once allowed the first batch of AGM’s to almost fully discharge (during heated winter storage) so blamed my first problem on that and have been careful to never allow this second batch of batteries to be discharged below about 60% of full and usually recharge them fully each day by using my genset with Heart invertor/charger. A Heart tech suggested over the phone that I use the wet cell equalization mode to bring the batteries back but I am hesitant to do this even though I do have temp sensors to regulate both charging sources. Any suggestions either about equalization of AGM’s or from other people with similar experiences about AGM batteries in general?

  2. Dave Wilson says:

    Jeff, I had the same problem with AGM’s. After talking with the folks at Ample Power (who made my smart regulator), they offered their opinion that AGM’s are not suitable for marine users without gensets. AGM’s like to stay fully charged, with occasional discharges. They also recommended equalization. Their suggestion was stick with flooded cell or go with gel cells. I went with flooded cells and have been happy ever since.
    Dave
    s/v Whisper

  3. Jeff says:

    Thanks Dave, for your reply and that’s the way I’m leaning right now too. But my battery location isn’t very well ventilated (under quarterberth) so I worry about gas buildup. But with temp regulated charging as long as all goes as advertised, I suppose it SHOULDN’T be a problem. But maybe a small exhaust fan that only kicks on when voltage is above about 13volts so it would only draw when batteries are being charged would do the trick.

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