This discussion makes me realise how much variation there may be in batteries from different manufacturer' Flooded may be standard, with removable caps, or the so-called "maintenance free" (that means they are designed to die one week after the warranty runs out). All gelled are sealed and are "valve regulated", which means that a tiny valve keeps a slight positive pressure. Nearly all AGM batteries are sealed valve regulated (commonly referred to as "VRLA" - Valve Regulated Lead-Acid). Most valve regulated are under some pressure - 1 to 4 psi at sea level. I also checked the Hawker Genesis spec's and they make note that their batteries are VLRA and that their performance in part is due to designing the battery to operate at higher positive pressure than other brands. If they have removable caps I assume they must have a pressure valve built into the cap. Drilling holes would eliminate any positive pressure and from reading their specs would not be a good thing. Based on above and my experience with the Lifeline batteries which are fully sealed (as I recollect the positive pressure is critical to the recombination of gases and both charge and life of the battery) I would verify the operational specifications before drilling holes. Has anyone used batteries made by Battery Energy. I have heard that they have superior lifecycles etc but do not know of anyone who has installed them. They guarantee to 20 years. Not sure where they sell outside of Australia. I know someone who is considering them for international cruising. Sure. And Hawker Genesis AGM's have a large plastic pop-top that unsnaps readily and has individual rubber caps on each cell requiring nothing more than pulling the cap off and injecting water with a syringe---I've done that also. AGM's come in many flavors. -mt From: electricboats@ Not sure about all AGM's but Lifeline rely on the battery remaining sealed to operate properly. If you drill a hole or break that seal in any way your $250 battery will be toast. I did not drill a hole but did cause a pin prick hole. The battery would charge to full voltage but would dissipate in minutes. On Jul 17, 2010, at 6:36 PM, Myles Twete wrote: I've done this to Optima Yellow Tops---main thing is that you'll want to use a Forstner or other drill bit that won't poke down into and damage the cell plates. I can't comment on how effective it was because not long after doing this, I left the batteries charging with an equalization charge that fried the batteries. I've read of others who've done this also. It'd really help to have a mapping of the best spots to drill into each cell before you do this---you could hit a conductor and that might not be good. -mt From: electricboats@
Sent: Saturday, July 17, 2010 4:28 PM
To: electricboats@
Subject: Re: [Electric Boats] Re: Optima vs Lifeline
Sent: Saturday, July 17, 2010 10:03 AM
To: electricboats@
Subject: [Electric Boats] Re: Optima vs Lifeline
Has anyone ever tried to drill a small hole in an AGM battery and add water to one that has dried out and then plug the hole and see if it can be brought back?
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