Brent, AGM batteries have a little pinhole opening on top of the case and although I haven't taken one apart, I understand there is an overpressure valve inside the pinhole. I once mounted one upside down. It did not leak, until I charged it. It leaked only a small amount, but I would not recommend upside down installation. I believe they are OK to use upside down, such as in a hydrobatic sub, but should not be kept in that position indefinitely. thanks, Alec The contents of this e-mail are intended for the named addressee only. It contains information that may be confidential. Unless you are the named addressee or an authorized designee, you may not copy or use it, or disclose it to anyone else. If you received it in error please notify us immediately and then destroy it. From: owner-personal_submersibles@psubs.org on behalf of Brent Hartwig Sent: Sun 7/6/2008 10:01 PM To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] 12 Volt DC Lawnmower Battery Test Update Jay, I've been meaning to compare notes with Alec and Kyle about what there conning tower height, from the top of the main pressure hull is compared to mine. Also of note, it looks like I have larger MBT's then are on there K-250's which would put me a little higher out of the water when surfaced. This in no way means that I think I have enough freeboard to be truly comfortable. For this reason, I've been seriously considering installing a 6 or 7 inch acrylic tube addition to the conning tower some what like the S101 sub. That would of course change the look of the sub and it's metacentric height. In that configuration, I think it would be safer as well as easier to see horizontally and down. The other option to make the current conning tower configuration safer, is the custom pontoon system I'm working thru with a guy that knows Zodiac designs very well. If we come up with some thing we think will work. I'll run the design thru you guys to get your input. I would like to find out if the AGM batteries have a vent and if so what kind. Perhaps they have a bladder of some type to deal with pressure differences. I've heard many times that they can be mounted vertically as well as upside down. I had expected that I would likely need to remove the batteries if I used the sub for wet exit training. But for a real emergency wet exit, I was hoping that the APM batteries would be a safer option. Corrosion issues of course are always fun to deal with. ;)' Regards, Brent H ________________________________ From: bottomgun@mindspring.com To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] 12 Volt DC Lawnmower Battery Test Update Date: Sun, 6 Jul 2008 17:54:58 -0400 Brent, The batteries would have to be in a waterproof container if going into saltwater. I believe even the APM batteries have a vent otherwise they would explode at altitude. As noted in his book, George moved to the K-350 design for a number of reasons...the cramped interior, minimal reserve buoyancy, and statics issues if I remember correctly. Adding gear to the K-250 design only compounds the issue. Look how little freeboard Alec's sub exhibits (not to pick on him). You will find getting into and out of a flooded K-250 an issue due to the tight nature of the interior and conning tower. The domed hatch will open explosively due to the large bubble that will be trapped there. If you didn't drain all of the air out of the rest of the conning tower but compressed it, you will be violently expelled from the sub. Corrosion will be a nightmare inside your sub after flooding it down 1 or more times, lock-out chambers of large subs experience this issue despite being easier to access and preserve. I wanted to be able to lock out of a K-250 also when I first viewed the plans for the sub back in 1974. Experience has taught me that this is not a good idea. R/Jay From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Brent Hartwig Sent: Sunday, July 06, 2008 5:27 PM To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] 12 Volt DC Lawnmower Battery Test Update Hello Jay, Will a sealed Optima type APM battery produce chlorine gas when submerged in fresh or saltwater? There was no real hydrostatic pressure applied to the battery, and it was not in the water for all that long, so the battery didn't leak as you noted. At least not enough to seriously damage the battery. I'm interested in configuring my sub to that I can do a wet exit safely if need be. Since the K-250's have the batteries inside, that makes things more difficult. Regards, Brent Hartwig
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