<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div id="yui_3_16_0_1_1452892352823_2947"><span>Brian,</span></div><div id="yui_3_16_0_1_1452892352823_2942"><span id="yui_3_16_0_1_1452892352823_2946">For what it is worth, Gamma has 8 internal AGM batteries and I have had no issues.  I am using lead acid (wet) golf cart batteries in my deep diver because I have them and crude oil is 30 dollars a barrel ;-)</span></div><div id="yui_3_16_0_1_1452892352823_2942"><span>Hank</span></div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"><font size="2" face="Arial"> On Friday, January 15, 2016 1:47 PM, Alan via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br></font></div>  <br><br> <div class="y_msg_container"><div id="yiv2594739201"><div><div>I am not sure Brian,</div><div>they give off very little gas. Certainly a lot less than wet cel batteries.</div><div>Mainly the gas is given off during</div><div>charging & in particular if the charging is not done right.</div><div>On my AGMs there is a glued on cover plate running across the</div><div>tops of all the valves to hold them in place. The valves themselves</div><div>are just a flexible cap. Any overpressure above a couple of psi just</div><div>forces out the side of the flexible cap. </div><div>I compensated mine with mineral oil, but used the scented baby oil </div><div>from the supermarket. The chemicals in the scented mineral oil</div><div>caused it to off gas more than normal. When I changed to unscented</div><div>it stopped, but even then it wasn't excessive.</div><div>Alan<br clear="none"><br clear="none">Sent from my iPad</div><div class="yiv2594739201yqt8308988786" id="yiv2594739201yqt63335"><div><br clear="none">On 16/01/2016, at 7:57 am, Brian Cox via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br clear="none"><br clear="none"></div><blockquote type="cite"><div><div style="font-family:Arial, sans-serif;font-size:10pt;"><div>Alan,</div><div>             I wouldn't mind knowing the workings of those AGM's since I will be using them inside my cabin.  Should I have a hydrogen monitor?</div><div> </div><div>Brian Cox<br clear="none"><br clear="none">--- <a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a> wrote:<br clear="none"><br clear="none">From: Alan via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">To: Personal Submersibles General Discussion <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">Subject: Re: [PSUBS-MAILIST] battery compensation<br clear="none">Date: Sat, 16 Jan 2016 07:49:25 +1300<br clear="none"><br clear="none"></div><div>Hi Brian,</div><div>the AGM batteries need to be kept at an internal pressure</div><div>of between 1-6 psi to reabsorb gasses. They have little one</div><div>way valves on each cell & are difficult to compensate.</div><div>Can go in to detail if you like.</div><div>Alan<br clear="none"><br clear="none">Sent from my iPad</div><div><br clear="none">On 16/01/2016, at 6:01 am, Brian Cox via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br clear="none"><br clear="none"></div><blockquote><div><div style="font-family:Arial, sans-serif;font-size:10pt;"><div>Hank,</div><div>                 Using AGM batteries you may have less issues with topping off the cells.</div><div> </div><div>Brian<br clear="none"><br clear="none">--- <a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a> wrote:<br clear="none"><br clear="none">From: hank pronk via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">To: Personal Submersibles General Discussion <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none">Subject: Re: [PSUBS-MAILIST] battery compensation<br clear="none">Date: Thu, 14 Jan 2016 18:47:38 +0000 (UTC)<br clear="none"><br clear="none"></div><div style="color:rgb(0, 0, 0);font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px;background-color:rgb(255, 255, 255);"><div><span>Tom,</span></div><div dir="ltr"><span>I think the relay will be okay, I think I have done it in the past, just can't remember where ;-)    </span></div><div dir="ltr"><span>Hank</span></div> <div><br clear="none"><br clear="none"></div><div style="display:block;"> <div style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px;"> <div style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div dir="ltr"><font face="Arial" size="2"> On Thursday, January 14, 2016 11:36 AM, TOM WHENT via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br clear="none"></font></div>  <br clear="none"><br clear="none"> <div><div><div><div style="color:rgb(0, 0, 0);font-family:arial, helvetica, sans-serif;font-size:10pt;">I think that your lead acid battery weight in water question would be a simple matter, but you likely would have to calculate it individually for each size of cell. I would think the density could vary with the composition of each size. Most battery manufacturers provide a spec sheet for their batteries so it would be simple from the weight and dimensions provided to calculate the density and the specific gravity of the cell.<br clear="none"><br clear="none">I have no ideas on the relays being in an oil bath. Would that lead to coking on the contacts?<br clear="none"><br clear="none"><hr><div style="color:rgb(0, 0, 0);font-family:Helvetica, Arial, sans-serif;font-size:12pt;font-style:normal;font-weight:normal;text-decoration:none;"><b>From: </b>"hank pronk via Personal_Submersibles" <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none"><b>To: </b>"Personal Submersibles General Discussion" <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none"><b>Sent: </b>Thursday, January 14, 2016 11:48:28 AM<br clear="none"><b>Subject: </b>[PSUBS-MAILIST] battery compensation<br clear="none"><br clear="none"><div><div style="color:rgb(0, 0, 0);font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px;background-color:rgb(255, 255, 255);"><div dir="ltr">Thinking ahead, I need to reduce the weight of my deep diver.  I am now planning external batteries- lead acid in oil.  This reduces the amount of syntactic foam needed.  My deal on CNG  tanks fell apart.  The ebay seller would not honour the sale, can't blame him.   I may go with store bought syntactic foam if business looks good with 30 dollar per barrel oil, Yikes.  </div><div dir="ltr"><br clear="none"></div><div dir="ltr">I am not sure how to go about the oil filled battery set up.  I assume the batteries are filled as high as possible with water then topped up with oil, then the compartment filled with oil and a rubber lid on that.  I assume you take a syringe with distilled water to top the batteries up from time to time.  This way you wouldn't have to drain the oil.</div><div dir="ltr">Does anyone know how heavy a battery weighs under water compared to in air?</div><div dir="ltr"><br clear="none"></div><div dir="ltr">I also am thinking about having the reversing relays for the motors in the oil tank to reduce the amount and size of wires penetrating the hull.  I will just send small wires for messaging to the relays.</div><div dir="ltr">Hank</div></div></div><br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" target="_blank" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"></div><br clear="none"></div></div></div><br clear="none"><div>_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a rel="nofollow" shape="rect" ymailto="m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