<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_1_1452794902923_3753"><span id="yui_3_16_0_1_1452794902923_3838">Hank,</span></div><div id="yui_3_16_0_1_1452794902923_3753" dir="ltr"><span id="yui_3_16_0_1_1452794902923_3802">the calculation is easy with the metric system.</span></div><div id="yui_3_16_0_1_1452794902923_3753" dir="ltr"><span id="yui_3_16_0_1_1452794902923_3843">If your battery is 30x20x20 for example, you multiply those dimensions.</span></div><div id="yui_3_16_0_1_1452794902923_3753" dir="ltr"><span id="yui_3_16_0_1_1452794902923_3899">This gives 12,ooo which is the cubic centimeter figure. Divide this by</span></div><div id="yui_3_16_0_1_1452794902923_3753" dir="ltr"><span id="yui_3_16_0_1_1452794902923_3941">1000 to give you how many liters volume it is. So 12 liters. This means you</span></div><div id="yui_3_16_0_1_1452794902923_3753" dir="ltr"><span id="yui_3_16_0_1_1452794902923_3971">will displace 12 liters of water which weighs 12 kg. </span></div><div id="yui_3_16_0_1_1452794902923_3753" dir="ltr"><span id="yui_3_16_0_1_1452794902923_4007">If your battery weighs 30 kg then subtract the 12 kg from that & your battery</span></div><div id="yui_3_16_0_1_1452794902923_3753" dir="ltr"><span>will weigh 18 kg in water.</span></div><div id="yui_3_16_0_1_1452794902923_3753" dir="ltr"><span id="yui_3_16_0_1_1452794902923_4054">Another way would be to fill a container to the top with water (fresh not salt) </span></div><div id="yui_3_16_0_1_1452794902923_4168">then put the battery in. Fill it up again to the top with water, measuring what you </div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">pour in. If you pour in 10 liters of water then that is how much it displaces, which</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">equals 10 kg that you subtract from your battery weight to get the weight in water.</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr"> As for oil compensating, there is a section in the manned submersible book.</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">Deep sea power & light make a sea battery.</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr"><a href="http://www.deepsea.com/products/seabattery/" id="yui_3_16_0_1_1452794902923_4295">http://www.deepsea.com/products/seabattery/</a><br></div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">It is a battery box with cables entering it & has a flexible diaphragm over it.</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">In the diaphragm is a bleeder valve to bleed off gas that mainly accumulates </div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">during charging. You would only need blue globe cable glands or similar for the</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">battery leads as the pressure is always ambient.</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">In the early days of car batteries, topping the battery up with oil to stop evaporation was</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">touted, so that isn't a problem.</div><div id="yui_3_16_0_1_1452794902923_4107" dir="ltr">Alan</div> <div class="qtdSeparateBR" id="yui_3_16_0_1_1452794902923_3842"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_1_1452794902923_3855" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1452794902923_3854"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1452794902923_3853"> <div dir="ltr" id="yui_3_16_0_1_1452794902923_3852"> <font size="2" face="Arial" id="yui_3_16_0_1_1452794902923_3870"> <hr size="1" id="yui_3_16_0_1_1452794902923_3896"> <b id="yui_3_16_0_1_1452794902923_3898"><span style="font-weight:bold;" id="yui_3_16_0_1_1452794902923_3897">From:</span></b> hank pronk via Personal_Submersibles <personal_submersibles@psubs.org><br> <b id="yui_3_16_0_1_1452794902923_4281"><span style="font-weight: bold;" id="yui_3_16_0_1_1452794902923_4280">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br> <b id="yui_3_16_0_1_1452794902923_4279"><span style="font-weight: bold;" id="yui_3_16_0_1_1452794902923_4278">Sent:</span></b> Friday, January 15, 2016 5:48 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> [PSUBS-MAILIST] battery compensation<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1452794902923_3858"><br><div id="yiv2593403126"><div id="yui_3_16_0_1_1452794902923_3857"><div style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px;" id="yui_3_16_0_1_1452794902923_3856"><div id="yiv2593403126yui_3_16_0_1_1452789352970_2427" 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 id="yiv2593403126yui_3_16_0_1_1452789352970_2427" dir="ltr"><br></div><div id="yiv2593403126yui_3_16_0_1_1452789352970_2427" 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 id="yiv2593403126yui_3_16_0_1_1452789352970_2427" dir="ltr">Does anyone know how heavy a battery weighs under water compared to in air?</div><div id="yiv2593403126yui_3_16_0_1_1452789352970_2427" dir="ltr"><br></div><div id="yiv2593403126yui_3_16_0_1_1452789352970_2427" 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 id="yiv2593403126yui_3_16_0_1_1452789352970_2427" dir="ltr">Hank</div></div></div></div><br>_______________________________________________<br>Personal_Submersibles mailing list<br><a ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org" id="yui_3_16_0_1_1452794902923_5572">Personal_Submersibles@psubs.org</a><br><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br><br><br></div> </div> </div> </div></div></body></html>