<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body text="#000000" bgcolor="#FFFFFF"> Here's simple solution. Get another tractor and switch back and forth. <VBG> RJ <div class="moz-cite-prefix">On 10/27/2019 8:41 PM, David Roden wrote: </div> <blockquote type="cite" cite="mid:5DB60107.7949.805167C2@etpost.drmm.net"> <pre class="moz-quote-pre" wrap="">On 27 Oct 2019 at 17:18, Chris Zach wrote: </pre> <blockquote type="cite"> <pre class="moz-quote-pre" wrap="">However I can see the value of T105 cells in this case, with 180ah of capacity they would probably handle this load a bit better. Then again my BB600's are probably 20 years old with another 80 years of life left.... </pre> </blockquote> <pre class="moz-quote-pre" wrap=""> If you're running a 90ah battery flat in 30 mins, your load is 180 amps! That's HUGE. Lead batteries do NOT like that kind of load. Not onlly does their cycle life go down, old man Peukert steps in to clamp down on just how much energy you can really get from those batteries. (Hint: it's not 180 amp hours.) But just for grins, let's see how Trojan T-105s would do for you. A T-105 is 225ah at C20, and has a reserve capacity of 115 minutes at 75 amps. Using Uve Rick's handy-dandy battery calculator here <a class="moz-txt-link-freetext" href="http://www.evdl.org/uve/battery.html">http://www.evdl.org/uve/battery.html</a> We see that at 180 amps, a T-105 will give you about 117 amp hours. So you'd gain about 30% runtime. But wait! For decent cycle life (and at 180 amps you're going to get less of that regardless), you shouldn't draw a lead battery down past 20% SOC. So let's use 80% of 117ah, which is about 94ah. I don't know how much T-105s cost these days, but I'm pretty sure they're not the $65 or so I recall them being 25-30 years ago. Is an increase of 4% runtime worth it? Especially when you consider the much shorter life? David Roden - Akron, Ohio, USA = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to the "etpost" address will not reach me. To send me a private message, please use the address shown at the bottom of this page : <a class="moz-txt-link-freetext" href="http://www.evdl.org/help/">http://www.evdl.org/help/</a> = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ Elec-trak mailing list <a class="moz-txt-link-abbreviated" href="mailto:Elec-trak@cosmos.phy.tufts.edu">Elec-trak@cosmos.phy.tufts.edu</a> <a class="moz-txt-link-freetext" href="https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak">https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak</a> </pre> </blockquote> </body> </html>