Hi John, When I first got my M17, I replaced the flooded lead acid group 24 battery which was at end of life... My choice was a sealed ultra pure lead AGM group 24 battery providing 76 AH of capacity, with a self discharge rate of about 1-2% per month, 400 charge/discharge cycles to 80% depth of discharge and over 900 cycles at 50% depth of discharge, the cost was about $320 USD. http://www.canadiantire.ca/en/pdp/nautilus-group-24-pure- lead-agm-deep-cycle-battery-0102496p.html It doesn't do anything to decrease the weight but it's given it's characteristics I expect to get 5-7 years of life out of it. It provides enough capacity to continuously service Serenity's max sailing power budget (@ 0.6 amps) for LED Nav & Cabin lights, VHF, depth sounder, & chart plotter when coupled with the 50 Watt flexible solar panel that is mounted on the forward hatch. The theory is I can cruise indefinitely, subject of course to my Admiral's permission! Cheers, Keith *Keith R. Martin, P.Eng.* *Burnaby, B.C. Canada* *Serenity, M17, #353* On 28 December 2017 at 14:56, John Schinnerer <john@eco-living.net> wrote:
On 12/28/2017 12:39 PM, Thomas Buzzi wrote: ...
Two things Jerry warned about,especially if that extra weight is placed high in the boat. Some times it is best to paint in the features you want to look at while at anchor and forgo the real wood appeal. I also went from a Series 24 to a series 27 battery, another mistake. This size boat with its limited displacement will not tolerate a whole lot of extra weight.
I have been doing the math on the battery issue as I may finally get a house battery for the coming season. Or not...reasoning as follows...
One take is, I have very minimal power requirements and use all portable electronics (VHF, GPS, headlamp, LED cabin & anchor lights) with plenty of spare batteries. So - no house battery needed. My LED bulb retrofit nav lights, if I am even moving at night, can run for many hours off a small rechargeable 12V battery pack.
The other take is, for price/performance, lithium batteries are pretty much a clear winner. Yes, the up front price for a "small" battery seems high, the "sticker shock" effect. But if you know much about batteries you can get by the sticker shock. For example:
1. they will last much longer than lead-acid of any type/price, with essentially zero maintenance. Lead-acid need at least trickle-charging off-season even if they are the sealed variety, and a desulfator if you want full battery life.
2. the high cost per amp-hour (AH) of lithium is more than offset by the fact that you get 100% depth of discharge (DoD) for the full life of the battery. Lead-acid batteries tolerate a much lower DoD, and the higher the consistently used DoD, the shorter their life.
So a much smaller lithium battery AH rating gets you the same usable AH as a far heavier, higher maintenance, shorter lived lead-acid.
For example I could get a 20AH lithium ($275-$300) like this: https://nexgenbattery.com/shop/batteries/12v-20ah/ ...and repeatedly use all 20AH, for thousands of cycles. Small and light and zero maintenance.
Or I could get a typical series 24 "marine/RV dual-purpose" 65AH lead-acid like this or equivalent: https://www.westmarine.com/buy/west-marine--dual-purpose-flo oded-marine-battery-675-mca-group-24--15020183 I pay ~45% less up front. I do get a lot more weight and bulk for my money, it's true... :-) But with this kind of battery I need to keep my depth of discharge down to 20-30% or I start to shorten battery life significantly. That means I only have a max of 20AH usable anyhow...same as the lithium above, which is far smaller and lighter and longer-lived and near zero maintenance.
So if I get a house battery, I'll probably get a lithium in the 20AH range.
cheers, John S.
Fair winds,
Tom B
On Thu, Dec 28, 2017 at 2:27 PM, brad kurlancheek <bkurlancheek@gmail.com
wrote:
Wow - that is just an incredible job you did on the cabin. Inspiring!
Re: http://msogphotosite.com/Scripts/StoryTechnical/ storytechnicaldetail.php?id=108
Here fwiw is my little effort at it, for installing wood panels onto the cabin sides - M15, on page 8. http://nockamixonsailclub.org/sites/default/files/ TheCompassDecember2017.pdf
-- John Schinnerer - M.A., Whole Systems Design
- Eco-Living - Whole Systems Design Services People - Place - Learning - Integration john@eco-living.net - 510.982.1334 http://eco-living.net http://sociocracyconsulting.com