Hey John-
Some observations and comments regarding your table "Battery Comparison".
First, "Load Corrected AH" --- Just looking at the 210FT Blue batteries, you show 196 and 190ah "Load Corrected AH". The specs I found online for the battery shows 185ah (20hr rate, or 9.25amps). Thus, the two values you show (196 and 190) should each really be much smaller than 185ah since the currents are each 21 and 28amps, respective. A better number might be 150ah.
Second, the table's column "Cycle Life" shows 2000 cycles to 50%DOD for these batteries. Online info I've seen shows "500+" cycles to 50%DOD. That's a Yuge difference.
Third, more columns could be added for the THINK/Enerdel, TESLA, Volt, Leaf surplus battery options, e.g.:
THINK/Enerdel 70ah 42v(nom) 24.5amp 2500 cycles to 80%, 80%Cap left 2400wh(usable) 30kg 80wh/kg TBDvol TBDrange $500 cost
Finally, the battery comparison should use the Cycle Life, Usable Energy and Cost info to give a Cycle Life Cost. Also, WH/m^3 and Cost/N-m columns might be useful.
-Myles
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of 66b6dcd5b59507e7d751ea81382ea1f6
Sent: Tuesday, June 27, 2017 3:14 AMHiTo: electricboats@yahoogroups.com
Subject: RE: [Electric Boats] Battery specific energy and power in relation to volume and density [1 Attachment]
[Attachment(s) from 66b6dcd5b59507e7d751ea81382ea1f6 included below]
Hi Myles,
Indeed, this was the point of my post and in my asking Hannu's knowledge of 'non boat' batteries. I agree re heat as we deal at such low loads compared to cars. Taking your reply a bit further, I just put this attached spreadsheet together for a boat that cruises at 4 knots using 1,000 Watts of battery power in calm conditions, for 4 different battery scenarios, all with similar ranges and battery cycle and calendar lives. Wh/Kg and volume are for the packs.
For simplicity I've kept the sheet as a direct drive so all scenarios work. The results will surprise some I suspect, especially when you look at range vs price, not to mention weight and volume. Mine is actually the 3rd (albeit the non Bluetooth Smart version) scenario. But being LiFePO4 they are the safest lithium chemistry I think for boats, plus they can do high C rates and have superior cycle life. The 4th wasn't around when I converted my boat.
The results are one of the reasons (for a small sailing yacht) I advocate as few batteries as possible and a small Honda 900W or 1600W continuous rated generator as a back up. It's the least expensive way and as a sail auxiliary the range is sufficient I'd say under battery power - we're meant to be sailing after all. This setup gives me 2 or 3 nights away on the boat, sailing when possible and subject to the wind there is generally no need to start the generator. I have a separate AGM house bank (2 x 12V 130Ah) with an inverter for a small kettle, grill, toaster etc.
I do my best to explain that in the link below where you can also see just how restricted for room I am, especially as I can only just reach out over the batteries to get to the PSS shaft seal if there was ever a problem.
https://www.victronenergy.com/blog/2016/08/29/multiplus-magic-small-generator-big-power/
John R.
Posted by: "Myles Twete" <matwete@comcast.net>
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