13 volts and a nice big crane

Ravenswing is up and running on lithium batteries. We came back the next morning and found all four “parallel 4 packs” had balanced out to 3.28volts. Anton caught my tired typo the whole the other night; the parallel wiring of four cells of course kept the voltage in each new 400 amp hour battery at the 3.5volt level. All 16 cells had been hand-leveled at 3.28volts about four months ago, so I was happy they had not changed at all while waiting for this week. So we then proceeded with wiring them in series, to get up to a 400amp hour, 12v battery.

13.18v is pretty low, so we hooked up an old car battery charger rated at 10amps, which struggled to get the pack up to 13.31v after a couple hours. We’re ok leaving it there until the charging sources are hooked up.

There are three serial ‘jumpers’ between the four 3.5v groups. Note the one in the middle goes through a 150amp fuse; this is the first line of defense safety for a bad short circuit situation.

The previously installed 12v distribution panel matches the digital meter, and is a good at-a-glance basic tool.

But JoeS, a Bay Area Multihull veteran ocean cruiser, wants more details! Here goes, Joe…

I’m thinking of a max charge limit of 14volts (Joe does 13.8).

Lower limit discharge voltage is still up for debate. I need to read up on my CALB cells again, and ask the supplier EV.tv for their reco.

We’re installing a CellMon to monitor the voltage of each 3.5v 4-cell grouping. I’m judging that our usage and our charge pattern will be non-stressful duty for this bank, and thus it’s not necessary to monitor all 16 cells individually. I haven’t decided about installing any battery temperature sensors.

The CellMon will signal out to a loudspeaker alarm when a high or low limit has hit. I believe a second signal can be created at another voltage value, which we can send to the battery protection cutoff to shut down the power immediately. That device is planned to be the Victron BP-100. It is Bluetooth enabled and gets programmed from a phone / iPad app.

Primary battery monitoring is a Victron BMV712. This is also Bluetooth driven by an app. We mounted it at the nav / comms desk but it isn’t wired to the battery yet. Pretty sure it handles battery temp, if so we’ll get that sensor.

All three charging sources will be brought in to a common bus setup, then routed to a smaller Victron battery protector – BP65. This will be set with a lower limit than the BP100’s master cutoff, so all charging sources will be cut off from the battery before the battery gets “too full”.

The one decision not made yet is how to control the four 100watt solar panels. I’m leaning towards four separate circuits, each using a Genasun 140 Lithium profile MPPT controller. This will be the best at dealing with shade management (because the panels are in four different places around the boat). The alternative is bringing all four solar panels into a Victron MPPT controller (150/30 model I think). I like the idea of all-Victron because their stuff works well together. But does anyone know if the single controller can do differing shade per panel management well? Arlene and Glen, have you dealt with this?

Joe, the BMV712 is lithium-programmable. You tell it your ‘tank is full’ setting (e.g. 13.8v) and it does all the math from there, providing % of capacity left, and all kinds of other info. I’m excited to have it on the boat’s iPad.

All of this battery management stuff won’t happen until after the mast build journey, so we’ll stop talking batteries for now.

Early today we motored from Richmond to San Rafael Yacht Harbor. It’s not talked about much, but perfect for us with a big crane and it’s a DIY-only yard. You can’t hire them to work on your boat, but there are contractors swarming the place. And some funky toothless guys. (And gals). The yard crew is very competent with 30-45′ boats.

They swung the boat just a few feet above some late model cars – yikes!

Farrier’s design does look pretty swanky once you can get a few steps back. I love this angle…

Labor Day Yard day 1 was all about the dagger trunk. It was much more involved than I planned, as I realized hull-builder Howard had wrapped the Kevlar keel-line protection up into the trunk about three inches, and that buildup at the very bottom of the trunk was really screwing up the dagger fit. It was arm and back burning work to reach up past the foil block and rasp & shurform & grind as needed. I also had to rip out all the shims I installed during last November’s haul out. Argh for me, and at one point I wanted to punch Howard in the face. But by 7pm tonight the board goes up and down, fits snugly and the exit slot is re-epoxied. Keen followers will remember a few months back I sliced off 1.5″ from the aft edge of the board. Next time we’ll talk about the crash bumper that’s replacing that cutout. Stay tuned.

7 thoughts on “13 volts and a nice big crane

  1. Hi Greg…I can remember well the day out on the bay with you and Jim…a day I will relish .
    Jim spent a few days here in WV. and naturally talk about Ravens Wing was one of the topic’s…LOL


  2. Wow, thank you for further elaborating your setup. I’m very impressed!

    Lithium voltage levels are far simpler to control than the variable lead-acid profiles, but with a few caveats dealing with cell-level overvoltage and undervoltage protection, and life-extending storage levels.

    I had separate “controlled” battery inputs operating at various levels coming from two different solar controllers, outboard motor regulators, windgen, and a couple of different ac-input chargers which crudely worked feeding my unorthodox mixture of successfully paralleled FLAs and AGMs for the seven years of cruising. Not something I would do so cavalierly with Lithiums.

    For Lithiums on my present trimaran with 48v used for powering the Torqeedo or my home-based solar trailer, I haven’t yet progressed far enough to feed these disparate sources through a single regulated controller for each 12v and 48v battery bank – which is why I’m reading what you’re doing with great interest, but don’t have much to contribute.

    Adding complexity, in the back of my mind has always been Lithium control for two different states:
    1. “Float” (or perhaps lightweight “liveaboard”) mode where plenty of power is available and where keeping the pack at around the long-life storage 40% SoC is sufficient, vs.
    2. “Passagemaking” where (especially) overnight power demands require full battery bank capacity utilization.
    I haven’t pursued this to see if this concept has been implemented in the Victron or any of the commercial controllers.

    I like your idea of a separate MPPT controller for each solar panel, since onboard panel shading is an ever-present and ever-changing condition, for which simple diode panel isolation is inadequate. I couldn’t readily find the Genasun “Lithium” output voltage specs so can’t comment. Wow, Victron has sure expanded their product line since I last looked! It doesn’t appear that their controllers handle more than one solar input.

    Enough – hope your mast turns out as well as expected, and perhaps at some point in the future we can get together in person on your boat to discuss this further, as I’d sure like to see the wonderful product of your hard efforts.


  3. Hi Gregg ,Thank you for the up dates from your most 2 recent blogs You are getting charged up on the batteries ,great now the mast eh Hope all goes well for that . I think Jim is waiting too ,all the best . I will forward this to my bro Tom for his viewing
    Thanks Bill in Victoria B.C


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