On the hook, and some techie stuff…

Hi all, and  of course the two of you know…!

Matachen Bay was great, as always, we got to see friends at Playa Hermosa restaurant.  Alisia and Varo keep cuatomers happy!  Same place we always stop for great food and friendship!


We only spent a couple days in Matanchen this year, we will probably get back there! Before March.   Met new friends at anchor as always happens here, s/v Pandion.

We got to Puerto Vallarta area and anchored at La Cruz de Huanacaxtle around the end of January 2020.  After Matachen Bay near San Blas, we did an overnight passage and anchored out front of Marina Riveria Nayarit. A beautiful place, and there are around 50 boats here in the anchorage.  Maybe more than we have seen here since first arriving in Jan 2013.

Been doing little projects, made some covers for fuel cans the companion way. We have  nice access to the town via the dingy dock. I think that last year it was like 40 peso a day to use the dock and drop trash, etc.  This year it’s 80 pesos, still less than $4 USD so who can complain!!!

We settled in and Jim started a dental procedure for a crown after getting the temp filling the day before we left San Carlos a month ago.  A crown here  is $4700 pesos or around $250 USD.  No temporary, the dentist ground down the broken tooth and took impressions and in a week we went back for the crown.  Not fancy but seems to work out well.

La Cruz is a fabulous little town,;;

As always a picture is worth a thousand words!

Local iguana in the Huanacastle tree in the town square…

Great food, educational and fun events…

Synthetic rigging:

Boaty boat is doing well, had some weather since installing the dyneema stays and have to say that I would do it again if opportunity came up.  We tend to set and forget our standing rigging when we put in the Stainless wire rigging.  With the dyneems, since it is new we are checking it a lot more and it gives us a good feeling for rig integrity! Thi sstuff is stronger than steel and our adjustment period is probably coming to an end, two months.  Today we lubricated the turn buckles with some chain lube and will be checking on them regularly since when we removed the steel rig, one of the turn buckles seized up and was very very difficult to remove. A big yes vote for dyneema.


Techie stuff… We woke up to a dark boat…

Boaty Boat was all dark and scary on Saturday 2/1/2020 when we got up.  Not knowing what the H___? We turned off all power usages and sources and then turned the battery master over to the starter batteries and then fired up the DC panel again.  Starters were fine at 12.8 Volts, and now the house LiFePO4’s were at 11.8 volts from not supplying any voltage at all…


Decided to make coffee on the outdoor grill, since the propane solenoid uses one amp,  and then decide on a plan of action to address the situation…

Not knowing how or why.

The Victron battery monitor was reset to 100 percent and zero amp hours used. And when we got up, there was no power available from the attached house batteries, the 400 amp hour bank of LiFePO4’s?

We had our coffee, then emptied the lazarette to get access to the house batteries.  Checked the 4 batteries individually and each was showing 11.9 volts. (I just now realized in writing this that I did not disconnect them from the parallel connection harness to do this check, big oops). So the next couple days work may have been in done under questionable assumptions…

The next couple days, assuming:

  • the batteries are good,
  • the battery on board BMS (battery monitor system) in each battery) tripped at low voltage around 11.5 volts and
  • the LiFePO4 batteries disconnected via their BMS circuits and shut down until load was removed allowing the BMS to sss it’s reset – reconnect voltage?.


Our plan was to bring up the DC necessary uses on the boat using the starter  battery bank of two 100 amp hour lead acid batteries testing at full (12.8 volts) and start the motor.  If the system monitor panels were showing no excessive  explainable loads we would charge via the diesel alternator at around 70 amps.

Since it was a dark and cloudy morning and forecast was for more of the same for 3 or 4 days, we decided to go to dock at the marina and figure out what happened…

On dock, at Marina Riveria Nayarit,  we are thinking the boat battery monitor when not having seen battery full in a few weeks got lost on the amp hour in and out calculations. We were not paying due attention to the voltage readout readout and he 5 amp draw on the refrigerator took the system voltage to 11.5 where the BMS on the LiFePO4’s did their job and said “NEVER MORE”.


After running the motor in the anchorage for an hour+ and motoring into the marina we discharged the house bank completely:


After discharge we used the shore charger and charged up, shore charger was set on a very conservative profile and amps dropped from the 30 amp charger capacity initially obtained down to 10 amps over 17 hours :

chg 1

We then turned everything we have on board, ON, and discharged the house bank:


Almost looks like we are missing a battery?  Have to dive the lazarette again and disconnect the parallel harness and check each battery when disconnected from the harness…

Did that today and all 4 100Amp Hour batteries are reading exactly the same voltage as have always done…

So our original theory is holding and we just blew through  the bottom of the battery minimum voltage threshold on the BMS!!!

We are a bit concerned at the capacity number down to 290 from 310 Ah a couple of years ago…   So we ran a second capacity test before leaving dock and got 290 Amp Hours again.  A 6% loss from original testing 3 or 4 years ago.  Not great, but bet we would be replacing our lead acid batteries about now if we had gone that way.

Bottom line, we just did not watch the voltage the way we should have and the LiFePO4’s got run down to below 11.5 Volts so the on board battery monitor shut them off!

We left dock all charged up and the sun is out so we are doing well!

noun: lazaret
a small compartment below the deck in the after end of a vessel, used for stores.
FIN again
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4 Responses to On the hook, and some techie stuff…

  1. SailVivacia says:

    Good troubleshooting and explanation on the problem with the LiFePo’s. Nice to know your system (BMS) works the way you designed it to. I’m surprised at the capacity loss. Weren’t you expecting to be able to get a longer life overall from these batteries vs. FLA or AGM? Still an interesting proposition for us the next time around if only the prices would come down. When I checked just recently, it would cost us easily three times as much for the same capacity in AGM’s. Still… I would love that weight savings.
    Cheers, A&E

  2. svhajime says:

    Hi Alan, love your info… I still think the LiFePO4 batteries are going to out perform lead acid tech in the long run. Mine seem to be not so good quality as folks are seeing today. Looks like I started with 310 Amp Hr and now have 290 so 6% in 3 or 4 years is not soooo bad. Not having 400 when we started is BAD and I in MX could not figure out how to complain… My Lead Acid GC2’s 6volt golf cart batteries 400 Amp Hr nominal, probably only supplied 180 Amp Hours so we were happy then… I’ll email you a Stan Honey “notes” pdf on LiFePO4 install in their boat… And the fellow’s videos on our Jan 08 2020 post at the bottom has info to LiFePO4 which should bring the cost down in the $550 per 100 Amp Hr range. If you follow his links on the youtube pages…

  3. Martin says:

    I came across this page by chance. After studying these pages (http://nordkyndesign.com/category/marine-engineering/electrical/lithium-battery-systems/) about the LiFePO4 batteries I will stay with lead acid batteries due to the KiSS (keep it strictly simple) principle. I hope the link helps a little bit. Fair winds and best wishes from Switzerland.

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