Do we trust the E38's 40yr old AC and DC breakers?

[Kenneth K]

FWIW, I'm attaching the current, still in progress version of my wiring diagram

Why a shunt for the starter battery? Are you putting a monitor on that bank as well (most people don't).

Do you want the solar controller to always power both banks? The house bank has passive draws (monitors, smart switches, bluetooth, etc) that require the bank to be trickle charged regularly. The starter bank, when unused, has only a very small self-discharge rate, and only needs to be topped up every few months if unused. You could add a manual switch, or an ACR with an on-off switch, to allow you to periodically add the starter bank to solar. This ensures all the solar charge is dedicated to the house bank except when you choose otherwise.

 

[Vtonian]

Follow up, post more YT 'research', apparently there's no safe DIY way to verify a breaker will actually trip, and my only real evidence I can't trust the old ones is the melting wires that runs to and through the AC breaker and outlets. I was running a space heater in there yesterday and then fired up a little vacuum for a while, wondering if that might trip it, which it didn't, but I did feel the wire that jumps from the main to the outlet breaker and it was good and warm. I forgot to put an ammeter on it to see what it was drawing, I'll do that today, but reading up a little about breakers, I take it the old ones work on an electromagnet, that throws the breaker on a surge high enough to actuate the switch.

That seems pretty straight forward and in a pretty sealed device like a circuit breaker, even an old one, it seems entirely possible nothing is wrong, at least not with all of them. Since all my AC breakers are 20A and I don't use one of them at all, I'm thinking just swapping the suspect one out for a never used one would be an adequate temp fix, until my proverbial ship comes in and all new panel budgets are unloaded at my dock.

Anyone here actually found bad breakers they can attribute to old age in a marine environment? All new will eventually be very comforting but on some kind of anecdotal scale, what's the likelihood that these are any more unsafe than they were new?

I don't want to TMI myself but this all started because I just wanted to get the furnace working so I could dive on the boat and warm up after. Can't start the furnace? Rip all the wires out, of course! Some people will do anything to avoid getting in cold water... Well, that and finding all the batteries were dead.

 

[Vtonian]

Why a shunt for the starter battery? Are you putting a monitor on that bank as well (most people don't).

Do you want the solar controller to always power both banks? The house bank has passive draws (monitors, smart switches, bluetooth, etc) that require the bank to be trickle charged regularly. The starter bank, when unused, has only a very small self-discharge rate, and only needs to be topped up every few months if unused. You could add a manual switch, or an ACR with an on-off switch, to allow you to periodically add the starter bank to solar. This ensures all the solar charge is dedicated to the house bank except when you choose otherwise.

Thanks, Kenneth K. I'm learning by wire: monkey see, monkey do. I saw multiple shunts somewhere, maybe a fancy Victron schematic, and assumed it must be a best practice, or maybe just a good way to compensate for my insecurities about delving into the LFP + AGM mixer. My BP is fighting with my KISS, much like my last two brain cells.

Re: the solar controller, my 'understanding' so far is that the principle to KISS the risk to the alternator and electronics from the LFP's BMS shutting itself down mid-charge is to always be charging the trustworthy AGM, and let the DC/DC charger handle delivering to the sketchy LFP as needed. Otherwise, it looks like most people end up buying stock in Victron.

Does that sound correct?

 

[Nick J]

Re: the solar controller, my 'understanding' so far is that the principle to KISS the risk to the alternator and electronics from the LFP's BMS shutting itself down mid-charge is to always be charging the trustworthy AGM, and let the DC/DC charger handle delivering to the sketchy LFP as needed. Otherwise, it looks like most people end up buying stock in Victron.

Does that sound correct?

Yes, this is one of the simplest ways to protect against the BMS disconnecting the battery and causing a damaging voltage spike. LiFePo4's aren't really sketchy, they just have electronics in them that can disconnect the battery and that needs to be accounted for. There's plenty of other ways to address the BMS disconnecting, but they all require sending a signal to an alternator regulator so the field current can be switched off before the batteries go off line.

I've used the same method you're proposing and it's worked well. You can even see the effects of the BMS turning off on the Renogy app and hear the engine load increase and decrease as the BMS does its thing. With the AGM acting as a spring, the system functions without damage.

One of the downsides, is the limitations in charging capacity due to the DC to DC charger. I don't know of too many DC to DC chargers capable of more than 50 amps. You can stack them, but that adds up in complexity and cost to the point that it may be better to get a good alternator regulator and a BMS that can communicate with it. Getting a better BMS and alternator is on my list, but it's a lower priority item with the current system functioning adequately.

 

[Vtonian]

Thank you, Nick, appreciate the benefit of your expertise.

My thought on the charging capacity is, for my sailing habits (pretty manual), which don't require much house power very often but occasionally for some duration (welcome aboard, family, and all your devices!), mostly the solar should do duty as a trickle charger, with the LFP providing the buffer for the little bit of auto pilot and power winching I might do. On a longer journey, I'm not ashamed to keep a little Honda generator on board to cover a critical need and empty batteries.

The thing that tipped the scales for me to go for LFP now was how cheap it's gotten. If I abuse the battery and mess it up, and only get 5yrs out of it, kinda so what, as long as the rest of the old electrical systems haven't blown up and/or burnt me down.

It's Friday afternoon, to the boat!

 

[southofvictor]

Just catching up on this thread but haven’t seen mention of using an ELCI breaker for the shore power input. Not sure if it’s ABYC standard yet but it’s Euro standard. If you’re adding a smartplug they make an ELCI or you can get one from Blue Sea. On our E38 the panel is a bit too far from the shore power input to be in spec but a surveyor told me it’s close enough to be functional.
BTW our shore power input cabling is 10AWG not 12. It steps down to 12AWG for distribution. Blue Seas has a useful webapp for ampacity and OCP calculations at http://circuitwizard.bluesea.com/#
and here’s a simple wire sizing app that runs without internet connectivity. https://apps.apple.com/us/app/dc-wire-sizer/id629190351t

 

[Vtonian]

Just catching up on this thread but haven’t seen mention of using an ELCI breaker for the shore power input. Not sure if it’s ABYC standard yet but it’s Euro standard. If you’re adding a smartplug they make an ELCI or you can get one from Blue Sea. On our E38 the panel is a bit too far from the shore power input to be in spec but a surveyor told me it’s close enough to be functional.
BTW our shore power input cabling is 10AWG not 12. It steps down to 12AWG for distribution. Blue Seas has a useful webapp for ampacity and OCP calculations at http://circuitwizard.bluesea.com/#
and here’s a simple wire sizing app that runs without internet connectivity. https://apps.apple.com/us/app/dc-wire-sizer/id629190351t

Thanks, SOV. My club isn't requiring an ELCI ATM but has checked the boat for issues so for now, I'm squeaking by. I already have a SmartPlug, and have replaced that idiotic 12ga wire with a 10ga, along with replacing the single pole 30A breaker with a DP. I also have GFCI receptacles, but do have an ELCI in the queue for the next budget.

In case someone stumbles on this in the future and wants to know exactly why an ELCI is important, there's a nifty little article at B/S that splains what they do and how they work (with pictures and everything!) and that helped me move this onto a budget instead of relegating it to a 'someday' list.

https://www.bluesea.com/resources/1381/AC_Ground_Faults_the_Boater_and_ABYC-Understanding_Equipment_Leakage_Circuit_Interrupters_%5BELCIs%5D_and_Ground_Fault_Circuit_Interrupters_%5BGFCIs%5D_to_make_your_boat_safer.