How are people charging Li/LA hybrid setups?

[CaptainRivet]

Originally Posted by Pete7

"I’ve been (over)thinking" perfect example above.

How about one of these for a simple alternative system.

If you want to sail off grid, you have a choice of reliability and a "keep it simple" approach, or fixing complex systems in remote places when it all goes pear shaped. Which will you choose

fully agree on that.
and hanging on to a dangerous, unrelaible stone age technology which also makes everything overly complex and marrying 2 technologies that does fit together and creating even more hassle by doing so. and still talking and discussing about VSR which is simply forbidden to use with LFP due to many senseful reasons just shows you have no idea how LFP really works in reality...i don't know any sailor who had lithium and wanna go back to lead...

and if then use an X2-BMS which is the only real well engeneered BMS and simple approach to use both in parallel...they eg have it on RAN2 Najad and he is a wise, technological educated sailor with vast experience.

And all the theories of the are arm chair LFP users...the ones they have it on their boat longerterm and properly installed are just shaking their heads about all what is posted in this thread and be very happy they got rid of lead.

and with cell prices of 90Euro for grade a EVE304AH i have to even agree with Fuss it even makes sense now to use them as pure starter battery (and great backup for house)
4 of them, active balancer, a 130Euro BMV 712 + cut off relay and 20 Euro cell voltage measure and 100Euro for a case you have for 600Euro 304AH and real 1000CCA that starts every <100hp engine for the next 15 years. cheaper then even FLA batteries and 1000% saver, more reliable and robust.
no complex floating and 5 phases charging BS, gasing and maintenance.


the only config where any lead makes sense is
a) daysailors or costal cruiser with small boats.
b) older, not much power hungry boats with a small engine and dumb 50 to 90A automotive alternator where you simply keep the lead and use a 15-30A Dc2DC charger as cheap and simple install method so you get some charge from the alternator and its not going up in smoke. upgrading alternator makes no economical sense here. but scaling that up to have 4x30AH DC2DC like i saw lately make 0,0 sense and the 4 DC2DC costed more then a proper regulated heavy duty alternator...
c) or a lead starter also as surge dump protection with an argofet spilting diode as a simple install if your alternator has an internal temp regulation and puts out serious current like the Mitusbshi 115A or Valeo 125A one for 400Euro new as you cannot cut their charge because no access to field wire and when you modify you loose internal temp regulation and protection. charging of lead is solved by argofet and regulator of alternator.

[Ryban]

I stumbled across rotary switches designed for AC source/output selection:
https://www.bluesea.com/products/cat...otary_Switches

But I wonder if there's a version of these that would be suitable for DC work at the current required (30 amps+). If so, then I could get away with using only 1 DC-to-DC charger. This simplifies things both in terms of cost and placement (especially if I want to do two DC-DC chargers in parallel for 60A), and slightly increases complexity in wiring the selector switch.

[Pete7]

Not sure I fully understand the query. Our LFP can absorb all the 700w solar, shore power and alternator power we can generate even consecutively.

Put it all on a bus bar and the let the MPPTs and Orion sort it out, which they will.

Pete

[Ryban]

Originally Posted by Pete7

Not sure I fully understand the query. Our LFP can absorb all the 700w solar, shore power and alternator power we can generate even consecutively.

Put it all on a bus bar and the let the MPPTs and Orion sort it out, which they will.

Pete

I think the main issue was to keep the LA and LFP banks separated but still allow cross-charging as needed, and avoid having the LFP directly connected to the alternator since I am not installing any smarts to safely disable the alternator in the event the BMSes shut-off.

The way it's drawn above:

1. Solar normally charges LFP bank
2. Alternator normally charges start LA battery.
3. Orion DC-DC can be selected to allow alternator to charge LFP bank as well (up to the 30A if using a single, or 60A if I use 2 in parallel).
4. The Orion DC-DC charger can be selected to charge the start battery from solar (less likely we'll use it this way, given the start battery should always be fully charged ). However, our start battery currently is high capacity -- 230AH -- so we can also use it as back-up to the house.

[Pete7]

Ok, that's clearer thanks.

We have a switch between the engine start battery and the Orion, actually its a blue seas circuit breaker that will function as a switch. So only connect it occasionally when we want to boost the charging whilst the engine is running. We turn it off before shutting down the engine to avoid taking 27A in the real world when its hot.

Equally like your diagram we have battery switches that can be used to isolate the LFP.

That leaves us the option in the event of a complete meltdown of isolating the LFP and using the Orion in power supply mode rather than charge mode to supply domestics.

So 3 way switch not needed, you can do it simpler with just a switch and the bluetooth options on the Orion.

Pete

[Pete7]

Inverter should be on the DC distribution bus rather than the charge bus, though appreciate they are linked. Use Victron Power In with 4 extra bolts to create fuse boxes with HD bus bars.