Battery charger redesign

[AlexLbk]

The alternator is not charging 6 batteries - just 3. The engine start, thruster batteries do not need charging as they only use a few amps at a time and they get priority so are charged within minutes of startup. The alternator is correctly sized as is the original mains charger. Your "problem" is your high consumption, so extra capacity is the answer if you want to consume at your current rate. space considerations do lead to lithium, but a bank that size (300Ah+ compared with your current usable 150) is a big investment in both batteries and systems to use them properly.

The current usable is 140*3/2=210, lithium should give me around 600 with 4 206Ah batteries. Correct?

 

[Portofino]

I have 3 140Aah batteries. They were tested both using the carbon pile tester and by discharging at C20 rate. They definitely do not have full capacity anymore, but based on tests they hold 85-90% of the original capacity. They will die eventually and at that point I will throw LoPO4 in and bump the capacity to around a 800AH. That will get my overengineered solution to add more value. For now my goal is to keep the batteries topped off while at sea.

It’s just the house batts that get stick .
Post # 1 said 2x140 Ah .

The others unless erroneously connected permanently are just a side show .The engine batt will charge up via a split diode first from the alternator when running , they only ever drop a few amps anyhow .Same for your thruster batts .

Its those house batts that need beefing up sos they don’ t drop / discharge too deep too often .

Are you absolutely sure it’s safe to run the engine and AC charger via the geny simultaneously?

 

[AlexLbk]

It’s just the house batts that get stick .
Post # 1 said 2x140 Ah .

The others unless erroneously connected permanently are just a side show .The engine batt will charge up via a split diode first from the alternator when running , they only ever drop a few amps anyhow .Same for your thruster batts .

Its those house batts that need beefing up sos they don’ t drop / discharge too deep too often .

Are you absolutely sure it’s safe to run the engine and AC charger vis the geny simultaneously?

I am hoping not to do that that anymore, but I made it from Florida to New Jersey this way, that's 1500 miles and around 3 weeks of running all day everyday. I'm not 100%, but it worked fine.

 

[Tranona]

The current usable is 140*3/2=210, lithium should give me around 600 with 4 206Ah batteries. Correct?

Yes, sorry I misread your original and missed your house bank is 3*140. Still well within your engine alternator if you keep them above 50%, but 40A mains is under - should have been 60A, although you have solved that with the 150A.

 

[vas]

The current usable is 140*3/2=210, lithium should give me around 600 with 4 206Ah batteries. Correct?

correct.

 

[AlexLbk]

Well, I tested the setup today, ran for a couple of hours, house battery stayed at 97% SOC. Killed the engine and hung out in the bay for a couple of hours with everything running. SOC went down to 90%, on the way back the battery went back up to 96%. Shunt amps drifted from +25A in the very beginning down to -3A.
The thruster and engine batteries were float charging during the whole time.
Thanks for everyone's feedback.

 

[vas]

losing 10% of SoC in 2h is A LOT though

 

[AlexLbk]

Spent 8 days out last week. House batteries stayed charged at 98% even after running kettle and coffee machine along with now 4 refrigerators and an additional freezer I just added, nav, TV, music system (I had kids on board). Thruster batteries connected to the victron dc-do charger didn’t fair that well especially in the NYS canal locks where I had to run thrusters a lot to keep away from the disgusting wall. Victron didn’t switch to absorbtion at all, even when the batteries were down to 30%. I’m suspecting that charge separator somehow interferes with Victron charger ability to detect thruster batteries SOC. The easiest way to test that assumption is to add two more DC-DC chargers and remove the charge separator. That is a pretty expensive option however. Anyone has any thoughts on this?