Mainship 400 going with Lithium I think?

[jefndeb]

Hello all,

I am planning to replace our 2 House 8D AGM 200ah batteries with 2 new Epoch DP12300H 300ah Lithium Dual Purpose batteries. Partially because our DC bow and stern thrusters are supplied from the house bank, (via the factory) which is really odd and I know it is killing these deep cycle batteries when blast them with a 525 amp draw multiple times on a windy day of trying to dock. Could you guys do me a favor and offer suggestions as to "where in the diagram" I would make the changes when I replace these 2 house AGM batteries to Lithium?...

I hand traced the wiring in the boat one weekend in order to develop a better understanding of the DC system and I created this Visio diagram for reference.

When I say changes, I say this because I plan to keep the one AGM 8D engine starting battery so think I have to modify the charging system somehow so the AGM battery is "isolated" so it is is charged with the correct AGM charging voltage and not the new Lithium charging voltage setting. Am I saying that right?

I know I can reconfigure the Alternators Balmar AH-5 External Regulator for Lithium and the Victron MultiPlus as well but understand that the AGM 8D shouldnt be charged with these new values..

I guess I am asking this...how does one reconfigure this system (add devices? DC to DC charger?) in order to charge both the new Lithium house bank and the AGM starting battery from the alternator with the correct charging profile...

your suggestions are appreciated...

 

[Clark]

I'm not seeing many replies to your post. It seems like there are a number of problems and questions with the schematic diagram. First, to get it out of the way, the fusing to protect wires seems to be missing is some cases. For example, the path from the house to the breaker panel has no fusing. Similarly, there's no fusing on the top bow thrusted to the first battery and on the bottom start battery to the alternator.

Second side point, I don't know if there is a normal position for the switches. Are the house batteries normally switched paralleled? Is the bow thruster switch normally open or normally closed, effectively paralleling the thruster battery with the house bank. Where does the negative from the bow thruster battery go, to the house battery negative so the shunt reads correctly when the switch is closed or to the negative bus so that the shunt read correctly when the switch is open. Granted, thruster doesn't use many AH, but it should be wired correctly depending on whether the thruster battery is part of the house or not part of the house.

Third, you have 4 charging sources here. Two battery chargers, a solar charger and finally the alternator. It is important to figure out what sources charge what batteries. Is the solar charger able to be set to charger the LiFePO4 batteries? If it is set for Li battereis then they will not be set for lead acid. ACRs from the Li to the lead batteries may not be good with the different charging profiles so maybe DC-DC 3 stage chargers, as from Victron and others, are needed. But then, they can also charge when inverter/chargers or solar chargers are running. Also, are all of the ampacities of these wires suitable for Li and do all the fuses have the sufficient AIC for a Li bank.

I seems to me that you would want to look at a redesign of the whole system based on what you want to accomplish. It is likely not going to be a simple cut and connect a wire here or there. What sources do you want to charge each battery? I recommend a GOOD marine electrician to design a system for you. Ignoring fusing, wire ampacity or the AIC rating can cause a fire, especially with Li.

A last small point, the stern thruster will cause a voltage drop when it is operated and it may cause sensitive electronics to drop out because of the transient, but it may not be damaging your house battery. I have 3 8D house batteries with a 650 amp steady state stern thruster and I have no concerns about battery damage. I would look at the battery CCA or MCA specifications and the thruster specifications to determine if they are out of align.

Clark

 

[SteveK]

This is just my opinion. Assumption single engine, one ALT.
1) I would not go dual purpose batteries, also with LFP I would not go 2 banks. Reason, with LFP house you can discharge to near zero when needed. The old system of two banks gave you a second chance if over discharged. If you have enough for needs, no worries.
2) keep the AGM start. I would add thrusters to it directly or switched and away from the house. I see you have a bow thruster bat, will that stay due to distance and line loss? Again with a switch in place I would move to the start battery as backup.
3) I would charge the new house bank from all sources directly and then charge the start battery from the house via DC2DC.
4) Not sure why you need an isolator for batteries OR how the ALT & Balmar regulator is wired to the battery. It should go direct to the house bank.

 

[DavidM]

David

 

[Avalon36]

Hello all,

I am planning to replace our 2 House 8D AGM 200ah batteries with 2 new Epoch DP12300H 300ah Lithium Dual Purpose batteries. Partially because our DC bow and stern thrusters are supplied from the house bank, (via the factory) which is really odd and I know it is killing these deep cycle batteries when blast them with a 525 amp draw multiple times on a windy day of trying to dock. Could you guys do me a favor and offer suggestions as to "where in the diagram" I would make the changes when I replace these 2 house AGM batteries to Lithium?...

I hand traced the wiring in the boat one weekend in order to develop a better understanding of the DC system and I created this Visio diagram for reference.

When I say changes, I say this because I plan to keep the one AGM 8D engine starting battery so think I have to modify the charging system somehow so the AGM battery is "isolated" so it is is charged with the correct AGM charging voltage and not the new Lithium charging voltage setting. Am I saying that right?

I know I can reconfigure the Alternators Balmar AH-5 External Regulator for Lithium and the Victron MultiPlus as well but understand that the AGM 8D shouldnt be charged with these new values..

I guess I am asking this...how does one reconfigure this system (add devices? DC to DC charger?) in order to charge both the new Lithium house bank and the AGM starting battery from the alternator with the correct charging profile...

your suggestions are appreciated...

I replaced my AGM house bank with a 400Ah LiFePO4 Battery. Start batteries and thruster battery remain AGMs. They are charged via 2 Victron DC 2 DC chargers off the Lifepo4 house bank. The thruster battery is located right next to the thruster to minimize voltage drop. From what I have read, I have serious questions about "dual purpose" Lifpo4 batteries as Lithium batteries don't generally respond well to momentary shock loads. With everything you've got going on, I would encourage you to consult a marine electrician with experience installing combined lithium/lifpo4/AGM battery solutions.

 

[Capt Ray]

I also use a DC-DC charger to charge my LA / AGM starter/bow thruster battery bank from the solar/LiFePO4 bank as needed. It is a charger that I can turn off and on. (All VictronEnergy components.)

Typically:
On shore power or underway (w/ stock CAT alternator) DC-DC charger is OFF. (Alt charges the AGM starter bank.)
On anchor, typically, the DC-DC charger is turned on.

This boat was wired with a bunch of house loads on the LA/AGM bank (cabin lights, running lights, anchor light, head, fresh water pump, etc.) It is too much work to move all that to the LiFePO4 bank so, whenever we secure at anchor, I simply turn on the DC-DC charger so the Lithium keeps the AGM bank "up" to charge for the night or extended stays on the hook Obviously, the DC-DC charger is configured for the correct charge profile for the target's battery chemistry.

The only times we need the generator is for A/C or Heat, or extended days on the hook with little to no sun.

The DC-DC charger is the ONLY connection between the two DC systems on this boat.

Two fridges, and the 3000VA inverter are on the LiFePO4 bank, and a redundant bilge pump and alarm for the aft bilge.

 

[SteveK]

@Capt Ray with your setup, why bother turning the DC2DC off?
no right/wrong just curious

 

[tiltrider1]

I do not know what to say to people who want to start engines or run thrusters off of LFP batteries.

There just isn’t any real knowledge base out there to draw from. It might work great, it might not.

I would say the best program would be to spread the load over multiple BMS’s. 4 200amp BMS’s could easily meet 600 amps.

Unfortunately, my thruster recommends 1000 CCA and my CAT engines also recommend 1000 CCA. For this reason I have a start bank and a thruster bank, neither are LFP.

 

[Avalon36]

I also use a DC-DC charger to charge my LA / AGM starter/bow thruster battery bank from the solar/LiFePO4 bank as needed. It is a charger that I can turn off and on. (All VictronEnergy components.)

Typically:
On shore power or underway (w/ stock CAT alternator) DC-DC charger is OFF. (Alt charges the AGM starter bank.)
On anchor, typically, the DC-DC charger is turned on.

This boat was wired with a bunch of house loads on the LA/AGM bank (cabin lights, running lights, anchor light, head, fresh water pump, etc.) It is too much work to move all that to the LiFePO4 bank so, whenever we secure at anchor, I simply turn on the DC-DC charger so the Lithium keeps the AGM bank "up" to charge for the night or extended stays on the hook Obviously, the DC-DC charger is configured for the correct charge profile for the target's battery chemistry.

The only times we need the generator is for A/C or Heat, or extended days on the hook with little to no sun.

The DC-DC charger is the ONLY connection between the two DC systems on this boat.

Two fridges, and the 3000VA inverter are on the LiFePO4 bank, and a redundant bilge pump and alarm for the aft bilge.

Why are you turning the DC to DC chargers on and off? What is charging the Lifpo4 when you are underway or on the hook? A stock 80 amp alternator puts out 20 amps continuous after 10 minutes which is typically enough to bring the AGMs back up

I do not know what to say to people who want to start engines or run thrusters off of LFP batteries.

There just isn’t any real knowledge base out there to draw from. It might work great, it might not.

I would say the best program would be to spread the load over multiple BMS’s. 4 200amp BMS’s could easily meet 600 amps.

Unfortunately, my thruster recommends 1000 CCA and my CAT engines also recommend 1000 CCA. For this reason I have a start bank and a thruster bank, neither are LFP.

Which is why Start and Thruster banks are separate and use AGM chemistry. They can handle the momentary high load requirements of those systems better. Lifepo4 (lithium chemistry) batteries do not handle repeated loads like that well. More BMSs will not improve the situation.

 

[Capt Ray]

Agree, from what I have been told by many LiFePO4 mfgrs: traditional lead acid batteries can tolerate the "abuse" of high amp / short duration hits like starters and bow thrusters... better than LiFePO4 can. While Dakota makes a dual purpose DL+ line of dual purpose Lithiums, most have said that that chemistry is fundamentally less tolerant. Best to stick with FLA or AGM for that. Let the Lithium house battery bank handle refrigeration, lights, head, bilge pumps, inverters, etc.

I have started, then stopped pursing the idea of putting the salon A/C on our Solar/Lithium bank for sunny days at anchor. The initial "hit" when the compressor comes on may be unhealthy. I need to research this some more, cuz some of our favorite Youtube channels have saiboats using Solar/Lithium A/C during the day when the sun is beating down on them. "Soft Start" A/C options etc.??? I simply don't know [yet].

As for the question of "Why turn off the DC-DC charger when underway?" That is a fair question. The DC-DC is smart enough to not over charge a bank that has adequate voltage levels when underway. I guess my answer is this: I like to see/monitor the solar/lithium bank behaving on its own during the day independent of the lead acid bank... and I like to see/monitor the lead acid bank behaving on its own independent of the solar/lithium. It is simply a monitoring / evaluating position to ensure everything works independently as it should. Certainly, it is a fair and good question!

 

[Dougcole]

I sincerely hope this does not create thread creep, because Jeff asks some good questions, but a couple of things.

Our Mainship 400 is twins with no thrusters, so the wiring set up is pretty different, less complex in some ways, more in others.

I know your motor is bigger but I still think an 8D starting battery is way overkill. I start both engines off of a single group 31, it works great. The 31 died this summer in the Bahamas (7 years old) and I had to replace it with what I could get, which was a group 24, 750 MCA start battery. Fired them both off just fine for the remaining six weeks we were there. I swapped it for another 31 when we got home.

There is a "DC Main" breaker on the main panel, in front of all of the DC loads other than bilge pumps, windlass and electronics. Also, most of the cabling on the 400 is quite oversized, I think it is 3/0 IIRC, it's one of the few things Mainship did right from a wiring perspective.

Our boat had the odd split 8Ds (1 each side) for both house and start loads when we bought it. the loads were divided between the banks in a very random way. I combined all of the house loads on a single bank (currently 6 6V FLA GC) and added a dedicated start battery as referenced above. The start and house banks are connected through an ACR. I like this set up a lot better.

I have 300 watts of solar on an MPT dedicated to the house bank.

My plan next year is to switch to lithium for the house bank and keep the FLA for starting. One motor with the original hitachi "dumb" alt isolated to the start and the other engine with an upgraded alt and regulator (probably Balmar) isolated to charge the house bank. My loose plan is no ACR or DC to DC charger.