Changing house bank from AGM to Lithium on an older Outremer 55

[Baronkrak]

Originally Posted by fxykty

The 12V+ power to the first positive relay bus is fused at its origin (3A). That bus splits the power to the four relay NO ports of the Quattro and solar controllers, then through their common ports to the positive fan bus. The three fans are connected to the positive fan bus. The fan negatives are connected to 12V-. I’m using 14AWG wires and every individual component can take 3A or more. AFAIK that means no other fuses are needed.

Attachment 282307

The green, yellow, blue, red and black sensing wires that terminate to the box labelled TAO.

[fxykty]

Originally Posted by Baronkrak

The green, yellow, blue, red and black sensing wires that terminate to the box labelled TAO.

Do you mean that in addition to the fuses in the box that the sensing wires should have fuses close to their terminals? If so, why?

[aqfishing]

I do not understand when someone says they use 200 to 300 Ah per day. To me this is meaningless unless you know the volts? Or am I missing something? Help!!!!
Is it not more important to know how many watts you consume in a day (or any other period).
So you have 100Ah 12v battery will give you 1200Wh. So you can draw 100A for 1 hour at 12v….?
But if you have a 100Ah 24v battery you should be able to draw 100Ah at 12v for 2 hours???
(DoD and system inefficiencies aside)
So in my mind Ah is meaningless without knowing volts.

Or am I missing something? Still new to all this and trying to make sure I am understanding correctly.

[sailingharry]

Originally Posted by aqfishing

I do not understand when someone says they use 200 to 300 Ah per day. To me this is meaningless unless you know the volts? Or am I missing something? Help!!!!

I'm not sure if you were saying this tongue in cheek or not. Assuming you are truly confused.
Approximately 98% of sailboats on the water today are 12 volt systems. Maybe 99%, but will say 98%. Unless stated otherwise, it is safe to assume that the poster has a 12 volt system.
Up until very very recently, very few boats had Watt hour meters. I would venture to say that fewer than 10% of the boats on the water today have Watt hour meters or Watt meters. Many have ammeters and amp hour meters.
The vast majority of batteries, if not all batteries, are natively advertised and sold in Ah. A few do a conversion from a Ah to Wh, but native data was Ah and the Wh is a calculated value.
Many, if not most charging sources are rated in A, not W. I challenge you to find an alternator or battery charger that is rated in W.
Given all of the above, the vast majority of boats and the vast majority of equipment are configured and used in such a way that A and Ah are an extremely easy to use shorthand for W & Wh. Conversions to W and Wh only add confusion and complexity.
It may not be pure, and it may not be technically accurate, but it is exceptionally functional.
In my case, I have 780Ah of batteries according to the label. I have 270A of alternators according to the label. My inverter has a 120A charger, according to the label. My switch panel has an amp meter. According to the amp meter on the panel, my chartplotter draws about 5A. My battery monitor reads Ah. My solar chargers are rated at 15A each. I consume about 120Ah overnight. It would take a spreadsheet to change all those numbers into Watts -- and they would all be natively measured in Amps, just converted to Watts.

[aqfishing]

Originally Posted by sailingharry

I'm not sure if you were saying this tongue in cheek or not. Assuming you are truly confused.
Approximately 98% of sailboats on the water today are 12 volt systems. Maybe 99%, but will say 98%. Unless stated otherwise, it is safe to assume that the poster has a 12 volt system.
Up until very very recently, very few boats had Watt hour meters. I would venture to say that fewer than 10% of the boats on the water today have Watt hour meters or Watt meters. Many have ammeters and amp hour meters.
The vast majority of batteries, if not all batteries, are natively advertised and sold in Ah. A few do a conversion from a Ah to Wh, but native data was Ah and the Wh is a calculated value.
Many, if not most charging sources are rated in A, not W. I challenge you to find an alternator or battery charger that is rated in W.
Given all of the above, the vast majority of boats and the vast majority of equipment are configured and used in such a way that A and Ah are an extremely easy to use shorthand for W & Wh. Conversions to W and Wh only add confusion and complexity.
It may not be pure, and it may not be technically accurate, but it is exceptionally functional.
In my case, I have 780Ah of batteries according to the label. I have 270A of alternators according to the label. My inverter has a 120A charger, according to the label. My switch panel has an amp meter. According to the amp meter on the panel, my chartplotter draws about 5A. My battery monitor reads Ah. My solar chargers are rated at 15A each. I consume about 120Ah overnight. It would take a spreadsheet to change all those numbers into Watts -- and they would all be natively measured in Amps, just converted to Watts.

Hi. Thanks for your response, it certainly was not tongue in cheek. The commercial vessels I work on all run 24v systems with 24v alternators and starters. Only the dedicated radio bank is 12v (with its own charger).
I did think to myself at the time that it is probably assumed as a 12v system, but decided to ask anyway. I guess its one of those things like how you set your plotter, course up vs north up. Peoples brains just work differently but at the end of the day the result is the same. I think in terms of watts and a battery as a tank full of watts or Wh not amps. Not sure watts correct!

[fxykty]

Yes, the boat is 12V. All energy values are in amps and amp hours, except the Quattro.

3 years after the initial change from AGM to LFP I am kicking myself for not considering changing the house system to 24V at that time - we planned to be relatively heavy consumers with electric galley and as a cat have long distances from engine alternators to the battery. 24V would have allowed us to avoid all the 120mm^2 (AWG 4/0) we ran to our engine room and doubled to our 5000W inverter/charger. Oh well.

Now to change from 12V to 24V would be prohibitively expensive (2x alternators, inverter/charger and one or more 24-12 converters at a minimum) and we probably wouldn’t downsize the already run cables anyway.

Almost done with all the rewiring to accommodate a second 700Ah battery in parallel. That will be documented next.

[fxykty]

Another two full days of extreme sweating to prepare the battery area for a second battery. Thankfully have two sets of various lengths of 120mm^2 cable with terminal lugs, so one set taken to rewire the existing battery and a second set for the new battery, ensuring both batteries will have equal lengths of cables to the main bus bars (positive and negative).

1) Installed second t-fuse holder and 500A fuse, second BlueSeas RBS 7713 (battery positive disconnect controlled by that battery’s BMS), second BMS, second BMS shunt. Also rewired the first BMS’s relay outputs and distribution bar to accommodate the several independent and several paralleled relays. Each battery has its own BMS and a single battery can be disconnected if necessary with the second battery continuing as designed.
2) Reorganised the previous separate charge and load positive busses with a single positive bus. Keeping the separate bus could have been done but would have required two more RBS and a fair bit of extra complexity. Since we already have an inverter/charger breaking the strict charge/load separation, and I didn’t want to add a third bus just for it, we’ve gone to a single positive bus. On the charge side nothing really changes with either BMS stopping charging for both, while on the load side either BMS can turn off the inverter. Other loads will continue until low battery disconnects. Not ideal as that will require a manual override to reconnect the battery for charging, but low battery disconnect hasn’t happened yet in three years of full time living aboard so not expecting that to change.

Everything is now ready for the second battery and for a nice change from all the previous work, I won’t have to take the boat dark with no power. Instead, the first battery can operate on its own and power the boat until I turn on the second battery’s BMS and it connects it to the positive bus bar. Parallel operation will commence.

The only thing left to do is to charge up the first battery to 14.4V to match the second battery before I parallel them.

Here’s the BMS wall, including the DC-DC 12-12 converter for clean power for the navigation equipment.


Here’s the compartment from above. The front of the boat is to the right and the BMS wall is on the left side (relative to the boat). This compartment is under our salon seating and used to contain a water tank (we moved it under the nav station, where the original AGM batteries used to be).
ATTACH]282570[/ATTACH]

Here’s the power distribution wall. You can see the two RBS feeding the positive bus bar near the top, with the negative cables from battery and shunt joining at the SmartShunt and then feeding the negative bus bar. The Cerbo will display and manage the system as a whole.

[Baronkrak]

Originally Posted by fxykty

Do you mean that in addition to the fuses in the box that the sensing wires should have fuses close to their terminals? If so, why?

The connections at the box look terribly vulnerable to short circuit. I am also not a great fan of Victron shunt that need a positive so close to a negative and their glass fuse tend to metallize. On land maybe but near seawater, very vulnerable.

https://community.victronenergy.com/...re-hazard.html

[s/v Jedi]

I’m just reading this thread for the first time. The smartest thing you did in the OP was contact Julia Yu from Skypower International to get that great start with quality Winston cells and the great care and service from Julia.

The only things I would have done differently is I would have used the BMV instead of SmartShunt (for multiple battery support) and I would have opted for 24V, as well as two 3000VA Multiplus units instead of one 5000VA.

You need a second battery of equal capacity though. Maybe needed for redundancy or just for extra capacity when both are online. In that case you can still fix the BMV issue by giving each battery it’s own BMV and using the SmartShunt for combined capacity monitoring. You then also gain the programmable relay function in the BMV’s for things like putting one in storage mode etc.

You got a great system anyway

[fxykty]

Second battery in parallel installation DONE!! A few configuration adjustments still need to be completed but displays show everything correctly. Cerbo nicely shows the system as a whole, while the individual BMS show the stats for each battery. On connection of the second battery, whose voltage was within 0.04V of the existing battery, there was a small current exchange until both batteries got to within 0.00V of each other. Now they’re maintaining near perfect synchronisation with same current from/to each one.

@Jedi, I’m using TAO BMSs to manage each battery and the master BMS provides a shared charging regime that applies to both batteries. As explained earlier in this thread I decided not to go to 24V and stayed with 12V - now two 700Ah @ 12V batteries in parallel.

@Baron, no need to worry about the TAO sensing wires’ fuse box shorting out due to water: (1) no water spray can get into the compartment and (2) if water floods our salon and enters the battery locker there is a drain there and we’ve got way bigger problems than the TAO fuses short circuiting - all the rest of the system will have shorted already.

[fxykty]

Originally Posted by Baronkrak

The connections at the box look terribly vulnerable to short circuit. I am also not a great fan of Victron shunt that need a positive so close to a negative and their glass fuse tend to metallize. On land maybe but near seawater, very vulnerable.



https://community.victronenergy.com/...re-hazard.html

I’m using a VE SmartShunt and independent bus bars, not the Lynx system. Other than the voltage sense wire there’s no positive near the SmartShunt. And I have T-class fuses on my battery positives to protect the smaller mega fuses in the VE modular fuse holders that protect all the wires leaving the positive bus bar.

[s/v Jedi]

Originally Posted by fxykty

Second battery in parallel installation DONE!! A few configuration adjustments still need to be completed but displays show everything correctly. Cerbo nicely shows the system as a whole, while the individual BMS show the stats for each battery. On connection of the second battery, whose voltage was within 0.04V of the existing battery, there was a small current exchange until both batteries got to within 0.00V of each other. Now they’re maintaining near perfect synchronisation with same current from/to each one.

@Jedi, I’m using TAO BMSs to manage each battery and the master BMS provides a shared charging regime that applies to both batteries. As explained earlier in this thread I decided not to go to 24V and stayed with 12V - now two 700Ah @ 12V batteries in parallel.

@Baron, no need to worry about the TAO sensing wires’ fuse box shorting out due to water: (1) no water spray can get into the compartment and (2) if water floods our salon and enters the battery locker there is a drain there and we’ve got way bigger problems than the TAO fuses short circuiting - all the rest of the system will have shorted already.

Attachment 282624

Great, yes, the BMS can replace some of the functionality of the BMV. Not a storage mode control but you can probably program a relay inside the Cerbo to do this as well