Rewiring my boat

[waughoo]

LF,

Good to see you made some progress!  I would be interested to know if you find a stbd side mounting location for the inv/chg.  Moving some weight over there would be great!

[tmac]

Antoni - I'd be really interested in seeing your updated wiring diagram now that you've implemented Lithium in your system.  I just purchased two LiFePO4 batteries on Maine Sail's recommendation (see his latest write-up) and am planning out all the changes I'll have to do on my boat to accommodate them.  In particular, I'm interested in how you'll address the very different charging profiles between your starter battery and the house batteries, and also what modifications you made in the alternator portion of the system.

[LogoFreak]

Detailed wiring diagram is still being revised and polished, but I can explain how my system is designed.

Kept it as simple as possible. Victron multiplus compact (12/2000/80) as my house bank charger, keeping original alternator (I believe it's the 51A but need to confirm), agm starter battery with alternator output going to it. Victron Orion dc-dc 30A charger charging the lithium house bank from agm while engine running.

If it turns out my alternator is the larger 105A I'll get a second dc-dc charger to parallel it in and charge house bank at 60A.

Once I have the completed diagram completed and checked by the marine electrician I'm working with I'll share it here.

[tmac]

Antoni,
As I mentioned, I've been planning out my system also, and I'll admit up front that I'm no Electrical Engineer, but I have been communicating with a technician at Sterling, which has a line of products similar to Victron.  My boat already had a Sterling AC charger when I bought it – the prior owner was an avid follower of MaineSail. 
Here are the issues that I've learned must be addressed when installing a hybrid Lithium and lead acid system, and you may already have considered these, but I'll share them anyway in case they benefit anyone else.  For all you that are EEs, be gentle with me if I've made any errors.

• Since there aren't any AC chargers that can output two separate charging profiles, you'll need to set up your charging profile as a compromise to the lowest common denominator between the two banks.  For example, if the Lithium wants 14.4V bulk and 13.8V float, and the lead acid want to be charged at 14.6v bulk and 13.6 float, set the profile to be 14.4V bulk and 13.6V float.
  Now before anyone jumps on this statement, I know LiFePO4 manufacturers recommend no float charge, and I questioned the Sterling technician about this, and this was his response: "A float charge of 13.6V or 13.8V is below the point a full lithium battery will continue to draw power. Charging at 13.8V will only draw a battery up to about 80-90% full, and if the battery is already above that in capacity then it poses no risk of current flow at all, and only improves the performance on output. Lithium doesn't require a float voltage, but a correctly rated float voltage causes nothing negative in my experience at all and I'm yet to actually see any evidence to the contrary on a lithium iron phosphate system."
  In my case, I'm considering just setting the AC charger to charge the lead acid, and then let the DC to DC charger take care of the Lithium bank.  That way both banks get exactly what they need as far as a charging profile.  I know there's a loss of efficiency with the DC to DC charger, but that doesn't matter as much to me with shore power charging. 
  
• Charging a Lithium bank with your alternator can easily burn up your alternator.  Since the Lithium bank has so little internal resistance, it will cause your alternator to output at a higher amperage for longer periods of time, generating a lot of heat.  This is doubly true if you are running at lower engine RPMs because the alternator fan isn't turning fast enough to cool the alternator efficiently.  Watch this Victron video https://www.youtube.com/watch?v=jgoIocPgOug&ab_channel=VictronEnergy  This is why smart external regulators are typically recommended, which can be set with charging profiles and temperature sensors to regulate the alternator output.  Sterling actually has an external regulator that doesn't require you to remove the alternator's internal regulator – it can override the internal regulator, and it can also use it as an emergency backup if the external regulator fails.
• Since the BMS on your Lithium bank can shut down the charging cycle without notice, you need to protect your alternator from a voltage spike.  This can be done in a number of ways.  One is to always have the lead acid batteries in the charging circuit to absorb the spike.  Another is to add an Alternator Protection Module (APM).  Victron makes one and so does Sterling.
• You will want to take a look at your battery bank switch and think about what will happen in the following scenario:  Your starter battery is fully charged at 13.6V, but your house bank has been discharged to 12.6V.  Someone turns the battery switch to "BOTH".  There will be a sudden rush of current as the two banks attempt to equalize – especially since the Lithium bank can accept a charge so readily due to its low internal resistance.  This could potentially heat up your hardware far in excess of what you would want.  I'm planning on either eliminating the "both" option or else use a switch with a key so that only I will be able to use the "both" option after verifying the charge state of both banks.

Good luck on your project.  I'll be interested in seeing your success.

[LogoFreak]

Emac,

1. Your statement is correct however not relevant to my particular intended installation. The charger/inverter will only charge my lithium bank for which it's programmed for.

2. correct again about alternator frying itself IF it was wired to charge a lithium bank directly. My alternator is internally regulated and will be charging the agm starter battery for which it's been designed (actually it's designed for flooded lead acid but it's ok to charge agm as well. I have to still verify which exact model I have but suspect it's the 51A version, it is more than ok to supply a constant 30A charging current.

3. Correct again, which is why the alternator output is going to agm starter battery. A dc-dc charger will be drawing 30A from alternator output thru the agm battery and charging the lithium bank with an appropriate charge profile.

4. Correct, paralleling in a low battery with a fully charged one will create a massive amount of inrush current. For that reason I don't have a 1-2-B-O switch, just several on/off switches.

[LogoFreak]

Slow progress but a step forward non the less...

[Noah]

Opted for Portside after all? BTW, you can drill some inspection holes under that floorboard to help you guide/rout wires if need be. No need to put covers on them.

[LogoFreak]

Yes, for the time being it's the least complicated location. I will be drilling a couple of larger holes in the floor as you indicated to route wires from inv/chg to a Victron lynx distributor, as well as the ac wires to shore power and ac panel.

[Noah]

That's where my charger is located too. The file box contains my various manuals and instructions for onboard equipment.

[LogoFreak]

Some progress pics. So far I have the main dc disconnect wired in with lynx distributor and the disconnect for the inv/chg. If all goes well and I get the wire I ordered I should have it all running by the end of the weekend.

[waughoo]

I dig it!! 

[Noah]

No heat shrink on your switch cable lugs?

[LogoFreak]

Work in progress, everything is going to be well insulated.

[waughoo]

Noah,

Wait till you see his case ground on the inverter: SUPER clever solution.

[LogoFreak]

Noah, added the heatshrink, just for you 

Fixed the alternator output BS wiring, 4ga now supplies alternator output to a bus bar that is tied to starter lug where a 1ga wire is connected coming from the lynx distributor, fused with 200A fuse.

Multiplus install is nearly finished. Just need a yellow 2/0 cable and I can power it on