Adding Solar Charger/Second battery charger

[Letterkenny]

Hi all - I’m eagerly awaiting my boat and in the interim, I’m trying to plan out the upgrades I’d like to do. I have been trying to find some info on these but can’t find anything very useful on these exact items. A more immediate item I want to add is 1-2 100 watt panels. However, I am not quite sure how the MPPT controller would get wired in. I have attached the DC diagram for the boat. Is it as simple as wiring it to the house battery bank directly or is there any consideration for the battery charger or alternator? Any switches need to be added to switch off the controller when connected to shore power or running the main?

In addition, even though I know I won’t be doing large trips, I suffer from battery capacity anxiety. With the removable solar and brining along a portable generator, I should be fine, however, with the battery bank being 2x 80ah flooded batteries, I don’t have a ton of capacity. I am leaning towards two things. In the short term, I plan to add in one cheap flooded west marine starting batter and converting the current starting battery to be a house battery so that I will have 3x 80ah (the stock batteries are hard to find and the online retailers don’t ship to California). Option 2 that I may do off the bat or down the road is replacing with Lifepo4 batteries. I can essentially add 2-3 100ah Lifepo4 batteries at $500 or so each for the cheaper Amazon ones or potentially a large 200-300ah single. However, the stock charger (Cristec CPS3) doesn’t appear to support lithium and I would also still need an AGM or flooded battery for the starter. In the attached diagram, how would I go about adding a second dedicated charger for the lithium battery bank? Any issues with it being connected to the alternator with the flooded starting battery? If there is any advice or YouTube videos that cover this, that would be greatly appreciated. It seems most cover the panel installation or overview rather than the wiring logistics.

[rgleason]

Renogy makes a DC-DC charger that is good for LiFePo4 either 30a or 50a

[Letterkenny]

Originally Posted by rgleason

Renogy makes a DC-DC charger that is good for LiFePo4 either 30a or 50a

So how would that work if it looks like the main charger is wired to the terminal switches? Wouldn’t that essentially still want to charge the entire battery bank?

[dkenny64]

while it seems difficult its not..


I hope you have a switch to isolate the start battery from the house bank..


does you current shore power support adding a 2nd unit?

if so then you can just parallel the solar the shore charger.. if you stay with AGM or FLA batteries.. going to Lifepo4 use the DC-DC that was already suggested.


for have the solar charge both, start and house, banks..use 2 controllers..the outputs tie to each bank.. the inputs are parallel to the solar panel.


hope this helps
dkenny64

[Letterkenny]

Originally Posted by dkenny64

while it seems difficult its not..


I hope you have a switch to isolate the start battery from the house bank..


does you current shore power support adding a 2nd unit?

if so then you can just parallel the solar the shore charger.. if you stay with AGM or FLA batteries.. going to Lifepo4 use the DC-DC that was already suggested.


for have the solar charge both, start and house, banks..use 2 controllers..the outputs tie to each bank.. the inputs are parallel to the solar panel.


hope this helps
dkenny64

If you look at the diagram I posted, it doesn’t appear to have some sort of switch between the two. I found another diagram in a video and I think for the lithium and lead acid battery banks, I’ll just need to take the wiring from the alternator and wire directly to the starting battery and then wire a DC to DC battery charger from the starting battery to the terminals.

[dkenny64]

that diagram has all the batteries tied together all the time..
worst case is all batteries die...then you cannot start the engine...


2nd. I don't think you understood about how I suggest connect the solar charges.


panel to MPPT1 this to start battery
panel to MPPT2 this to house battery.. the MTTP outputs aren't connected...


the alternator needs to have an isolator so can feed both house and start banks



if you make the house lifepo4 then put a DC-DC charger in series with line from alternator to the house bank.. this would after the isolator..
if this doesn't make sense I'll try to draw you a picture.


-dkenny64

[smac999]

Originally Posted by dkenny64

that diagram has all the batteries tied together all the time..
worst case is all batteries die...then you cannot start the engine...


2nd. I don't think you understood about how I suggest connect the solar charges.


panel to MPPT1 this to start battery
panel to MPPT2 this to house battery.. the MTTP outputs aren't connected...


the alternator needs to have an isolator so can feed both house and start banks



if you make the house lifepo4 then put a DC-DC charger in series with line from alternator to the house bank.. this would after the isolator..
if this doesn't make sense I'll try to draw you a picture.


-dkenny64

some horrible advice.

the alternator isolator would get removed and the alt would feed the start battery direct. the dc to dc would go from the start battery to the house battery.

remove the wire from battery charger to house bank switch so it only charges the engine bank.

now the alternator and show power will charge the engine battery. and the engine battery will charge the house. make sure the dc to dc charger is voltage triggered so it only charges the house if the engine one is charging. and can be programed for lithuim. I like realy like the mastervolt ones.

solar could then go to either battery it would not really matter. if you want to be able to charge both then run it to the start battery and it will also go through the dc to dc to the house. though there really isn't any reason to have the engine battery charged from solar so it could also go straight to house.

[dkenny64]

Originally Posted by smac999

some horrible advice.

the alternator isolator would get removed and the alt would feed the start battery direct. the dc to dc would go from the start battery to the house battery.

remove the wire from battery charger to house bank switch so it only charges the engine bank.

now the alternator and show power will charge the engine battery. and the engine battery will charge the house. make sure the dc to dc charger is voltage triggered so it only charges the house if the engine one is charging. and can be programed for lithuim. I like realy like the mastervolt ones.

solar could then go to either battery it would not really matter. if you want to be able to charge both then run it to the start battery and it will also go through the dc to dc to the house. though there really isn't any reason to have the engine battery charged from solar so it could also go straight to house.

you are entitled to your opinion.. but there lots of ways to make this work.
my suggestion is how my boat is wired and it works fine.. at the moment my batteries are all FLA.. but I'm planning on going to lifepo for the house banks in the future..then the house banks will be charged by a DC-DC..fed from the diode isolator..since its there and works.. for charging the start from solar..think about not connecting to shore power and not running the engine..the start battery will slowly die..
you lost me on the house only being charged while the start battery is charging?? so when the start is done charging everything shuts off?? not sure that's exactly what you ment..


-dkenny64

[Letterkenny]

Originally Posted by smac999

some horrible advice.

the alternator isolator would get removed and the alt would feed the start battery direct. the dc to dc would go from the start battery to the house battery.

remove the wire from battery charger to house bank switch so it only charges the engine bank.

now the alternator and show power will charge the engine battery. and the engine battery will charge the house. make sure the dc to dc charger is voltage triggered so it only charges the house if the engine one is charging. and can be programed for lithuim. I like realy like the mastervolt ones.

solar could then go to either battery it would not really matter. if you want to be able to charge both then run it to the start battery and it will also go through the dc to dc to the house. though there really isn't any reason to have the engine battery charged from solar so it could also go straight to house.

So essentially map it to the second photo I shared but rewire the charger to be directly to the starting battery and then I believe the DC to DC should have a wire to connect to the alternator and charger to have it only activate when there’s power through one of these sources? I’ll look into mastervolt. Was planning on Victron originally. This all will likely be overkill for my cruising plans and probably won’t even need solar if I go lithium considering the wattage and portable generator (or not need that and go strictly with solar).

[smac999]

the charger already goes directly to the battery in the first pic. it's fine you just need to remove the wire to the house battery.

the dc to Dc will trigger off input voltage. IE over 13.5v it will turn on. so only when the engine battery is charging. the new bluetooth victrons are also ok. the dc turn voltage on can be set to anything. I think max 30a though. but you could run 2.

[rgleason]

Listen to smac

[Letterkenny]

Originally Posted by smac999

the charger already goes directly to the battery in the first pic. it's fine you just need to remove the wire to the house battery.

the dc to Dc will trigger off input voltage. IE over 13.5v it will turn on. so only when the engine battery is charging. the new bluetooth victrons are also ok. the dc turn voltage on can be set to anything. I think max 30a though. but you could run 2.

Thanks. I’m still trying to decide what exactly I want to do and if this is overkill for my situation at the end of the day (Brand new flooded batteries and I’ll likely be doing week long or so trips at the high end with marinas in between). A follow up question, if I plan to keep the flooded versus changing for lithium off the bat, I’ll want to add in a fourth battery so I can have 3 house and 1 starter. That said, it won’t be the same brand of battery as the other three but would be same amperage and also flooded. How would I go about wiring this?