R31S to Lithium

[ggreen]

I took delivery of a new 2025 Ranger Tug 31S. I love the boat but was surprised that the House bank was AGM instead of Lithium which is featured in the Ranger Tug website. I would like to replace the AGM with lithium and was wondering whether the installed inverter/charger, Volvo D4 alternator and the solar charger can support the change to Lithium batteries for the House Bank only. If not, what would need to be changed or added. Also, can the installed solar charger support a second solar panel of the same wattage that came with the boat or if the current solar panel was changed to a single higher wattage panel.

Thanks

 

[Martin610]

In general, switching to Lithium is not plug and play. We need more details on what exactly your equipment is.

Most of the time the solar charge controller can support lithium. However, if its a two bank unit, you might be able to charge only the house bank. Again, we need the specifics of the panel and solar controller to know if another panel can be added.

The Volvo D4 alternator is an issue. I think you would have to add a DC to DC charger, or a regulator of some kind. Some people mount a separate alternator for the lithium but I don't know if that's possible with the D4.

Your inverter/charger is charging both house and engine/thruster batteries. It would have to be able to support both chemistries.

This is never a trivial undertaking. One of the posters here, Submariner, has some nice videos on YouTube that cover this type of conversion. You could probably learn a lot from these videos.

-martin610

 

[SKing]

In my opinion as long as you have fresh AGM's don't make a change yet. Just gather info for when the batteries degrade. Meanwhile invest your energy in solar. As long as your housebank carries you through a 15hr night, then you recharge fully its irrelevant. Put 400 wats of solar on the boat and you should be good.

 

[ggreen]

Thank you all for your information and recommendations.

 

[H28]

In general the chargers have settings for lithium, my 2018 RT29S controllers do. Easy check: just look in the manuals. As for solar controller capacity, don't take anyone's advice but the manufactuer's IMHO. I had the same question and emailed Morningstar customer support. they were great. To wit:

"Hi David,

You are on the right track with your math, however it's more accurate to take the Isc rating of the panels and add those.
I'm estimating your 140 watt panel Isc to be around 9 amps so you could easily add another 140 or even 160 and still be under the 25 amp rating of the Duo.

The other thing you can do to be absolutely certain is to use our string calculator, found at this link:

String Calculator - Morningstar Corporation

+

string-calculator.morningstarcorp.com

Best regards,

Roy"

I wound up ugrading my solar panel (stock was 140) to a 200 watt panel and then bought a portable 200 watt panel with its own controller to supplement as needed on our Great Loop trip (with starlink and a portable freezer, we were sucking down power). Yes, you can hook up two controlled s/p's to the battery bank.

 

[Submariner]

Switching a R31 to LFP wouldn't be any different than when I converted my R27 to LFP. But the R31 has more space for the components.
DC to DC chargers would be necessary in-between engine and house. Solar controller and Inverter/Charger most likely will need to be upgraded to support LFP.