Removed extra start battery. Replaced FLA house with Lithium

Captain Starbucks

In effort to make my boat a better fishing and camping tool, I've put her on a diet and boosted the juice.

I've never quite understood why boats with an option to parallel a house battery for engine starting also have an extra start battery. Seems like a lot of extra weight. I chose to remove the extra start battery and buy a brand new start battery. I bought flooded lead acid of the same size that was removed, but the most powerful one I could find. So now we're down to just two batteries, start and house.

Next, I removed the heavy FLA house battery and replaced it with China's finest 100 AH with built in Bluetooth. It's a Vairer brand found on Amazon for about $275. I'm not saying this battery was good or not, just saying I bought it and it's working well so far. It does have it's own shunt and has its own app so no need for a Smartshunt. I will say though, the Victron Smartshunt that I have for the 36 volt trolling motor bank is superior.

Now that I've chosen to different chemistry types of batteries that are going to be charged in the same charging system, it was time to figure out how to get them both safely charged. I opted for the Smartshore Marine (formerly Yandina) Combiner 100 Lithium. This device is a simple combiner that knows to combine the batteries when it detects charging, and separates them when it detects no charging. Simple as that and it's only $130 and light. The difference in the lithium vs not is the lithium combiner disconnects at a slightly higher voltage.

Aside from having the stern of the boat a little lighter (about 70 lbs), the biggest difference I notice is on the electric reels and overnights. I fish usually 600-800' deep and with the old battery setup, the reels would start to slow after fishing a hot spot for 20-30 minutes. Not bad, just start to slow. I'd start the engines and once the previously installed Blue Seas combiner closed (not available in lithium) the reels would sing. Now with the lithium, the reels sing full speed the entire time. Plus it's nice watching how many amps the reels are pulling and battery power with the frustrating built in shunt app.

Overnights, we only get the battery down to upper 80%. Granted, this is summer time and we're not using much power just a few lights, charging devices and running the diesel stove/heater all night.

Another nice thing is that the lithium battery gobbles juice when charging. It's fully charged in no time flat.

I did have to buy a different battery mount. Same brand, only need the longer plastic bolts. Attwood All-Plastic Group 27 Hd Battery Tray (Part #9098-5 By Attwood Marine)

WCF · Posted: Thu Jun 20, 2024 11:34 am Post subject:

What is the current draw/charging rate of the house battery when drained down? Since you have an app/built in shunt, I assume you have some numbers.

I tried to use a similar ACR with a similar setup and did not feel comfortable with the load on the outboard's charging system and how often the relay switched. Maybe just particular to my setup though.

jkidd · Posted: Thu Jun 20, 2024 2:52 pm Post subject:

So how do you handle the near zero internal resistance of the Lithium battery?
You can burn up the stator.
The stator will deliver enough voltage to charge a flooded lead acid battery and can't charge an AGM or a Lithium battery to full capacity. It would eventually damage the agm battery unless you top it off with a charger on a regular basis. The Lithium battery likes being ran between 10% and 90% you will just lose capacity.

Please tell us why you choose to not use a DC to DC charger.

T.R. Bauer · Posted: Thu Jun 20, 2024 5:29 pm Post subject:

My concern with any LIFEPO4 setup is frying the wiring and the alternator. It is enough of a concern that it has made me pause with installing one in my RV and live with the commercial FLA configuration I have now. With that said, I have an LIFEPO4 on my boat too for a house battery, but my ancient old charging system only puts out 10 amps per outboard....no concern with wiring or anything else because it doesn't do anything....pretty pathetic system really. Does that bluetooth shunt feature limit the charge amps as well as discharge? If so, that is pretty cool.

WCF · Posted: Thu Jun 20, 2024 6:09 pm Post subject:

thataway · Posted: Fri Jun 21, 2024 12:31 am Post subject:

I am concerned with the voltages involved, that is does the engine "Alternator" put out enough, with out damage. The web site is not clear, but states:

T.R. Bauer · Posted: Fri Jun 21, 2024 11:46 am Post subject:

Captain Starbucks · Posted: Mon Jun 24, 2024 9:32 am Post subject:

I figured there would be a few questions on the install. I'll do my best to try to answer them.

Why not a dedicated Lithium charger? For one, you simply don't need one IF the lithium bank is separate from the house/start bank at rest. I will agree that a dedicated lithium battery charger is the way to go, but the reality is, you are just getting optimization. My electric car charges itself every time I back off the accelerator. Is that optimum for its charging profile? of course not, but it sure works.

Captain Starbucks · Posted: Tue Jun 25, 2024 9:36 am Post subject:

Here's a screenshot of the app that controls the built in shunt in the Viaer Chinese battery from Amazon. It works fine, but not nearly as smooth as the Victron app.

Here is a screenshot of the Victron app that controls the Smartshunt in my trolling motor battery bank. Here, it is in the charge config by showing 12 volts charge at the top. Once it's done charging, it automatically goes to 36 volt series mode through the Trollbridge 36.