KISS Dual Battery or Fancy

[Wrecked Rooster]

Putting a dual battery setup to paper and would like to ask y'all what you would do/consider with my situation.

Option 1: I can go the KISS method and install a 75 Ah AGM battery with a Blue sea dual battery kit that comes with a dual circuit plus switch and their ACR:

https://www.amazon.com/dp/B000RZNP5K/?coliid=I20MT2RFCD7TVP&colid=1AY3V469JYI4D&psc=1&ref_=lv_ov_lig_dp_it

This would keep things simple with just turning the switch on/off and have the option to switch to combine in an emergency to start the boat. The ACR would keep the AGM house battery topped off while we were playing around while keeping everything isolated to not cause a drain on the starter battery while we are anchored and continuing to listen to music. I could add an additional 75 Ah battery if one isn't enough.

Cost:
75 Ah AGM: $65
Blue sea add-a-battery: $120
Total: $185

Option 2: Go a little fancier. I can install a 100 Ah LiFePO4 (lithium iron phosphate) that I have already, that I obtained for free. I would use this battery as my house battery to run audio when anchored. I think I would have to use a standard switch:

Amazon.com: Blue Sea Systems Battery Switch m-Series 3 Position Selector, 6008: Industrial & Scientific

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And would not be able to use the more simple (in my mind) dual circuit plus switch from the KISS method above. I can't use the ACR to charge the lithium batteries and would have to purchase a DC-DC charger to charge the house battery while under way, but I honestly do not think this will be necessary as you get more of the full capacity of the lithium battery.

Cost:
Battery: FREE
Blue sea switch: $45
DC-DC charger (if I decide I need it): $115
Total Cost: $45

Pros & Cons:

• Get the full (mostly) Ah of 100 out of the lithium vs the 37.5 Ah of the AGM @ 50%
• LiFePO4 setup is cheaper since I got lucky with a battery
• AGM setup I don't have to worry about switching the battery switch when we stop the boat to hangout. Granted, I could leave the starter battery on for short stops and just switch to the lithium house battery when I know we are stopping for awhile. And hope to remember to switch it back before going on our way.
• AGM (especially with 2 of them) would give me some "free" ballast for surfing at 60 lbs each.

So, which setup would you go with? I'm sure there are other pros and cons to each, but these are the ones that stand out to me. If I could use the Dual circuit plus switch from Blue Sea on the lithium setup, I think I would be good to go. However, it looks like with that switch you run all of your house stuff (in my case, mainly the audio equipment) to the house battery and the engine to the starter battery and they pull from those sources the whole time you are out. That would mean the audio system would be constantly pulling from my house battery with no way to charge it, which wouldn't work. Thanks for any help.

 

[HangOutdoors]

Either way works. Option 1 is cleaner via chemistries. Either way depending on how far you drain down either the AGM or the LiFePo4, you will need to put them on a charger.

Not sure what you mean by DC-DC charger, but the NOCO Gen 5's charge Wet, AGM, GEL and LiFePo4. So getting a 2 bank one will take care of both batteries regardless of what scenario you go for.

I have the 4 bank one. I also have the Wet Starter Battery, A Northstar AGM TPPL for the house and two LiFePo4 Batteries in my setup. Blue Seas Add A Battery with ACR for the Starter and House so I don't have screw with switching the switch since I am wired correctly. Just on and Off and they both work. I can combine if I ever need to.

Lots of threads here on this exact topic.

 

[Wrecked Rooster]

Either way works. Option 1 is cleaner via chemistries. Either way depending on how far you drain down either the AGM or the LiFePo4, you will need to put them on a charger.

Not sure what you mean by DC-DC charger, but the NOCO Gen 5's charge Wet, AGM, GEL and LiFePo4. So getting a 2 bank one will take care of both batteries regardless of what scenario you go for.

I have the 4 bank one. I also have the Wet Starter Battery, A Northstar AGM TPPL for the house and two LiFePo4 Batteries in my setup. Blue Seas Add A Battery with ACR for the Starter and House so I don't have screw with switching the switch since I am wired correctly. Just on and Off and they both work. I can combine if I ever need to.

From my understanding (and I called blue sea to confirm) the ACR cannot charge LiFePO4 batteries. They take a DC-DC charger to charge them properly. It would/could hurt your alternator (or whatever these bots have) as well as the lithium battery bank to charge off the alternator via the ACR. I have a NOCO charger to charge the lithium battery once I get home on shore power. The DC-DC charger allows you to charge your lithium bank while underway on the water, keeping it topped off between stops.

 

[HangOutdoors]

If you are draining it down that much, I wouldn't put it in. The Stator's on our boats don't put out a lot and aren't good for depleted batteries. The first option is better but if you are depleting you will have to shore power. If you deplete you won't be able to get them back up, topped off till on shore power.

Also ACR don't charge at all. They are just relay's. The regulate which battery to charge depending, that is all they do. All charging is done from our stator's which are not as strong as a true altenator.

 

[HangOutdoors]

IMHO, I would get a Solid AGM TPPL Battery which will cost more but do better for you in the long run. Put it in with the Add A Battery and ACR and you will be very happy. All batteries are not made the same.

 

[Wrecked Rooster]

If you are draining it down that much, I wouldn't put it in. The Stator's on our boats don't put out a lot and aren't good for depleted batteries. The first option is better but if you are depleting you will have to shore power.

I'll be honest, I have no idea how much power the audio system will be draining it. I'm just trying to get ahead of it and not be left stranded with a dead battery on the water. I carry a battery pack jump starter just in case as well.

The DC-DC charger helps the stator (thanks for letting me know what we have) by providing the energy the battery needs without pulling it directly from the stator, or using it to provide all of the electricity if that makes sense.

 

[Wrecked Rooster]

IMHO, I would get a Solid AGM TPPL Battery which will cost more but do better for you in the long run. Put it in with the Add A Battery and ACR and you will be very happy. All batteries are not made the same.

This video is only 2 min and is a better explanation what a DC-DC charger does versus a VSR/ACR.

 

[Wrecked Rooster]

If you are draining it down that much, I wouldn't put it in. The Stator's on our boats don't put out a lot and aren't good for depleted batteries. The first option is better but if you are depleting you will have to shore power. If you deplete you won't be able to get them back up, topped off till on shore power.

Also ACR don't charge at all. They are just relay's. The regulate which battery to charge depending, that is all they do. All charging is done from our stator's which are not as strong as a true altenator.

Do you know how much power the stators on our motors put out? There's a 65A and a 120A add a battery kit from Blue Sea.

 

[HangOutdoors]

I put the 120A in as others have.

 

[HangOutdoors]

My build for what it is worth

https://jetboaters.net/threads/wiring-and-battery-addition.32539/

I mounted mine to a piece of King Starboard and then mounted the starboard to the sidewall of the compartment.

 

[Wrecked Rooster]

My build for what it is worth

https://jetboaters.net/threads/wiring-and-battery-addition.32539/

I mounted mine to a piece of King Starboard and then mounted the starboard to the sidewall of the compartment.

I like it! I'm going to try this setup with an AGM battery and see how it works out. I can add a second AGM if needed or get id of the ACR, add a DC-DC charger and go the LiFePO4 route while keeping the same switch.