Lithium (LiFePO4) for Dummies

[mpearson]

I'm thinking about making the jump to a LiFePO4 house battery bank.

I don't have enough brain cells left to become an expert on the subject, so I'm asking folks like Warren and others who know the subject to tell me if I'm doing something stupid.

I hate buying from Amazon, but there are some relatively inexpensive options that have very high user ratings. I don't have enough boat bucks to get the very nice US-built systems like Battleborn.

I'm considering replacing 3 of my old 12V lead acid batteries (88 Ah each) with this 410 Ah beast:

https://www.amazon.com/Redodo-Lithium-LiFePO4-Battery-Capacity-Lifetime/dp/B0B4575RGW/ref=sr_1_3?crid=3APGMTRHN0U2V&keywords=Redodo+12V+410Ah+Lithium+LiFePO4&qid=1678334664&sprefix=redodo+12v+410ah+lithium+lifepo4%2Caps%2C147&sr=8-3&ufe=app_do%3Aamzn1.fos.17f26c18-b61b-4ce9-8a28-de351f41cffb

It's an incredible capacity upgrade given the much higher real drawdown on LiFEPO4.

Other background info: I'm planning on keeping my Lead Acid starter battery. My relatively new Yanmar came with a big 120A alternator. I've got a relatively new ProMariner Battery Charger (ProNautic 1230P) 30 amp.

Given all of that, is this the best approach??:

1. Wire the battery charger, alternator, and solar so they charge the new house bank. Or I’ve heard I could fry my alternator going to LiFePO4, so maybe they should all be wired into the starter battery?
2. Configure the battery charger so that it is optimized for LiFePO4 (if that is where it is wired)
3. Get a DC to DC charger (like 30A Victron), and use it to charge the other battery bank
4. Should I keep the A/B battery switch?
5. I have an older Blue Sea battery State of Charge monitor, but it doesn't have a profile for Lithium banks. So I'm thinking of getting a Victron monitor
6. I know people get religious about this, but I'm thinking of keeping my Windlass on the starter battery to avoid spikes, etc. that can fry electronics.

Are there other big ticket items I'm forgetting?
Thanks in advance for any advice.
-Mark

 

[terry_thatcher]

I encourage you to read the detailed discussion of this upgrade at Attainable Adventure Cruising. John at AAC is not an opponent of the switch, but he and those who contribute to the site have lots of good advice and cautions. Oh, and you might consider a Wakespeed regulator if you make the switch. I may spring for one even with my old flooded lead batteries.

 

[Warren Holybee]

Here is the executive summary. 1st, you can choose from a "drop-in" (which isn't) or build a bank from cells. Building from cells is much more complex, but offers better ways to deal with some issues. I would suggest drop-in for you based on your not wanting to become an expert.

I offer 2 brands that while I have not used personally, from my research are the only 2 I would consider. Kilovault, or Epoch. Neither are top-tier expensive, and neither are as cheap as what you will find on Amazon. But both seem to be the best you can get in a drop-in at any price.(IMHO better than Battleborn even though they are half the price) The issue with cheap amazon batteries is that unless you cut one open and look, you have to assume that even though they are rated for 100A, they are wired internally with 10AWG wire and components that might stand up to 100A for a short time, but not continuously.

LFP will smoke that 120A alternator, unless you convert it to externally regulated and get a wakespeed (preferred) or balmar regulator for it-with a temp probe to monitor the alternator temperature. So, connect the alternator to the start battery, and all other sources to the LFP battery. Use a DCDC from the start to LFP to charge the LFP with the alternator. If you need more than 30A charging while the motor is running, do the alternator upgrades.

The Bluesea won't work with the LFP. I have one, and it is useless for SOC (but fine for everything else it does). The Victron is dead on exact for LFP SOC. Be sure to set it up correctly, the defaults it ships with are for lead-acid.

Do whatever you want with the windlass. It will (probably) work fine either way. If connected to the LFP, you will want to check the current requirements and the current limits of the LFP battery (remember, the cheap Amazon batteries often have 10AWG wire inside!) But, if the LFP can handle the current, the higher nominal voltage will work better. But, it works fine now at the lower voltage, so... do what you want.

Some issue regarding the A/B switch. I would not attempt to start your engine from a random Amazon LFP. I might attempt it in an emergency with a Kilovault or Epoch.

LFP is without a doubt the single best upgrade I have done. It is a game changer. The upgrade you are considering will more than triple your usable capacity. And you won't need to worry about damaging the battery by not fully charging it like you do with lead. In fact, they prefer not to be fully charged, so the best thing you can do is just ignore them unless they get really low (like less than 10%). You can run them to zero (where the BMS turns them off) without damage, other than your loss of power on the boat. I expect mine (and expensive system built from cells) to last me 20 years. If I ever sell Eliana, the LFP batteries will go in my next boat.

 

[mpearson]

Wow, thanks for that executive summary, Warren! That's exactly what I was hoping for, and I appreciate it. Where are you living now, anyway? Someplace around the SF bay area? If so, I'll buy you lunch or dinner the next time I'm down there. Are you living on dirt or Eliana?

Yeah, I'm checking out Balmar's adapter thing that would allow me (I think!) to use their alternator regulator on the newer Yanmar's alternator. I need to get back to Zia to see if the alternator that came with the engine is the Valeo. From my memory, it sure looks like it.

Smart Ready Retrofit for Yanmar - Balmar

Smart Ready® Retrofit for Yanmar Engines Equipped with Valeo Alternators Now Yanmar Owners can Easily add Balmar Multi-Stage Regulation without Disposing of the Valeo Alternator Present on Recent Production Yanmar Engines A Simple Retrofit of the 120A/12V or 60A/24V Valeo Alternator Converts the...

balmar.net

It would be very nice to be able to use ~120 amps out of the alternator instead of only ~30. If by chance that gizmo works, would you recommend then sending the alternator output to the house bank too? and the DCDC feeding the start battery?

I'm also checking out Kilovault and Epoch per your recommendation.

Thanks again!
-Mark

 

[terry_thatcher]

Remember to check out Wakespeed regulator.

 

[mpearson]

Thanks, Terry - I'm checking into Wakespeed too. I can't remember: do you have one installed?

I've been reading about my alternator on the web (correct or not?) that realistically I'll never see 120A out. More like 60-65A. If that's the case, I'm re-thinking going down the alternator gear upgrade path. If I got 4 times the charge from a well-behaved alternator, I'd be more inclined to lay out some significant boat bucks.

And I think our use pattern will let us use solar for most our routine big loads (fridge and watermaker). Both of which we have super energy efficient systems.

So maybe for the next year or two, we will direct the alternator to the start (lead acid) battery, solar to (LFP) house, and DCDC charger to feed from the start to the house. Which is what Warren was (I think) recommending if I don't go down the upgraded alternator/regulator path.

Gosh, I remember when going "off grid" only required a buck knife, some matches and a piece of waxed canvas. I guess my "creature comfort" requirements are higher now.

 

[Warren Holybee]

With the wakespeed or balmar, your alternator will put out 120A, for a short time, and then slowly ramp down to where the temp stabilizes at a safe level. It might be higher than the estimates you read online. 50% is a "safe" level for setups without the temperature probe. With the probe, you can run full tilt until it gets hot, and then only back off enough as is necessary to protect the alternator. My point being, if you want to charge from 0% to full, then the alternator will be crippled. But if you want to put 50Ah or 100Ah in the battery fast, it might run at near 120A long enough to do that. Since you have solar, and LFP isn't damaged by not fully charging, a little boost of 50Ah when the battery is very low might be all you ever need.
I currently have a DCDC charging my LFP from the start battery, even though I also have a balmar with a temp gauge. I primarily rely on Solar, and really dislike the balmar even though it is highly regarded. It's 40 year old tech, barely updated to mostly be compatible with LFP.

 

[terry_thatcher]

I have run a Balmar regulator for years. I agree it is not smart like a Wakespeed ( and the price reflects that) but it has served my limited needs (400 amp hours of house bank and a started battery. I have not decided if I will invest in a Wakespeed this year. I have also run a 100 amp Balmar alternator for two decades, with one precautionary rebuild at 15 years. But it is a large case and very robust. Unfortunately the new Balmar 100 and 125 are small case devices and not as strong. My new Beta will come with a Balmar 125 and I will downrate it by 10 or 15% since it is not as robust. I have for years carried a spare 100 amp on board. But both alternators are useless on the Beta, which has double foot mounting. So, I will have two perfect alternators to dispose of. I have listed one of them on our site, on EBay, and on Craig's list in Seattle, Portland, and the Bay area. No sale for three months. I will also have a Perkins 4-108 and spare parts. It still always starts and runs well, but I got tired of replacing worn parts. Maybe I should have kept it.