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Lithium (LiFePO4) for Dummies

mpearson

mpearson

Mark Pearson
Staff member
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:


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
 
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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.
 
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.
 
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.

balmar.net

Smart Ready Retrofit for Yanmar - Balmar

Smart Ready® Retrofit for Yanmar EnginesEquipped with Valeo AlternatorsNow Yanmar Owners can Easily add Balmar Multi-Stage Regulationwithout 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 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
 
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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.
 
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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.
 
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.
 
I did more research and talked with other folks. Ended up buying a Kilovault Lithium battery (like Warren recommended. Thanks Warren!).

I'm cooking up a schematic of how to put this all together.

Following drawing is a "work in progress" and although it looks a little nasty, it's no where near as bad as my hand drawing was. ;)

If anyone has any comments or suggestions about this, I'd love to hear them. This is the first phase of the upgrade. Eventually, I'd like to install an alternator regulator (as discussed with Terry & Warren) and perhaps have the alternator and battery charger feeding the lithium, and the B2B feeding the starting battery from the lithium.

1680188348830.png
 
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That looks pretty good. The main fuse (you marked with a ?) should be a Class-T fuse. And there is no reason to spend extra money for an isolated DCDC charger because your two batteries are not isolated from each other (they share a common negative bus). Be cautious using the battery combine to start the engine. It will _probably_ be fine, but the currents will probably exceed what the kilovault is rated for. I would leave it as you drew it, and then make sure I never get into that emergency. Mine is actually set up the same way, and what I have done when my start battery was drained is combine the two batteries, let the LFP charge the start, then uncombine them and start from the normal start battery.

With 400W of solar you should need very little if any alternator charging. I have heard 2nd hand that Yanmar warranty doesn't allow alternator upgrades (???) so the DCDC instead of an alternator upgrade is probably fine for you.
 
Warren - roger that on combining only in emergency. And good idea to (if time permits) to let the LFP charge the ‘start’, then disconnect and use the ‘start’ only.
Thanks for all your advice!
 
Hi Terry - we only have the stock 120a alternator (and regulator) that came on our new Yanmar.
 
The path of least cost is to leave your stock alternator and starting battery in stock configuration. Add a 40 or 60 amp DC/DC converter to charge the LiFePo battery bank. I would not put the A/B switch in the system, ( in the BOTH) position you are asking for trouble). Wire your solar panels and your battery charger to the house bank. Victron makes a vary nice bi-directional DC/DC converter that will charge the house bank with the alternator running, and then charge starting battery from the house bank when the engine is not running. Using a DC/DC converter will guarantee that the load on the alternator current will not exceed 40 or 60 AMPS and prevent early life failure.
One more thing, buying a UL listed battery is the only way you can insure a good product, remember most of these batteries are made from Chinese manufactured cells.

my two cents...
 
Thanks for the input John & Jose.

Jose - you suggest the battery charger should go to the house bank (instead of the Start battery as shown in my drawing above). And that the B2B Victron charger would charge the House bank from the Starting when the alternator/engine is running, and feed from the House bank to the Starting battery when the alternator/engine is not running. That seems like it would work, too, but maybe be a bit more complicated?? I guess one reason would be to avoid having a potentially problematic BOTH/Combine switch if the Starting battery is dead?

Under your scenario, I wouldn't need a switch that did BOTH/Combine. Because the House would always be topping off the Start if need be.

Did I get that right?

How about a situation where there is some kind of unintentional draw on the Start battery while we are off the grid? And it would then drain both the Start and House?

What do you think about Warren's idea of only using the BOTH/Combine switch to charge the Start battery, then disconnect before starting the engine? I know that is less than fool-proof, but in a pinch?

I appreciate the conversation.
 
Mark, yes you got it right. It is not a good idea to connect banks of different capacities and internal resistance characteristics. If you have a large bank trying to charge a smaller one with a shorted cell, very bad things can happen. I use a 1/2/both switch to select which bank starts the engine. I will provide a schematic later,
 
I left my 1/2/ both switch in place mostly because I was lazy, it was already there when I did the conversion and I just left it. I agree it is probably better to replace it with an on-off for the start battery. The LFP as its own on-off.

That said, my start battery is showing age, and I don't have a shore charger, solar is direct to the LFP, so my start only charges when the engine is running. Turning it to All for a few minutes before starting brings it back to voltage. This could be an issue if a cell shorted in the start battery, but otherwise not a problem.

On my endless list is a re-engineering of my battery bank. I'll be replacing my Balmar with a Wakespeed, a shore charger, and a way for solar to charge both banks. At the time I installed LFP I was in Virginia, and I needed an upgrade, but was time and budget constrained to get back to the west coast.
 
Mark,
mpearson said:
Thanks for the input John & Jose.

Jose - you suggest the battery charger should go to the house bank (instead of the Start battery as shown in my drawing above). And that the B2B Victron charger would charge the House bank from the Starting when the alternator/engine is running, and feed from the House bank to the Starting battery when the alternator/engine is not running. That seems like it would work, too, but maybe be a bit more complicated?? I guess one reason would be to avoid having a potentially problematic BOTH/Combine switch if the Starting battery is dead?

Under your scenario, I wouldn't need a switch that did BOTH/Combine. Because the House would always be topping off the Start if need be.

Did I get that right?

How about a situation where there is some kind of unintentional draw on the Start battery while we are off the grid? And it would then drain both the Start and House?

What do you think about Warren's idea of only using the BOTH/Combine switch to charge the Start battery, then disconnect before starting the engine? I know that is less than fool-proof, but in a pinch?

I appreciate the conversation.
Click to expand...
Mark, here is the electrical system on Siboney. I am using AGM bbatteries because at the time I needed the batteries the new tech was still too pricey. To change over to LiFePo batteries, the VSR/breaker combination would be replaced by the DC/DC converter and the battery charger would be connected to the start battery, this would eliminate the need for a bidirectional DC/DC converter. This is the battery charger and the DC/DC converter play nice together.
 

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jose santin said:
Mark,

Mark, here is the electrical system on Siboney. I am using AGM bbatteries because at the time I needed the batteries the new tech was still too pricey. To change over to LiFePo batteries, the VSR/breaker combination would be replaced by the DC/DC converter and the battery charger would be connected to the start battery, this would eliminate the need for a bidirectional DC/DC converter. This is the battery charger and the DC/DC converter play nice together.
Click to expand...
After further examination the changeover to LiFePo house bank would also require re routing the alternator output to the starting bank. I would leave the solar hooked up to the house bank.
 
Mark, here is a rough sketch of what a LiFePo house bank would look like. Yes I drew in 6v agm's instead of the 200 Ah LiFePo batteries but you get the idea. I am not sure if the combination of a battery charger feeding a DC/DC converter would work, some consulting with the manufacturer might be needed.
 

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jose santin said:
Here is an interesting option to those that have re-powered with engines that use the mitsublshi 120A alternators, The nice thing about this product is that it allows external charging without the need to modify the alternator.

VRC-200 Charge Reference Controller | Nordkyn Design

Advanced alternator and charger control for high-performance charging solutions.
nordkyndesign.com nordkyndesign.com
Click to expand...
That is more expensive that an external regulator, and does not monitor alternator temperature. It says it is for LFP, but for LFP you really need to monitor alternator temperature.
 
Warren Holybee said:
That is more expensive that an external regulator, and does not monitor alternator temperature. It says it is for LFP, but for LFP you really need to monitor alternator temperature.
Click to expand...
Yes, it does not monitor alternator temperature, it it does allow you to set maximum charge current, which in turn will control max temperature. As far as price, the price is quoted in NZ dollars, this price is equivalent to US $350, This is cheaper than the price I found for the Wakespeed. As as I mention, it requires no modification to the alternator. Let me know if I am mistaken.
 
NZD makes a big difference. Even still, if spending that kind of money I would do it differently. It's very personal though. In my case I have enough solar, so it isn't an issue. My alternator charges my start battery. I have a DCDC charger, but also have a switch to turn it off, and it is always turned off.
 
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