The Offshore Voyaging Reference Site

Lithium Buyer’s Guide—Budget: Economy Options

Options 4 to 9

In the last chapter in this Buyer’s Guide, we specified and costed out a fully functional lithium-based system, including heavy duty alternator with regulator, inverter charger and lead-acid serial backup, using gear primarily from a single high-quality manufacturer.

We also looked at how much design help and advice to pay for, and the probable costs of professional installation.

The total came out in excess of US$20,000, including installation, and an owner who opts for a huge system capable of supporting electric cooking and/or air-conditioning could spend US$40,000 without breaking a sweat (bad pun), particularly if installing those high-current (amperage) loads resulted in having to upgrade the boat to 24 volts.

And even that’s not the limit. I can easily see a complete system exceeding US$50,000 for an owner aiming to go cruising with all the comforts of home1.

Yikes, all those options cost a hell of a lot of money!

Let’s try to come up with a more attainable option and compare it to the base-system hardware price of approximately $14,000 for Options #1 to #3. Then, we can examine what sacrifices in functionality, safety, and insurability will be necessary to achieve those savings.

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More Articles From Online Book: Electrical Systems For Cruising Boats:

  1. Why Most New-To-Us Boat Electrical Systems Must Be Rebuilt
  2. One Simple Law That Makes Electrical Systems Easy to Understand
  3. How Batteries Charge (Multiple Charging Sources Too)
  4. 5 Safety Tips For Working on Boat DC Electrical Systems
  5. 7 Checks To Stop Our DC Electrical System From Burning Our Boat
  6. Cruising Boat Electrical System Design, Part 1—Loads and Conservation
  7. Cruising Boat Electrical System Design, Part 2—Thinking About Systems
  8. Cruising Boat Electrical System Design, Part 3—Specifying Optimal Battery Bank Size
  9. Balancing Battery Bank and Solar Array Size
  10. The Danger of Voltage Drops From High Current (Amp) Loads
  11. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 1
  12. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 2
  13. Battery Bank Separation and Cross-Charging Best Practices
  14. Choosing & Installing Battery Switches
  15. Cross-Bank Battery Charging—Splitters and Relays
  16. Cross-Bank Battery Charging—DC/DC Chargers
  17. 10 Tips To Install An Alternator
  18. Stupid Alternator Regulators Get Smarter…Finally
  19. WakeSpeed WS500—Best Alternator Regulator for Lead Acid¹ and Lithium Batteries
  20. Smart Chargers Are Not That Smart
  21. Replacing Diesel-Generated Electricity With Renewables, Part 1—Loads and Options
  22. Replacing Diesel-Generated Electricity With Renewables, Part 2—Case Studies
  23. Efficient Generator-Based Electrical Systems For Yachts
  24. Battery Bank Size and Generator Run Time, A Case Study
  25. A Simple Way to Decide Between Lithium or Lead-Acid Batteries for a Cruising Boat
  26. Eight Steps to Get Ready For Lithium Batteries
  27. Why Lithium Battery Load Dumps Matter
  28. 8 Tips To Prevent Lithium Battery Black Outs
  29. Building a Seamanlike Lithium Battery System
  30. Lithium Batteries Buyer’s Guide—BMS Requirements
  31. Lithium Batteries Buyer’s Guide—Balancing and Monitoring
  32. Lithium Batteries Buyer’s Guide—Current (Amps) Requirements and Optimal Voltage
  33. Lithium Battery Buyer’s Guide—Fusing
  34. Lithium Buyer’s Guide—Budget: High End System
  35. Lithium Buyer’s Guide—Budget: Economy Options
  36. 10 Reasons Why Hybrid Lithium Lead-Acid Systems are a Bad Idea
  37. 11 Steps To Better Lead Acid Battery Life
  38. How Hard Can We Charge Our Lead-Acid Batteries?
  39. How Lead Acid Batteries Get Wrecked and What To Do About It
  40. Equalizing Batteries, The Reality
  41. Renewable Power
  42. Wind Generators
  43. Solar Power
  44. Watt & Sea Hydrogenerator Buyer’s Guide—Cost Performance
  45. Battery Monitors, Part 1—Which Type Is Right For You?
  46. Battery Monitors, Part 2—Recommended Unit
  47. Battery Monitors, Part 3—Calibration and Use
  48. Battery Containment—Part 1
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Iain Dell

I’m very grateful for this dispassionate analysis. Like many, I’m attracted not just by the obvious advantages of a Lithium system but also that undefinable desire to possess the latest ‘Gucci’ technology. However, I screwed up by adding too much extra weight to the stern with an arch and solar panels. With advice from Eric & yourself that’s now mitigated to an acceptable extent and I’ve got 380W of solar to feed 285A AGM domestic bank. That’s supported by a Balmar 100A to which I just fitted a serpentine belt to amazingly better effect.

We cruise about 5 months a year. Even with the so-so weather around the UK & Irish coasts this past 2 years with many nights at anchor, the batteries are regularly topped to 100% even after I’ve charged the batteries for the electric outboard, the 1KW Ecoflow brick that powers Starlink and the paraphernalia of ‘normal life’ that we drag onboard. Despite that I was still hankering after Lithium, feeling that I was somehow missing out. Your ‘do nothing’ description has encouraged me to take the ‘don’t be stupid again’ option; my system isn’t broke so I’ll take your advice and not fix it.

Iain Dell

Hi John – as I write we’ve been away from shore power about 3 weeks, pottering around the Isles of Scilly in variable conditions. I plug the Ecoflow into the inverter in the morning and it’s normally charged in about 3 hours despite being restricted by the inverter to only 200A. On most days the solar then fully tops the batteries to 100%. I could always plug it direct into its own panel I suppose but I’ve enough clutter and am not clever enough to do anything beyond the simple where electricity is concerned.

I’m a fan-boy for the Ecoflow which has revolutionised life on the hook, meeting all AC loads including in extremis about 2-3 hours of a dehumidifier (useful for UK weather). Other than that as well as Starlink it keeps the plethora of laptop, iPad, iPhone etc charging needs from bothering the batteries and the missus can even simmer stuff at very low power on her portable induction hob at times thus saving gas. The 1050W version works for me so far with its 10kg weight stowed midships (thanks, Eric!).

Steven Schapera

Iain – your post resonates very closely with my own position. For that reason I’m keen to know more about the Ecoflow (I will do my research) but can you comment on the 1kw size? If you were doing it again, would you buy the same size or go bigger? Did you consider the Ecoflow (mobile) solar panel as an alternative to a permanent mount. I have NO SOLAR, my batteries are Lifeline AGM’s, but I’m thinking the Ecofliw mobile solar panels would work at anchor which is (mostly) when I need it.

Iain Dell

Hi Stephen

The advantage of the 1KW size is that you can easily (and less expensively) add another 1KW expansion unit to it. When you come to sail you can shift the weight around to best effect; I wouldn’t like the big increase in both weight and dimensions of a larger size. So far the 1KW is proving enough for me but it’s nice to have an easy upgrade option if needed. If I was in your position I’d almost certainly go for the largest size of folding panel I could mount, or perhaps two smaller ones together.

William McAusland

I’d be interested in opinions on the ‘lithium hybrid’ configuration gaining popularity here. It seems a simple, low cost, way to add lithium batteries to an existing lead acid installation. I’ve not yet had an opportunity to install such a system, but it does appear to resolve many of the issues often associated with conventional lithium conversions – including the potential for the BMS to isolate the battery while entering harbour on a dark and stormy night!

The configuration and technical advantages are well explained in this page on a Dutch website:- – sadly not recently maintained.

There is lively discussion on the “12 volt boating group” on Facebook :-

You will need to join – then search for ‘hybrid’

Finally, I can recommend this charming account of installing a hybrid system on a canal narrow-boat, where a pragmatic solution to avoiding alternator overheating is discussed:-

Michał Palczyński

Hi William,
hybrid system looks tempting and I had one for two years.
Nobody on internet forums mention about how many amps you need to float LA batteries @13.2V. I had 50Ah LA battery contacted to LFP and it was consuming 0.5A! My friend has same experience. So if you plan to have more LA connected to lithiums that can be huge waste of energy.
Plus battery manufacturers don’t recommend mixing chemistries.So I gave up on this idea.
Good luck

Andre Langevin

Hello John you would save an additional layer of money by using a Smart BMS 200 which will replace the DC-DC because then the Start circuit will be feed directly to the Smart BMS 12-200 which will provide the isolation. So only two components to integrate Lithium on a current lead-acid battery/alternator. 1-Lithium battery and fuse 2-Smart BMS 12-200

This is the simplest i could get on my lithium installation. No DC-DC convertors and the Balmar 250 feed the start battery but the current all flow to the “alternator stud” of the BMSes to the current defined (about 100 A each total 200A of charge). This setup has 2 BMS in parallel for 2 Lithium battery banks.

Andre Langevin

In my configuration the Balmar 250A is connected to the two AGM (victron) start battery which have almost the same voltages as the Smart Lithium. There is a rule in the Smart BMS 200 that says: when AGM reach 13 volt then start dumping though to the Lithium. But also i had to add a rule to the MC 618 alternator regulator to say that absorption is limited to 2 hours. Without too much electronics (CAN BUS) interconnexion, i achieved the desired results which is to have the alternator replenish the Lithium and still have complete independance between either lithium banks or the AGM banks.

I understand many other configuration would work as well. This one has been made to bypass the 200 A limit of the Smart BMS 200 (limit that the Lynx doesn’t have) for the Multiplus 3000.

Edward D Simper

I have just returned from a friends boat in Panama. The intention was to help him
sail to Seattle. He has put in Drop in lithium batteries coupled with VIctron inverter/charger, cerbo, Orion dc to dc 30 amp, Digital Multicontrol and GX Touch 50 monitor. The batteries are not VIctron and I do not think that their BMS communicates with anything. In the 6 weeks I was there the batteries did 2 load dumps while tied to the dock! The VIctron controls would not work at all until a tech did a software update. Even after that the monitor gave continuous alarms and a message saying software update needed even though that had just been done. He also had 600 watts of solar and an 100 amp alternator. Neither he nor I could understand the problems with the VIctron management system and I personally think that VIctron is attempting to become too tech and forgetting that offshore boats are not in a position to do software updates and may or may not want to control things with Bluetooth, which incidentally would not work for us. This boat is about 2000 nm short of a circumnavigatIon all done with lead acid and a simple wired controller and Magnum inverter charger. Your option 9 above sounds right on. I decided that the electrical system was unreliable and coupled with some other boat issues I chose to fly home home rather than embarking on an 8000+nm voyage. The owner has recently come across 3 other boats with similar VIctron systems and the same problems. They are hopeful that he will figure it out and help them.

Let’s hear it for simplicity as opposed to ever increasing complexity in the name of high tech. AGM’s, solar, Duogen and occasionally charging from the engine worked flawlessly for us for 26,000 nm on our own boat.

Steven Schapera

Hurrah! After agonising over the temptation to “go lithium” I finally came to my senses and reminded myself that for the last 24 years my big Lifeline AGM’s have served me very well (helped, of course, by the advice received on this website for proper maintenance / equalising of AGM). I have NO solar. I am a “coastal cruiser” in the Mediterranean so get access to shore power every few days – at least. Or, I have a small Honda generator for charging emergencies, and of course the engine when that’s running which is (unfortunately) fairly frequently in a windless summer. I’m sticking with what I’ve got and what I know. 🙏

Steven Schapera

Sounds like wise advice, and 100W of solar isn’t going to create any deck issues. Thanks for the push!

Matt Marsh

Even if it’s within your DIY abilities, is it within your tolerance for frustration and committed time?

I’m quite capable of properly engineering and installing a lithium system at any of the cost / fanciness tiers John’s discussed in this series. But…. my time is not infinite. Every hour I spend on the boat re-fitting stuff like this is an hour that I do NOT spend actually sailing. So, here I am with (probably) the cheapest and most basic electrical system of any of the AAC authors’ boats. Apart from the VHF-DSC set and the LED bulbs, every bit of it would be instantly familiar to a mechanic teleported through time from 1939.

Before going down the “Budget Lithium” road, you really need to ask yourself whether troubleshooting electronics, reading technical manuals, reviewing schematics, etc. is something you genuinely enjoy.

If it is? Great. Go have fun. Spend some money and build something cool. Enjoy your puttering.

If you’d rather spend every possible moment at the helm, or swimming at anchor, or rafting up for sundowners? Then consider, seriously, whether you’d prefer to choose a system that’s simple and proven, or to pay an external expert to install and debug the fancy things you want.

Evan Effa

Hi John,

Not to stir the pot too much but having recently installed an LFP housebank (2 x460Ah Epoch batteries) for our Nordic Tug coastal cruising boat, I do have a few comments.

Yes. It is a huge amount of work to install the new system and to properly isolate the start and thruster lead acid battery banks from the LFP Housebank but the performance of the LFP bank is a total game changer.

With our ~ 960 Ah of house bank (the Epoch’s have more than their rated capacity) we can run our HW tank off the battery bank and electively use a 120V induction cooker with the ability to easily replace the energy expended no matter what the state of charge. The voltages stay consistently North of 13.2V and all instruments and appliances run more happily.

Generator runs in winter are way shorter & I no longer need to be pushing for 100% SOC before ending a generator run. In summer the LFP take everything the solar panels can throw at them and despite the HW tank & induction cooking loads achieve 99%+ SOC by day’s end.

I’m very pleased.

Would I willingly go back to a Lead Acid housebank? Not at all thank you.

(I doubt there are many boat owners who having switched to a well functioning LFP house bank would ever willingly go back to lead acid. )

As I understand it, it is a ABYC ‘recommendation’ not a requirement to have a warning of BMS shutdown. So far that has not happened with our conservative charging parameters. In addition, the risk of damage from a sudden BMS shutdown can be mitigated by using DCDC chargers for the alternator feed and having a backup DC converter from the housebank to House DC panel to avoid a loss of power to critical instruments and controls.

Although I could have gone with DVCC control for charging, I was not willing to replace my perfectly good Magnum inverter charger at this point.

As it’s turning out having the mix of Victron & Magnum chargers is working quite well without any MOSFET / BMS shutdowns.

At the time that I set out to build this system in early January, the Epoch’s were easily half the price of Victron LFP with the Epoch’s seemingly sporting a robust build quality. On the other hand, Epoch’s documentation and support is pretty poor and as you point out it is a buyer beware situation; but, I’ve been lucky to have 2 excellent batteries with flawless performance so far.

Since January though, the economics have changed with Victron’s drop in LFP pricing.

If I were to do it again, would I make the switch to LFP again? Absolutely.

Would I go for Victron instead of Epoch with their better documentation and warranty support?… maybe; but I really can’t complain about the actual performance and function of these Epoch batteries.

They have been flawless.


I hope this is relevant comment. I am a lake cruiser given to cruises in the 7 to 8 Day range. I had flooded lead acid batteries fail after six seasons on the first day of my current cruise. I was willing to replace my flooded batteries with the same technology but it wasn’t available locally and I was in a hurry. I opted for AGM batteries which were available. It turns out that my current solar controllers are not suitable or adaptable to the new AGM batteries. I had purchased the old controllers from OceanPlanet when I bought my solar panels from them. I reached out to OceanPlanet and Bruce Schwab contacted me immediately. We swapped emails going through my daughter because we’re in a remote location with no cell service. We could only text. Bruce saw us through the transition and new charge controllers are on their way. Bruce also advised how I was to use the old charge controllers safely until the new ones could be installed. We’re a small client spending small dollars but they don’t treat you like that. Ocean Planet is a remarkable company. Whatever electrical system you buy for your boat, you want that kind of service and reliability in my opinion.

Mark Gadue

Frederick Gleason


Thank you for this Buyers discussion, including option #8 Halfway Option, which I believe is the reverse of what I have done.

Because we don’t have room for much solar (100w) we will depend on alternator charging, to reduce charge time, so our system will necessarily require direct alternator charging of LFP.

The first step was to reconfigure a new larger case bus alternator (160a) for external regulation with an old Balmar regulator, and serpentine belts. This is power managed down to 50a for our current 215a FLA batteries.

The next big step would be to purchase and install a Victron Smart Battery Protect BP-100 (protection from LFP discharge, system on/off switch, bluetooth), a Lynx Smart BMS and a Wakespeed WS500 (with bluetooth and communicating with Lynx via VE BMS Canbus) and a 200-300ah Victron LFP Battery which is compatible with the Lynx.

There would be no monitoring other than the Lynx BMS Bluetooth and Victron app and the bluetooth Wakespeed app, and the perhaps a 712 Battery Monitor or maybe smartshunt.

There would be no inverter. Charging of the FLA battery needs to be worked out.

Frederick Gleason

I’ve read that the batteries themselves have bluetooth so presumably we would be able to monitor battery SOC, cell status, etc.

A Victron 200ah LFP is about $1200 and 300ah is about $1700

The entire additional system is expensive at about $1900 plus the cost of the battery minus the wiring and smaller parts of the system.

Frederick Gleason

Thanks for the link. I like the fact that the Victron BMS-battery-lynx and Wakespeed system is proven and communicates in compliance with ABYC, also that insurance issues are improved.

I see that you had 24v 200ah (1000ah @12v) for M&R56. I will need to check loads to see if 12v 200ah is enough for this boat.

The backup will just be 70ah FLA charged by an Orion 30a DC-DC. I’ll carry a starter pack for emergency engine starts (30hp yanmar).

I am hoping the bluetooth apps for Victron and Wakespeed will be adequate for our needs.

Stein Varjord

Hi Frederick,

I notice you mention that 200Ah @24V = 1000Ah @12V.

I assume that’s just a typo, but for the records, it’s 400Ah @12V.

Emile Cantin

Hi John,

Any reason why your #8 “halfway” option goes with the most expensive BMS Victron sells? They offer much cheaper BMSes (like $1k cheaper) that also feature an alternator input so you can connect an existing alternator to the Lithium bank. These ones are 12v only, but the Ve.Bus BMS & SmallBMS both support 24v and are a fraction of the Lynx in terms of price.

Emile Cantin

Still, the Lynx BMS is $1300+ CAD while the SmallBMS is $73 CAD, and the SmartBMS CL 12/100 (the one I’m talking about with the alternator port) is $230 CAD (prices from I understand not wanting to throw away anything, but I’m pretty sure anyone considering these options would be okay deferring a boat buck’s worth of expenses, especially since in that proposed configuration it’d end up saving almost a quarter of the total expense.

You make a good point about monitoring, but we can probably reuse whatever monitoring solution we already had for lead-acid batteries if it was a good one, and even if we didn’t, we can get the BMV-712 for $269 CAD which still totals less than half the price of the Lynx (and also includes a physical screen, pretty handy).

Regarding the alternator, you can use the SmartBMS CL 12/100 with the stock alternator, then later you can upgrade to an externally-regulated one which looks at the “Allowed-to-Charge” wiggle wire (Wakespeed has a profile for this) which I think is a smoother upgrade path before going full-on CAN.

So yeah, the Lynx system looks pretty spiffy but I’d probably avoid the Lynx BMS for a budget-conscious owner at this point in time. Hopefully they drop the price like they did for the battery.