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Boat Batteries – Help me Make a Final Decision

4arch

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After pretty extensive research that included making a spreadsheet of almost every LFP battery currently on the market with stats such as shipped cost and cost per 100Ah, I’ve finally narrowed my boat battery choices down to four. The goal is a battery of about 3-400Ah with low temp charging protection and external monitoring.

Option 1: Aolithium 3x 100Ah for a 300Ah battery at $1,302 shipped
  • Pros: Redundancy is provided by 3x parallel batteries. Great build quality. Openable case to inspect internals or if BMS ever needs replacement. 300A continuous discharge possible.
  • Cons: Uncertain how long the company might be around and what the warranty support is like. Smallest capacity and highest cost per Ah.
Option 2: EG4 LifePower4 1x 400Ah for $1,599 shipped (includes current sale pricing)
  • Pros: Amazing build quality. For all the complaints about the company odds are better than many others they’ll still be around to honor it down the road, minimal wiring/cables.
  • Cons: Don’t love the idea of only having a single battery. If it fails on a trip or needs to be sent in for warranty service I’m out of luck. Lowest potential discharge rate at 200A continuous. Monitoring is by PC instead of Bluetooth (not a major con).
Option 3: DIY 460Ah (2x 4s 230Ah EVE cells and 2x Overkill BMSs) at $1,375 shipped (not including battery boxes)
  • Pros: Highest capacity overall and lowest cost per Ah for batteries with Bluetooth monitoring. Known quality of all the components. Redundancy is achieved with 2 parallel packs.
  • Cons: Use of my time to assemble the packs. Not great options for casing the batteries. Extra cost for miscellaneous parts and battery enclosures.
Option 4: 3x cheap (+/-$300 per 100Ah) Amazon batteries for around $900 shipped
  • Pros: Absolute lowest cost overall and per Ah. Redundancy is provided by 3x parallel batteries. If a battery dies it can easily be swapped out with only $300 sacrificed.
  • Cons: Probably no warranty support. No Bluetooth monitoring so no way of what’s going on internally. Very little faith that these batteries will provide the 10-20 year service life the other contenders might as it’s a sealed box if anything goes wrong inside.
Curious to hear what you’d chose or if there are others I may not have considered?
 
After pretty extensive research that included making a spreadsheet of almost every LFP battery currently on the market with stats such as shipped cost and cost per 100Ah, I’ve finally narrowed my boat battery choices down to four. The goal is a battery of about 3-400Ah with low temp charging protection and external monitoring.

Option 1: Aolithium 3x 100Ah for a 300Ah battery at $1,302 shipped
  • Pros: Redundancy is provided by 3x parallel batteries. Great build quality. Openable case to inspect internals or if BMS ever needs replacement. 300A continuous discharge possible.
  • Cons: Uncertain how long the company might be around and what the warranty support is like. Smallest capacity and highest cost per Ah.
Option 2: EG4 LifePower4 1x 400Ah for $1,599 shipped (includes current sale pricing)
  • Pros: Amazing build quality. For all the complaints about the company odds are better than many others they’ll still be around to honor it down the road, minimal wiring/cables.
  • Cons: Don’t love the idea of only having a single battery. If it fails on a trip or needs to be sent in for warranty service I’m out of luck. Lowest potential discharge rate at 200A continuous. Monitoring is by PC instead of Bluetooth (not a major con).
Option 3: DIY 460Ah (2x 4s 230Ah EVE cells and 2x Overkill BMSs) at $1,375 shipped (not including battery boxes)
  • Pros: Highest capacity overall and lowest cost per Ah for batteries with Bluetooth monitoring. Known quality of all the components. Redundancy is achieved with 2 parallel packs.
  • Cons: Use of my time to assemble the packs. Not great options for casing the batteries. Extra cost for miscellaneous parts and battery enclosures.
Option 4: 3x cheap (+/-$300 per 100Ah) Amazon batteries for around $900 shipped
  • Pros: Absolute lowest cost overall and per Ah. Redundancy is provided by 3x parallel batteries. If a battery dies it can easily be swapped out with only $300 sacrificed.
  • Cons: Probably no warranty support. No Bluetooth monitoring so no way of what’s going on internally. Very little faith that these batteries will provide the 10-20 year service life the other contenders might as it’s a sealed box if anything goes wrong inside.
Curious to hear what you’d chose or if there are others I may not have considered?

Are you on a sailboat or trawler? How far between ports would you be? What loads have you calculated?

I am curious as to what you are working with as if you are in the Bahamas, you may not be more than a few hours from land. If you are in the Caribbean not more than a day or two. If open water for a month, that is a whole different concern.
 
Also I wouldn't worry about 10-20 years. If any of these companies are around in 5 years, would be surprised. Also in 5 years salt or unobtanium batteries may be the new cheap hotness and you will swap out anyway. Just musings....
 
Are you on a sailboat or trawler? How far between ports would you be? What loads have you calculated?

I am curious as to what you are working with as if you are in the Bahamas, you may not be more than a few hours from land. If you are in the Caribbean not more than a day or two. If open water for a month, that is a whole different concern.
It’s a 40 foot sailboat and I’m doing coastal cruising on the US east coast. Could be up to 48 hours without charging. Running a danfoss fridge and freezer as the major loads plus all the typical boat things. Replacing a 440Ah (220 usable) flooded bank that has mostly been fine as far as capacity.
 
Also I wouldn't worry about 10-20 years. If any of these companies are around in 5 years, would be surprised. Also in 5 years salt or unobtanium batteries may be the new cheap hotness and you will swap out anyway. Just musings....
Yeah my thinking is kind of turning toward just buying the cheapest thing that has a reasonable tear down and low temp cutoff and assuming I’ll just swap out $300 batteries if problems arise or technology advances.
 
Will did a tear down of the Powerurus 100Ah $400 and other than the sticky foam (could be beneficial for a high vibration environment like a boat), the build quality is better than the common cheap $300 ones, and has Bluetooth so you can monitor SOC and cell voltages. Their app appears basic but functional. I’ve researched these budget batteries for almost a year now and this is the one I’m convinced is the best bang for the buck. They also have a 200Ah version, $715 on Amazon right now. I’ll be purchasing soon. I messaged them on their website and they answered my questions right away.

What gives me more faith in the Powerurus is it’s made by Roypow, who has a very good reputation. Roypow also makes a higher priced waterproof brand (under the Roypow brand) that has even better build quality that Will also reviewed, but the price is higher than I want or need for my use case.

Also, like you I originally wanted the redundancy of 2x100Ah to have a backup. But the lower cost and only needing to monitor one battery (you have to switch the app between batteries, no way to view them as a single bank) has swayed me. Would suck if the single battery kicks it, but it’s also not the end of the world.
 
Will did a tear down of the Powerurus 100Ah $400 and other than the sticky foam (could be beneficial for a high vibration environment like a boat), the build quality is better than the common cheap $300 ones, and has Bluetooth so you can monitor SOC and cell voltages. Their app appears basic but functional. I’ve researched these budget batteries for almost a year now and this is the one I’m convinced is the best bang for the buck. They also have a 200Ah version, $715 on Amazon right now. I’ll be purchasing soon. I messaged them on their website and they answered my questions right away.

What gives me more faith in the Powerurus is it’s made by Roypow, who has a very good reputation. Roypow also makes a higher priced waterproof brand (under the Roypow brand) that has even better build quality that Will also reviewed, but the price is higher than I want or need for my use case.

Also, like you I originally wanted the redundancy of 2x100Ah to have a backup. But the lower cost and only needing to monitor one battery (you have to switch the app between batteries, no way to view them as a single bank) has swayed me. Would suck if the single battery kicks it, but it’s also not the end of the world.
I like the Powerurus a lot too. It's definitely a contender, interchangeable with Aolithium as my option 1 battery. The teardowns of Aolithium show a similarly impressive build quality. What maybe gives it a slight edge for me is the case is openable. Probably wouldn't ever tinker with anything inside but it's nice to be able to pop the hood and confirm the internal build matches the videos. Of course, Aolithium is about $35 more per 100Ah and those $30-40 differences start to add up when you're putting together 3-400Ah banks.
 
Replacing a 440Ah (220 usable) flooded bank that has mostly been fine as far as capacity.
You won't need a large bank when running LFP. The reason is the LFP doesn't need absorption or reach full charge.

12V system it appears? I'd simply go with 2 Overkill BMS and 8 304Ah cells in DIY with CALB or EVE cells from 18650. This allows you to swap cells down the road if needed and have redundancy.
 
Do you need low temp charging protection on a boat?
I'm trying to figure out a situation where you'd be using the boat and charging below freezing.
It's easy to add temp protection to any battery system with a victron sensors so I wouldn't make a selection based on that feature.

Is this a 12v system? I assumed so, but wanted to make sure we were all on the same page.

It's a lot easier to manage a single 400ah pack, than (4) 100ah packs in a bank. You have fewer connections, no worries about inconsistencies between discharge and charging, etc.

Have you looked at https://www.epochbatteries.com/
Excellent build quality, and rated for wet environments.
 
It’s a 40 foot sailboat and I’m doing coastal cruising on the US east coast. Could be up to 48 hours without charging. Running a danfoss fridge and freezer as the major loads plus all the typical boat things. Replacing a 440Ah (220 usable) flooded bank that has mostly been fine as far as capacity.
No Chargex Lithium Iron batteries out of Tampa?
 
Do you need low temp charging protection on a boat?
I'm trying to figure out a situation where you'd be using the boat and charging below freezing.
Bilge pumps are often wired directly to batteries so if it's a freezing cold day and the bilge pump kicks on then the charger could try to engage a charge cycle to compensate for the draw of the pump. This would be very highly unlikely as the boat is always winterized late November through March with everything disconnected and the charger turned off. To be extra cautious, I could connect the pump to the flooded engine starter battery. So no, I don't truly need low temp protection. Just seems strange to me on principle that any LFP is sold in 2023 without low temp protection.
It's easy to add temp protection to any battery system with a victron sensors so I wouldn't make a selection based on that feature.
I have a newer Xantrex inverter/charger I'd rather keep and it doesn't have this feature. Adding extra Victron equipment would negate the cost savings of buying a battery without temp protection built in.
Is this a 12v system? I assumed so, but wanted to make sure we were all on the same page.
Yes it is 12v.
Have you looked at https://www.epochbatteries.com/
Excellent build quality, and rated for wet environments.
Yes but probably overkill for my needs since the batteries are in a dry compartment. They actually cost more than a SOK marine battery.
 
After pretty extensive research that included making a spreadsheet of almost every LFP battery currently on the market with stats such as shipped cost and cost per 100Ah, I’ve finally narrowed my boat battery choices down to four. The goal is a battery of about 3-400Ah with low temp charging protection and external monitoring.

Option 1: Aolithium 3x 100Ah for a 300Ah battery at $1,302 shipped
  • Pros: Redundancy is provided by 3x parallel batteries. Great build quality. Openable case to inspect internals or if BMS ever needs replacement. 300A continuous discharge possible.
  • Cons: Uncertain how long the company might be around and what the warranty support is like. Smallest capacity and highest cost per Ah.
Option 2: EG4 LifePower4 1x 400Ah for $1,599 shipped (includes current sale pricing)
  • Pros: Amazing build quality. For all the complaints about the company odds are better than many others they’ll still be around to honor it down the road, minimal wiring/cables.
  • Cons: Don’t love the idea of only having a single battery. If it fails on a trip or needs to be sent in for warranty service I’m out of luck. Lowest potential discharge rate at 200A continuous. Monitoring is by PC instead of Bluetooth (not a major con).
Option 3: DIY 460Ah (2x 4s 230Ah EVE cells and 2x Overkill BMSs) at $1,375 shipped (not including battery boxes)
  • Pros: Highest capacity overall and lowest cost per Ah for batteries with Bluetooth monitoring. Known quality of all the components. Redundancy is achieved with 2 parallel packs.
  • Cons: Use of my time to assemble the packs. Not great options for casing the batteries. Extra cost for miscellaneous parts and battery enclosures.
Option 4: 3x cheap (+/-$300 per 100Ah) Amazon batteries for around $900 shipped
  • Pros: Absolute lowest cost overall and per Ah. Redundancy is provided by 3x parallel batteries. If a battery dies it can easily be swapped out with only $300 sacrificed.
  • Cons: Probably no warranty support. No Bluetooth monitoring so no way of what’s going on internally. Very little faith that these batteries will provide the 10-20 year service life the other contenders might as it’s a sealed box if anything goes wrong inside.
Curious to hear what you’d chose or if there are others I may not have considered?

Sun Fun Kits 304AH is nice and easy build, $1256 makes it the cheapest option while still having quality components and genuine cells: https://www.sunfunkits.com/product/54/sfk-v4-premium-heated-w200amp-bms-wbluetooth-ready-to-build

Their is also the prebuilt but its $250 more: https://www.sunfunkits.com/product/...f-heating-136v-lithium-iron-phosphate-battery.

I have 3 sfk kits, very pleased with the performance/price ratio.
 
Have you considered old school AGM batteries



I've always been concerned about the fire risk involved with lithium
 
Have you considered old school AGM batteries



I've always been concerned about the fire risk involved with lithium

The article does not mention the lithium chemistry involved in the fires. LiFePO4 tends to be more stable and reliable than say Li-ion, which is more than likely what was used in those fires.
 
Look for batteries that are fully field serviceable, such as SOK (could be others these days):
- case opens, bolted conns vs welded, etc.

If one "battery" fails, not only is it fixable in the field, but you can overhaul it in various ways:
- replace the bms with your choice, to gain more features, etc
- one cell dead, the others are still good ... carry one space cell, field fix a "dead" or problematic battery

Sooner or later, everything fails or gives grief ... how it fails, and how field-fixable, and the support from the vendor to get there, is also important. Perhaps more so on a boat, depending on excursion lengths & such. Basically, a spares program, and a field-serviceable program ...
 
Sun Fun Kits 304AH is nice and easy build, $1256 makes it the cheapest option while still having quality components and genuine cells: https://www.sunfunkits.com/product/54/sfk-v4-premium-heated-w200amp-bms-wbluetooth-ready-to-build

Their is also the prebuilt but its $250 more: https://www.sunfunkits.com/product/...f-heating-136v-lithium-iron-phosphate-battery.

I have 3 sfk kits, very pleased with the performance/price ratio.
These were on my radar but they were OOS for a long while. Pricing per Ah is in the same neighborhood as EG4, PowerUrus, and Aolithium. Paying for assembly puts them in SOK and KiloVault territory. The value proposition starts to get interesting when you use cells from 18650batterystore. Brings the cost down almost to budget battery levels.
 
I would look at larger cheap drop ins. 3x100ah batteries means a lot of cabling, and you have to be careful with cable lengths etc. there are some decent 300ah batteries that have low temp cutoff and offer reasonable charge/discharge. Will you have draw 300 amps for any extended period of time? Not likely. Most cheap drop ins have Bluetooth monitoring these days.

For the build it yourself route, you can definitely do more from a closed loop communications standpoint on the cheap. Buying this off the shelf is absurdly expensive if you even have a passing knowledge of LFP batteries. Some of those companies certainly make a nice product, but they are quite simply not worth the premium they charge, especially as the cost of the cells continues to drop. Doing a DIY battery that has all the bells and whistles can cost more than might initially account for, if you want a fully integrated system, however you can make it very solid. You can have contactors instead of mosfets for charge/discharge cutoff, which allows for much higher loads if desired. I built my own battery for my boat, and it was a good experience overall, and they have performed well. That was several years ago before the current landscape of very inexpensive drop ins, some with decent features and build quality. I would likely go in that direction if I had to do it again.
 
I like the Powerurus a lot too. It's definitely a contender, interchangeable with Aolithium as my option 1 battery. The teardowns of Aolithium show a similarly impressive build quality. What maybe gives it a slight edge for me is the case is openable. Probably wouldn't ever tinker with anything inside but it's nice to be able to pop the hood and confirm the internal build matches the videos. Of course, Aolithium is about $35 more per 100Ah and those $30-40 differences start to add up when you're putting together 3-400Ah banks.
Do you know if the Aolithium bluetooth app can monitor each cell individually? I installed it on my phone but I can't see where each cell voltage is listed, only an aggregrate. The Powerurus app looks a bit more basic, but it does display the voltage of each cell.

Thanks for the tip on Aolithium, looks good, but I wish they had a 200Ah model (lower cost, fewer cables).
 
Do you know if the Aolithium bluetooth app can monitor each cell individually? I installed it on my phone but I can't see where each cell voltage is listed, only an aggregrate. The Powerurus app looks a bit more basic, but it does display the voltage of each cell.

Thanks for the tip on Aolithium, looks good, but I wish they had a 200Ah model (lower cost, fewer cables).
I think I read on one of the forum or video comments you could install the JBD app to see cell voltages on Aolithium. Don’t know how reliable that is though.
 
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