Need some recommendations and advice on LiFePO4 battery build

[BeerBrewer]

I would like to put together a 12V 4-cell lithium (LiFePO4) battery together for my travel trailer and I need a few recommendations and advice.

First, is was thinking of purchasing the Grade A EVE cells (280 ah to 304 ah) from a site like 18650batterystore.com or DocanPower.com as I heard that these are reputable sites. Is this true? Are there other sites that I should consider?

I was planning upon using an Overkill BMS (https://overkillsolar.com/product/4s-bms-120a-lifepo4-threaded/). Its got temp protection and it will handle a 120 amp continuous discharge, which is more that enough for my needs. Is this a good enough BMS? Should I consider another?

Lastly, I've read that I'll need a variable voltage DC charger so that I can initially balance the cells but I'm not sure what to buy. Thoughts?? I did find other posts requesting the same thing, but the links no longer worked. Would this one work that I found a Amazon work or should I go larger? (https://www.amazon.com/NICE-POWER-V...=1698168319&sprefix=varia,aps,97&sr=8-17&th=1)

Your help is appreciated!

Thanks

 

[chrisski]

I was planning upon using an Overkill BMS (https://overkillsolar.com/product/4s-bms-120a-lifepo4-threaded/). Its got temp protection and it will handle a 120 amp continuous discharge, which is more that enough for my needs. Is this a good enough BMS? Should I consider another?

I use an Overkill BMS.. 120 amps is around 1400 watts. That way run your microwave, but not the AC. If that is what you want than fine.

A good power audit will be better.

Lastly, I've read that I'll need a variable voltage DC charger so that I can initially balance the cells but I'm not sure what to buy. Thoughts?? I did find other posts requesting the same thing, but the links no longer worked. Would this one work that I found a Amazon work or should I go larger? (https://www.amazon.com/NICE-POWER-V...=1698168319&sprefix=varia,aps,97&sr=8-17&th=1)

I got one a little bigger bigger and the only difference is the bigger one would be twice as quick.

https://www.amazon.com/gp/product/B082HXVRNF/

I think the correct terms are constant current and constant voltage.

 

[sunshine_eggo]

I would like to put together a 12V 4-cell lithium (LiFePO4) battery together for my travel trailer and I need a few recommendations and advice.

First, is was thinking of purchasing the Grade A EVE cells (280 ah to 304 ah) from a site like 18650batterystore.com or DocanPower.com as I heard that these are reputable sites. Is this true? Are there other sites that I should consider?

Generally yes. don't be surprised if your cells fall short by 5% on capacity.

I was planning upon using an Overkill BMS (https://overkillsolar.com/product/4s-bms-120a-lifepo4-threaded/). Its got temp protection and it will handle a 120 amp continuous discharge, which is more that enough for my needs. Is this a good enough BMS?

Yes.

Should I consider another?

JK has active balancing.

Lastly, I've read that I'll need a variable voltage DC charger so that I can initially balance the cells but I'm not sure what to buy. Thoughts?? I did find other posts requesting the same thing, but the links no longer worked. Would this one work that I found a Amazon work or should I go larger? (https://www.amazon.com/NICE-POWER-Variable-Adjustable-Switching-Regulated/dp/B0C69NHPKD/ref=sr_1_17?crid=1ZVOJ0IMYR7F0&keywords=variable+power+supply&qid=1698168319&sprefix=varia,aps,97&sr=8-17&th=1)

That one sucks...5A Any decently rated 30V/10A is better.

Download and read beginning to end a couple times:

Top Balancing LiFePo4 Cells using a low cost benchtop power supply.

To get the paper, click on the orange at the top of this page. This is a tutorial with detailed steps on how I top-balance my LiFePO4 Cells using a low-cost benchtop power supply. To get the tutorial, click on the orange "Download" button...

diysolarforum.com

 

[Q-Dog]

I don't like having a single failure point that can shut everything down, so, I would build or buy 2 smaller betteries. Then, if one fails or shuts down you only lose half of your system capacity.

 

[Tomthumb62]

I don't like having a single failure point that can shut everything down, so, I would build or buy 2 smaller betteries. Then, if one fails or shuts down you only lose half of your system capacity.

This is good logic, if you can afford it. In my use case, the only thing I really need to keep up is the fridge and freezers. As much as I’d love to have extra batteries, I have a decent generator that already was on hand.

Of course if one is preparing for the “end times” my method might fall short if I couldn’t access gasoline anymore. If that’s my time to go, I’m okay with that, but I realize not everyone is okay in the slightest with feelings of compromised safety. But if the skies go dark for weeks or months, solar will be the one to fall short, unless you’re Musk with 189 tetra giga mega octo watt hours of battery.

 

[Brucey]

This is good logic, if you can afford it. In my use case, the only thing I really need to keep up is the fridge and freezers. As much as I’d love to have extra batteries, I have a decent generator that already was on hand.

Of course if one is preparing for the “end times” my method might fall short if I couldn’t access gasoline anymore. If that’s my time to go, I’m okay with that, but I realize not everyone is okay in the slightest with feelings of compromised safety. But if the skies go dark for weeks or months, solar will be the one to fall short, unless you’re Musk with 189 tetra giga mega octo watt hours of battery.

Yes with many US states now going gung ho towards some promised land of "fossil free", endless dark skies will certainly put those with all electric setups in potential danger. Banning natural gas hookups in new builds soon in NY state, only solution is heat pumps. So if a blizzard comes thru, and power is taken out for days...better hope they have some type of generator system. Versus if they had natural gas/propane they'd just need something small to power the furnace blower and electronics...and stay alive.

 

[Q-Dog]

This is good logic, if you can afford it. In my use case, the only thing I really need to keep up is the fridge and freezers. As much as I’d love to have extra batteries, I have a decent generator that already was on hand.

Of course if one is preparing for the “end times” my method might fall short if I couldn’t access gasoline anymore. If that’s my time to go, I’m okay with that, but I realize not everyone is okay in the slightest with feelings of compromised safety. But if the skies go dark for weeks or months, solar will be the one to fall short, unless you’re Musk with 189 tetra giga mega octo watt hours of battery.

If the battery is for emergency use, one is probably fine. If you are living off of the battery, you might want at least 2. You don't really want a thawing freezer and no lights because a cell in your only battery went over or under voltage and shut down the entire system.

 

[NCislander]

I can vouch for the 18650 Battery Store. I purchased (32) LF280K cells from them earlier this year. Quality LiFePo4 cells.
I use JK BMS's on my battery banks. Happy with both decisions.
I use a Wanptek 10amp variable power supply for battery balancing/charging tasks.
P.S. The 18650 Battery Store I visited onsite, battery cell pickup. Established brick/mortor business.

 

[Tomthumb62]

Yes with many US states now going gung ho towards some promised land of "fossil free", endless dark skies will certainly put those with all electric setups in potential danger. Banning natural gas hookups in new builds soon in NY state, only solution is heat pumps. So if a blizzard comes thru, and power is taken out for days...better hope they have some type of generator system. Versus if they had natural gas/propane they'd just need something small to power the furnace blower and electronics...and stay alive.

The only way you’ll get my wood stove is by prying my cold dead hands from it lol ?

Wood, solar, wind and hydro are all sustainable. Though I really really really hate those wind turbines. So dang ugly. Maybe someone will develop a new wind turbine design that is only slightly less efficient but 99% less ugly. I will vote no anytime wind power shows up on our ballots and I think most people here, regardless of political orientation, tend to agree. Unless they change the design.

 

[Brucey]

The only way you’ll get my wood stove is by prying my cold dead hands from it lol ?

Wood, solar, wind and hydro are all sustainable. Though I really really really hate those wind turbines. So dang ugly. Maybe someone will develop a new wind turbine design that is only slightly less efficient but 99% less ugly. I will vote no anytime wind power shows up on our ballots and I think most people here, regardless of political orientation, tend to agree. Unless they change the design.

Yeah let them put the wind turbines off shore and go with jumbo units to optimize efficiency. Apparently there's a huge problem with some of Siemens wind turbines failing way quicker than they had anticipated, warranty disaster and huge losses.

 

[BeerBrewer]

I don't like having a single failure point that can shut everything down, so, I would build or buy 2 smaller betteries. Then, if one fails or shuts down you only lose half of your system capacity.

I totally agree with your logic, but one step at a time. I estimated my worst case daily electrical requirement to be about 200 AHs and that would be with the heat running. About half of the load going to the Furrion all DC refrigerator. My end goal is to have a 2 batteries so we can camp off grid for at least 3-4 days. I also plan to purchase a generator.

Yes with many US states now going gung ho towards some promised land of "fossil free", endless dark skies will certainly put those with all electric setups in potential danger. Banning natural gas hookups in new builds soon in NY state, only solution is heat pumps. So if a blizzard comes thru, and power is taken out for days...better hope they have some type of generator system. Versus if they had natural gas/propane they'd just need something small to power the furnace blower and electronics...and stay alive.

I don't want to get into a crazy debate here, but the issue with gas stoves was more about childhood asthma that the environment. This article about pretty much sums it up. (https://www.usnews.com/news/health-...ulls-ban-on-gas-stoves-due-to-health-concerns) It's just my opinion, but there should be an easy fix for that issue too and its called proper ventilation. Lastly I don't believe for a second that NY State is banning gas installs on new builds.

 

[Brucey]

I totally agree with your logic, but one step at a time. I estimated my worst case daily electrical requirement to be about 200 AHs and that would be with the heat running. About half of the load going to the Furrion all DC refrigerator. My end goal is to have a 2 batteries so we can camp off grid for at least 3-4 days. I also plan to purchase a generator.



I don't want to get into a crazy debate here, but the issue with gas stoves was more about childhood asthma that the environment. This article about pretty much sums it up. (https://www.usnews.com/news/health-...ulls-ban-on-gas-stoves-due-to-health-concerns) It's just my opinion, but there should be an easy fix for that issue too and its called proper ventilation. Lastly I don't believe for a second that NY State is banning gas installs on new builds.

Starting in 2026 in upstate for buildings under 7 stories tall. I think sooner in NYC.

https://www.cnn.com/2023/05/03/us/new-york-natural-gas-ban-climate/index.html

 

[BeerBrewer]

Yeah..,. I have read all of these "news Flashes" but there is no mention of any such ban on the NY State web site....none that I can find.

 

[Brucey]

Yeah..,. I have read all of these "news Flashes" but there is no mention of any such ban on the NY State web site....none that I can find.

I don't know what to tell you. I live in upstate NY, the provisions were passed with the state budget in May this year. This isn't some scaremongering rumor. It's actually happened. Now whether it stands up to legal challenges remains to be seen.

 

[Tomthumb62]

Yeah..,. I have read all of these "news Flashes" but there is no mention of any such ban on the NY State web site....none that I can find.

Things that are on the table at the state level but not finalized are not going to be front and center like a news site.

I understand why governments do it this way. If they acted like “breaking news” for anything not finalized it would likely lead to a storm of rumors and hamper progress in a system that’s known to be heavy enough from beaurocacy. I mean look at California and “prop 65”. Intended to educate but tends to have the opposite effect…I always sigh, laugh and ignore anytime I see “proposition 65” on a product.

 

[Brucey]

Our idiot governor boasting about it

New York set to ban gas furnaces, stoves in new buildings

“We’re going to be the first state in the nation to advance zero-emissions new homes and buildings,” Hochul said.

www.politico.com

 

[Tomthumb62]

One of the best things I ever did: I turned off and got rid of television. I occasionally watch the news, but I know there’s always a liberal or conservative bias, except for the truly neutral (they do it better than most) news sources. Most likely you’ve never heard of the neutral news outlets, because they aren’t driven by clicks. Clicks sells ads which makes any company driven by clicks most likely, driven by profit motives.

Government websites aren’t perfect and may not deliver news like info, but there are many politicians that try to do what’s best for everyone. The famous political names on television are just distractions to keep you clicking and making the non neutral news sources more money.

Don’t get me wrong, even the profit driven ones do occasionally produce good content, but it’s rare.

 

[BeerBrewer]

Hmmmm... My comment was directed at the fact the proposed ban was for health reason and not for environmental global warming issues....that's it, that's the extent of it. I also said that I didn't want to enter into a great debate and yet here we are. I'll believe the ban when I see it passed into law and not before. Why worry about something I have no control over?

In the mean time.....I need to put together a lithium battery.

 

[OTRwSolar]

I would like to put together a 12V 4-cell lithium (LiFePO4) battery together for my travel trailer and I need a few recommendations and advice.

First, is was thinking of purchasing the Grade A EVE cells (280 ah to 304 ah) from a site like 18650batterystore.com or DocanPower.com as I heard that these are reputable sites. Is this true? Are there other sites that I should consider?

I was planning upon using an Overkill BMS (https://overkillsolar.com/product/4s-bms-120a-lifepo4-threaded/). Its got temp protection and it will handle a 120 amp continuous discharge, which is more that enough for my needs. Is this a good enough BMS? Should I consider another?

Lastly, I've read that I'll need a variable voltage DC charger so that I can initially balance the cells but I'm not sure what to buy. Thoughts?? I did find other posts requesting the same thing, but the links no longer worked. Would this one work that I found a Amazon work or should I go larger? (https://www.amazon.com/NICE-POWER-Variable-Adjustable-Switching-Regulated/dp/B0C69NHPKD/ref=sr_1_17?crid=1ZVOJ0IMYR7F0&keywords=variable+power+supply&qid=1698168319&sprefix=varia,aps,97&sr=8-17&th=1)

Your help is appreciated!

Thanks

We just built a 12v 4s lifepo4 battery pack for our RV using 4, 304ah EVE cells from 18650batterystore (came with flexible busbars---nice to have in a mobile RV environment). Cells tested at slightly more than 304ah at .2c . Use a JBD 200a BMS (with bluetooth & heater terminal option). It's been our go-to BMS for our last few builds---a very reliable, reasonably priced unit. Use a 200a BMS because we routinely power a microwave and a/c unit (not at the same time).

We quit formally top-balancing our 4s cell packs in parallel at 3.60 - 3.65v using a power supply a few years ago. Nowadays we simply install a 4s Heltec 5a active balancer ($25-$30) with a switch connected to the "run" terminal. Switch it on to do the initial top-balance or whenever the cells require routine balancing. The Heltec can easily balance our cells to within 1-3mv in less than a hour. Works perfectly for our needs.

 

[Stepandwolf]

Yes with many US states now going gung ho towards some promised land of "fossil free", endless dark skies will certainly put those with all electric setups in potential danger. Banning natural gas hookups in new builds soon in NY state, only solution is heat pumps. So if a blizzard comes thru, and power is taken out for days...better hope they have some type of generator system. Versus if they had natural gas/propane they'd just need something small to power the furnace blower and electronics...and stay alive.

Or do like I have done, turn on the stove and oven, no power needed