Cheapest DIY 12V 100Ah LiFePO4 battery build? 60Ah?

[Ample]

Part-time RV situation. I'm contemplating a big DIY battery using some of the great experiences people have kindly shared. A single 280Ah battery will be more than what I need.

A single big battery would "all your eggs in one basket" though. So I'm thinking that maybe I should have a small backup battery for critical things such as a fridge and laptop charging. Because of the very long self-discharge of LiFePO4, I could have this backup battery charged up and just sitting in a corner of the RV ready to be plugged in should the main battery fail.

What could be the cheapest 100Ah LiFePO4 battery I could make? Any links to cells and a BMS would be welcome.

It could even be 60Ah if there's a big price difference.

I'm just looking for insurance against a battery failure when I'm on a long trip. If I was in an urban area when a battery failure occurs, I could simply pickup a $99 deep cycle lead-acid battery, but sometimes I'm fairly far away from civilization. Further, the benefits of LiFePO4 have me addicted.

I have a name-brand 100Ah LFP battery now and I could use that as a backup. But I have something else in mind for it.

 

[Deleted member 165]

What is the power usage of the refrigerator? I think you may be undersizing your battery a bit.

 

[Ample]

What is the power usage of the refrigerator? I think you may be undersizing your battery a bit.

It's a small fridge for an RV about the size of a cooler. Consumes about 4A at 12V for a few minutes several times an hour. Maybe 25Ah every 24 hours.

So even a 60Ah battery should be good for up to 2 days if no charging at all. A 100Ah battery would be completely fine (because that's all I run right now and I can cook, run lights, ventilation fan, etc.--everything).

 

[Loseby]

I'm wondering the same thing right now/having the debate on AGM vs. LiFePO for my minimalist minivan system. Like you I'm also seeking >50Ah of usable capacity; no fridge but I'd like 2-3 days of charging laptops, cell booster, and running hungry ham radios.

Thus far I have been considering a 100Ah system (80Ah usable); Will's deals page is pretty consistent with what I'm finding elsewhere. So $550 for 4 aluminum-case cells including US warehouse/shipping, and $50-100 for a BMS. A 60Ah system (50Ah usable) would be $336 for 4 cells, so that's also an option.

Which leads me back to AGM - I can get 100Ah (50Ah usable) of AGM for ~$200, or 60Ah (50Ah usable) of LiFePO for ~$400 with a cheap BMS. Yes, the LiFePO system will achieve far more cycles, but I'm also a cheap bastard who only uses the van on weekends.

But wait! In looking on Amazon at AGM batteries, I discovered this Miady LFP16AH 12V 16Ah LiFePO4 Battery for $46. Wait... $46? And it includes a BMS?! What am I missing here? Putting four of these in parallel should get me 50Ah usable capacity for <$200, which seems like a no-brainer over a big ol' 100Ah AGM. And just add more in parallel for more capacity later if needed.

 

[Ample]

I'm wondering the same thing right now/having the debate on AGM vs. LiFePO for my minimalist minivan system. Like you I'm also seeking >50Ah of usable capacity; no fridge but I'd like 2-3 days of charging laptops, cell booster, and running hungry ham radios.

Thus far I have been considering a 100Ah system (80Ah usable); Will's deals page is pretty consistent with what I'm finding elsewhere. So $550 for 4 aluminum-case cells including US warehouse/shipping, and $50-100 for a BMS. A 60Ah system (50Ah usable) would be $336 for 4 cells, so that's also an option.

Which leads me back to AGM - I can get 100Ah (50Ah usable) of AGM for ~$200, or 60Ah (50Ah usable) of LiFePO for ~$400 with a cheap BMS. Yes, the LiFePO system will achieve far more cycles, but I'm also a cheap bastard who only uses the van on weekends.

But wait! In looking on Amazon at AGM batteries, I discovered this Miady LFP16AH 12V 16Ah LiFePO4 Battery for $46. Wait... $46? And it includes a BMS?! What am I missing here? Putting four of these in parallel should get me 50Ah usable capacity for <$200, which seems like a no-brainer over a big ol' 100Ah AGM. And just add more in parallel for more capacity later if needed.

Thanks for pointing this out, Loseby! I don't know what to make of it. It's almost too good to be true!

If you do get it, please report back your results.

If you wire up 4 in series, consider hooking them up for optimal balancing: https://www.iotaengineering.com/pplib/balancedcharging.pdf

Aside: can you talk a little about your ham radio setup? Just some brief info on the type of radios and the antennas you are using as I find it interesting you are operating out of a minivan. I'm not a ham but find the technology somewhat fascinating and am wondering if a mobile setup is limiting in any way.

 

[vtx1029]

But wait! In looking on Amazon at AGM batteries, I discovered this Miady LFP16AH 12V 16Ah LiFePO4 Battery for $46. Wait... $46? And it includes a BMS?! What am I missing here? Putting four of these in parallel should get me 50Ah usable capacity for <$200, which seems like a no-brainer over a big ol' 100Ah AGM. And just add more in parallel for more capacity later if needed.

Did you see the C rating? I'd want at least .4C for a camping install. Otherwise yes that is dirt cheap

 

[vtx1029]

I have some 90ah and 60ah cells coming. Both are pretty affordable. (fyi I purchased more than just 4 cells of each one so my shipping may be different than yours)

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4 cells shipped to Minnesota is $142

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4 cells shipped to Minnesota is $109

Combine that with https://www.aliexpress.com/item/4000425316662.html?spm=a2g0s.9042311.0.0.5ae74c4d6jvG54
and you have a pretty affortable battery. Make sure to buy the bluetooth module.

 

[alfaeric]

From my investigations, the cheapest way is to find used batteries and try to assemble them into a 12V configuration. I even have gone down that path- with some neat 36V A123 battery modules. Turning those into 12V has turned into being a problem, since I need a battery welder to do it. Still working that out. But there have been both 24V and 48V modules on Battery Hookup, too. If I were to do this again, that's the path I would take, since 24V and 48V hardware is a lot more common. And the price/kw-hr is pretty much the same.

If one can cleanly take off the original BMS and then solder in one that you can work with, then it ends up being a pretty cheap solution to battery storage. The 36V modules I have are 384 w-hr new, so I figure 300w-hr. So for a 100A-hr*12V system, you need 4 of them. For example.

 

[alfaeric]

I have some 90ah and 60ah cells coming. Both are pretty affordable. (fyi I purchased more than just 4 cells of each one so my shipping may be different than yours)

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4 cells shipped to Minnesota is $142

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4 cells shipped to Minnesota is $109

Combine that with https://www.aliexpress.com/item/4000425316662.html?spm=a2g0s.9042311.0.0.5ae74c4d6jvG54
and you have a pretty affortable battery. Make sure to buy the bluetooth module.

How do you get such cheap shipping? For the second one, I'm getting shipping that is really expensive... To just the US. Both of the battery sets end up being over $200.

If that can be done, it's a great deal.

 

[Electric Personality]

How do you get such cheap shipping? For the second one, I'm getting shipping that is really expensive... To just the US. Both of the battery sets end up being over $200.

If that can be done, it's a great deal.

I have my doubts based on that link.

 

[vtx1029]

How do you get such cheap shipping? For the second one, I'm getting shipping that is really expensive... To just the US. Both of the battery sets end up being over $200.

If that can be done, it's a great deal.

I ordered 20 of them, Ask the shipper for a quote. it is usually cheaper that what is quoted

 

[vtx1029]

I have my doubts based on that link.

I hope not, but time will tell

 

[DASH]

Have You considered a Solar Generator? Add a solar panel, and You have a complete independent backup system, that can recharge the battery.

 

[Loseby]

Thanks for pointing this out, Loseby! I don't know what to make of it. It's almost too good to be true!

If you do get it, please report back your results.

I just bought the following on Amazon as a proof-of-concept, I will report back later this week

• 1x 12V 16Ah Deep Cycle LiFePO4 Battery, 2000 Cycles Miady LFP16AH
• 1x Mroinge MBC055 6V/12V 5.5A Smart Vehicle Battery Charger Maintainer
• 1x Watt Meter Power Analyzer - Greatlong 130A Power Analyzer

Did you see the C rating? I'd want at least .4C for a camping install. Otherwise yes that is dirt cheap

I'm hoping the C rating is a typo? I am a relative newbie (my EE degree is very rusty) but here's what the data sheet shows, on a supposedly 16Ah battery:

• Charger Current 10A
• Max Charge Current 40A
• Discharge Current 42A
• Max Continuous Current 42A
• Max Pulse Current 80A

My system will NOT have a permanently installed inverter or any individual load over 20A. Also, building a parallel system with 3-6 batteries should spread charge/discharge load...?

Have You considered a Solar Generator? Add a solar panel, and You have a complete independent backup system, that can recharge the battery.

Yes, I really want to like the Jackery, but the problem for me is limited charge and discharge rates on the external DC ports. My ham radios can draw up to 15A on transmit, and most "generators" only have 10A cigarette lighter sockets. Additionally they charge from DC super slow!

Aside: can you talk a little about your ham radio setup? Just some brief info on the type of radios and the antennas you are using as I find it interesting you are operating out of a minivan. I'm not a ham but find the technology somewhat fascinating and am wondering if a mobile setup is limiting in any way.

Yes! The mobile radios I use are VHF/UHF local coverage, the same Motorola XPR4550 radios used in commercial fleet vehicles. They require a 12-36" antenna mounted somewhere on the exterior of the vehicle, and are single DIN sized just like a car's head unit. They draw ~1A on receive and 7-8A on transmit, and often times I'll have two running. I also have a Yaesu FT-891 HF (shortwave) radio which requires a much larger antenna, often hung from a tree. This draws ~1A on receive and 15A peak on transmit.

The van is a Ram Promaster City, the cargo version of a Fiat Doblo "people carrier". There are no seats in back, instead I've built a futon lengthways. It's quite comfortable to hang out in the back and play radio while camping, then put away the radios and pull out the futon for bed. My only real limitation to "operating mobile" thus far has been power while stationary, which is why I am here

 

[alfaeric]

I ordered 20 of them, Ask the shipper for a quote. it is usually cheaper that what is quoted

Interesting. If i get back into that position, I will ask for sure. Have you gotten yours? Or have you posted about getting them? I'd like to read your experience.

 

[DASH]

Yes, I really want to like the Jackery, but the problem for me is limited charge and discharge rates on the external DC ports. My ham radios can draw up to 15A on transmit, and most "generators" only have 10A cigarette lighter sockets. Additionally they charge from DC super slow!

This Solar Generator has 12V/25A output plug, and can accept up to 700 watts PV. Plenty of other features too. There are downsides: Cost; $1,000+ (but not bad for what it does), Heavy 50lbs. Now available for sale, but not scheduled to be delivered till September. Crowd sourcing Project.

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There's additional information about it, on this forum.

 

[vtx1029]

I just bought the following on Amazon as a proof-of-concept, I will report back later this week

• 1x 12V 16Ah Deep Cycle LiFePO4 Battery, 2000 Cycles Miady LFP16AH
• 1x Mroinge MBC055 6V/12V 5.5A Smart Vehicle Battery Charger Maintainer
• 1x Watt Meter Power Analyzer - Greatlong 130A Power Analyzer

I'm hoping the C rating is a typo? I am a relative newbie (my EE degree is very rusty) but here's what the data sheet shows, on a supposedly 16Ah battery:

• Charger Current 10A
• Max Charge Current 40A
• Discharge Current 42A
• Max Continuous Current 42A
• Max Pulse Current 80A

My system will NOT have a permanently installed inverter or any individual load over 20A. Also, building a parallel system with 3-6 batteries should spread charge/discharge load...?


Yes, I really want to like the Jackery, but the problem for me is limited charge and discharge rates on the external DC ports. My ham radios can draw up to 15A on transmit, and most "generators" only have 10A cigarette lighter sockets. Additionally they charge from DC super slow!


Yes! The mobile radios I use are VHF/UHF local coverage, the same Motorola XPR4550 radios used in commercial fleet vehicles. They require a 12-36" antenna mounted somewhere on the exterior of the vehicle, and are single DIN sized just like a car's head unit. They draw ~1A on receive and 7-8A on transmit, and often times I'll have two running. I also have a Yaesu FT-891 HF (shortwave) radio which requires a much larger antenna, often hung from a tree. This draws ~1A on receive and 15A peak on transmit.

The van is a Ram Promaster City, the cargo version of a Fiat Doblo "people carrier". There are no seats in back, instead I've built a futon lengthways. It's quite comfortable to hang out in the back and play radio while camping, then put away the radios and pull out the futon for bed. My only real limitation to "operating mobile" thus far has been power while stationary, which is why I am here

Where did you find the data sheet of the 16ah battery? I also purchased one to see how it shakes out. Sounds like you have a solid plan to me. Wonder how many you could pack into a 50cal ammo can?

Interesting. If i get back into that position, I will ask for sure. Have you gotten yours? Or have you posted about getting them? I'd like to read your experience.

I ordered them about 3-4 weeks ago so if its like my last order of cells I have another 5-7 weeks before they show up.

 

[tim0shel]

I am interested in that battery for geez I dont know but will not be hard to figure something out. I already have in the works a solar generator using the 280ah batteries. Keep us updated on that battery how it tests out.

 

[mboehk]

I have some 90ah and 60ah cells coming. Both are pretty affordable. (fyi I purchased more than just 4 cells of each one so my shipping may be different than yours)

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4 cells shipped to Minnesota is $142

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4 cells shipped to Minnesota is $109

Combine that with https://www.aliexpress.com/item/4000425316662.html?spm=a2g0s.9042311.0.0.5ae74c4d6jvG54
and you have a pretty affortable battery. Make sure to buy the bluetooth module.

That's an insane price, not even close to the rest of the market. I can't figure out how it's possible at all.
Let us know if they work out because it seems impossible, but if true they will change the whole market.

Mike

 

[sremick]

That's an insane price, not even close to the rest of the market. I can't figure out how it's possible at all.
Let us know if they work out because it seems impossible, but if true they will change the whole market.

Considering 280Ah cells (the most popular right now) can be had for just over $80/ea., that price on 90Ah cells is pretty much spot on for current market prices $/Ah.