Economical LiFePO4 car battery replacement?

[supersignman]

I'm wondering if these cells from Battery Hookup could be a legit LiFePO4 car battery replacement?

https://batteryhookup.com/products/new-case-with-6x-3-2v-74ah-lifepo4-prismatic-cells

They were originally intended for 12V starter batteries and have a 600A discharge rate for 10 seconds which should be enough for most cars. You might need to put multiple banks in parallel for a diesel truck though. At $30 ea. x 4 = $120, you're looking at the same price the average lead acid car battery costs these days (and some are way more than that) but these should last 20+ years where an average lead acid car battery is scrap in 5 years.

I realize the big drawback is low temp charging in cold climates though. You would need some sort of heat wrap around it in those situations but if you're in an area where it doesn't get below freezing at night, would this work? I'm guessing you'd probably need some 1"x1/4" thick copper bus bars between cells to handle that much current but those would be easy to make from a piece of flat bar.

The other thing I'm thinking about is the availability of car batteries during a time of war or during a time of hyperinflation. As expensive as they are now, what will they be then? In that situation, you could just make sure you didn't drive the car when it was below freezing if you didn't have a way to heat the cells. The other great thing about these cells is that you could use them in your solar storage bank until you needed them in your car because they work out to only $.12 per watt hour.

I regards to a BMS, from what I gather, you could wire them so they could discharge without the BMS and charge with the BMS. In a crisis situation, I'm thinking you might not even worry about a BMS. If you checked the cells and top balanced them every few months, would you even need a BMS? I would think the average car alternator would provide the correct voltage to charge these since their full voltage is only slightly above a standard car battery (3.2V x 4 = 12.8V).

 

[DIYrich]

Battery is rated for 180a continuous discharge. Don't know if it can maintain that at low temps.

What is Considered to Be a Good CCA Rating for a Battery?​

A small car can be started with a battery featuring as little as 150 CCAs. Larger vehicles such as pickup trucks and SUVs will require a battery with 400 to 500 CCAs. It's possible to find batteries with CCA ratings as high as 1150. But just because you can find it, doesn't mean that you need it.​

Might need to parallel 2 or 3 banks depending upon the size of your car.
Definitely want battery temp monitor to disable charging when near freezing or below.

If the SHTF, then anything is better than nothing. So, make an extra 16s bank for your Solar, and remake it into a 4s3p when desperate (with 4 extra cells, just in case).

​

 

[MrSparkle]

I do not remember what member have this signature, but it feels spot on.

"BMS or BE a MESS!"

Bms prime function is not to balance cells, but to protect from over/under Voltage, over Current, over/under Temperature, etc.

 

[supersignman]

Battery is rated for 180a continuous discharge. Don't know if it can maintain that at low temps.

What is Considered to Be a Good CCA Rating for a Battery?​

A small car can be started with a battery featuring as little as 150 CCAs. Larger vehicles such as pickup trucks and SUVs will require a battery with 400 to 500 CCAs. It's possible to find batteries with CCA ratings as high as 1150. But just because you can find it, doesn't mean that you need it.​

Might need to parallel 2 or 3 banks depending upon the size of your car.
Definitely want battery temp monitor to disable charging when near freezing or below.

If the SHTF, then anything is better than nothing. So, make an extra 16s bank for your Solar, and remake it into a 4s3p when desperate (with 4 extra cells, just in case).

​

I actually didn't realize that small cars could be started with only 150 CCAs. Once the car is actually started, the battery is pretty much just along for the ride because the alternator takes over from there and puts current back into the battery.

 

[wpns]

I actually didn't realize that small cars could be started with only 150 CCAs. Once the car is actually started, the battery is pretty much just along for the ride because the alternator takes over from there and puts current back into the battery.

The only other constraint you have then is the battery charge current, if it's too high you risk burning out the alternator. Also, if the battery overcharges and the BMS takes it offline, the alternator may not work properly without a load and the voltage could get very high.

IMHO, LFP just isn't ready for drop-in LA replacement.

 

[aronhoustongy]

I'm wondering if these cells from Battery Hookup could be a legit LiFePO4 car battery replacement?

https://batteryhookup.com/products/new-case-with-6x-3-2v-74ah-lifepo4-prismatic-cells

They were originally intended for 12V starter batteries and have a 600A discharge rate for 10 seconds which should be enough for most cars. You might need to put multiple banks in parallel for a diesel truck though. At $30 ea. x 4 = $120, you're looking at the same price the average lead acid car battery costs these days (and some are way more than that) but these should last 20+ years where an average lead acid car battery is scrap in 5 years.

I realize the big drawback is low temp charging in cold climates though. You would need some sort of heat wrap around it in those situations but if you're in an area where it doesn't get below freezing at night, would this work? I'm guessing you'd probably need some 1"x1/4" thick copper bus bars between cells to handle that much current but those would be easy to make from a piece of flat bar.

The other thing I'm thinking about is the availability of car batteries during a time of war or during a time of hyperinflation. As expensive as they are now, what will they be then? In that situation, you could just make sure you didn't drive the car when it was below freezing if you didn't have a way to heat the cells. The other great thing about these cells is that you could use them in your solar storage bank until you needed them in your car because they work out to only $.12 per watt hour.

I regards to a BMS, from what I gather, you could wire them so they could discharge without the BMS and charge with the BMS. In a crisis situation, I'm thinking you might not even worry about a BMS. If you checked the cells and top balanced them every few months, would you even need a BMS? I would think the average car alternator vehcile wrap advertising would provide the correct voltage to charge these since their full voltage is only slightly above a standard car battery (3.2V x 4 = 12.8V).

yes great for If SHTF, having something is always better than nothing. Build an extra 16s battery bank for your solar setup, and in a pinch, you can reconfigure it into a 4s3p setup (with four spare cells for backup).

 

[supersignman]

Yes, if you notice, the price of the cells has dropped from $30 ea. to $23.50 each since I first posted this. That means a four-cell car battery is less than $100.

I have a practical question regarding the necessity of a BMS in this situation though... if you top balance all the cells before configuring them into a 4s car battery, how much individual cell voltage drift are you going to get over time if you have a well tuned engine that typically cranks in 2 seconds? I know there are people who say it's blasphemous to have a LiFePO4 battery without a BMS, but what if the 2 second draw from the starter drained less than 1% of the capacity of the battery bank - which was then immediately re-charged by the alternator? Your battery bank is only going to cycle from 100% to 99% and back to 100%, etc. under normal conditions. If the conditions stayed like that over a log period of time (say a couple of years) would you still have individual cell voltage drift which could eventually cause a cell to go over voltage when charging?

The reason I'm questioning this is because I watched a Youtube video on this subject where the guy gave the standard advice of how you should never do this without a BMS... but down in the comments there were multiple people from all over the world who said they had done this successfully without a BMS in their cars for years. They were mostly people from third world countries and remote areas where sourcing normal lead-acid car batteries was difficult.

 

[wpns]

I mean, even our Fearless Leader @Will Prowse has been rumored to have done this in the past, but the various functions that the BMS provides would seem to be at least desirable if you can provide them. {Cell,Battery}-{Under,Over}-{Temperature,Voltage,Current} and the usual array of comms, so you can tell how the battery is doing, are pretty much requirements in _MY_ book, but raw cells will certainly work, for a time, probably without catastrophic failure, if you want to save a few bucks.

 

[supersignman]

The problem to me is finding a BMS (and the cost of it) that can handle a 600A draw. Personally, I've never seen a BMS commercially available that would deliver that much amperage but I'm sure somebody makes one somewhere. I'm guessing it would cost more than the combined cost of the cells though. We're in a situation now where the price of these cells has fallen to $23.50 ea. If you're someone who has several vehicles, tractors, generators, lawnmowers, etc., how much are you going to spend on lead acid batteries per year in the future with the cost of them going up so much? If a typical lead-acid battery lasts 4 - 5 years, you might need to figure on budgeting a few hundred dollars per year for lead-acid replacements as they age out.

My plan is to run these cells without a BMS and then remove the bus bars to do a top balance once a year if necessary. You can also easily check the individual cell voltages with a volt meter at any time if you leave the studs exposed. I've only put one of these batteries on a generator so far but it has worked great and the no-load voltage loss over time without a trickle charger has been next to nothing. Pic is attached. You can get the M8 battery terminal adapters on Amazon really cheap.

 

[Ruff]

They make a Lithium-Ion car battery, not so sure about multiple uses though.

I have an" AntiGravity" brand Lithium-Ion battery in my Mini Cooper. Since it may spend a long period of not being driven, this has allowed me to not use a trickle charger. It has set in storage for more than 2 months and still started right up. The slower self discharge was one of the main reasons I bought it. It has a built in emergency jump start feature as well, just push a button on the battery (or on the small key fob) and then start the car. I have not yet needed this feature so I cannot tell you is it really works or not. Not a big deal on my weekend toy. Not so sure I am ready to put one in my daily driver. They claim a better self discharge rate than FLA battery and a life span that is up to 4 times longer.

The operating warnings state:

OPERATING TEMPERATURE. This product is designed to working ambient temperatures between -–10°C to 60°C (–4°F to 140°F). Do not operate outside of temperature ranges. Do not jump start a frozen battery. Do not charge a Frozen Battery. Only charge within the range of 0°C to 45°C (32°F to 113°F) Discontinue use of product immediately if the battery becomes excessively warm.

COMPATIBILITY. The product is only compatible with 12-volt stock systems in vehicles. Do not attempt to use product with any other type of batteries or in series or parallel with another battery, or interior electronics could be damaged. Use with, or Jump starting other battery chemistries may result in explosion, injury, death or property damage. Contact the battery manufacturer prior to attempting to jumpstart the battery. Do not jump start a battery if you are unsure of the battery’s specific chemistry or voltage.



Jeff

 

[supersignman]

Will Prowse started his Youtube channel as a broke guy living in an RV and became very successful because there are a whole lot more broke guys out there that could relate to him than there are rich guys who can afford to spend thousands of dollars for the latest and greatest setups. He even said the most popular video he's had (and the most popular page on his website) has been the hand cart with a battery and an AIO. Maybe this idea of an economical lithium car battery replacement would make a good video and allow him to get back to his roots?

One of the things I'm working on now is heating pads. I found these on Amazon ( https://www.amazon.com/gp/product/B0BDYBTNCD/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1 ) and I'm working on being able to insert them in between the slot between the 1st & 2nd cell and the 3rd & 4th cell (which would only require 2 per battery) along with a toggle switch to manually turn them on when temps are under freezing. Even though I live in Alabama, for this to work on a daily driven vehicle, I need to be able to heat the cells up on cold mornings. Starting the car under freezing won't damage the cells but a problem will arise when the alternator kicks in to recharge them. It would require going out and turning the switch on a little while before you wanted to leave, but in my situation where freezing temps only occur a handful of nights per year, that wouldn't be a big hassle. If someone wanted to make this really slick though, they could have an automatic temp sensor that turned the heating pads on. You'd risk them running the battery down though if you didn't drive the vehicle often.

 

[k490]

I'm not sure this would be an issue with a single 12V 100 ah Lithium battery but I do know it is an issue with a larger battery bank. Alternators are not designed to dump max current for long periods of time. Lead acid naturally reduces the current load fairly quickly as it approaches 80% charge. Even if you have a 180 amp alternator they can't push out 180amps for an hour it will overheat and melt it down. LIfepo4 battery will pull lot of current automotive regulators do not have current limiting they work off voltage regulation.

 

[Ruff]

Well I have one of the antigravity life pole batteries in my mini Cooper for more than a year. Granted most the time it sits in the garage with a cover on it. One of the reasons I went with this is so I wouldn't have to use a trickle charger on it. I drove it four to five hours a day for 2 weeks and 6,200 miles during MTTS 2024 this last summer from Albuquerque New Mexico to Seattle Washington. But I had to drive from Kansas City to New Mexico and back and have not seen any ill effects. It is back sitting in my garage and all seems fine.I do understand what you were talking about, and I guess we'll see how well the denzo alternator holds up on the little car
As I said it first, this is not my daily driver, and I would not put one in my daily driver.

 

[MattiFin]

The problem to me is finding a BMS (and the cost of it) that can handle a 600A draw. Personally, I've never seen a BMS commercially available that would deliver that much amperage but I'm sure somebody makes one somewhere. I'm guessing it would cost more than the combined cost of the cells though. We're in a situation now where the price of these cells has fallen to $23.50 ea. If you're someone who has several vehicles, tractors, generators, lawnmowers, etc., how much are you going to spend on lead acid batteries per year in the future with the cost of them going up so much? If a typical lead-acid battery lasts 4 - 5 years, you might need to figure on budgeting a few hundred dollars per year for lead-acid replacements as they age out.

My plan is to run these cells without a BMS and then remove the bus bars to do a top balance once a year if necessary. You can also easily check the individual cell voltages with a volt meter at any time if you leave the studs exposed. I've only put one of these batteries on a generator so far but it has worked great and the no-load voltage loss over time without a trickle charger has been next to nothing. Pic is attached. You can get the M8 battery terminal adapters on Amazon really cheap. View attachment 264328

Instead of high current BMS I’d use just balancer. If you run your battery totally empty it might be smart to discard it. Best case you just lose significant part of capacity and cycle life, worst case it is going to catch fire later on.

IMHO Cold temperature charging is biggest problem with Lifepo4. Some charging is ok before it turns to fire bomb but nobody is able to tell you the safe charching limits below freezing temps.

 

[AdriftAtlas]

Unless one can ensure the battery stays above freezing it's a nonstarter.

 

[supersignman]

I wanted to update this thread with my latest improvement to the battery. I added the silicone heating pads (shown in foreground) I linked to in the previous post and they work great. I wired them in with a toggle switch so it's a manual system you'd have to engage several minutes (or longer depending on how cold it is) prior to starting the vehicle in freezing conditions. You could leave the switch on while driving to continually heat the batteries but you'd need to remember to turn it off at some point if the vehicle was going to sit for a while. I used two 30W pads in parallel and the total battery capacity is 947 watt hours so it would take approximately 15 hours to drain the battery if you accidentally left the switch on. If you lived in a really cold climate, you could always put the battery in an insulated enclosure.

It's a design that should appeal more to the preppers of the world rather than those who assume our hyper-complex supply chains will always be working in perfect order. It should also appeal to those who think the fiat currency known as the US dollar might someday revert to the mean value of all fiat currencies in history.

 

[sunshine_eggo]

I do not remember what member have this signature, but it feels spot on.

"BMS or BE a MESS!"

Bms prime function is not to balance cells, but to protect from over/under Voltage, over Current, over/under Temperature, etc.

@Craig

 

[MrSparkle]

You could leave the switch on while driving to continually heat the batteries but you'd need to remember to turn it off at some point if the vehicle was going to sit for a while.

Shouldn't there be some simple components like timer-switch/button?
Say one made to turn it self off after 30 minutes? Just pop the button and batteries are warmed. After 30 minutes it turns it self off.

 

[supersignman]

If the prime function of a BMS is to protect from over/under voltage & over current (disregarding temp if you can manually control that), then it seems like a BMS in a closed system wouldn't be critical where the charging device (alternator) is incapable of providing more amperage or voltage than the cells can handle.

People with a prepper mindset have a Plan A, Plan B, Plan C, etc. for future contingencies... and this seems like a good Plan B for those who prefer not to walk.

 

[supersignman]

Shouldn't there be some simple components like timer-switch/button?
Say one made to turn it self off after 30 minutes? Just pop the button and batteries are warmed. After 30 minutes it turns it self off.

I'm open to suggestions if there is an inexpensive, simple way to incorporate that!

 

[HarryN]

The main risk is that if the battery becomes disconnected from the alternator for any reason there will very large voltage spike.

For example if the bms trips for any reason.

This spike will wipe out most of the electronics in the 12 volt system, including the alternator.

It is a very painful lesson.

If it were me, I would instead look at a super cap starting "battery" and a very small lead acid battery companion.

 

[Rocketman]

My brother needed a new battery for his side by side - the parts store had a lithium battery.

Shortly after installing it - he was out for a ride a few miles from town - and the battery burned up- luckily he was able to get it out of the side by side.

Here is a post I did about it.

R

Thread 'Smoking battery -literally “Up in Smoke”'

Mar 28, 2024

My brother needed a new battery for his side x side. He bought a Bosch Lithium battery group 20 size.

It was working great until it just died and got very hot and was smoking (venting?). I figured I would pass along the photos. Only used it a few times.






Lucky he was only three miles from home.

Because I have a big DIY lithium battery in my MotorHome, he called me to talk about it.

His old battery is the original, only 2000 miles and 2 years old.

My thought was the alternator is highly overcharging the battery and so I suggested he...

• Rocketman
• Replies: 3
• Forum: Up in smoke... learn from my mistake!

• 
• 

To me it’s all about the BMS. No bms - no install. If the BMS can’t easily handle the amp draw - no install.
But what happens if while going down the road and the BMS cuts off…
Voltage spike?…
Fried alternator?
Fried Computer?

 

[scubadoo]

A BMS can be very basic. Ours is.
There is no circuitry to isolate the battery from the alternator, well no more than the original starter LA batteries.

- - - - -
Just my battery pack experience and what has worked perfectly for our 11 years of fulltime travel and counting.
It can't possibly be unique.
As mentioned a few times on this forum our now 11 year old 4 cell Sinopoly LiFePO4 battery has both powered our class C motorhome and started the 3.9l turbo diesel truck engine perhaps a couple of thousand times during our full-time travels.
The "BMS" circuitry is entirely external and basic.
We don't experience the temperature extremes often encountered by others.
The stairwell mounted battery has never been below 4°C as measured at the battery terminals.
Ensure no charge source exceeds 14.1V. Current control is uncessary since the cells can handle whatever I could possibly supply from my charge sources.
Original 100A rated alternator direct charging at c80A until all but full.
Despite all the doomsayers the alternator has survived those 11 years without releasing all its smoke yet. We must have a magic one.

Victron solar controller - 50A - "float" at 13.45V while the sun shines.
Victron battery charger - 30A - rarely used.
Victron 200A BatteryProtect for RV. 16V HV (disaster protection) and 12.2V LV shut down. Never triggered except to test.
Fuses and circuit breakers will hopefully protect in the extremely unlikely catastrophic failure of some device.

Cell balancing has proved unnecessary over the years but I do occasionally check.
I have measured a 50mV differential at 14.1V but there can be no cell capacity variation despite all the theory thrown my way. Forcing the cells to 3.65V and "perfect" balance within 5mV takes a few seconds at 20A and achieves absolutely nothing apart from perhaps psychological satisfaction for some.
A few mWh capacity is involved at most. Continued absorption at 14.6V also adds nothing.

2 years ago I parallelled a 4 cell 280Ah EVE LiFePO4 battery pack (no internal BMS) to the mix.
Absolutely no balancing issues to date either.

FWIW The Sinopoly battery at the last annual capacity test has lost less than 6% in all those years of according to some "abuse". Converted to Ah down from 315 to just 299!

A now few years old photo of a previous Juntek battery monitor showing the peak current involved in starting the truck from the Sinopoly battery pack.

 

[supersignman]

Great information scubadoo. Thanks! That's the kind of real-world experience I was hoping to learn about. I also wasn't familiar with the Victron Battery Protect until you mentioned it. I just looked it up... and I might have to add some more Blue to my RV too!

 

[defeedme]

i'll just leave this here..