Anyone using a LiFePO4 battery on their mill?

[woodchuckc]

I've been mulling over the idea of using a 100 AH LiFePO4 battery on my 2001 LT40 Super Hydraulic mill with a Kubota D42 diesel, and was curious if anyone was using a battery with this chemistry instead of a traditional lead acid battery.  On paper, it would seem like a good choice - you can draw it down to basically zero charge without damaging it, their "life" is several thousand charge cycles, and weight is about half or less (although that is really not important).  The major downside I can see is that for charging, LiFePO4 batteries have specific voltage and current requirements that I don't think are compatible with using the engine alternator for charging. Also, they don't like really cold temperatures but I am in Tennessee and I don't use the mill when it is really cold anyway.  What I was thinking about doing would be to get rid of the alternator on the engine altogether and get a couple of 100 W solar panels and a 20 A MMPT charge controller to charge the battery (I use my mill stationary in a pole barn that doesn't have electricity).  Most of the time when using the mill it is during the summer months when it is so hot out that I cut for a couple of hours in the morning, do something else in the hot part of the day, and then cut for a while in the late afternoon and evening, so the battery would be charging during prime time for solar generation.  I could always add another 100 W panel (or two) if I wasn't generating enough electricity to keep the battery charged up.

Anybody doing something like this currently?  Also, please feel free to comment about anything that I might be overlooking which makes this a bad idea!

[Ben Cut-wright]

"Also, please feel free to comment about anything that I might be overlooking which makes this a bad idea!"

It's not a cranking battery.

Modify my comment:  It appears the BMS in that battery does permit 600 max cranking amps.

The manufacturer does recommend special charging considerations. The BMS can shut the battery down if charging voltage or amperage goes out of range. 

[Southside]

I have them on portable chicken coops to open doors, activate nest boxes and run LED lights. Winter hasn't been an issue, each has a solar charger and charge controller. 

[woodchuckc]

"Also, please feel free to comment about anything that I might be overlooking which makes this a bad idea!"

It's not a cranking battery.

Modify my comment:  It appears the BMS in that battery does permit 600 max cranking amps.

The manufacturer does recommend special charging considerations. The BMS can shut the battery down if charging voltage or amperage goes out of range.

Thanks - I know LiFePO4 batteries can be used as starting batteries if the BMS supports the high current draw required, but it can be difficult to find that spec sometimes (especially with the less expensive batteries).  I don't think that the smaller LiFePO4 batteries used on motorcycles, lawn tractors and such even have a built-in BMS.

[sealark37]

Are you having problems with the factory electrical system?

[JoshNZ]

They definitely need a charge controller, lithium chemistry is constant current charge up to a certain voltage then constant voltage charge after that to full. I'm sure you would damage it if you connected it directly to an alternator trying to float charge.

No reason other than price you might try what you're doing.

I'm not familiar with the mill but, if the hydraulics are electrically driven rather than taken off the engine I don't know if I'd get rid of the alternator.

[scsmith42]

I don't understand what problem that you are trying to fix?

Lead acid batteries are fairly inexpensive, and a quality one will last for 5 - 7 years.  Your mill is already set up to charge a L/A battery.  Your annualized battery costs are probably around $20.00 per year.

If you go Li/Po you will spend more $ on the battery, have to spend $ on solar chargers and wiring, in order to save $20.00 per year?  I'm not seeing it.

[ladylake]

 
 No way I'm spending big bucks for a fancy battery when I can go to a heavy truck shop and buy one under $100 for a powerful group 31 which last for years.  I like to keep my money in my pockets.   Steve

[OlJarhead]

The problem I see is that they require specific charging needs the mills alternator might not provide but if it does and they have the cranking amps I guess it could work.

[Joe Hillmann]

You also CAN'T charge a lifepo4 battery AT ALL below freezing.  The bms wont allow it.  And if the bms does allow it the battery will be damaged.  

A lifepo4 battery can put out power down to 20 or 30 below, but it cant take power below 32f above zero.

Personally, I think it is a bad idea.  The mill is built for lead acid.  Lead acid is kind of cheap.  And lead acid is easy to get your hands on. If you own a mill you probably have half a dozen other lead acid batteries that you can borrow temporarily for your sawmill if you need to in a pinch.

I have nothing against lifepo4 batteries, but in this situation lead acid meets your needs much better.

[YellowHammer]

Some of the newer generation LiPos are being designed and even certified to charge off alternator systems, just this week Mercury outboards approved them for their engines, but Yamaha still does not.  LiPos generally have very specific advantages and disadvantages, and are a much better fit for mobile craft with constraints of weight and size, such as aircraft, boats, or depleted energy cyclic vehicles, such as EVs where energy density and charge rate are also critical.  Their energy density is very high, so have significantly reduced weight, sometimes 10% the weight and space of a flooded lead battery, but thats not really an advantage on a sawmill.  They have a very high potential charge rate, again not really much advantage, and have a hugely increased cost, at least the later generation ones or "safe" ones.  I was looking at some this week for our new offshore boat, $3,000 for a 30 lb battery with a decade long warranty that was equivalent to what 300 lbs and $300 dollars of flooded lead battery did.  Huge difference and huge advantage with huge cost increase.  They are generally more durable, and can be dead cycled more, but again, not really much advantage on a mill or other alternator charged source.  They also have an increased fire risk, and that alone is a black mark.  I watched a half million dollar boat burn to the waterline 20 miles offshore a couple years ago, later blamed on an incorrectly installed and charged Lipo.  For ground based, non mobile banked reserve systems where footprint, mobility and weight don't really matter, I think flooded lead acid is still the best choice, even in the form of AGM.  For an Electric Vehicle or Electric Aircraft, LiPo is the clear winner.    

[Joe Hillmann]

Lifepo4 batteries arent a huge fire hazard.

The lithium ion ,on the otherhand, burn very hot and cant be put out by regular means.  They will burn underwater or when cut off from oxygen.

[MattM]

You also CAN'T charge a lifepo4 battery AT ALL below freezing.  The bms wont allow it.  And if the bms does allow it the battery will be damaged.  

Not entirely true. You can buy heated lifepo4's, that are good below freezing. If the BMS detects that it's too cold your charging power will goto the heating element inside the battery case and once the battery is up to temp it will start charging.  ;D

[woodchuckc]

Thanks to everyone for the feedback!  I am not currently having problems with the charging system, so that is not the reason I was thinking about it.  I do need a new battery (I'm using a battery borrowed off of some other equipment temporarily), so that is why I was thinking about it.  It sounds like although doable, there is no real-world advantage to speak of.  I'll just go with a regular AGM battery.

Thanks again!

[richhiway]

Just no reason to spend the money. 
Solar panels and a battery would never keep up to the electric hyd.
When you put a load on a automotive type 12V system the alternator supplies the amperage,if the load is greater then the alternator output, it pulls from the battery then is replenished quickly by the alternator. On the mill at idle you can here it pull the motor down when you put a load on it as in raising the head or returning the carriage. 

For example(simplified) if your car is running with no electrical accessories the alt. might be putting out 5 amps, turn on the headlight,15 amps turn on the heater fan, 20 amps etc. The alt supplies the amperage.

If you had a snowplow with elec hyd motor (like on the mill) and you ran it on and off as you plowed a driveway it might draw 100 amps, so it would pull more then the alt can output so it will pull the battery down. For some time maybe a minute or two the alt would then put out the 20 amps, plus what it takes to bring the battery back, probably 50 60 amps, slowly coming back to the 20 amp load you are running as the battery recovers. A solar panel would never keep up.
 

[Sod saw]

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Hi all,  The answers here are mostly correct, and useful  although piecemeal.

We have two hydraulic pumps on our LT40.  We have a lead acid battery that is new, in the saw battery box.  The alternator is working fine.

We have 4 solar panels as our only electricity at the saw building, each one being 100 watts feeding a charge controller that feeds directly to a separate lead acid battery that sits on the floor under the hydraulic pump box.  This battery is connected directly to the 12 volt buss that comes from the side of the frame rail contact providing me with "always available" hydraulic functions.

Those solar panels are connected 24/7.

enough background.

When sawing, I do not always return the head to the ends of the rail track where the alternator can recharge the hydraulic battery.  I rely on the floor battery to power the hydraulics.

The solar panels generally keep that floor battery charged if I do not use it much.  However if I cut and turn, cut and turn, cut and turn the solar panels will not keep up with the huge hydraulic load.  I find that the saw head needs to be parked at the ends of the mill bed to reliably recharge the hydraulic floor battery.

If you are going to rely on only solar to keep the battery up, a couple of hundred watts will probably not cut it.  Even when not cutting full time (I don't).

I would not hesitate to use modern batteries on board a boat but would suggest a small lead acid battery in the system to prevent the lithium battery from reaching full charge and shutting itself off thereby possibly killing the alternator.  The small lead acid battery should provide a constant load on the alternator preventing the alternator  from dying.

Dreaming and playing with solar is fun.  Keep it up.


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[Sod saw]

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Recently I have discovered this link to a review of various batteries.

This link is to a chart that will grow as the "U-tuber" will add to the list as he reviews more batteries.

The guy's name is Clark and as I look at other videos of his I get the sense that he seems to be competent.

Here is the link.    https://docs.google.com/spreadsheets/d/1dyJf7SuYQFxorzdIANKgf7Qk3hviZYzSHoNdjxqUKeM/edit#gid=0

I am not competent using this computer so if this link does not function, please let me know how to fix it.

When you look at the chart, you will have an opportunity to view the actual video of the review of any of the batteries, along with some math, etc.


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