I have not been to impressed with Will Prowse he is often in over his knowledge base. He is simply wrong on this one. For a 144 volt system you need a 48S BMS for Lifepo4. You should be able to find them all the way up to 600VDC without much issue I know the 48S are commonly available online I have looked at them for a tractor project in my distant future. Check out this YouTube channel.
Jehu Garcia has built his own business out of his love of building EV conversions and battery packs. He talks about how the EV market uses relays to handle the current load. Basically you wire a small BMS to monitor the batteries to a larger relay. When the BMS trips it trips the high current relay. You should have that relay already in the Geo and should just need the low cost low current BMS.
I am glad the inverter worked out I did see the price has jumped. I haven’t found a cost effective solution to a higher wattage inverter. I honestly gave up looking for one and bought a DC motor for my project instead of trying to use an AC motor I have on hand.
@DanNH
I need to clarify. Will was displaying drop-in 12v LiFePO4 batteries. My first choice is a drop-in replacement. Building my own battery will be an armchair exercise, until I get a slough of free batteries. I definitely am not paying for parts that I have to build. I am just not smart enough or careful enough to pull it off. The longer I hangout with the robot teams, the better my wiring skills are improving.
Do you think batteries are going to continue to drop in price, inspite of the potential inflation?
He is correct that the drop in batteries at 12 volts won’t allow you to hook them up in serries. It has to do with the way they designed the BMS in the box. I looked into that in detail a while ago and decided to build my own but I have decades of experience working with electronics.
Will battery prices continue to drop? Yes they are going through the economy of scale we saw on solar panels over the last 15 years. I would guess over the next 5 to 7 years the price of storage will drop in half as all the new factories come on line and the EV market takes off. There will be growing pains and it will largely depend on how well the market guessed the demand for EV. It looks to me like 2022 will be a tight year but by 2025 I suspect we will see a major drop in price and probably a new cell chemistry take the lead. There are a few on the verge of commercialization at the moment the next year will sort out if they can be scaled up to mass production or not. My take on the battery market is about the same as the EV market as they are the major customer. I think for 2022 the economy will continue to be very tight but that it won’t impact EV sales. I believe the interest in EV and the acceptance of them as the future of transportation is far enough along now that the slow down will come in the form of a drop in ICE sales and the EV market will remain supply limited maybe as far out as 2025. That said with all the factories comming on line to build batteries and the downward pressure form companies like GM and Ford on the battery manufacturer for price I think the cost will continue to fall. Big companies negotiate prices for a year or more when they enter deals at the scale we are seeing in that market. I have been in those negotiations before it is shocking how much pressure you can put on a supplier when you are discussing over 1 million dollars in sales per year. I once gave a major electric motor manufacturer what I thought was a crazy low price point less than half the list price and in 3 months time they came back and told me that they thought I would like their next offer it was 15% below what I had requested. I was very impressed as the competitor I was using was about 15% above the number I had given them in the first place. These companies know how to cut margins with their suppliers which will force the battery companies to optimize the production lines.
If I was in your situation I would look into the large single cells for that Geo. I forgot the name for them off the top of my head but they are common in the DIY community. You simply bolt a ring terminal to the top of each cell hooking them in the serries parallel configuration you want. The BMS hooks up to the most negative terminal in the pack and to each positive then pulls in a relay contactor for the main output of the pack. Not much harder to hook up than the 4 12 volt batteries you hooked up already except that there are more connections. Buying small 18650 cells and building a bigger pack is a lot more work for the cost savings. I have been going down that road and honestly I am not convinced it was worth the savings. But I am far enough along that I will finish this project.
I have 8 drop in lifepo4 120 AH batteries that are able to just replace the old lead acid /AGM ,GEL cells and they have inbuild active balance and BMS , and can be wired in series but only to created 26 volts , there BMS is not powerful enough to use as a cranking battery and so i bought a Hybrid cranking battery of 25AH with 1900 ccc of Maxwell super caps all in the size of a small car battery , its the most amazing sound hearing it spin up a 4 liter petrol engine like it was taking off on steroids, the engine fires up so fast and will never go back to lead acid after using this , for maybe a $100 bucks more than a standard size battery for my size truck and a life of 20 plus years its a no brainer for me .
Dave
Maxwell 500f have a discharge of around 50% after 3 days , but i could be wrong it could be tons less than that , because the hybrid battery i have also have lifepo4 cels in built it may take many months before its down too low to start the truck But if that’s the case it only takes a few mins to fully recharge the caps again to start the engine with no damage of the battery or caps at all and once driving the caps and battery are fully topped off again
I had my first failure of the Remy AGM 31 series today. To be fair it was a starting battery for the excavator, not on the golf cart. Those batteries seem to be doing fine. The battery that failed would only give three volts when the excavator engine was cranking. The remarkable thing was when I went to Remy to possibly buy a set of replacements they told me it would be $730 for two of those batteries. Needless to say I went home without them.
We have started buying calb lithium iron phosphate cells. They are 100 amp hour at 3.2 volts for 100 bucks. The manufacturer claims that they have 2000 cycle life. I don’t know if they’ll work for starting batteries or not but the price is comparable to lead acid so it might not hurt to try. For sure the h is getting its magneto and hand crank again.
I think the only issue you’ll run into is charging them, not sure what your alternator/generator would put out for a 4S of those cells. I hear conflicting stories about replacing your starter battery with lithium. Motorcycle guys saying they love it, RV guys saying don’t do it. Annoying and confusing.
You will definitely want a good BMS if you use lithium ion for a starter. The issue as said by others is the charging voltage. I would look into the generator or alternator and voltage and regulating it to meet the charging voltage of the lithium batteries. Also don’t charge lithium batteries below freezing temps some of the chemistries will definitely electro plate the lithium on the wrong side of the battery when they are too cold to charge. I am too tired tonight to remember all the details of the charging of lithium. But over charging or cold charging will definitely damge them.
The good news is I don’t have to worry about cold weather charging for a while.
I called the battery guy and had him come get my old cores…now we are even Steven. I may have to look at Walmart and flooded batteries.
It makes that 1946 D2 down in lake linden look like a deal!
Given the current diesel prices i would think long and hard before buying one. I own some and this is the first year i am actually happy to he haying with old gas tractors.
I keep watching the battery technology there are some interesting options on the horizon. CATL in china has started producing their sodium ion batteries for markets in Asia they plan on mass production next year. Those will be about half the cost of lithium ion once they hit mass production. There is a prototype pre production run in Massachusetts of a polymer battery that could be as cheap as $20 per kwh but it is probably a few years out IIRC they made something like 10,000 cells for $65 per kwh but are looking for funding to build a mass production company. Those will be bulky (5x lithium ion by volume but lighter) and thus for stationary storage or for those of use who don’t mind bulky solutions for converting older equipment. My guess is by 2025 i will be able to afford to convert some of my old tractors to electric. Ofcourse that requires time i never seem to find for projects. Speaking of which i need to go unload the 160 bales i got yesterday before my baler broke then see if i can get it going today without having to wait for parts… the joys of farming with antiques.
Hi Bruce , let me get this straight that’s $100 per cell , so 400 for 4 cells is still pretty good if they are new cells , but don’t even think of using them without a very good BMS with a High amp rate other wise they wont last long at all , i have some hybrid lifepo4 car battery’s , the cells are 25AH and the capacitors are rated 1900AH and weighs in so light you can carry it with 1 finger , i have run this in my 4 litre Hilux for 6 months now its speed at turning the engine over is amazing , today i just ordered 2 more @$400 each 1 for a John deer front end loader and the other a Nissan ute .
Dave
Dave the speed you see cranking the motor is because lfp have 3.2 volts per cell so 4S is 12.8 volts. Now you consider the voltage lag under load of lead acid and you probably have 2 or move volts cranking that starter much higher speeds than lead acid can handle. If you could get a 24 volt system from a military motor instead of the 12 volt alternator and lights on a commercial motor lithium in a 7S configuration would be a much closer match and would charge better. But i would still want a very good BMS.
I have a project to build an electric tractor which i started last year the BMS and inverter/charger are the only major components i need to select still. I will probably buy the inverter i posted here a while back i just haven’t because i am not that far along.
Ok I ordered 12 more CALBs . I want to trial them in the golf cart. They are 100ah, and it looks like they can handle charging at 1c or 100 amps. I don’t have anything that can do that. The flex max only goes to 80amps. I guess the thing I am concerned with is the end of charging cycle. The flex max may handle this.
My little rant about this is that we aren’t selling an offgrid power system, but rather a fantasy. These people see us with no power lines and think “Hey! I want to be independent too!” Then they shell out for some sort of system that fuels the illusion of being independent. It’s because everyone is absolutely thrilled to see that $500,000 roadgrader coming down the road to let them out. The truth is we are all very dependent on each other here.
Still, we do enjoy showing folks how to set up solar power.
True Bruce Jackson. We are all dependent on each other. Just the nature of being human.
Having the Freedom to choose who; and how much we are dependent on; is what is the goal.
Imagine a Rural USofA where the Rural Grid-out electrification program had never happened.
Those willing to scrimp, save, buy-invest and build did have electrical power. Instead of being just wind tower turbines and brought in fueled IC engine-generators they’d sure to have evolved to PV solar as a component too. Also sure to have evolved to grow your own engine fuels of seeds oils, alcohol crops. Woods for electricity too.
“Back to the Future” Not the fantasy version. The for-real verson.
S.U.
Good question! IDK. If in doubt, call your township tax assessor and ask him (or her). I am willing to bet that it is a purely local decision whether or not your taxes go up, for a solar installation. Around here the taxes don’t go up because of that. One of the installations I’m doing right now is for the township supervisor, and that person doesn’t even want it inspected, so it won’t be grid tied. It’s a strange world I live in.
This is completely correct. Back about 15 years ago i installed a wood gasification boiler in my home my best friend from highschool did the same in his. We where only a few miles apart but in different towns. His taxed went up with the increase in home value mine didn’t because the town i lived in didn’t tax wood wind or solar his taxed wood but not wind or solar.
because everyone is absolutely thrilled to see that $500,000 roadgrader coming down the road to let them out. The truth is we are all very dependent on each other here.