Can you make your own lithium batteries?

[Gypsy Freedom]

yo nat, if you want to build your own, you might consider the sinopoly prizmatic cells. you can get a "kit" for a 100 amp hour lifepo4 with bare cells and bus bars with nuts and bolts for around $600 on amazon https://www.amazon.com/gp/product/B...8cc64320d04ad4b3fb26ab560fbe6f&language=en_US

add a BMS of your own concoction or one of the aliexpress 4s ones maybe a balancer to get you started. still not dirt cheap but connecting 4 new prizmatic cells to make a battery is a lot easier than building for banks of 10 and then wiring them in series. similar price but a lot less work

if i had the discretionary cash to replace my bank, i would get 2 of their 400ah kits and put in 8s configuration for a 24v 400ah bank to replace my 4 trojan j185 batteries. but my trojans are still pulling their weight...

 

[Natgreen]

Awesome. Yea...I been thinking of building a 24v system too. But that will be on the back burner for awhile for me. I don't have an immediate need for it yet especially looking at the price tag. Im going to be building out my system with that in consideration though.But that 400ah 24v bank would be so sweeeeeeet.

I started my solar system with a 150w renogy panel. 30$ home depot pwm charge controller and a marine battery.Every year I add or upgrade something. My batteries aren't holding a charge like they used to so I'm trying to get some lithium upgrades in it but man a 400ah 24v bank would be awesome but pricey. I'd like to start moving it in that direction though.

 

[Natgreen]

Still tho. Even buying that kit, I would only be saving 30% plus won't have the warranty and safety features of a battle born like was discussed.

 

[IGBT]

Still tho. Even buying that kit, I would only be saving 30% plus won't have the warranty and safety features of a battle born like was discussed.

Not even 30% since you still would have to buy a bms and duct tape

 

[Gypsy Freedom]

yup, not much in savings. especially at the 100 amp hour size range. the 400 amp hour kits are only (lol) $2100 for new sinopoly prismatic cells.
other than a $30 dollar cell balancer i wouldnt need much as all my other hardware is ready for lifepo4 and encompasses the aspects of a BMS equal to 220 am (at 24v). so $2100 (x2 for full bank) for the sinopoly vs $4000 for battle born now i am getting closer to saving half. my trojan would cost close to $1600 to just replace FLA with FLA or i could jump up to the firefly carbon foam batteries ( wich i have installed in a friends rig and really really like them) would cost $5000 for 8 of them to direct replace ah for ah the trojans. so $4200 on lifepo4 when the time comes doesnt sound so bad

that is in the same price range as buying a used/salvage tesla model S battery module and is a much more normal voltage pack than dealing with the teslas.

 

[Natgreen]

Yea. The saving are exponential. I thought about that and starting with 100ah or 200ah and expanding from there but I heard it's not a good idea to string these in parallel more than 2. What other hardware do you have that acts as a BMS?

If I could find those prismatic cells used then I might have a tangible plan. I been looking for them too. They're not easy to come by.

 

[Gypsy Freedom]

the large bare prismatic cells can be done in parallel just like lead acid or the lil cylidical cells you posted. some of the commercial drop in systems with integrated BMS are limited on how many you put in parallel but that is a BMS issue, not a cell issue

controlls are almost all Victron. smart battery protect, smart battery sense module, smart solar charge controllers, victron inverter and a balmar smart meter at the core. it gives me redundant high volt and low volt cut offs that are fully programable to the hundredth of a volt. charge controller is programmable to the hundredth of a volt and can be set to stop charging with a low volt cut off and can be set with a no float stage as well. there are bits and bobs as well, different fuses and some relays and a whole pile of wires... lol the only thing i dont have would be cell level low voltage disconnects in case the cells get to far out of balance. but i can monitor the cell level stuff with alarms so i think i can live with that on lifepo4. also i should be able to reconfigure some of the cell level alarms to the smart battery protects with a relay and get a shut down if they got out of balance. they dont have any where near as bad a track record as the lithium ion especially in fractional C use like in an RV

 

[jonyjoe303]

The bms I recommend and I have been using going on 3 months is the chargery bms8t. You can find for about 100 dollars. This is fully programmable on the low and high cutoffs and works on all lithium chemistries. This bms uses mechanical contactors (relays/solonoids) to shutoff power, this makes them very useful for use in solar systems. It can balance at 1.2 amps per cell. It also has two temp probes to monitor battery temperature. It has a loud audible alarm when a limit is reached. It comes with a 100 amp shunt that can measure amps in/out of battery and can give a SOC of battery, but that is it's weak spot. It tracks watthours instead of amp hours, I don't rely on it for SOC. 
Everything is programmable from the LCD control unit.

You have to supply your own contactors (2 of them one high cutoff, one low cutoff), I been using a 4 dollar 30 amp automotive relay as a contractor. If your running more current you can use even larger contactors. Unlike the small BMS, these are limited only by the size of the contactors. 

 

[Gypsy Freedom]

i like the sound of programmable. will this do an 8s pack?

 

[Natgreen]

Anybody have experience with these? My agm batteries were mighty maxs. American company and good batteries in my experience. I seen they have 100ah lithium batteries for 800$
https://www.mightymaxbattery.com/p3878828/ml100-12li-12v-100ah-deep-cycle-lithium-battery.html
I got a 10% off coupon. Thinking about getting these.

 

[izifaddag]

while 3.7 or so is the nominal voltage for a lithium ion cell(18650s for ex) a fully charged cell is over 4 volts. if you put 4 in series you have more than 16 volts. only a few inverters out there that can handle that without faulting.

There is a simple answer to this. You use a BMS with a limiting output. The ones I use are limited at 12.8 volts. This is typical. It is true what you have said regarding both the batteries and inverter but the BMS is the answer. To try using LiFePho4 without BMS control is very silly.

 

[izifaddag]

Anybody have experience with these? My agm batteries were mighty maxs.  American company and good batteries in my experience.  I seen they have 100ah lithium batteries for 800$
https://www.mightymaxbattery.com/p3878828/ml100-12li-12v-100ah-deep-cycle-lithium-battery.html
I got a 10% off coupon. Thinking about getting these.

Natgreen that is a good price. You are doing the right thing moving away from AGMs. They were good for my truck but that is an intense burst of current for a short while then rest and recharge. No matter what the config with LA they deteriorate too soon and really don't like going less than 80%. Bob talks about 50% in one of his videos but that is a bit daring. Also deep cycle is a misnomer. Decharge them too much and you kill them. If setup correctly LiFePho4 is a much better way.

 

[Mobilesport]

After you factor in burning your vehicle down it'd be more exspensive.
Imo , cheap insurance to pay the premium on rebuilt professionally designed battery.
Unless you know for sure what your doing