How To Convert 12v 9Ah Lead Acid Battery Into 12v 14Ah Lithium-Ion Battery Pack 

i have a few of those lead acid batteries that are dead dead dead (one being a literal 80 mv...yeah) i was/am afraid to cut into them since i dont/didnt know how much, if any, battery acid is left in there this video did raise my confidence a little about the acid in there, but still have a few reservations since ive never dealt with something like that

The plastic base isnt thick enough for screws, anyway the glue seals it from water getting in.

Link for the welder is in the video info

Why purchase a new case (if indeed you can) when you can get an old one for nothing?

@@juliocosta5818 - Because of all the mess and time wasted dealing with lead cells?

Just rinse with a dilute solution of bicarbonate of soda to neutralise any acid, then rinse with plain water. What you must do is make sure all the batteries in a single parallel set are near to the same voltage, to prevent potential damage from the heavy current which would flow if they were connected together in very different charge states.

@@melkiorwiseman5234 that makes sense! Thank you 🤓

The case is made for SLA, which is heavy and swells up. Li-Ion is light and strong and doesn't really need a protective case. It's mostly to protect the wires, mount the hardware, and to look nice.

Would it have been as cost-effective to build, though? (I have my own concerns with this project-I think I'd have preferred to build a case for the batteries than deal with the lead and the fact that the newly built battery could be mistaken for a common SLA and used improperly…)

You need the alternator to be higher than the battery, so that it can charge the battery to full.

@@orppranator5230 Sure but even it it only gets to 14V the batteries will still be at approximately 95%, which in fact will prolong the life of the batteries. There are commercial drop in replacements in LiFEPO4 chemistry to be used in place of Lead Acids. I suspect they don't do any boosting for charging as it will be impractically expensive. In any case having 4.2V max on regular Lithium Ion battery makes this dangerously battery incompatible with alternators/generators/dynamo due to relying on BMC on not letting the batteries go above 4.2V (as with 14V they will be pulled to 4.7V otherwise in 3S configuration). BMC will disconnect the battery from the charging circuit, and in case of the generator charging will cause the system voltage to spike to 18-20V in some cases. This can even happen with solar applications.

for a lead replacement its better to use LFP with a simple active balancer, BMS would disconnect when charging to full and that's very bad, LFP wont explode even at over 4v

@@knghtbrd Lead won't hurt you if you don't eat it or leave it on your skin for days. Believe me, if you build a battery, you won't forget it's a Li-Ion.

Lithium ion batteries require a BMS (battery management system) to keep the cells balanced, and to avoid over charging or over discharging. A BMS becomes critical when the original equipment was designed for a different battery technology. #1: If you only look at the overall voltage a few years of use can result in aging drift. That is some groups of cells may charge to a higher voltage than others. Example: 4+4+4=12v and 3.5+4+4.5=12v too, but the second example over-charges one of the cell groups. The higher the voltage the fewer charge/discharge cycles you get----to the point that limiting charge to 80% of rated capacity will give you 3 to 4 times as many charge/discharge cycles (a trick some systems designed for lithium batteries follow when battery life is a higher priority than battery capacity). A decent BMS will keep the voltages of each section of the battery perfectly in balance with other sections. #2: AGM (absorbed glass mat) lead-acid batteries (or any lead-acid battery) loves to be trickle charged. But trickle charging any lithium battery will destroy it, and in the case of lithium ion might cause a fire. A BMS will cut off charging a fully charged battery system, even though the equipment the battery is installed into wants to trickle charge it. #3: Over discharging a lithium battery is bad and can drastically shorten the life of the cells or even kill them. This is also true for lead-acid, but if equipment is designed for lead-acid, its low cut-off voltage will be different than what a lithium battery needs. A BMS will disconnect the battery when it senses the cell voltages have fallen too low. If the equipment happens to cut off discharge at a higher voltage then the BMS, no harm, no foul (but you don't get the full capacity of lithium). Food for thought: Lithium iron phosphate (LFP or LiFePO4) would be a better choice than lithium ion for an application where a little more weight and size is worth the added safety of not being a fire hazard. For example a kid's toy car or scooter, or something like a UPS (uninterruptible power supply). For a laptop, a phone, or a car, the size vs capacity tradeoff is often worth the trouble of the added safety systems. Note that the working voltage of LFP cells is lower than lithium ion, so a different BMS is needed, but you still need one. Also, if your equipment needs more than one lead-acid battery in series for a higher voltage, it'd be best if your lithium replacement's BMS could see across the whole string of cells. Example: a typical smallish UPS will use two lead-acid AGM batteries and work at 24 volts. So best to build a single replacement lithium battery that is the physical size of two of the original batteries, with a single BMS that looks across the full 24 volts of lithium cells. See point #1 for why.

@@ScottyDMcom Thank you so much that you have taken pains in highlighting me on charging and the need of the BMS in lithium based cells. From the explanation I could get that the lithium based cells require proper charging voltage and the charging is not dependant on the how much current goes in to battery pack. Am I right in this understanding? Please correct me if not?

the BMS has a balance ic, the chip use resistors to drop the battery voltage when pass 4,2v, and stop discharging the cell at ~4,19v, so it's necessary to charge the pack a little bit more than 12,60v, like 12,65, 12,70...

I use an led as indicator for each cell, the led (with current limiting resistor) is in parallel with the big resistor, so I know when the BMS is balancing and which cell get charged first...

The parallel connected cells are forced to remain at the same voltage as each other by the simple fact that they're all connected. The circuit handles balancing each set of parallel cells with the other sets.

You need 4 lifepo4 cells, they are perfect for 12v

yeah whats the point in using case of a dead battery that makes up 5% of the battery and replace the other 95% at that point you're just making more work for yourself while creating a hazardous mess.

@@darkshadowsx5949 It looks cool and is sturdy. For some people (myself included) that's worth it. The lead should be properly recycled anyway, so yes it's (extremely) hazardous, but could be handled properly by someone who knows what they're doing

I was wondering the same thing. I tried different lead acid brands and they seem to last 3 years tops. Seem even a NINH thing that can work for a few seconds would even be a great idea.

No this guy made it wrong actually 4S battery pack is real alternate to 12v lead acid batteries

Well, you can buy them for UPS, so I would think so. UPS chargers are gentle, and the voltage is right.

@@Bob_Adkins That's what I was thinking. The BMS is built into the battery in this design so it should be alright. The main thing is the estimated time on battery and battery percentage probably won't be accurate and I'm not sure you could calibrate it given the differences in voltage drop between Li-ion and lead acid. That could complicate things for controlled shutdowns when the UPS gets to a certain battery level/time remaining.

@@your_new_sjw_waifu Yeah, if your UPS reports battery condition, it will be inaccurate but you can mentally compensate. I think it's worth it, lead-acid batteries are awful, last only 2 years for me. The LA batteries can also show a false voltage, they check 12-13v but when power trips they only last a minute. Load testing twice a year is a headache. Li-Ion is usually good if the voltage is good, and should last many years if kept at 4.0v per cell. Li-Ion doesn't like to be stored at maximum voltage (4.2).

@@Bob_Adkins Yeah, I could mentally compensate but I couldn't have my computer reliably shut down and turn the PSU off when battery level reached 5% or there's 5 minutes remaining (whichever comes first). Risk of unclean poweroffs really defeats most of what makes a PSU worth it to begin with.

@@your_new_sjw_waifu Your concerns are real, it's not a perfect solution. Someone should make a BMS that will make the battery voltage correct, and act just like a LA battery.

No. Lead cells and lithium cells have different minimum voltage and maximum voltage so it is not recomended.

@@user-yz8do8vu1s ... 🤔 ... BMS is made for that .....

@@yvonf2312 you need different bms. A bms made for lead cells won't work on lithium cells.

​@@user-yz8do8vu1s But he installed a BMS in the battery, right? Would he have to take the lead battery BMS out? I don't understand the math of 21 cells with 2000 mAh not adding up to 42,000 mAh . Is it the number of cells in parallel that determines the capacity?

@@paddlepower888 to get 12 V you need to add 3 banks of paralel lithium cells in series. Series connections don't add up on capacity but voltage.

its safe , on lipo setting charge max voltage is set to 4.2v on li-ion is 4.1v

@@MrDexi87 wouldn't it be irrelevant which Lithium setting it's charged with, as long as the whole pack isn't over-volted? I mean could this pack be used (and charged) like an SLA Pb battery? That's why there's a BMS, right?

@@fluffyfloof9267 true , but if u charge 1s with 4.1v max voltage u can increase battery life, that's why imax b6 using lower voltage for charging li-ion cells ...

@@fluffyfloof9267 I'd like to know this as well. BMS's generally seem pretty straightforward in their operation, except when it comes to charging the cells properly once everything is assembled. This video was basically the first example I've seen where the creator actually touched on this area but still I have some unanswered questions... Like do these cheap BMS's disconnect charge when input voltage exceeds the lipo voltage ratings? What is the safe charge voltage and amp range for a 3S7P pack with a bms like the one in this video attached to it? I realise that depends on the cell specifications but in general (assuming mixed cells) what would be an average safe range for such a battery? And just as importantly, what WOULD HAPPEN if you used one of these batteries as an SLA replacement in a typical standby 300-600W UPS, for instance? Would it be safe? If not, why not? If someone says it's a 3S Li-Ion battery and therefore lower nominal voltage than the SLA it's replacing, that doesn't really explain why it's not suitable. We know that most UPS's will cut out at around 10.5v and charge up to max of around 15v. if the BMS can cut off charge at appropriate times (10.5v - 12.6v = 3.5v - 4.2v per cell, respectively) then there should still be an overlap range of compatibility even if its not a perfect match, yeah ? As far as I can see, all it means is that the cells will never fully discharge further than 3.5v, which is a good thing because it means way more use cycles. Sure you won't get the full 14ah of capacity, but even if you get the 7-9ah of the original SLA battery, it seems like a win

Right. the lead acid battery is about $20-30, but lithium batteries in the same size as the lead acid battery are almost triple that, but worth paying for due to the higher number of recharge cycles per dollar, and because the spot welder alone costs over $50. I doubt I'll use the spot welder for anything else and finding defective" power drill batteries with an average cost of $0.80 per cell isn't something I do well. I've begun to establish limits to the things I want to DIY. And you gotta love the disclaimer at the bottom of this video's description!

not rentable

Bro you need to dyor, the world isnt here to answer questions and if they answered that question, you would have a million more. Go learn stuff and be an adult

Aka, an accident waiting to happen! 😉

For a small 7ah replacement pack like this, it's probably fine. But in general I couldn't agree with you more. Blows my mind how this plastic cell holder and nickel strip method is still the "de facto" way for building lithium packs of various sizes, even in the homebrew powerwall space, where hundreds upon hundreds of cells are combined into a single pack in this way. Besides for just the safety hazard, it seems like any kind of cell-level maintenance is bound to be a total nightmare as you basically need to tear the whole pack apart in its entirety in order to get the cells isolated for testing. Who wants to sit there stripping welded nickel when conventional battery spring mechanisms could be used instead? I have thousands of 18650's waiting to be put into packs, and this is where I've stalled with my build. I'm trying to find a better way to build packs as I refuse to use the same holder+nickel strips method that everyone else is using. I believe there is a far better way to assemble packs that is not only easier and cheaper to do, but also much more future proof. the problem is, I haven't been able to figure out exactly what that is, or find anyone who's come up with a good enough or easily approachable/DIY design. You either need a 3d printer, or to buy expensive parts, for instance. Meanwhile raw materials like sheet wood/plastic are readily available for cheap... Someone just needs to think out of the box and come up with a better design rather than everyone being a copycat of something that's frankly awful.

Very professional looking job Great 👍

The long ones connect each row of seven batteries in parallel. The short jumpers connect the rows in series. Without the short jumpers, each row doesn't produce 12 volts. That's the limit of my electrical knowledge.

The idea of using multiple jumpers is to share the load across several connections. In theory you could just use a single link to connect each parallel set in series, but using multiple links allows them all to share the load and run cooler.

Yeah, for 12v you need 4 3.2v Lifepo4 cells

Not to mention, you're not figuring in the cost of his spot welder. If you do not have one that will cost another $100+. But hey, he already had the stuff and was using recycled batteries so HIS cost was minimal. I think I'd rather buy or use something else for the box than go through that recycling nightmare. Sometimes it's just not worth the effort. You're right about the voltages also, it wouldn't work right with 12 volt stuff.

This battery would not be usable on a UPS, unless one would figure out a way to charge it with 12.6 volt constant voltage...

@@VERYMADSTUDIOS That is certainly possible, but I stated usable on a 36V UPS. I didn't say it would work on a 12V UPS. In fact I said it is a problem.

but sometimes guys its fun making some diy stuff than buying a perfect battery(i just told my thought pls dont be rude to me)😁

those are probably on thingyverse or other open 3d printing libraries

As far as I can see the batteries are salvaged from other battery packs...

In the US there are several battery sellers for used 18650’s. Often times, these can be purchased for $0.50 each with about 90 to 95% capacity vs new cells. At that price, his 21 lithium cells would have only cost $10.50, which is fantastic. Add a little $ for the BMS and this is a fun project.