diy solar

diy solar

Cheapest DIY 12V 100Ah LiFePO4 battery build? 60Ah?

Where?

I guess all my searching failed to find these kinds of deal, best I've been seeing were around $1 per amp hour.

I must be doing something wrong because I'm finding prices about in line with Will's recommendations, sometimes a bit cheaper but not 3/4 off.
 
That's an insane price, not even close to the rest of the market. I can't figure out how it's possible at all.
Let us know if they work out because it seems impossible, but if true they will change the whole market.

Mike

If you are talking about domestic prices yes they are insane. If you are ordering from China nope that's normal.

Considering 280Ah cells (the most popular right now) can be had for just over $80/ea., that price on 90Ah cells is pretty much spot on for current market prices $/Ah.
Yep I agree.
 
Where?

I guess all my searching failed to find these kinds of deal, best I've been seeing were around $1 per amp hour.

I must be doing something wrong because I'm finding prices about in line with Will's recommendations, sometimes a bit cheaper but not 3/4 off.
You somehow missed this monster of a thread in this same forum:

Follow along with the fun. It's an educational read and it's not over yet. It was enough to make me buy some for myself.

vtx gave you the tl;dr answer.
 
Where did you find the data sheet of the 16ah battery? I also purchased one to see how it shakes out. Sounds like you have a solid plan to me. Wonder how many you could pack into a 50cal ammo can?
The data sheet is in one of the images on the Amazon listing (12V 16Ah Deep Cycle LiFePO4 Battery, 2000 Cycles Miady LFP16AH) and now attached here :) Looking at the datasheet again, I now see the concern about 0.2C. On paper the battery is capable of much more than that, but it might not like it. That's okay with me, my system will not have large loads, and this will be mitigated by running a bank of them in parallel.

Considering how cheap they are, I am concerned about packs failing, potentially causing the other packs in parallel to run at a unhealthy charge rate. Since it is a parallel system, is there any reason I couldn't run them on a fuse block, like so?

cce64b13-4905-437e-add3-b0dfd8689364.jpg
 

Attachments

  • 81nl2GA8txL._AC_SL1500_.jpg
    81nl2GA8txL._AC_SL1500_.jpg
    145.7 KB · Views: 28
On that spec sheet the max charge current of 40amp = of a 2.5c rate. But looks like @ .2c it is tested at for 2000 cycles. I ordered one to replace a back up battery for my smart home hub and alarm system so cant go wrong there.
 
The data sheet is in one of the images on the Amazon listing (12V 16Ah Deep Cycle LiFePO4 Battery, 2000 Cycles Miady LFP16AH) and now attached here :) Looking at the datasheet again, I now see the concern about 0.2C. On paper the battery is capable of much more than that, but it might not like it. That's okay with me, my system will not have large loads, and this will be mitigated by running a bank of them in parallel.

Considering how cheap they are, I am concerned about packs failing, potentially causing the other packs in parallel to run at a unhealthy charge rate. Since it is a parallel system, is there any reason I couldn't run them on a fuse block, like so?

View attachment 17069
Thanks for the spec sheet. I had not seen it before and was going off of what one of the reviewer's was saying. Yeah I would not worry after seeing the spec sheet.
Looks like you have a solid plan, just make sure to top charge each battery before connecting them and maybe run a cell monitor so you know when to pull them off and balance charge them.
 
Thanks for pointing this out, Loseby! I don't know what to make of it. It's almost too good to be true!
If you do get it, please report back your results.
I also purchased one to see how it shakes out.
OK, the mythical $46 16Ah 12V LiFePO4 battery and other necessary goodies arrived Friday from Amazon warehouse in Las Vegas. I gave it one complete cycle so far on a camping trip this weekend, and pretty pleased with the results. I think I'll proceed with 3 more.

Initial Voltage: 12.44 V
Initial Charge: 14.8 Ah (so it arrived *almost* dead)
Discharge: 13.2 Ah
Recharge: 13.8 Ah
 
I also got my 16ah battery but my capacity tester decided to let out the white smoke so no testing was performed.
 
Also had gotten mine and pulled the top off I cut the cables and used a lever nut to connect to the solar charge controller. This is all housed in a very small case that I keep in my car. So far its charged but I have not put any load onto it. I have a cigarette lighter socket which I could plug my fridge into so I may try that see how long it will run the fridge.
 
Got a new capacity tester and tested the 16ah amazon battery. I put an 8amp load on it and pulled 15.8Ah out of it before it hit 10.2v but it may have not been fully charged, so I'll do another test again tonight to see if its any different. But can't complain at all with that.
 
Mine received was not fully charged I charged it and ran my fridge off of it over 4hrs before I had to leave and did not want to leave it running while I was gone. More test later on.
 
Total newb here, thanks for bearing with me.. Regarding those miady 16ah batteries, with seven in parallel yielding 100ah, would the parallel set up be able to connect to say a 1500w pure sine inverter? The terminal tabs are small, so what run low gauge wire to parallel them and then tap in to the positive tab on #7 and negative tab on #1? Is this safe? Would there be bms issues? Thank you.
Also— the last q&a on that 16ah battery on amazon, the seller says series ok but parallel no go.. why?
 
Last edited:
Total newb here, thanks for bearing with me.. Regarding those miady 16ah batteries, with seven in parallel yielding 100ah, would the parallel set up be able to connect to say a 1500w pure sine inverter? The terminal tabs are small, so what run low gauge wire to parallel them and then tap in to the positive tab on #7 and negative tab on #1? Is this safe? Would there be bms issues? Thank you.
Also— the last q&a on that 16ah battery on amazon, the seller says series ok but parallel no go.. why?
You are saying parallel but talking like you want to wire it in series.

You would really be pushing things but yes I think its possible if you wired them all to a buss bars. You would be pulling around 20 amps per battery with a full load.
 
Thank you. Could I go with wire connection? I may be wrong but since the batteries are already 12v each, and I want to stay at 12v, I would need parallel, not series, right?
 
Thank you. Could I go with wire connection? I may be wrong but since the batteries are already 12v each, and I want to stay at 12v, I would need parallel, not series, right?
Yes I would wire them all to a common buss bar(s)
Correct parallel
 
Just found this site and thread! I have 2 of the Miady 16AH batteries in my Amazon cart and am considering purchasingthem, along with a dual battery isolator kit, the Greatlong 200A Power Analyzer and a FOXSUR LiFePo4 12v/6a / 24v/3a charger. My intent is to do some proof of concept testing using my 2018 Silverado as RV with 12v/24v compressor type refrigerator as a load. With 2 batteries, I think I should be able to connect either in series for 24v/16ah or parallel for 12v/32ah using simple/short 4 gauge cables. Silverado has standard 12v dc cigarette connection and a 120v ac connection. My intent is first to use the 120v ac connection to power the 12v/24v charger during travel to charge the batteries alternately in series and parallel configurations then to operate the refrigerator from the batteries until one or the other falls below some predetermined threshold to determine the best method of operation. I expect to find the 12v is most cost effective choice considering the Silverado, like most vehicles, has a 12v system and therefore won't require significant modification for its intended use as an RV. This should work for short (weekend) trips. However, my intent is to eventually add the capability to add solar and a generator/land power to the system plus increase the size of the battery bank.

Am I on the right track? Is there an easy way to charge the batteries in parallel @ 12v and then change to 24v series for use with 24v accessories or vice versa and are there any benefits/negatives of one over the other? Thanks for the help.
 
Just found this site and thread! I have 2 of the Miady 16AH batteries in my Amazon cart and am considering purchasingthem, along with a dual battery isolator kit, the Greatlong 200A Power Analyzer and a FOXSUR LiFePo4 12v/6a / 24v/3a charger. My intent is to do some proof of concept testing using my 2018 Silverado as RV with 12v/24v compressor type refrigerator as a load. With 2 batteries, I think I should be able to connect either in series for 24v/16ah or parallel for 12v/32ah using simple/short 4 gauge cables. Silverado has standard 12v dc cigarette connection and a 120v ac connection. My intent is first to use the 120v ac connection to power the 12v/24v charger during travel to charge the batteries alternately in series and parallel configurations then to operate the refrigerator from the batteries until one or the other falls below some predetermined threshold to determine the best method of operation. I expect to find the 12v is most cost effective choice considering the Silverado, like most vehicles, has a 12v system and therefore won't require significant modification for its intended use as an RV. This should work for short (weekend) trips. However, my intent is to eventually add the capability to add solar and a generator/land power to the system plus increase the size of the battery bank.

Am I on the right track? Is there an easy way to charge the batteries in parallel @ 12v and then change to 24v series for use with 24v accessories or vice versa and are there any benefits/negatives of one over the other? Thanks for the help.

I would check with the battery mfg if you can connect these batteries in series. Some BMS's will allow it and some will not.

for Parallel just wire them to a buss bar and then wire a charger to that buss bar. If series would work you can use a 24v charger or 12v chargers hooked individually to each battery.
 
vts1029: Thanks for the info. Why a bus bar rather than cables connecting +/+ and -/- for 2 batteries connected in parallel? Does this have to do with balancing input and output to batteries? If so, I think I can accommodate that by connecting to + on one battery and - on the other.

I think I probably need to do some more research regarding cabling for BMS equipped batteries. I thought I could connect 2 same manufacturer and size batteries together pretty much like I would 2 lead acid or AGM 12v batteries of same manufacturer and size. Apparently, I'm missing something regarding these 2 12v LiFePo4 BMS equipped batteries? So, the Battery Management System (BMS) for an individual battery may have a conflict when 2 of the same batteries are connected together in series? Is there anything on the spec sheet that would tell me about this and if so what? I don't feel like I should have to contact a manufacturer every time I want to connect 2 identical 12v batteries together in series, but if so, it is another reason to use a 12v system versus a 24v system. Thanks again. Please advise.
 
Back
Top