Anybody know anything about the Fullriver lifepo4 single cells 26650, etc.

[VicRC]

Hello I am new here and I have just starting reading up on solar systems and wanted to tinker with it. Anyways I have been tinkering in the RC hobby for a long time and about 5-6 years ago I have been using mainly A123a and Lipo cells to power things. Lipo require extreme care however I only use them for hi powered requirements. The A123s are extremely forgiving, these were pulled from Dewalt power packs. I build 12.8v (4S10P) pack from them and replaced my SLA portable battery which typically last me 2-3 years. I do charge my A123 pack through a balance charger and in 5 years they are still going strong from day 1. Outlasting any portable batteries I have ever used.

I now have some Tenergy 32650 LFA 5500mah cells and will make 4s packs for a small off grid solar hobby (man needs another hobby) project. I have tested these cells and I can draw on average 4500ma from them down to 2.7v. I built a 4s5p pack for testing and at 12.8v 27.5A about the same size as a 12V 18A SLA battery and half the weight. However these are much cheaper than A123s, not sure how long they will last but its worth looking into. These are going for a little over $1 each and 20 cells is way cheaper than SLA that will eventually die in two years.

I am hoping these Tenergy cells will be a great alternative as solar batteries and a cheaper source for A123 cells.

[Sunking]

No question the AGM would be best for my water pumping project, 16-20 lbs is much better than the car battery i am getting tired of carrying now, it is just from a hobby aspect that i also wanted to experiment with lifepo4 for the learning and tinkering (i have an electronics store - 32 years now), I would never want to brick any expensive battery of any chemistry type just playing with it, but the LFP cells that i am looking at are only $30 to make a 12v 10ah pack, so that raised my curiosity. That being said if it is very difficult or low chance of success then i would not want to even waste my time and the 30 bucks on it.

Depends on what $30 means to you. For me is play money or what I would put in a Shriners Kettle and think nothing of it. Seems like you have a fair grasp of electrical so the risk is minimal. So if loosing $30 does not hurt much, goferit. Let me know if I can help.

[LETitROLL]

No question the AGM would be best for my water pumping project, 16-20 lbs is much better than the car battery i am getting tired of carrying now, it is just from a hobby aspect that i also wanted to experiment with lifepo4 for the learning and tinkering (i have an electronics store - 32 years now), I would never want to brick any expensive battery of any chemistry type just playing with it, but the LFP cells that i am looking at are only $30 to make a 12v 10ah pack, so that raised my curiosity. That being said if it is very difficult or low chance of success then i would not want to even waste my time and the 30 bucks on it.

[Sunking]

The small AGM is a pretty good option, if i want a easy lighter than what i got now option without any hassles (and i might). If i did play with the lifepo4 , I start by hooking up all 8 cells in parallel and walk away for the initial middle balance?,

Certainly how you start. but LFP (what you are calling LiFeP04) do not lend themselves well to Middle Balance because their Charge/Discharge is so dang flat. Where as LCO (cobalt) and LMO (manganese) have a nice slope. With LFP you have to go to the top or bottom to balance them where there is a steep slope at either end. The reason commercial LFP batteries are Top Balanced is because it is really the only way you can make a consumer product work. To Bottom Balance you really need to connect all cells in parallel to do it correctly and there is no easy way to do that with a commercial product. It could be down but would require relays and some complicated processing and that means expensive and adding mechanical failure points. Understand?

That is why I asked to consider a commercial made LFP drop in replacement because they have been initially balanced with built-in BMS. Only thing you have to provide is a charger you can set to 14.2 to 14.4 volts of the proper current range to use them. If that interest you look for e-bike and motor cycle 12 volt LFP batteries.

If you want to Bottom Balance, say so and I will help you with some options if you can convince me you have the skills. You really cannot hurt yourself so much as you can destroy the batteries if you go to far down, You do have the right idea, you put them in parallel and discharge them down to 2.4 to 2.5 volts.

You can also Top Balance with the cells in parallel and is the best way to do the initial Bulk Balance. But you have to have a very well regulated charger of Power Supply to charge at 3.6 volts, not 3.15 OK?

My best advice for your application is to use a UPS grade AGM battery. AGm batteries made for UPS are made for Fast Discharge times, and I can help you find them. Nothing special to charge them as they can use any charger made for Pb batteries which I think you already have. A 12 volt 20 AH battery will not be as lite weight as a 4S 5 AH LFP, in fact around 8 times heavier. A 12 volt 20 AH AGM will weigh in around 16 to 20 pounds if that helps.

So what do you want to do?

[LETitROLL]

Well no other battery has a nominal 3.2 volt nominal cell voltage. I do have another idea for you to consider. Consider a 12 volt 15 to 20 AH AGM. If you go with LFP as Mike said you need an answer for the initial Bulk Balance.

Option B is they make 12 volt LFP batteries as drop in replacements. They already have been Balanced and do have a BMS built in to make them Drop In replacements for consumers. Pricey though.

The small AGM is a pretty good option, if i want a easy lighter than what i got now option without any hassles (and i might). If i did play with the lifepo4 , I start by hooking up all 8 cells in parallel and walk away for the initial middle balance?, then If i one at a time charge each individual cell to 3.15v or so (i think my victron may do that, i have to check?) Is that a proper "top balance"?, and am i correct in my understanding that a bottom balance involves taking each cell down with a load or power resistor to a precise voltage and make sure they are all done the same?, that may not be too bad with the cells i am looking at because they are only 5500mah.
thanks

[Sunking]

Well no other battery has a nominal 3.2 volt nominal cell voltage. I do have another idea for you to consider. Consider a 12 volt 15 to 20 AH AGM. If you go with LFP as Mike said you need an answer for the initial Bulk Balance.

Option B is they make 12 volt LFP batteries as drop in replacements. They already have been Balanced and do have a BMS built in to make them Drop In replacements for consumers. Pricey though.

[LETitROLL]

1) do your initial cell balance
2) what will be you method for LVD, if, on the way to retrieve the pump, you stop to smell the flowers and it wants to over-discharge the battery

So far i have never left it unattended while pumping, but certainly would not want a distraction to cause me a problem, so i was going to run some sort of LVD.
thanks

[Mike90250]

1) do your initial cell balance
2) what will be you method for LVD, if, on the way to retrieve the pump, you stop to smell the flowers and it wants to over-discharge the battery

[LETitROLL]

Just looking to play around with some lifepo4 cells, dont want to spend much money so i know i will be dealing with lesser quality batts, just want to make sure they are indeed lifepo4 and not some counterfit other chemistry pretending to be lifepo4. I pump some water up from a spring at my cabin (not very often) and currently using a used car battery that is working fine to run the shurflo 12v pump, but the battery is tired (10 years old) and gets heavy on the 600' long, steep trail packing it down and back to recharge, the pump draws close to 5a for this particular lift, and i run it about 30 minutes maybe 3 or 4 times per week when i am around there. I see some cheap 26650 5500mah 3.2v supposed lifepo4 cells i can get for 3 bucks each in bulk, just wondering what pitfalls i would be looking at to run 2p4s pack for 12v 10ah which should be super light to pack and i think could do okay with a .5C draw for 20-30 mins. I have a Victron 75/15 with cable and software to set the current limit and voltages proper just not sure if there is anything to look out for with those particular batts or the 2p arrangement.