Hello,
I'm seeking recommendations for a charger that can top-balance my 1yo LiFePO4 batteries before integrating them back into my system.
Here are the details:
- Battery Configuration: 4 x 3.2V LiFePO4 cells in series
- Capacity: 280Ah (total for all cells)
- Individual Cell Voltage Variance: 3.345V - 3.63V
I plan to put the cells in parallel for top balancing, but I need guidance on selecting the right charger I can't find a suitable charger for a 3.2V cell. Safety features are essential since I'm unsure about the maximum charging current (A) for my specific battery setup, can't find a datasheet on them.
Affordability is a factor, but not at the cost of compromising reliability. (able to set a charge cut-off would be a good plus)
Any help would be invaluable in helping me find the best charger for this task, looking for experience-based recommendations only please?.
Thank you for your assistance.
Barry
These are fairly cheap converted server power supplies. The only downside is they don't have a current cutoff. There are other telecom power supplies on Aliexpress that are quite powerful and have some features including current cutoff, capacity limit cutoff, etc in the 2000W to 3000W range for $120 to $250. You won't touch any "professional" product in that power range for that price. I like the look of the ZTE chargers but they are the priciest of the bunch at $250'ish or higher but for a 3kw charger itspretty impressive (running it on 110V is going to cut the current output in half....I typically look at the 0-60V 0-50A model but they have a 0-120V 0-25A model if run on 220V-240V)
Now as far as top balancing....if this is your standard top balancing new cells that were shipped at 30% SOC this kind of high amperage charger is great since it SHOULD be able to get down to 3.65V...might have some loss in power in terms of current when you use a low voltage, might want to ask the seller how it performs at 3.65V. I've seen a couple of them reviewed on YouTube for charging 4S 12V packs and people seem to love them. For a budget minded person living the van life this could be a lifesaver in terms of getting them something that can charge their 200-400Ah of 12V batteries in an afternoon to get them back going after a couple rainy days if they don't have DC to DC charging off their alternator. I don't know of any other option approaching 100A of 12V charging power this cheap.
For actual balancing you'll want an active balancer (most cost effective method at $10 for a 4S 5A balancer). Keep in mind the amperage number on the active balancers is only seen when the cells are 1V apart. The closer they get, the less current there is balancing the energy around.
For more expensive but still cheap options the ToolKitRC M8S is an 8S hobby style charger packed full of features. Bonus points is it can do 24V LiFePO4, a lot of hobby chargers only go up to 6S. The old M8 and early firmware versions for the M8S had issues but it has all been smoothed out. It is a little bit of a pain in the butt with calibration as it seems to lose voltage and current calibration any time you do a high current charge that gets the charger quite warm. The internal fans SUCK and heat dissipation slits in the charger shell suck. I use a PC fan to help compensate for that failure. At about $45 its an insanely feature stuffed charger/discharger (fairly low power if just using the "internal" setting, has an external setting that works great with power resistors and a regenerative setting capable of the full 400W/18A of power like an iCharger which is awesome). Tons of RC related features for servos and whatnot (shit I'm clueless about). Best of all it has a power supply feature. I believe 0-30V 0-18A. Charger is max 400W/18A, balance current is 800mA, voltage input 7-30V so it will boost a 12V input but two HP DPS 460W server power supplies in series at ~25V is a great $30 option to get its full potential and its only running those power supplies at 50% of their rating when max'ed out.
You can get $8 HP DPS 460MB's if you are patient on eBay. Might have to buy 2 at a time but I've never spent more than $10 shipped on an MB and $8 shipped on an EB. I've seen 4 packs of EB's go for $24 shipped. I got lucky and snagged a refurbished still in the packaging MB for $10 and a good condition used MB for $8. I think the only difference is efficiency.
Find many great new & used options and get the best deals for (Lot of 2)Genuine HP Switching DPS-460MB A Power Supply 643954-101 HSTNS-PL28 at the best online prices at eBay! Free shipping for many products!
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I think this is a two pack of earlier models for $14 shipped...not 100% sure but can't say if the mod is identical. Most likely is. I prefer working on the EB's or MB's
Find many great new & used options and get the best deals for HP HSTNS-PL14 460W Switching Power Supply 100-240V AC - Lot of 2 at the best online prices at eBay! Free shipping for many products!
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Y Cable (I found a cheaper one on Amazon but its 2x C13 to 1x C14 and I would much rather have this style):
Buy a Tripp Lite 6ft Power Cord Y Splitter Cable 5-15P to 2xC13 10A 18AWG 6' - power splitter - IEC 60320 C13 to NEMA 5-15 - 6 at CDW.com
www.cdw.com
I bought this Nylon M3 kit because I converted more than one set of two PSU's into a 24V:
All you really need are enough pieces to isolate the DC board on the #2 PSU aka the Floating PSU. #1 stays untouched. You could do it with maybe 4 washers, two 12mm screws, and like 4 nuts. So if your local hardware store happens to sell this stuff individually or in small packs maybe go that route but this was much easier and has enough hardware to convert like 40+ PSU's into 20 24V PSU's.
I think I bought 110mm shrink for individually wrapping each PSU and then 220mm for wrapping them together? Pretty sure those measurements are correct for the 460W PSU's. I also added a layer of electrical tape (would have used barley paper if I had some at that time) on top of the bottom unit for another layer of safety.
Cost for 1m of each size on Aliexpress was like $3 each tops. Cheaper if you bought 5m or 10m....might as well if you make 18650/21700 battery packs.
I chose to use these 4mm banana plug/binding posts on the first one I made. They are kinda big though....so used something different for the second one I made
Second one I bought something like this off Aliexpress
Find many great new & used options and get the best deals for 10Pcs High Current M5 Type 4mm Female Banana Jack Socket Binding Post Connector at the best online prices at eBay! Free shipping for many products!
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Could these be higher quality? Maybe?
Find many great new & used options and get the best deals for 5 Pairs Binding Post M5 Thread Power Amplifier Connector Banana Plug Jack Socket at the best online prices at eBay! Free shipping for many products!
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For the 4mm banana sockets I used a dremel and sanded flat one edge and then soldered that to the pad on the PSU. Lots of different ways to do it, ideas all over RCGroups and Thingiverse. Thingiverse also has cases for covering the terminals.