i need some thoughts about direct charging. i am currently using a123 batteries and loving every bit of it. i have a mastech power supply for a direct charging set up. the specs are variable, 50v and 20a max. takes about 15 mins to charge a 4600mah 5s2p pack at 16amps, which im currently running on my sc8. a123's are the ULTIMATE track basher batteries. i literally charge for 15 mins then run 15- 20 mins nonstop all day long. and now, as we all know they are lipo batteries that are rated to charge at 5C!. so if a 5000mah lipo, on a 5c rate charge, you could charge at 25amps! only problem is chargers these days are only up to 7 amps mabe 12 amps max. so i need some thoughts about direct charging lipos. i have tried searching about direct charging a lipo, but nothing pops out. technically a power supply is a charger. since my mastech power supply is variable, i could control the voltage and amp output. my main concern is over charging, since lipo batts are really sensitive. do they make a charging voltage cut off that would be inline from the power supply to the batteries???? on my a123, the batteries are done charging when the amps drops all the way down to 0-5 amps. im not sure if lipo would be the same. and also does lipo have a special way of charging?

well thats all ive been thinking about. if this is possible, my charge time on the new 5c lipos would be as fast as if i was to charge my a123. i could go up to 20 amps!!!!! any thought or anything would help. i need more info before i buy a $200 lipo and toast it trying to charge it.

thanks

I run a123s too - same 5S1P pacs, usually run a pair wired in parallel so I have 4600mah for runtime. I charge mine at 10amps since thats all my Hyperions 0610i charger will allow. The newer 0720i will charge at 20amps so its getting better - charger designers are recognizing the need for more charger output power and higher charge rates.

Lipo uses the CC/CV charge routine - it charges at constant current (1C up to 5C as you mention) until the cells hit max voltage of 4.2v. The rest of the charge is at constant voltage allowing the cells to top off as amps decline.

I don't see any safe way for you to replicate this process with what you're using for a123s. You will damage a lipo overcharging - if not swelling it, then you're losing cycle life due to internal changes you're causing.

Get one of the high power chargers that will charge at high rates and protect yourself from destroying or compromising an expensive lipo. Oh the other thing - do some more research - the significant time savings comes from jumping from 1C to 2C charging with lipo due to the way the CC/CV routine works.

hmm im not too sure but that cc/cv sounds alot like direct charging.
when i charge my 5s1p a123 is i set the voltage on the pover supply to 18 volts then plug in the pack. then the voltage drops down to what ever the battery voltage is. then slowly set my amps. which i use 16 amps. through out this proses i have a diode + a fuse + a watt meter [to read the amps/ volts/ mah etc.] in line with from the power suply and batt. now while i charge, the pack wont go above 18v because i set the voltage to 18v max. now while the pack is taking the charge the voltage will go up to 18v then the amps slowly drops down to zero amps[ which indicates the batts are done, since it is not taking anymore amps] but the voltage stays at 18v constant. sound preety much like constant current/ constant voltage.

OK, as long as your equipment is accurate enough to prevent any overcharge, sounds like you may be doing the same thing, just manually. There are chargers like the MRC 977 and 969 that don't measure the small voltage differences accurately enough to be recommended for charging lipo. Even if you successfully are able to charge a lipo without swelling it, it may be a while before you realize if your process is damaging or not.

Damaging a lipo shows 2 ways - the obvious swelling or puffing and a decrease in cycle life due to internal changes from over/underdischarging and high temps. Lipo is not as tolerant as a123 cells are.

You still have to balance the cells.

ill try them on a cheaper lipo first.

thanks for the inputs.!!!!

ill probably end up getting the 20amp hyperion later on.

That would make things simplier since thats a balancing charger where the charging/balancing is done at the same time.

If I was you I would search for lipo fires first.. to see the damage they cause when overcharged.. All it will take is forgeting that batt for 20-30 min and you could lose your house or garage... Part of my job involves designing and maintaining a lipo charge and test center and I have seen a cell batt (Alot less energy then an rc batt) explode and shoot a ball of flaming chemicals across a room and stick to someones back because one of the engineers dismised a safety step (guess what happened to THAT engineer?)
that person was lucky to be wearing a sweater over a shirt that day!

Just my 3 cents

What he said.... I bought the platinum 4800 Mah batteries from Orion when they first came out. After about a months use I got bored with rc and threw them and my gear in a box and tucked them away in my closet. Here about 5 months ago I got back into the hobby and did some research on lipos before I tried charging them again. You wanna talk about some volatile lil s.o.b's! I put them in the heaviest cooking pot I owned and duct taped the lid on for safe measure when recharging them lol. Luckily they work fine... but after seeing all those videos of them exploding and catching fire, I don't recommend charging lipos any other way then how the battery manufacturer and the charger manufacturer suggest. Even then I would still suggest a fire proof lipo bag to store and charge them in.