Charging Lipos Questions.......

[kylelnsn]

Hi all,

I am currently building a trex 250 clone, waiting on parts at the moment. Although i have a few questions re charging lipos.

I have ordered a Accucell-6 for use with my Turnigy Lipo 850mAh 3S 45C which i have two of. i am trying to work out the settings to charge at for day to day use. what amperage should i charge at.

I have not ordered a power supply for it, but i was going to use PSU for a computer.

My question is why do we choose these? What is the benefit.

Thanks all appreciate your help.

[raptorheli2]

charge at 850mah for 1c. that gives you the longest life cycle (in theory) from the packs. if it were me i'd charge them at 1 amp quite happily and charge a few of them at 1 time via an adapter for parallel charging. i.e if you have 3 packs at once on charge charge at 3 amps.

reason for a PSU power supply is cost/reliability and they hit their given numbers-which some of our modelling PSU's are not capable of doing.

cheers

[kylelnsn]

So if i use a 400w power supply do i get 400w on the 12v lines? is this too much?

[challis349]

That is only a 50 watt charger, the psu shouldn't do any damage, but you would be much better getting a 5amp laptop psu, as this will be good enough for that charger, should leave you enough for a few more batteries too

[cjcj1949]

You can't get 400W like that. If the power supply is 12V it will give you 12V. The more load you put on it the more it will struggle. The 400W tells you it will give up the struggle at 400W. To work out the amps a psu will give you you just need to know that watts is volts X amps. So If you have a 50W charger and you feed it from a 12V psu it will give 4 amps while working at 50W. Watts is power. You probably know about it from cars. A 100kW car goes better than a 50kW car. It usually costs more to insure as well.

There are lots of things that will cause lipos to die early. One of them is parallel charging if you do it wrong. Do it right and they will last longer. Its mainly about derating them or not pushing them. Don't charge too high or discharge too low (in volts). Don't use when cold (Warm them to 30 Centigrade). Don't let them get too hot. Don't take too much current in discharge or charge. Store them below 10 Centigrade at 3.85V per cell.

There's lots of info on this under electric vehicles. They can make NiMhs last 8 Years in a car, or you get them replaced for free. The basic idea though is as I said above. There's an 80% rule that you might find useful. If you want a 5 minute flight, especially when cold. Give them a 1 minute gentle warmup, then a 1 minute rest. Fly for 2 minutes, rest for 1 minute, then fly for the other 2 minutes.

It works for us older flyers as we can't concentrate for more than a few minutes and we get tired easily. Our hands get cold as well so the break gives us a chance for our fingers to warm up.

You can break most of the rules above and still get lots of cycles. Break them all and you may find it expensive.

[rob12770]

100kW car ? mines petrol..