The ministry of silly questions pt1

[cambs flyer]

Last week for something better to do I charged up my new 450 batt to check the charger and balance unit plus to see how fast it took, which was set at 500mah

On Thursday my heli is being tested, do I need to charge the batt again, on the understanding that the charger won't pump more in the cells thats needed, or will the charge last just over a week.

Also what charge rate should I charge a 2100mah Align batt, as I've heard a too high level can damage the battery, and my charger has 250ma, 500ma, 1.0a, 1.5a & 2.0a settings.

Which one would be best for a good hard charge without waiting for ages or doing damage.

Again many thanks for any advice.

[David Drew]

1C = 2100 mah, so charge at that. Fully discharged would take 1 hour. But as you only go to 20% left it should take less.

Lipos hold their charge for a long time, but need to be kept warm when fully charged.

[gazza]

You won't need to charge the battery again mate. The discharge losses on stored lipos is very little.
2.0amps will be the best charge rate. This will be just under the recommended 1C charge rate for that pack anyway.

To work out the safe 1C charge rate just divide the pack capacity by 1000.
ie 2100 / 1000 = 2.1.. So 2.1 = 2.1amps.

[Sesame]

If the lipo is fully charged and not plugged into anything ie there is no drain on the battery, the level of the charge should not drop, that is one of the advantages of a lipo battery, if it were a Nimh you would have to charge it again to bring it up to full charge.

ok this bit I think ive got right but someone will correct me if I am wrong. lipos are always recommended to be charged at 1C for a 2100mah battery this is 2.1amps(I think) if you go to 2C you will charge the battery up faster but from what I understand you will reduce the lipos life

[gazza]

Yeah that's right.
To charge at 2C which would be 4.2amps the charge time would be virtually halved but so would the life of the battery...
For those who keep a record of cycles I've always been told that whenever a 2C charge is carried out then it should be counted as 2 charges.

Always charge at 1C unless absolutely necessary.
Lipos also don't like to be trickle charged either...You can charge at 0.5C (1050 amps) If you don't mind the wait but I don't think a chargerate below that is recommended.

Also, as David says it's important that if you are storing a fully charged lipo then ideally it should be kept at room temperature or thereabouts.
Cold temperatures can kill a lipo by sending it into an overcharged state as the pack voltage will rise with a fall in temperature.
Storing a lipo that is only say 70-80% charged in cold temperatures is fine however. The ideal storage charge is 50%.

[cambs flyer]

You chaps are bloody brilliant thanks ever so much.

Great so I can charge my Rex batts at 2.0A, wonderful, I know I've only got an El Crapo charger and balancer, but so long as I know I'm not doing any harm when charging it's peace of mind, and luckily my charger doesn't charge higher than 2amps

This is what I brought, please be kind.

http://www.simplyt-rex.com/catalogue...-dc-12v-a-1079

http://www.simplyt-rex.com/catalogue...ancer-a-1079bl

I know there not great, but I can't afford much better till after the house is finished.

So my BCX2 800mah batts should charge happily at 500mah.

Thanks for the great info everyone.

[moyesboy]

All the above is good advice.
Basically its the 1C or 2A charge rate.
They hold their charge well - a top up after several months, otherwise they are good to go.

I never head that low charge rates could be bad, but depending on how good he charger is I guess a very low charge rate might make detection of full charge more difficult for the charger.
Charging at 0.5C (1A for your pack - 1.05A strictly speaking) is super safe to preserve your pack so do that when you have plenty of time and charge 1C during the flying session.

I found that my series multi function charger and balancer only charge to what my cellpro4 thinks is 90%. My cellpro detects cold temps and will then only charge to 90%. So I guess if charged with my jamara pro peak and prolux balancer my packs will be ok in the cold!

[gazza]

Yeah mate they look fine..No worse than the flightpower Vbalancer arrangement anyway.
The BCX2 batts will be fine at 500mah, I would even chuck a thousand in as it's nearer 1C rate than 2C if you know what I mean and the batts arent expensive. Up to you bud

[cambs flyer]

Thank you MB, they say if you don't ask your never know, and at the risk of looking dumb (after what I done on Saturday evening is this possible)

Is 1C the equivalent to 2amp rate, and to be super safe charging my batts at 1.5Amp's is poss' the best rate.

Sorry if I'm sounding dumb, I've been reading up on curves and such these last few days and the heads exploding right now.

[marktigere1]

Just to add, I was advised from instructions by Andrew at Maxpoly to charge a new Lipo at about 1/2 C for the first couple of charges to allow the Lipo to 'bed in'.

For a 2100 mah Lipo that would be 1000ma or 1 Amp. Charging at 500ma would also be fine.

Cheers

Mark

[cambs flyer]

Yeah mate they look fine..No worse than the flightpower Vbalancer arrangement anyway.
The BCX2 batts will be fine at 500mah, I would even chuck a thousand in as it's nearer 1C rate than 2C if you know what I mean and the batts arent expensive. Up to you bud

Thank you bud' I think it's starting to make sense slowly, my CX2 batts have been as good as gold and boy have they had a hammering, charging from a 12V batt for me is the way to go, (so far anyway)

[cambs flyer]

Thank you too Mark, the bedding in charge period was also a concern, and as I'm likely to buy some of theres batts in the future thats blinding advice.

[David Drew]

Is 1C the equivalent to 2amp rate, and to be super safe charging my batts at 1.5Amp's is poss' the best rate.

1C is the battery capacity / 1000

2000 mah / 1000 = 2A = 1C
3000 mah / 1000 = 3A = 1C

2000 mah @ 4A would be 2C and would charge in 1/2 hour
3000 mah @ 6A would be 2C and would charge in 1/2 hour

So just charge at 1C = capacity /1000. No need to deviate from that unless you really want to get that last flight in & the occasional 2C charge will not harm.

It's really part of the FUN of electric.

[cambs flyer]

Many thanks David, it's all coming together now, these rates are the basically battery load Vs optimal charge load, for sustained longevity of batt life and speed of charge being a health balance of the two.

[kevinh]

talking of balancing are you balancing the cells as well as charging?

dont need to do every charge, cant remeber what the ratio is to charge and balance.

i normally do 1 in 5 charges is a balance charge