Moving to Lithium

[Mouldy]

Re: Moving to Lithium

As i said 40%... but;

Looks like they have made it a direct purchase price now.. originaly it was only for a few robot builders and heli flyers etc then flightpower sent an e-mail out to all there sponsored teams to tell there friends the sponsorship code... now it looks like they've just chopped all there prices by 40%.

But for the money thats a really good lipo and would be more then enough for your fw.

[PJ-27]

Re: Moving to Lithium

Pasted from the rules (just for clarity):

7.8.2 Voltage Cut-out (Advisory) The robot should be fitted with an under voltage cut-out or alarm set at or higher than the battery manufacturer€Ÿs recommendation to prevent the batteries from becoming damaged by over discharge.
7.8.3 Fusing A fuse rated below the maximum burst discharge of the battery must be fitted.

[gizz]

Re: Moving to Lithium

Hijacking the topic.
Charged my LiP batteries for the first time today actually.
Its a 2s 250mAh battery for the ant (know this is fw topic)
I do know overcharging them past 8,4V will make them explode or similar, so my question is, stopped my charger at 8,4V charging voltage
but when i measure the batteries they have 8,25V according to my isntrument.
Is it okay to charge with a higher voltage than 8,4V for a 2s pack or is it only dangerous if the pack itself hits above 8,4V?

[Mouldy]

Re: Moving to Lithium

what charger are you using? you should be able to just set it to 2cell charge at 0.25 amps and hook up your balancer... it should tell you when there charged!

[gizz]

Re: Moving to Lithium

http://www.lrhhobbies.com/bantame-stati ... arger.aspx
This is the charger im using. No balancer it has got delta peak, charge timer and a maximum capacity function at least.
And the question im curious about is if charging with higher than 8.4v is dangerous to the pack or the only danger is if the cells own voltage is above 8.4v.
It seemed the charger had 0.15v higher voltage when charging than the pack had itself

[Mouldy]

Re: Moving to Lithium

Firstly... id suggest you buy your self a balancer... or buy a balance charger...This is essential to the rules.

Secondly- a 7.4v (2cell lipo) will only register at 7.4v when flat... its running voltage will be higher.

An example is that in 540 i run a 6cell lipo (22.2v)... when fully charged it actually runs at 25v... even under load.

[gizz]

Re: Moving to Lithium

Yeah I will look into a balancer or a balance charger, the batteries doesn't have balancing leads but that could be sorted.
Yeah I do know it says 3,7v per cell but its really 4,2V when charged.
But my question remains as when reading up on charging LiPos it says if you charge the cells 1-3% above 4,2V they might explode,
but is it ok to be charging with lets say 4,3V to a cell until it reaches 4,2v or would that also make it explode?

[grant_ploughbot]

Re: Moving to Lithium

If your using a proper lipo charger then it will charge in 2 stages, CC (constant Current) and CV (constant voltage). It first charges in CC at a set rate of charge untill the voltage starts to get close to the 4.2v per cell level. It then switched to CV at 4.2v untill the battery is charged. As it's getting nearer the end of it's charge the current from the charger should decrease and the voltage stay the same. If your charger is going over 4.2v then I would stop using it ASAP.

[gizz]

Re: Moving to Lithium

Okey. Yeah reading the manual it mentioned those 2 methods but not cleary saying it used those, but it is labeled as a LiPo charger aswell.
I will mail the manufacturer and ask aswell.
Yeah I stopped it at 8,4v for my 2s pack but when measuring the pack it had 8,25V, but that's almost full anyways

[gizz]

Re: Moving to Lithium

Found this on ebay: http://www.ebay.com/itm/New-RC-iMAX-B6- ... 5162c#shId
Anyone who have bought from that place before?
Price seems too good to be true altho the seller is top rated.

[PJ-27]

Re: Moving to Lithium

I bought one of those from Hong Kong (I don't think it was the same seller though) for £8.

The postage took ages! (Several weeks if I remember rightly) but it arrived. I think there are some cheap clones going around, and I believe mine to be one of those.
It works fine though, the display went a bit crazy the other day but that passed with a simple switch on turn off.

Oh and the manual is written in a gibberish language.

[leorcc]

Re: Moving to Lithium

The price is about right, roughly what it would cost if you bought it from Hobbyking.

http://www.hobbyking.com/hobbyking/stor ... UINE_.html

Keep in mind you will need a 12V to 18V power supply along with this charger, it doesn't plug into an outlet directly. The Imax B6-AC does have a 110V-240V power input built in.

[PJ-27]

Re: Moving to Lithium

Should have said, the one I picked up was the one with the built is PSU. Be wary of the HobbyKing PSU's they have really bad reviews I believe.

[leorcc]

Re: Moving to Lithium

I've got a 600W PSU from Hobbyking and it performs fine. But for robot events I'm taking the Graupner 200W PSU, thats a lot lighter.

[gizz]

Re: Moving to Lithium

Well i ordered one from hobbyking instead as it was roughly the same price and it was a genuine one