PDA

View Full Version : All this new-fangled technology...


F1END
03-08-2009, 02:02 PM
Hi,

I used to race at club-level back in the late 80's/early 90's and have recently got back into RC. I used to know roughly what I was doing with all the technology then, but am feeling out of touch now :s.

I have just got a brushless system (Novak SS5800 8.5T + Orion Vortex ESC) installed in my Durga, but it seems my battery isn't up to the job of running it for more than about 5 mins at full power. I was getting around 20-30 mins on a brushed modified, but apparently the discharge rate isn't high enough.

What I want to know is:

1: Should i go Lipo?

Baring in mind that I'm on a VERY tight budget and can't afford 100 lipo's and would rather not have to buy a new charger, which will give me a longer run-time, a 2400mAh Lipo, or a 3300mAh NiMh?

2: If I do go Lipo, is this charger any good? http://www.wheelspinmodels.co.uk/item/PX3840A-LB6-4A-Entry-Level-LiPo-Balance-Charger-12v-Input__74b3/

3: My ansmann ACX1 NiMh charger says it has a capacity range of 1400-3500mAh. Does this mean it WON'T charge, say a 4200mAh pack at all, or that it will just take it much longer? or just that it's not recommended, but it will do it?

4: All Lipo's seem to give a discharge rate (20C,30C, etc.) what sort of discharge rates do you get from decent NiMh's?

Thanks in advance,

F1END

Brooks
03-08-2009, 04:36 PM
If you want to stay in the game, you have got to go Lipo :thumbsup:
I use Trakpower 3600 30c lipo batterys, they are about 60 for 1
You really want a high C rating like 30c + for touring cars etc
That charger looks ok but i would recommend the Core UDC 20
It chargers lipo, nimh, nicd etc at a max 5 amps
Cost me about 40 as mine was Reconditioned but new about 60
Go lipo anyway !!!!!!!! :p

Si Coe
03-08-2009, 04:44 PM
OK - the charger looks fine, but I can't vouch for reliablity.

Like for like, a 3300mAh Lipo will run for logner than a 3300mAh NiMH due to its lower internal resistance. I suspect the higher then Lipos C rating the greater this effect, but have not tested this.
Also, once your lipo has run down, you can almost instantly recharge it, rather than needing to wait as with NiMHs. That means that in the course of a day you will get significantly more runs off a Lipo.

Value for money wise - these (http://demonpowerproducts.co.uk/product_info.php?cPath=46_142&products_id=2272) lipos are as good as they come. In practical terms you will get nearly twice the runtime of 3300NiMHs plus be able to recharge and be ready again an hour later. Therefore this is the equivalent of buying 2 or 3 NiMH packs, not merely one.


On the other tech - I expect your charger can charge capacities over 3500, it will just take over, but it is possible that it won't deliver more than 3500mA at a time (to avoid overcharging packs if it can't detect the peak). The solution there is simply to start it again!