Charge time 1800Mah 7.2V

[lykan]

Ok I have a new battery its a hump pack, 7 cell 1800MaH NiCad. I can either trickle charge it or quick charge it. It came half charged and tehey said to discharge it all the way before use (did that)

What I need to know is how should it be charged the first time trickle, or quick peak charge?

If I need to quick charge it, how many amps 3 or 4.5?

If I need to slow charge it, how many hours should I trickle it and at what rate?

Any help is mucho appreciated..

thanks

 

[Candyman]

Well, I'll address what I can. Usually they recommend cycling the pack a couple of times before you use it. That means charge it then discharge it. Don't trickle. With 1800 mAH batts you should use a charge rate of 3-3.5. 4 might be a bit too high and cook the batteries. If you're going to trickle, my Super Brain 959 trickles at .1 amp. But if you're going to charge at that rate, be prepared not to use the batteries for a few days. 'Cuz it will take that long to charge them...

 

[lykan]

Ok I have decided to go ahead and charge these guys three amps. The question is how to discharge them. I have plug in with a resistor solderd to it (hooks up to dshcarge the batteries). But I hve no idea how long it would take.

The resistor is 30ohm 10% 10watt

So should I discharge with the resistor,
or sould I discharge them in the veicle wit the wheels off the ground?

 

[Candyman]

To discharge you want to expose the batteries to a load that's close to the load when driving. Typically regular packs are discharged at 20A. Unfortunately me and Ohm's Law aren't really getting along these days. So I don't know what size resistor you'd need. You may want to see if you can find info on bulb dischargers. These are things you can make at home using like 10 car signal light bulbs and they will discharge your pack safely.

 

[lykan]

Hrmm would putting it in the car, and running it at a constant throttle setting, either doing circles, or with the wheels off the ground work? Unfortunetaly I'm about 1/2 hour from town and our LHS guys are stinky :llama: 's

 

[Wardo]

Charging a NiCad pack at 3 amps will do nothing for it. You'll gain slight amounts of runtime but prolly not enough to matter.

Nicads like 5 amps for the initial charge and 6 amps for a second peak before running. You'll gain some punch out of the pack charging it this way and cut charge time alot also.


I've seen people charge Nicads at 8-9 amps before also, it works but kills it's life.


Depending on what you use for a charger/power supply, you're prolly not keeping up at 4.5 amps anyway when the voltage rises in a 7 cell pack.

 

[lykan]

I have a novak peak II charger. The power supply is a huge 120ac to 12v converter. It has enough juice to power a an entire motor home. I also have a traxxas max peak II, but I dont understand the dial on it ;(

it has Mah ratings, not sure if thats the trickle charge, rate, the fast charge rate, or if you mach the MaH of the pack to the Mah on the dial.

Thanks for the tip tho, Ill try peaking it at the 4.5 amp setting and see what it does for it.

 

[militarymaxx]

Peak detection chargers are nice. They sense when the pack is at full or near full charge and then defaults to a trickle charge. You'll hear lots of talk, mainly from the pros, about overcharging. They don't pay for their batteries and often get only one run out of a pack. They have crammed so much juice into it that it roars out on the track. But the pack is pretty much dead after the run. Make youself a homemade discharger out of brake light bulbs. 8 to 10 bulbs will give you the discharge rate that you'll need. If not, running the car until dead is the next best thing. Be careful when discharging that you don't fall into a 'negative polarity' state with the pack. When this happens, you basically discharge the pack to zero and keep going (negative). This will kill the pack. When using the light bulb setup, discharge until the bulbs are very dim, but not completely out. Good luck.

 

[Wardo]

1157 bulbs are what you need for the discharger. Any auto parts store has them cheap.


When discharging without a auto cutoff, if one cell is lower in charge then the rest, when you discharge to zero, the one low cell will go below zero and into reverse polarity.