Battery questions

[hypercar]

Hi everyone,

Just looking for some answers to some battery questions I have. This is all regarding NiMh, not Lipo. Haven't gone Lipo yet, but I will soon.

1) My first pack is a Reedy Itellect that I assembled myself. When I plug it into the charger, it doesn't seem to register. I double checked all my solder joints and resoldered a few, still no luck. Any ideas? Some people at my lhs have suggested some cells might be bad.

2) When soldering my packs together, sometimes I have a very difficult time getting the solder on the battery to melt (I put a tiny bit on the battery and a tiny bit on the metal bar). Any idea why this may be? I'm using a Weller soldering gun, that big one with the trigger. Should I be using a little iron instead?

3) Reedy, Orion, Maxamps, Trinity, or others. Any preferences? And why? I know Maxamps doesn't use matched cells, but the pack of theirs that I have is great! A friend of mine ran a Reedy and a Trinity, and got a way longer runtime from the Trinity.

Any thoughts would be great! Thanks!

Sean

[SS Pede]

1) I assume the charger works with other packs? If so, I'd say triple-check those joints and/or read number 2). You can use a multimeter to measure the voltage of each individual cell to see where they are at. A dead/damaged cell may read a very different (even negative) voltage from the good cells. But a cell would have to be REALLY dead to break the circuit within the pack and make the pack "invisible" to the charger. If a cell reads zero volts this could be the case.

2) A soldering iron is recommended for battery work, not a gun. I don't know the ins and outs of why, but basically a soldering gun is not going to adequately heat the joint. People tend to recommend a chisel/wide-tip iron that is 40 watts or more. The more powerful the soldering iron is, the faster it can heat the cell and wires to make a good connection. You don't want to heat the cell for too long because it could be internally damaged, so a powerful iron is important.

3) There are a million and one places you can get batteries. The important thing is have a pack made of good, name-brand cells. Personally I don't know which matchers are the best, but many people have great experiences with smaller matchers. Check out places like Promatch Racing, SPC, and a bunch of others I can't think of right now if you want good matched packs for perhaps less than you would pay with Orion/Trinity/Reedy etc.

Sometimes batteries are just the luck of the draw. Your Trinity pack might work great while your friend's theoretically identical pack dies in two runs because a cell goes bad. A matched pack is more likely to run reliably and last a while because it is made from pre-screened cells that have to "pass the test" before they are put into packs. If you get a pack from someplace like Maxamps you may do just as well, but you may also get a dud cell now and then.

[BTE214]

Depending on your charger and if the condition of the batteries you may have to force them to take an initial charge. You could use a wall charger to start the charge and get some voltage in them so your charger will recognize it.

[Jason MaxAmps]

I know Maxamps doesn't use matched cells, but the pack of theirs that I have is great!

Sean

I'm glad you like the pack. The main reason we don't offer matched cells is that our main focus is on Li-Po. NimH is an old technology that is slowly falling to the wayside and we feel that it is better to invest our time in the new rather the old. When your ready for Li-Po give me shout and we'll get you set up with what you need. Once you do make the change you'll never go back.

Take care,

Jason

[Peg Leg]

My battery question is, what is an average temp for a battery to have right after it's used? Should they be about 170 or so? Thanks

[guver]

It can be anything really. If it's usedd slow enough then it will be ambient temp. If it is pulled way to fast then it could be well over 200 deg F. Average may be 120-150 deg F.

[cgandersen]

1) I had this problem... try "forcing" a charge into it... once I was able to get it up to full charge, I had no problems from then on...

2) I also had this problem with my first pack. The problem isn't with the type of soldering device you have, the problem may be two fold: first, you need to have a drop of solder on the tip of your solder gun/pencil... this will cause the solder on the pack/bar to almost instantaneously head up... doing it the other way (with no solder on the tip) is causing the heat you're trying to apply to the solder blob on the cell to get absorbed into the cell itself, making it really really hard to heat up the solder itself, and possibly damaging the battery in the process... the other problem I had is that I couldn't get the solder to stick to my tip... I fixed this by getting a little tub of "tinning" agent from Radio Shack to tin the tip of my iron... once I did this, solder would stay on the tip of my iron... of course, if you have a really good tip, then it may not be an issue, but I was using a ghetto tip from Radio Shack so I constantly have to tin the tip of it...

[ghubernj]

Intellect batteries have a bad habit of automatically discharging when they sit around for a while. Do like the others said and try to force some energy into your battery pack. After doing so, let the pack sit for a day or so and they try to fully recharge it.

Later,
Gary
www.surgeworldwide.com

[hypercar]

I actually ended up sending the pack in to Associated and they forced a charge into it and got it going. That's exactly what it was, it just sat around too long.

For future reference, though, how would you "force" power into your battery? The best I can do is plug it into a charger and try and charge it. The charger I currently have only goes up to 4amps, which is what I leave it on for my B44 packs anyway, so I can't "force" any more in than that. how would you guys do it?

And since posting this thread, I've run an Orion matched racing pack, the Reedy matched pack, and 3 MaxAmps packs. The MaxAmps ones are by far my favorites. They last the longest, run consistently, and they seem to keep their punch alot longer. I bought a couple MaxAmps packs for my Xray M18 too. I really like MaxAmps.

[GSMnow]

What kind of charger are you using?
In NiCd mode, it should let you start a charge even at zero volts. Some will do it in NiMh mode as well. When I have a NiXx cell at 0.0 volts, I like to hit it with 2 amps and watch the voltage. Hopefully it will come up over 1.2 volts fairly quick. Once all the cells are active at 1.2 volts, then set the charger for a low charge current to top out the pack. A slow charge rate seems to let the cells re-form better. Hitting a zeroed out cell with high current may bring up the voltage fast, but from my experience, the cell will have much more niternal resistance and less capacity after that. Using a lower current seems to bring them back without killing as much capacity. It will take a few cycles to get full punch out of it, and they never seem to be as good after going to zero. This is a big difference from the old NiCd cells. Many racers used to zero out NiCd's to get a biggger punch and longer run, but zeroing a NiMh cell kills it. I like to keep my IB and EP 4200's over 1.1 volt.

[hypercar]

Right now I'm using a Prophet Plus 2
http://www.rcslot.com/pc-radio-control-slot-cars/DYN4054.html

But I have a Hyperion EOS0606i coming soon, along with some Lipos for my M18. I'll also use this charger when I finally go Lipo with my B44.
http://www.maxamps.com/EOS0606i-AC-DC.htm

The Prophet Plus 2 I bought just to get started. I didn't want to get into the extreme details of battery maintenance and tuning when I was getting back into the hobby, I just wanted to have some fun. So while I do know proper maintenance and care would make them last longer, I'm really just having fun.
I don't have a voltmeter, so I don't watch the voltage of the cells. I just charge them, run them until the car starts slowing down, then switch them out. Maybe I'll pay more attention when I get the Hyperion. As long as its easy. :)

[tireshredder]

That’s what is so cool about LiPo power! Set lvc at 3v/Cell and use a balanced charge. Then you can basically forget about it, mega cycles, save lots of money, and have a ton of fun!
Later,