Run time question

[xsvtoys]

If this is a dumb question I apologize, I am just starting out and am looking for somewhere where i can get some good RC information.

Is 20 minutes of running about right for a 1500 mA 6-cell pack?

That's what I got on my first run on an Evader BX.

I had ordered 2 battery packs from Tower, and apparently one was bad, as it would not run for more than a minute, then would "charge" in one minute. Tower has been very good for support though, they are sending me a new battery pack (Duratrax) and also some pieces that were missing for mounting the Evader spoiler.

I'll put some information on the Evader BX post after I get some more time on it. I had to order a new radio antenna also, due to an "accident' by my son : ( The car doesn't work too well with a broken radio antenna :(

[sosidge]

20 minutes is a lot of runtime from a 1500 pack.

I assume you have a peak charger - that "bad" battery may have been ok, just false-peaking - you can test whether a battery is charged by whether it's warm to the touch - if it isn't warm, push the button again.

[xsvtoys]

Thanks, I do have a peak charger, Duratrax Piranha to be exact. I actually have tried what you suggested, hitting the button again. I also ran it down and tried recharging again, but it still just runs for about 1 minute.

Tower is sending me a replacement and told me to just keep the bad one, so if there is any way to revive it I can have an extra.

I don't have a discharger. Is this recommended? What is the advantage of the discharger compared to just running the battery all the way down in the car?

[sosidge]

A discharger is a useful thing to have with NiCd's to keep them in good condition - they can get a "memory", which will decrease their runtime - storing them discharged will help stop this.

NiMH cells don't need a discharge.

There's no need to go over the top with a discharger - just get one of the little self contained boxes, or a bulb discharger - it's well worth getting one with a voltage cutoff though, to stop the cells getting too low.

Running the battery flat in the car is ok, but stop running it as soon as the motor and steering responses become delayed - otherwise you can damage the battery by letting it go too low.

The useful thing with a discharger is you can do a "clean" cycle, i.e. a full charge, then a full constant discharge, which is a bit kinder on the battery pack.

[highroller]

20 minutes with a 1500 is very good runtime.
If you've got some soldering experience try breaking the battery you think isn't good apart, use needle nose pliers to remove the tin tabs that's connect each cell together, the lightly sand the battery ends. Get some single cell shrink, battery bars or braid, wire and connectors then reassemble the pack into a side by side configuration. If you are careful in remove the connector and wire you may be able to reuse it.

Since you are only using it for recreational use (no serious racing) 1 auto lightbuld may be fine, it will take longer for the pack to discharge but you run less risk of reversing a cell or damaging it if the bulb is left on too long. Just remove it when the bulb dims or starts to go out but not completely out.

[xsvtoys]

Cool, I'm up to try that, like I said, looks that pack is a freebie anyway. I can handle soldering and the like.

Here's another newbie question: I've read in a few places that the standard battery connectors and motor connectors should be replaced for higher speeds. I presume this is becuase they create a high resistance?

The question is, what would you replace them with? Are there some special connectors to buy for that?

I don't really need to do this tight now, because this car seems to run plenty fast for me, but I'm sure if I stick with it a while....well, faster is always better eh?

[sosidge]

Yes, different connectors are more efficient - the standard Tamiya style connectors will melt under heavy loads, and waste battery power. The bullet connectors used to connect the motor are also pretty inneffective.

A popular kind of connector for the stick pack batteries is the "Deans" connector - for the motors, you can fit Deans as well, or just solder directly (what I do) - you will notice an improvement in the cars performance - and more importantly, you won't end up with melted connectors.

[xsvtoys]

OK I found the Deans connectors easily enough.

Just to make sure I understand, you would make a committment to slice off all the connectors on all your batteries AND your charger, and replace them with these.

Also, I can see getting rid of the bullet connectors on the motor and directly soldering the wires. Is it possible to service the motor this way? I'm thinking in terms of cleaning it with Powershot, which I haven't done yet but I'm sure I will. I can see cutting or desoldering the wires to change motors, but not for every time maintenance is needed, so I assume you can kind of let it hang away from the car while you clean it?

Another question (and thanks to everyone for tolerating me). I charged a few batteries in a row on my Piranha Peak Charger, and I noticed that sucker gets pretty hot. I take it this is normal?

Thanks again.:D

[sosidge]

First off, don't know the Piranha charger - but it's not surprising it gets hot - my charger has a built in fan, and still gets hot after charging one pack...

Second - if you go for deans on the batteries - you've got to go the whole hog and fit them on the charger as well - you couldn't use crocodile clips or anything.

Motor soldering isn't a hassle if you have a soldering Iron to hand - if the leads are long enough, you can hang the motor out - I do with my Tamiya Mini - but we like short leads cos they waste less power.

You could use deans on the motor as well - but switch them compared to your battery connectors, so you don't plug the speed controller in the wrong way by mistake.

[corwin99]

I took the Kyosho adapter that came with my charger and took one end off it and solder a deans connector to one end so my charger could do both deans and tamiya adapters. It works fine like that so far...

[highroller]

There is a noticeable different in speed using a side by side setup over a standard assembled stick pack. Using either battery braid or bars provides much better current flow and lowers the resistance. Adding a good wire (12 or 14 guage) plus a good connector: Deans, Sermos (power pole), Astro Flight, Race Prep offer the least resistance short of hard wiring.

[BIGBADBOWTIE]

I have the Piranha charger for my daughters T3 truck. The charger used to get VERY hot after one charge. I went down to the local hardware store and bought a small AC fan (3X3X2). I wired it in directly to the incoming AC source(after the fuse).That way as soon as the charger is plugged in the fan runs. I fixed it to the front of the charger over the factory vent holes so that it draws the heat out of the charger. It pulls in cool air through the bottom 2 holes and keeps it very cool now. I charge all of her packs before we head to the track. I have charged up to six - 6 cell 2400 packs one right after the ather and the charger stays cool.


Ray