Getting There.. But Yet Another Question!

[racecar 0]

Hopefully someone will have experienced this problem and can help put our minds at rest.

Both cars are TT01 chassis, both were running charged 2300 NiCD batteries, both ran no problems for about 25 minutes around the local tennis court. Then within minutes of each other both stopped running smoothly and began stop start movement. We let them sit for a couple of minutes and then regained smooth running for a matter of a couple of minutes and then again ran stop start. I put this down to the batteries which were warm and so packed up and came home. As soon as we got back home one of the batteries went onto the Discharger and has been on that now for 19 hours with the LED still glowing strong. I would have thought that the battery would have discharged by now, so if they had a lot of charger left in the batteries (as would appear by the fact that the discharge light is still on) what is causing the cars to run in an pulse fashion.

Is the heat build up too much for the batteries or the motor or are the batteries run flat but have a large amount of residual charge left over that is not capable of moving the cars.

If it is heat build up and we are in very cold winter months, I presume that I need to install some heat sinks on the motor and maybe the battery clamp.

What's the consensus out there?

Thanks again

Andrew

[mymonsterbeetleisbroken 16]

25 minutes of running from a 2300 nicad pack sounds ok to me, i think the batteries have simply reached the point at where your esc's fail safes have kicked in, as they think the packs are too low to power the cars without loosing control of the radio gear.

what esc's are you running?

after you let them sit for a few minutes, did they drive again at full speed - as if the packs were still fully charged?

either that, or there was interference around, or the radio gear's batteries have got too low.

i've never used a discharger before, so i'm not sure why they haven't discharged yet. how about putting the batteries back in, and laying the cars upside down or hold the wheels of the ground - and waste the packs until they can't even turn the wheels, that's what i normally do, takes about 3 -4 minutes until the pack is so dead even the servos don't work properly.

[racecar 0]

Thanks mymonster.

The ESC is the TEU-101BK from Tamiya, it's all stock at the moment, no upgrades whatsoever.

The first battery pack took 19 hours and 20 minutes to discharge, the second one is now sat wheels off the ground on a simple workstation I've just made (cut out from some high density foam block) and the eldest is sat in the lounge watching scrapheap challenge running the battery down.

So we'll see where that goes from there.

Is there any guidelines to how long various battery capacity will run for, I know that there is no scientific guidelines as all chassis, drivetrains, tyres never mind how its driven will give a definitive guide, but just some approximates ones would be useful.

Thanks again

Andrew

[terry.sc 17]

Sounds like there's nothing wrong with the batteries, the duration is about right and the 'problem' you have is just the batteries being flat.

What type of discharger are you using? A proper discharger will dump a fully charged pack in an hour or two, it sounds like you have an equaliser there designed to finish off the discharging after a discharger has been used. When the car won't run there is still at least 6 volts in the cells, but that's as low as the batteries need to go. If you are running the cars until they won't run any more then the batteries don't need discharging after use.

Discharging is only useful if you are racing as the length of the races means the battery pack never gets discharged. The battery pack just gets used to being run for 5 minutes, so the pack will run fast for 5 minutes, then slow to a crawl as the memory effect means that is what it is used to. If you aren't racing you never have the problem of repeatedly running for the same short length of time, so you should ever need a discharger.

[racecar 0]

Now this is why I post on here, cos from reading the responses I'm learning all the time.... brilliant!

The discharger is a NosRam gravity stickpack model, bought from Modelsport UK and it didn't cost a great deal so if its a bit surplus to our current requirement then that's not a problem.

we'll run them till they stop and then they can be recharged to go again.

Thanks

Andrew