Differences in mA charging?

[rat95dyna]

Hey all,
This is my first official post here, so be gentle!
I have been running rc cars for 34 years now but have always been the backyard basher type. My first car was a funky unit that ran on AA batteries and did not have proportional steering. Great fun, though!
I have had major fun with Tamiyas (Sand Scorcher) and AE (original RC-10) but have always run NiCad's with a timer-type charger. Now I find myself with a 4800 mA/hr NiMh and was wondering the differences between charging it and the old type, lower rated NiCads. Any words of advice?
Can I use my old 15 minute timer charger on the new batteries and if so does it take more than one cycle?
Again, I just do this for the pure enjoyment, not for the trophies!
Thanks in advance!

Mick.

[Grizzbob]

Hey all,
This is my first official post here, so be gentle!
I have been running rc cars for 34 years now but have always been the backyard basher type. My first car was a funky unit that ran on AA batteries and did not have proportional steering. Great fun, though!
I have had major fun with Tamiyas (Sand Scorcher) and AE (original RC-10) but have always run NiCad's with a timer-type charger. Now I find myself with a 4800 mA/hr NiMh and was wondering the differences between charging it and the old type, lower rated NiCads. Any words of advice?
Can I use my old 15 minute timer charger on the new batteries and if so does it take more than one cycle?
Again, I just do this for the pure enjoyment, not for the trophies!
Thanks in advance!

Mick.

No worries, alot of things have changed, but it's not too hard to learn. Now while your timer charger can charge NiMh's to some extent, it WILL take more than one round on the timer to peak them, but exactly how much will vary by the capacity of the pack you get(the higher the capacity, the longer it'll take). But there is another issue with NiMh's over the older NiCd's, & that's how they behave when they're at their peak. When NiMh's peak, that's the absolute limit to what they'll take, almost ANYTHING beyond that & they will heat up VERY fast(& burst if you're not very careful), which is why it's far better to use a modern peak detecting charger on them, one that can tell when they're reaching their peak & shut off before any damage is done. It'll save you time, headaches & money in the long run to have a good charger, regardless of the kind of battery you have.
And while on the subject, have you thought about LiPo's? The price of them has gotten a LOT better in the last year or so, & while you also need a LiPo-specific charger to handle them, the price of those are decent too(& it sounds like you'd benefit from a new charger, anyway). They are FAR superior to NiCd's or NiMh's in how well they run & how long they last(as well as how much you can use one in a day, while NiCd's & NiMh's can only safely run once or twice in a day, LiPo's can run pretty much as many times as you want at any time, you can LITERALLY pull it out of your car & put it right on the charger immediately, where the others MUST cool down first for a few hours). One LiPo pack will serve you well for a LONG time, you can run as hard as you want, & it'll stay cool the whole time. And in addition, most if not all LiPo-ready chargers can basically handle ANY kind of battery you need to charge(in fact, mine from Core R/C can even do Lead-Acid batteries if neccessary). I realize that you might be on a tight budget, but I really think you'd love them in the long run, it's definitely worth the investment, whether you're a racer or a basher.....:cool:

[terrible-t]

Like you, I started with the Gold Tub RC10. Nicd were 1200-1500mah. The timed charger of Prostech timed chargers. Absent till early 90's, NiMh were introduced. I was told that the early charger for nicd should NOT be used on NiMh. NiMh were made of different chemicals. Useing Nicd charger would over charge(cook) NiMh with heat in 15minutes. Shortening the life of NiMh. So I believe spending the duckets for NiMh Charger but can be use for NiCds. NiMh chargers has the capability of adjusting amperage at .01 increments to 10v. One hour for full charge and peaked is good enough for bashing around. Lipo's are the newer batteries around and soon NiMh are the dinosours lie NiCd's. Lipo charger take a longer time to charge cuz again a different chemical, and limit charge amps. They could be charged at anytime.

[Grizzbob]

Like you, I started with the Gold Tub RC10. Nicd were 1200-1500mah. The timed charger of Prostech timed chargers. Absent till early 90's, NiMh were introduced. I was told that the early charger for nicd should NOT be used on NiMh. NiMh were made of different chemicals. Useing Nicd charger would over charge(cook) NiMh with heat in 15minutes. Shortening the life of NiMh. So I believe spending the duckets for NiMh Charger but can be use for NiCds. NiMh chargers has the capability of adjusting amperage at .01 increments to 10v. One hour for full charge and peaked is good enough for bashing around. Lipo's are the newer batteries around and soon NiMh are the dinosours lie NiCd's. Lipo charger take a longer time to charge cuz again a different chemical, and limit charge amps. They could be charged at anytime.

Actually, it's not that bad, a timer charger won't cook a NiMh pack any faster than a proper peak charger would if it were set incorrectly. Both use the same type of charge current(a Linear constant current, no pulses, just a solid continuous amp rate), but of course a timer charger will just keep going until its timer runs out(& if a NiMh pack peaks before that, it'll fry itself before the timer runs out most likely). The real key to the difference between NiCd & NiMh charging is how much of a voltage drop a peak charger looks for before shutting off(which is where adjustable peak thresholds come in handy, like most modern chargers have). The typical voltage drop that works for NiCd's is around 15-17mV per cell in the pack, so for a 6-cell pack it'd be about .09-.12 volts. But NiMh's are MUCH more sensitive, for them you need a threshold of more like 2-4mV per cell(so the same 6-cell pack in NiMh's would need to have the charger shut down after a drop of around .012-.024 volts, beyond that you risk overheating a NiMh). But if you absolutely MUST save money & have a digital voltmeter, then you could monitor the pack's voltage yourself & be able to disconnect it after the appropriate voltage drop(but you're MUCH better off just getting a charger that can do that for you, MUCH less risk that way)....:cool: