Racers And Bashers Differences

[skip665]

Also, don't forget how much more fragile plastic is in extreme cold.

Yup I was jumping my Bush Devil and now have a small chunk missing out of one of the wheels! Doh!

[tamiya monkey]

So now i know to stop storing my nimh's fully charged, and leave in a lower state.

[Lemming]

So now i know to stop storing my nimh's fully charged, and leave in a lower state.

As I say, don't take this as the only answer, but it has definitely made a big difference to the capacity my batteries.

Maybe if I had a better (around 20amp) discharger things might be different.

If you are having issues with run-time / capacity then it might be worth trying a few times leaving them flat from a run (don't keep going until the car doesn't move though).

Steve

PS - If you do try this, please let us know on this thread how it goes. The more input we can get from real-world testing the better

[retroman]

Yeah, the cold weather does kill NiMH packs, as they give their best performance when they are slightly hot. That's the thing with NiMH, stuck between a rock, and a hard place- Don't get them too hot, or the life of them will be shortened, or keep them cool- better overall cell life, but take a dip in performance. This time of the year, I would recommend charging at 6 amps, and then sticking them in your pocket, to keep warm

For Silver Can, or Sport Tuned bashing, I still don't think you can beat Ye Olde Tamiya RC1400SP stick packs. Very punchy, and last for years

To be fair though, My GP3300's used to get a real hammering when i was racing; charging at 6 Amps, straight off the charger, and into the car without letting them cool.........And they're still going strong after 3 or more years

[GGtrialer]

so basically keep my NiMHs stored empty, just to the point the car is almost not moving or when steering takes over the motors power? if i race them in the now arctic sub zero temperatures of my front yard it will keep the packs life long but hinder performance? right?

i might just go out on the ice this evening and kill my pack so it wont be stored full for more than a few weeks.

[Lemming]

so basically keep my NiMHs stored empty, just to the point the car is almost not moving or when steering takes over the motors power? if i race them in the now arctic sub zero temperatures of my front yard it will keep the packs life long but hinder performance? right?

i might just go out on the ice this evening and kill my pack so it wont be stored full for more than a few weeks.

IMPORTANT!!! - This is just my opinion after my tests with my batteries and my vehicles - This is not to be taken as advice, purely discussion points or for others to use as a basis for testing!

I stop when the car slows rather than fully flat. NiMH cells can reverse polarity if dropped too low...

I would am storing them discharged to this rate, BUT I run (therefore charge and discharge) them once a month. I have NOT tried storing them in this state for any longer than 1-2 months - I have no idea what impact this would have.

NiMH discharges faster than NiCD (from my experience) so the pack will probably discharge after a few months.

On the heat issue:

The hotter a pack gets, the more it will shorten the lifespan (in theory)

Faster charge rates = faster discharge rate (at the same current draw) = More punch, but shorter runs

Fast charging (above 1C - 1 x capacity - 1 amp charge for a 1000mah battery) causes more heat and is often not recommended by battery manufacturers

Hard discharging causes more heat - my E-Maxx packs are seriously toasty after a run - my Hummer only gets the battery warm rather than hot

Hope this helps

Steve

[highflyer]

Great thread, should be a sticky!

[GGtrialer]

yes, very good information here!

[Novastar]

Really good informative thread and I read almost all of it It answers my long wondered about question of how far I should run my NiMH packs down. I'll try to avoid the current 39 degree celsius days for the health of myself and my battery packs !

[Butler]

To be fair though, My GP3300's used to get a real hammering when i was racing; charging at 6 Amps, straight off the charger, and into the car without letting them cool.........And they're still going strong after 3 or more years

To me this is what makes the difference. Between my dad, brother and I we have about 5 packs of GP3300 cells, some new some old, some matched. All will take a charge at 5amps and peak between 3400 and 3600, if discharged first. I have even left some for months before using.

We also have a pair of cheap green 3800mah batteries from china that will be going in the bin soon. They are useless. Wont charge to capacity, get really hot if you charge them a 1C.

I also had an Mtroniks 3000mah battery that had been really good. Also gave good punch and charged to about 3100mah. However after leaving this battery and one of my GP3300 cells a month. I hastily charged them both at 5amps on my Super Brain whilst away camping and being impatient. The GP3300 charged fine. The Mtroniks pack caught fire.

Great advice on this thread, but the quality of cells is a big factor. We don't look after our packs that well and they can get left for weeks, but the GP cells just take the abuse and perform great.

[Lemming]

To me this is what makes the difference. Between my dad, brother and I we have about 5 packs of GP3300 cells, some new some old, some matched. All will take a charge at 5amps and peak between 3400 and 3600, if discharged first. I have even left some for months before using.

We also have a pair of cheap green 3800mah batteries from china that will be going in the bin soon. They are useless. Wont charge to capacity, get really hot if you charge them a 1C.

I also had an Mtroniks 3000mah battery that had been really good. Also gave good punch and charged to about 3100mah. However after leaving this battery and one of my GP3300 cells a month. I hastily charged them both at 5amps on my Super Brain whilst away camping and being impatient. The GP3300 charged fine. The Mtroniks pack caught fire.

Great advice on this thread, but the quality of cells is a big factor. We don't look after our packs that well and they can get left for weeks, but the GP cells just take the abuse and perform great.

Definitely agree!

My Vapextech batteries (middle of the road packs) have been superb, but charging above 1C would not be recommended... They do get quite warm on 1C and seriously hot even slightly above that (1.1C). Then again, they always took above capacity when looked after (4400mah were happily taking 4500 - 4750). They are coming back up now that I am storing them mostly discharged after use, and charging them at 1C.

As Butler (and others) have said - Battery quality makes all the difference!

The biggest factor in charging any NiMH battery is the manufacturer recommendations. Most suggest 1C as maximum, some state that 1.2C or even higher is acceptable. My advice would be to ALWAYS go with the manufacturer stated (or lower) to avoid any issues. If there is known advice out there (such as regarding the GP cells - well documented for taking 1.2C to 2C charges) then people are welcome to try it, but taking into account that each pack is different - as is each charger.

Glad this thread is of use to people and provoking some good discussions.

Cheers all

Steve

[HereBeMonsters]

If quality makes all the difference, what can anyone recommend for:

a) a large capacity NiMH (or 2) for bashing

a medium capacity LiPo for racing - but has to fit in an M03 and a Manta Ray (which has a small battery compartment, wouldn't fit a 4200 NiMH pack I had)

Both need Tamiya connectors as I'm not going to faff around with different plugs for all my cars, chargers and NiCads...

[Lemming]

If quality makes all the difference, what can anyone recommend for:

a) a large capacity NiMH (or 2) for bashing

a medium capacity LiPo for racing - but has to fit in an M03 and a Manta Ray (which has a small battery compartment, wouldn't fit a 4200 NiMH pack I had)

Both need Tamiya connectors as I'm not going to faff around with different plugs for all my cars, chargers and NiCads...

For bashing, Vapextech is a good bet (their own website and on Ebay). Extremely cheap pro-rata to most, and if looked after properly they are decent packs. Quite a few members on here use them for that purpose and find them perfect.

Have about the same punch as GP cells which have been charged at 1C - GP cells when charged at higher rates do have slightly more punch though but shorter run-times.

No idea at all on Lipo, but got used to the problems of packs in other cars. I have fitted the larger modern cells in the M03, by spacing the arms out for the battery stays. My Hummer and FF01 both have the size issue though, and not come up with a fix yet. Using NiCD packs in them at present.

Not much help I know...

Steve

[retroman]

Totally agree about quality of cells..... You really do get what you pay for. I recently bought some cheap NiCad packs at around 10GBP per pack.......... I might as well have pulled 20 quid out my pocket, and set fire to it Utter rubbish. When put on my Pro-Trak, they would only discharge for 20 seconds when fully charged!! I now will not buy battery packs unless I know what cells are in them.

I think the Tamiya stick packs have Sanyo cells in them?? For me, it's either Tamiya stick packs, or GP cells, all the way. IMHO, they work out far better value for money in the long run.

My King Blackfoot has been pulling some serious wheelies tonight, with a stock silver can in it. The cells? Tamiya RC1400SP NiCads. I very much doubt it would be doing that with either of those two el-cheapo packs in it.....