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Old 10-06-2004, 06:56 PM   #1
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Battery questions

I have SMC GP 3300 matched cells. I read the SMC forum about recommended charge rates etc.

One thing that confuses me is the use of the term "traying". They recommend no traying.

I bought a Trinity battery discharge tray and I am going to guess this is what they mean by a tray. I think the discharge tray only discharges at 2Amps.

I have a Competition Electronics PitBull X3 that doesn't do dischargeing from what I understand from the manual page.

If I don't use my fancy discharge tray how do I discharge my cells properly?
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Old 10-06-2004, 07:12 PM   #2
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Jeff-Which tray did you purchase?

Where on SMC's website does it say NOT to tray the cell?

You wanna discharge with either a Integy Reactor 30 or a digital discharge device.Lightsbulbs and a Cutoff will even work but instead of 10 bulbs try to get more towards 14-16 lights for the increased amp draw.

I discharge my cells down to 5.4 and store them for the week.When I arrive at the track I take the cells out and apply them to the tray.Let all the lights go out and take the pack off and let it cool for about 15-20 minutes.I usually install a pack on the way to the track that way Im ready to charge when my stuff is setup.
In between heats if you dont wanna tray you dont have to but I do suggest Discharging inbetween heats.
In your email you were questioning NIMH having memory and so on.
Well the NIMH cells of today do have a small amount of memory.We are still loosing runtime with NIMH but not at the same rate as you would a Nicad if not discharged or trayed.


Hope this helps and keep the emails coming.lol.

It's not like the OLDSKOOL days things have changed.
I will do what I can to bring you up to current status.
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Old 10-06-2004, 07:17 PM   #3
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I bought the Trinity discharge tray. I didn't do much research before buying it. The Novak version seemed overpriced, so Trinity it was!

edit: The SMC reps on the SMC board on this site said "no tray". That's where I just read it.
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Old 10-06-2004, 07:20 PM   #4
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Personally I dont like the quality of the Novak and I run a Rayspeed.Your discharge tray is more than fine.

What does it say on top of the tray or do you have a model # of some kind?

Can you email me a pic?
Les
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Old 10-06-2004, 07:29 PM   #5
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Email on the way.

In case anyone else is interested the model number is : TRI22000. It's on the main Trinity site www.teamtrinity.com .

eit: fixed link.

double edit:

Here is the link to the forum where they say don't use a tray.

http://www.rctech.net/forum/showthre...threadid=31010
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Old 10-06-2004, 07:37 PM   #6
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Further info received from Korgae - Company representitive of SMC racing.

The following is a copy of the private message I received.

It's the same info as TexRacer stated! And TexRacer takes the victory as he answers the question quicker than the SMC guy.

Please, no tire burning donuts on the victory lap. We have to keep the track in good shape.


*************
Re: SMC cells

Hi.

For discharge:

use either a 30 or 35 amp rate down to 5.40V and then you can "tray" down to 0 volts.

For the 30 amp discharge, I would look at the Integy 30 amp discharge unti ( reactor 30) this stand alone unit will hook straight up to the pack and take it down to 5.40V

hope this helps

Korgae
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Old 10-06-2004, 08:02 PM   #7
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Jeff they were saying not to tray in the beginning due to the 1st generation of GP3300 cells that actually discharged themselves at a moderate rate and could reverse.

Now with the newwer versions of GP3300's like you have you wanna store at 5.4 but tray them before you charge them.

Some guys DeadShort but thats not needed right now.

The problem is YES 2 amps is too low of a discharge rate.We are NOT using the tray as a discharge device but more of a equilizing device.
Pick up a Integy Reactor 30 or another type of discharger at 30 amps.These units will usually have a cutoff of 5.4 or .9 PER cell.
The tray just makes sure they are all equal taking them down to 3 volts when the master L.E.D. goes out.
Thats .5 per cell and is still safe.
I would store them this way just use it when you arrive to the track.

Korgae is a great guy and full of battery info.
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Old 10-06-2004, 11:37 PM   #8
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TexRacer - What part of the Novak tray don't you like?
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Old 10-07-2004, 12:53 AM   #9
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I actually use the novak equalizer to bring the cells down to .9 per cell. This is as low as most companies recommend and will give you really good power.
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Old 10-07-2004, 07:05 AM   #10
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Default Battery Maintenance

We use a Novak board with wonderful results. I talked with Novak at the Mod Nats, and this is the regimine he reccommended:

Put GP 3300s on the board before every charge. Then charge as normal. When the pack comes off the track, put them back on the board. Take them off the board and store. Tray them again before charging.

The Novak board discharges at 1.5 amps, which is just too slow for me for the full discharge. I also believe heat is the enemy. (There are two schools here.) So, when the pack comes off the track, I cool it down on a fan. Then I use an Integy 30 to discharge, with the pack still on the fan. When the Integy says the pack is discharged, I leave it on the fan 'till it's cool, and wait for when I want to charge it back up.

Then I put it on the Novak board and leave it there until the moment I start charging so that when I charge, all cells are at the same starting point, 5.4. This gives an even charge, and we've noticed better performance with this method.

When the day is over, we discharge with the Integy & fan, put'em on the board, charge for 500 seconds at 5 amps, and take 'em home.

When you're running two or three classes, batteries almost become a full-time job for one person, but our batteries have as much punch as anybodies', more than most, and they last a long time.
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Old 10-07-2004, 05:34 PM   #11
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Quote:
Originally posted by Aaron Waldron
TexRacer - What part of the Novak tray don't you like?

A lot of racers at the track I go to, of whose opinions I respect, use the Novak Smart Tray giving it rave reviews. I like the idea of not having to babysit an equalizing pack. I am buying one the next time I am there. Some are setting the cutoff at 0.1 per cell saying that their batteries are rejuvenated at that setting.

Aaron Waldron,
What are your thoughts on the lower cutoff?

Grazie
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Old 10-07-2004, 08:19 PM   #12
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Aaron-It's a really nice tray.I would say it's more of the quality of it than anything else.
I have 2 of them(Novaks) I just prefer the quality of the RaySpeed tray over it.
The novak is a pain for some pack configurations.
Otherwise it's a nice tray.
Simply an opinion.
Les
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Old 10-12-2004, 03:18 AM   #13
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Young Chazz- You state you use a fan to cool your packs. This is bad for them. The cells need to cool slowly to not damage them. The fan cools the outside of the cells only not the important core of the cell. Any rapid cooling or any cold temperature for that matter harms the internals of the cells and could be dangerous.
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Old 10-12-2004, 09:56 AM   #14
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PHATT - Heat is the enemy of electronic efficiency. I have seen R/C racers cool batteries with fans for 8 years and this is the first I have heard of this being damaging to the cell.

We attend races in the southern California desert in the middle of the summer, and It is not uncommon for us to place our packs in tough ziplock bags and place them in ice water. Nearly everyone charges their batteries while sitting on a fan, because a battery will not completely charge if it is already warmer than it should be.

I understand your points but I have seen too many good results from keeping batteries cool to worry about over-cooling the cells.

beeoh - There are many different schools of thought when it comes to Ni-MH care. A close family friend runs an independent laboratory where they get to test stuff like this, and he swears the best is to store the packs completely dead, and he has numbers to prove his point. Others are dead-shorting their packs like we used to do at the end of the Ni-CD era.

Trinity, Novak, and other companies recommend the .9 volt cutoff method because it is tried and true to be safe and promote long cell life.
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Old 10-12-2004, 10:46 AM   #15
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There is no problem with cooling batteries with a fan after they have been run. The only thing that could damage a battery is super rapid cooling with cold air cans. Cooling with room temperature air can't hurt them. Charging with them on a fan can be harmful, but it does depend on the ambient temperature.
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