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dameetz
2008.06.03, 07:02 AM
How do you guys prepare your batt for race? . I notice that 1st time charge of the day will not have punch and speed. Usually I will charge my batt to full and use it about 5 mins of driving then I charge it again for the 2nd time and this time I usually notice it will have more punch and speed. Do you actually discharge your batt after a day's playing? I m currently using Intellect 750s and Orion 900s and both batt performed best after the 2nd chare.

Programmers
2008.06.03, 11:35 AM
I took loads of advice from a fantastic post in spoons blog:

http://blog.128racing.com/2007/01/battery-care.html

I now discharge the day before and slow charge them. On the day, I peak them in a quick charger before the race. I cycle them twice in one day and store them without charging after their second use.

R1WURKS
2008.06.08, 05:58 PM
we have found to get the best results from a higher discharge rate,3 amps to have the best results so far but using the cell on the track will give you even better results.but make sure you drive it all the way down.

EMU
2008.06.09, 02:42 AM
I do a slow cycle the day before, and peak it right before using at a higher amperage, the first charge should is the best run of the day. After 3 runs, I put my cells away since they start to run a little flat after that. I use 4 packs of Orion 900s, 2 sets of TSR 900s, and 4 sets of Duratrax 750s throughout my race night. I like the Duratrax cells for low amp draw classes, and the TSRs for mod, and Orions for stock.

What charger are you using?
What charge rate are you using?
Is there a trickle after?
How long are you waiting after the charge before you use them?
Are the batteries hot after they finish the first charge?

I dont discharge after using them. I discharge then charge them slow (<.5c) the day before racing. When I get to the races, I peak them right before I want to use them at a higher amperage (1c-1.5c). The longer you wait from the time that they peak to when they are used, the slower they will be. If the cells trickle after they peak, you want to remove them right after they peak. The trickle will make them run a little slower as well. I try not to let my cells trickle when I am racing if I can help it. For new cells, the trickle is good for the break in, but for cells that are going to be raced, the trickle slows them down a bit.

Cell temperature is also important. Warm cells have less resistance, and release the power better. Which is a reason to run the cells right after they peak. Cells that sit and cool off are going to last longer, but have less punch. Hot cells are not good, since they will overheat and you will lose power and lifespan. You should be able to hold the cells in your hand for at least 10 seconds, if they are hotter than that, you are charging at too high of a current for that cell, or you need to cool the cell during the charge.

My cells get VERY hot after my modified class runs. I usually use cool cells for that class. Although, for the low amp drawing classes, I like to use the cells right off the charger. The difference isnt huge, but it could mean the difference between 2nd or 5th place where I race. Many times we have the top 5 racers on the same lap throughout the race.

marc
2008.07.02, 12:57 PM
How do you discharge the batteries when not useing theme in the car? And what is the EXACT purpose of discharging theme anyway? Just to bring the volt's all the way down to 0 or what?

ProfoxCG
2008.10.09, 06:21 PM
I m interested in learning about batteries,

currently I have a SUPERBAIN 959
and I have not idea how to use it other than plug the batteries and hit START.

I have a few questions
1) what is "VENTING" ?

2) 750 mAh mean "milliam amps" - how many milliams is 1 AMP
the reason I ask this is because I can select the AMPs at which i can charger my batteries, and honeslty I have been selecting 3.0.. and I think im doing something wrong? what is the proper way to charge them,

I can set the charge is AMP and mV (what does that mean)

EMU
2008.10.09, 07:01 PM
You should adjust the amperage with the 959. I dont remember what the stock amperage is, but I am pretty sure that it is too high for the AAA's.

1A (amp) = 1000mA (milliamps)
1ah (amp hours) = 1000mah (milliamp hours)

You should charge around 1C. C being the Capacity of the cell. So if the cells are 1000mah cells, you should charge at 1A or 1000mA. If the cells are 750mah, you should charge around 700mA or 800mA.

Venting is when the cells overheat and release some 'liquid' from the cell out the top. It is not a good thing, and if a cell vents, performance is reduced.

mV is millivolts, basically you can set the change in millivolts for the peak. The lower the number the less of a change in voltage will be needed for charge termination. I usually use about 6-8mV depending on the type of cell.

Since you are charging in series, you should make sure to balance your cells before charging. You can balance by discharging the cells to a given voltage, the PN discharger works well for this.

ProfoxCG
2008.10.09, 11:16 PM
all batteries should be charger at around 1C ? what happens or could happen if i charge at 2C (like I have been?) would it charge faster? would I have less run time? etc.

What is charning in series?

also, If i have 4 8oo mah does that mean that the charger should be set at 3.2 amps? (basically the sum of all the ma?) or is it per cell mah value?

mV is millivolts, basically you can set the change in millivolts for the peak. The lower the number the less of a change in voltage will be needed for charge termination. I usually use about 6-8mV depending on the type of cell.

what change? what peak, what is peak? ( i am completely ignorant when it comes to batts)

Thanks,

EMU
2008.10.10, 04:36 AM
When the cells are setup in series, all cells are linked together like a chain. Each cells voltage is added to the other cells in the chain. When you charge in series, if the cells are not balanced, some cells have more charge than the others, the cells with more charge will be overcharged by the time the cells peak.

As the cells reach the limit of the capacity during the charge, they will drop in voltage. That is the peak. Hobby chargers allow you to program what change in voltage to use to detect the peak. The smaller numbers will need less of a change in voltage to conclude the charge cycle. They also have more of a chance to false peak. High numbers will charge a little more than the smaller numbers, and too high of a number will overcharge the cells a little.

When you charge at anything over 1C, you are reducing the life of the cell much more than you would at 1C. I charge higher than 1C. Most of my 900mah cells I charge at 1.5A when racing, and 1A when practicing. Some cells can take higher charge rates, others cant. My 750 Orion cells I charge at 500mA since I have seen a few vent at higher amps.

ProfoxCG
2008.10.10, 08:04 AM
okay so from what you are saying:

1) overcharging is bad: can cause venting and reduce the life of the batt.

2) can you explain the reason you charge your 900 mah @ 1C during practice and 1.5C during racing. what does this accomplis. (we are assuming here that you 900 can be charged at 1.5v without venting and techinally you are reducing the life of the batteries, but then again .5v will probably not kill you batteries. Also, the 750mah you charge at .5V, why not 1V ? will the vent at 1V?

I noticed some of my batteries' wrap has been ripping.. how do you know when the batteries are no longer good? is there a way to test for that?

If I take a Volt meter to a single cell I should get a ready of 1.2xx Volts, anything subtancially lower means the cell is no longer good? or am I wrong?

3) I am using a rig like this (pic) (http://www.batteriesamerica.com/4AAAT%20pic.JPG) to charge my batteries, is this considered in-line also as opposed having them in a "line" array.

4) in the tray above i can fit (4) AAA @ 1.2V each. Which mean I am going to be charging a total of 4.8V. Let's say each one of these Cells is 900mah, charger need to be set at 1Amp not (900 X 4 = 3.6Amp) correct? and if I am charging (8) the Amp will still need to be close to 1C

EMU
2008.10.10, 12:23 PM
You are confusing Voltage for Amperage in your above post.

I charge at 1.5A for races since I notice a considerable increase in power compared to 1A. I dont mind replacing my cells every 3 months when they start to go flat. I cycle every once in a while in a Lacrosse or Maha charger to see what the capacities are.

It is hard to judge a cell with a voltmeter. You only get the voltage, and not the capacity or punch. Most cells discharge down to .9v to be depleted, so testing with a voltmeter wont really do much except tell you what the voltage the cell is releasing at the state of charge it is in. I test for capacity by discharging in a Lacrosse or Maha charger, and use them in a car to see the punch. For stock racing, you want as much punch as possible. For modified racing you may not want as much punch.

When you charge at a higher amperage, the cells will typically have more punch but less run time.

The tray you are using charges the cells in series. 1.2v x 4 = 4.8v. They will normally peak around 6v (1.5v per cell), but when they start to discharge they will output about 5v. You do not multiply the amperage with each cell. 4 cells in series have a capacity equal to the lowest capacity cell in the chain. In parallel, the capacity increases but the voltage stays constant.

ProfoxCG
2008.10.10, 04:12 PM
a Lacrosse or Maha would be the oposite of charging in series correct?
those can discharge and charge single cells (which is better than a "larger" charger?

i went to my LHS today and spoke to someone who told me that for example, the venom charger will not charge or will stop charging the 4 AAAs if one of them for example fills up faster than the the rest, and also told me that i would dicharge them to a point but not evently. I would then need to individually dischage the AAA in a dicharger (Pn tray for example) to make sure all 4 cells are discharged to the same capacity before i atempt to charge them.

well for single AAA this is easy, what is done for a 1/10 lipo or Nihm pack where the cells are all soldered together?

x_zminiracer
2008.10.28, 06:44 AM
1.5 amps into AAA cells, can see needing battery's every 3 months. If you can afford that great.

In general, I use a dynamite vision peak ultra, set @ .8 Amp for race day and a couple of in tegy indi booster discharger's / charge racks.

I discharge them all and let them sit until all the packs are discharged then charge them up the day before.

@ home I use an older fma direct super nova computer charger discharger for matching an managing my packs. For my AAA's it is set at .8 Amp charge and 2.0 Amps for discharge.

Works perfect for me, my batteries have lasted a lot longer than 3 months and so far are all 100% or better of rated capacity. Personally @ 75% or less I responsibly dispose of the cells.

ProfoxCG
2008.10.28, 04:42 PM
I bought a PN discharge and charge tray, they seem to work great together hocked up with my "brain" charger. I am goin to get a Maha sometime down the line. (next week maybe)

I wonder if I can connect a second charging tray to my brain charger so charge 8 AAA at a time

cowboysir
2008.11.21, 09:55 AM
I wonder if I can connect a second charging tray to my brain charger so charge 8 AAA at a time

profox,

you can link 8 cells together if your charger has the capacity to charge 9.6 volts...I do this "bulk" technique sometimes to speed up getting a large quantity of cells ready for practice days.

The only issue I have is that when you link two sets of cells to do 8 total you get a charge that stops at the lowest mAh capacity in the group...say two different sets of 750's are a little lower in value it'll stop at the lower value.

ProfoxCG
2008.11.21, 05:43 PM
thanks, I have a few sets of the same mah