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Old 01-22-2009, 12:15 PM   #1
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Default How do i tell the state of my batteries?

Hi all,
I am pretty new to the sport. I jumped in head first and bought a "package deal" from someone who converted from electric to nitro. Now i have a T3/T4/B3/B4 and about 12 sets of matched battery packs, etc.

I am trying to get a handle on the state of the batteries and trying to understand how i can tell if they are up to snuff or a bottleneck. I have charged them all and ran them all and it seems to be a highly variable and random experience.....both because i charge them all up the night before i go to the track and on track day i just grab one out, pop it in and run. Some seem to do good and last 10-15 min or so, some seem to only last a min or 2, etc. I just havent wrapped my head around it yet, because i was also told to discharge them completely (with the lights or zero-izer) then recharge them to bring them back to life, etc..

Is there any way to understand the state of these things?

Here is the summary of the batteries i have:
4 SMC MATCHED 3300 PACKS ONE IS NOT BUILT YET,2 INTEGY 3000 MATCHED(PRACTICE) 1 FUSION 3300 MATCHED, 1 FUKUYAMA 3300 MATCHED, 1 PROMATCH 3300 AND 3 3300 GPS, ALL BATTERIES WORK AND WERE STORED WITH A CHARGE
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Old 01-22-2009, 02:44 PM   #2
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all nihm and nicad batteries loose charge over nite. to get the best out of them at track u need to discharge them , charge them , run them .discharge them again. and charge them up again after they cool. the second run will be better than first run. then u will know what u have . those batteries u have listed to well even after sitting. stay away from 4200's if u dont race weekly . they do poorly after sitting. hope this helps
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Old 01-22-2009, 02:51 PM   #3
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Make sure you watch your batteries while you charge them. A 3300 NiMh charging at 5amps should take around 40min to charge from a totally discharged state.

What type of charger do you have? Most good chargers have readouts telling you charge times and other data to help understand how the batteries are doing.

The battery pack should also be a bit warm after the charge. All cells should be about the same temp. If one cell is much warmer than the other, you might have a bad cell or cells.


Jerome
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Old 01-22-2009, 04:01 PM   #4
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Thanks. My charger does not have any readouts, it "auto" figures out what amp to charge at, etc. My guess is it just charges at 5amps. I will post the name when i remember what kind it is.

What is meant by "watch your batteries when you charge them"? Do i play an active role in the charging phase...I just press the go button and the light starts blinking when they are done?

As far as heat, i notice the first cell (on the red side) is much hotter then the rest...is that just because its getting all the juice to passthrough the line? I will have to check it when it completes.

Thanks all.
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Old 01-22-2009, 06:11 PM   #5
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What I mean by watch your batteries, especially with one that has no readouts, is that the pack might "false peak". This means it shuts off before it really is done.

All the cells should feel about the same. If one cell is hot then it might be "overcharging". After a cell has reached it's limits, it starts to overcharge which is actually "discharging". Then when you run it, you will over discharge that cell causing it to heat up more and damage the cell.

One thing that I do with my NiMh is to cycle them fully. This means after a run I will put them on the lights (10 auto bulbs) for a 20amp discharge until they start to fade. This is at about 5.4v for a 6cell pack. Then I have a cell discharge tray (Novak Smart Tray) that I bring each cell down to .9v each. This helps equalize the pack and allows for a full charging cycle next time. This is why I said that a 3300 pack should take about 40min at 5amps. If it takes more or less, it indicates a problem.

NiMh take a lot of work to maintain for race level. I like my LiPos but they are way more expensive to buy initially. With the price of NiMh packs going down, the LiPo packs cost anywhere from double to 5 times the amount. If they last the supposed 10x longer that is great! The only problem is one goof on a LiPo and it's over.... I usually get about a year of racing out of my NiMh before they are retired to the "practice box". I am just on my first year with my LiPos and one of my more expensive Orion packs just gave out.. it cost me $180 when I bought it! That's about 6 of my average NiMh packs..

Good luck and have fun!

Jerome
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Old 01-22-2009, 07:48 PM   #6
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You can get a great lipo for like 64.95 and a great dc lipo charger for 47.99.

Buying cheap nimh is like getting a savage beating.
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Old 01-22-2009, 08:54 PM   #7
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I have to agree, NiMh packs do take a lot of work, but if properly maintained they can last a long time. JeromeK99 has it pretty much down as far as charging and discharging. I would try to get a hold of a charger with more adjustabilty and read outs or invest in a volt meter. I have used a few different chargers but the two I like the most are the Novak Millinium and the LRP Pulsar series. Both give you NiCd and NiMh capability, adjustable charging amps, charge times, and charge MAH's. The LRP also has a built in discharger which is nice. I would also get a discharge tray. I recently picked up a Novak Smart Tray and that thing is awesome! I used to sit with my volt meter and have to watch each cell drop to .90 volts but the Smart Tray does it for you, just pop in the battery and push the button. If you plan on staying with NiMh packs for awhile a new charger and discharge tray are a worthy investment. You can also find them for fairly cheap since many people are switching to LiPo. I find that I can keep buying a few new NiMh packs every year or so and still be competitive at the track. Some packs I have are about 4 years old and they still work fine for practice or bashing.

As far as your packs go, cycle them a few times and you should know if they are race worthy or need to be decomissioned. If you are racing, you should be charging your packs at the track or the morning of the race. They will lose voltage while sitting. Also if one cell is getting much hotter than the rest it is probably bad. If you have a few packs that have a dead cell in them you can take them apart and put together a new pack with the good cells. You could also try zapping them with a battery zapper if you know someone that has one. With some care and upkeep, they will last quite awhile, unless the previous owner didn't take care of them, which you might find out later.
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Old 01-22-2009, 09:06 PM   #8
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Quote:
Originally Posted by RB FIVE View Post
Buying cheap nimh is like getting a savage beating.
RB, you just don't get it, do you?

Now that I have lipo and brushless, I find that I get bored easily. So reading posts that explain how great nimh are give me something to occupy my time!!!
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Old 01-22-2009, 09:32 PM   #9
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This thread is helping me a lot already. I don't understand why this site does not have a TUTORIAL section or some kind of KNOWLEDGE BASE to help us noobs. It will definitely decrease the amount of questions that are being asked all the time.

Thanks to those so far that helped out. Is there a specific site out there that has everything that we need to know about electric r/cs?
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Old 01-22-2009, 11:08 PM   #10
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knowledge base you say. This WHOLE site is a knowledge base! Of course, a lot of the "knowledge" is "based" on utter crap

I agree. Even a place where blurbs from the major product manufacturers would be good. At least you know they have the WORST case scenarios!
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Old 01-23-2009, 06:18 AM   #11
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You can always try searching for what you need. As you suspect, it’s quite possibly already here somewhere. Problem is, if a knowledge base was put together that covers a reasonable amount of info, well explained, it would be pretty big. So I suspect many would just go ahead and start a new thread anyway. See it all the time in the existing threads, the same question gets asked again in that thread because people don’t want to take the time to search.

No biggie though, plenty of experienced people are here with an honest desire to help. Yeah, you do have to slog through some goofy noobie posts sometimes to get it, but it usually works out. Its OK, we’ve all been there, and occasionally go back for a visit! Cheers guys.
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Old 01-23-2009, 08:30 AM   #12
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Thanks all for sharing the knowledge. I guess it all leads back to the one thing i have found out quickly in this hobby.....i have to spend a bunch more $$$...

I am on the cusp of deciding whether to go brushless, but dont want to spend the cash and i feel i am also getting closer to the cusp of "needing" to go lipo. Which by itself doesnt sound too crazy, but i have 4 cars (t4/t3/b4/b3) and about 14 sets of matched 6-cell battery packs, so going lipos would either mean i showed up to the track (with my son) with only 1 or 2 lipos and made a quick day of it....or i sell the house and buy a bunch of lipos.

Or unless you can run lipos and nimh's too i guess right? or do you have to change anything on the truck to go lipo?

Back to the recycling of my batteries. Can you help me understand when i should do what. Basically i dont run the cars during the week and then run them on the weekend. So what i have been doing is run each battery until it gets sluggish and slow, pop in another battery, repeat. When i get home from the track, i start charging them all up (they are in all types of states depending on when/why i pulled it when running). After about a day or so of "loosely" watching the charging, i have them all charged up. I dont touch anything until the night before or the day i plan to run them. Then i "top off" a few of them as time permits. I think what i end up with is some that are good since i topped them off, some that are pretty good because they held a good charge all week and some that are garbage because they didnt hold the charge...with no real method of keeping track of them.

Given this type of schedule, what would make more sense? To run them, bring them home, completely discharge them, charge them, let sit for a week, then use? or "top off" and use?

or

Run them, dont touch them until friday, charge them, run them saturday?

Thanks again all. As you can tell i am still learning....

-JD
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Old 01-23-2009, 09:59 AM   #13
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After or before the packs are charged, check each nimh cell with a multimeter. You can use a multimeter to detect bad cells. When discharged the cell should still give a certain reading and when charged you'll get a normal reading of 1.23, 1.24, 1.25 or more from each cell. Anything charged giving you a low reading such as 1.08 is generally going bad. You can remove the dead cells that don't put out any readings or are reading lower than normal. I haven't done this in awhile otherwise I can give step by step intructions. Either way use a multimeter or get one if you don't have one.

I use this one but you can get it even for less at places like Harbo Freight. Here are some


Another method to detect bad cells is to use an Integy 030 zero thirty quick discharger (discharges at 30amps) or the Duratrax version (discharges at 20amps). When discharging each cell, pay close attention to which bulb associated to each cell goes out the fastest. Mark that cell with a permanent marker. As you run and discharge the packs a few times over and that same cell is still discharging at a higher rate (almost right away), that cell is most likely bad. Also only use these dischargers after a pack has been run and never do it from a fully charged pack. After the packs are discharged use a Novak Smart tray SE or Tekin Battery doctor to balance the cells.


Finally, invest in at least two packs of lipo batteries. Very low maintenance but it does bring in the question of balancing cells but it is done automatically by getting a lipo balancer and adapter plugs. It is really easy. The best thing about dealing with lipo is that you don't deal with very hot nimh battery packs after charging, discharging and in some instances exploding.

Good luck!
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Old 01-23-2009, 10:45 AM   #14
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Quote:
Originally Posted by jd-santaclarita View Post
Thanks all for sharing the knowledge. I guess it all leads back to the one thing i have found out quickly in this hobby.....i have to spend a bunch more $$$...

I am on the cusp of deciding whether to go brushless, but dont want to spend the cash and i feel i am also getting closer to the cusp of "needing" to go lipo. Which by itself doesnt sound too crazy, but i have 4 cars (t4/t3/b4/b3) and about 14 sets of matched 6-cell battery packs, so going lipos would either mean i showed up to the track (with my son) with only 1 or 2 lipos and made a quick day of it....or i sell the house and buy a bunch of lipos.

Or unless you can run lipos and nimh's too i guess right? or do you have to change anything on the truck to go lipo?

-JD
It generally gets better as you go, you accumulate stuff, have a better idea of what you really need and don’t need, drive better and break less… hang in there buddy.

You absolutely can mix nimh and lipos. Main issue is not running the lipos all the way down. Ideally you have a recent speed control with a low voltage cutoff, or add on devices are available fairly cheap (~$20-30). Worst case time your runs, but be careful. Oh, and you MUST use a lipo capable charger. You can charge lipo the night before no problem.

And lipos can be recharged right away, so you don’t need anywhere near 14 packs. Our little 2 driver team typically runs 3 classes, with 4 lipos, 2 chargers. Each lipo probably equals 3 nimh or so. Just get one or two at a time, and use your best nimh to fill in as you go.

Oh, and if it hasn't happened yet, get used to your Son laughing at how slow you are! But when you watch him win his first race, well it will be worth it, trust me. Cheers to both of you.

Last edited by Dave H; 01-23-2009 at 01:48 PM.
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Old 01-23-2009, 02:01 PM   #15
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Well, we all have to start somewhere!

First off... if you can go brushless, then do it! Half of your work at the track will go away. Novak just came out with their budget Havoc BL system with a stock 17.5 motor for only $140! The motor itself is $80 just about everywhere. It also has LiPo cut off. This is very important if you go LiPo because if you run the pack too long, it's all over! Once you go below the recommended voltage, the pack is chemically ruined.

Now, just about all the brushed ESCs are older technology now and I do not believe that any of them have the LiPo cutoff.

I run both LiPo and NiMh, though I find myself using just the LiPo lately. It makes things very easy. I only have 2 of them and run 2 classes when I race. It takes about 30 mins to recharge my 3200 LiPo I run in stock and about 50min for my 5000 I run in mod. I just have to make sure to put it on my charger right after my race and I'm good to go for my next heat. You never have to discharge the LiPo after use and you can use it all day long without any loss of power!

Chargers for LiPos run anywhere from around $50 to $200. I found that my Orion LiPos rarely need balancing. I have a couple of $80 chargers that do great! They also charge NiMh and just about everything else too!

First thing I would do is invest in a couple of good chargers that can also do LiPo. They will give you the readouts you need to judge how your NiMh are doing. I would also get a discharge tray that brings each cell down. Because everybody is going LiPo you can find them pretty cheap (around $20) on the selling boards or eBay! You have a lot of packs, so I have to imaging that a few of them are ok.

On charging your packs.. I would do it the day before you are going to use them to save you some time at the track... then peak them right before you use them. They should be warm and not hot. Hopefully your charger doesnt lock out the peak detection... some do and will stay on no matter what for the first few min. This is bad.

Good luck!

Jerome
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