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NiMH veteran, needs a crash course in LiPo

NiMH veteran, needs a crash course in LiPo

Old 08-08-2008, 08:34 AM
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Default NiMH veteran, needs a crash course in LiPo

I can't say I dove into LiPo, more like tripped & fell into the pool. I was down to one NiMH pack and said "when this one goes south, I'll go LiPo." So that was last night's financial episode at the races when I showed up with one battery that refused to take a charge.

So twenty minutes and $150 on the credit card later I'm the proud owner of a Track Power 4900mAh, Deans lead, and one of those LiPo-proof bags. As luck would have it the guy I was pitting across from had an extra charger, so he ran it up to a full charge and I raced on it all night.

Now I need to ask some questions, because until now all my stuff's been really old-school simple & I really don't know much about using and maintaining LiPo packs:

1. I need a new charger/chargers. For the longest time I've used a couple of DuraTrax IntelliPeak AC/DC Pulse chargers, $55 a pop, and they're plug-and-go. Just a button, a knob to set amperage, and 4 LED lights that go on to tell you what charge mode it's in. All but brainless operation, and I'd like to keep it that way. I really don't need anything like an ICE or a Turbo35 or a Pulsar, what I need is something I can set the amperage, plug the battery in, push a button, and it charges the pack. Bonus points for AC/DC and if it has a balance lead.

2. If the charger doesn't have a balance lead, are there stand-alone LiPo balancers available? And how often should my LiPo pack be balanced?

3. I've heard LiPos don't trail off like nickel packs do as they discharge, they run at full power until they go empty and then just dump. I've also heard you do NOT want to take them past this point, but short of buying one of those LiPo cutoff modules or a new ESC does a LiPo pack give any kind of warning before it dumps (ex: all of a sudden you've got no top-end speed, etc.) and if so about how long can you keep driving without damaging the pack once you notice that warning?

4. I live in Wisconsin and race indoor electric in the winter, so how resilient are LiPo packs to very cold temperatures? I know whenever I would try driving one of my trucks in the cold with a NiMH the pack would drive almost as if it was in the process of dumping, but it would run like that for the full 5 or 6 minutes I'd normally get out of it. Warm it back up and it's just fine. But with the level of care people take with LiPos, would there be any real harm in leaving my LiPo pack with my toolbox in the back of my 1:1 truck while I'm at work?

5. As far as electric goes, I race weekly offroad during the winter and on-and-off in the summer with my TC dirt late model. I always had a plan for my NiCd and NiMH packs when they weren't going to be run for, like, a month or more. Is there anything I should do before I shelf my LiPo pack for awhile? During the week between races in the winter?

6. I would think they've been around long enough for someone to know; assuming it's taken care of what's the typical life span of a LiPo before they go bad for good? And is there a way to tell, like how one dead cell in a NiMH pack would get noticeably hotter than the other 5 during a charge?

7. For a pack like this, a 3 cell 4900mAh, what's a "safe" amperage to charge it at? I'm racing Stock Truck so I don't need to do anything like the crazy 10 amp charges guys were blowing up NiMHs with.
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Old 08-08-2008, 08:44 AM
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Originally Posted by OTE_TheMissile
I can't say I dove into LiPo, more like tripped & fell into the pool. I was down to one NiMH pack and said "when this one goes south, I'll go LiPo." So that was last night's financial episode at the races when I showed up with one battery that refused to take a charge.

So twenty minutes and $150 on the credit card later I'm the proud owner of a Track Power 4900mAh, Deans lead, and one of those LiPo-proof bags. As luck would have it the guy I was pitting across from had an extra charger, so he ran it up to a full charge and I raced on it all night.

Now I need to ask some questions, because until now all my stuff's been really old-school simple & I really don't know much about using and maintaining LiPo packs:

1. I need a new charger/chargers. For the longest time I've used a couple of DuraTrax IntelliPeak AC/DC Pulse chargers, $55 a pop, and they're plug-and-go. Just a button, a knob to set amperage, and 4 LED lights that go on to tell you what charge mode it's in. All but brainless operation, and I'd like to keep it that way. I really don't need anything like an ICE or a Turbo35 or a Pulsar, what I need is something I can set the amperage, plug the battery in, push a button, and it charges the pack. Bonus points for AC/DC and if it has a balance lead.

2. If the charger doesn't have a balance lead, are there stand-alone LiPo balancers available? And how often should my LiPo pack be balanced?

3. I've heard LiPos don't trail off like nickel packs do as they discharge, they run at full power until they go empty and then just dump. I've also heard you do NOT want to take them past this point, but short of buying one of those LiPo cutoff modules or a new ESC does a LiPo pack give any kind of warning before it dumps (ex: all of a sudden you've got no top-end speed, etc.) and if so about how long can you keep driving without damaging the pack once you notice that warning?

4. I live in Wisconsin and race indoor electric in the winter, so how resilient are LiPo packs to very cold temperatures? I know whenever I would try driving one of my trucks in the cold with a NiMH the pack would drive almost as if it was in the process of dumping, but it would run like that for the full 5 or 6 minutes I'd normally get out of it. Warm it back up and it's just fine. But with the level of care people take with LiPos, would there be any real harm in leaving my LiPo pack with my toolbox in the back of my 1:1 truck while I'm at work?

5. As far as electric goes, I race weekly offroad during the winter and on-and-off in the summer with my TC dirt late model. I always had a plan for my NiCd and NiMH packs when they weren't going to be run for, like, a month or more. Is there anything I should do before I shelf my LiPo pack for awhile? During the week between races in the winter?

6. I would think they've been around long enough for someone to know; assuming it's taken care of what's the typical life span of a LiPo before they go bad for good? And is there a way to tell, like how one dead cell in a NiMH pack would get noticeably hotter than the other 5 during a charge?

7. For a pack like this, a 3 cell 4900mAh, what's a "safe" amperage to charge it at? I'm racing Stock Truck so I don't need to do anything like the crazy 10 amp charges guys were blowing up NiMHs with.

OTE

life span of Li-Po

I ran a couple Orion Carbons hundreds of runs for over a year and they perform just as good as the day I brought um..
Never balance them but once just to see if it helped.
Balancer did`nt inprove much BDW ,found another 20 sec runtime thats all they were off...
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Old 08-08-2008, 10:51 AM
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TrakPower has some good Lipo info here Mike & should answer most of your questions. http://www.trakpower.com/index.asp?page=lipoExpert.asp

I am considering a 2nd budget charger myself and found out rctech member Bulldawg R/C has TrakPower Lipo chargers for $60 + shipping. Seems like a great deal, and small size makes it nice too. http://www.bulldawgrc.com/trpitpro50li.html
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Old 08-08-2008, 10:56 AM
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I was wondering pretty much the same thing as OTE. I don't know much about LiPo's and wanted to know about the Amps for charging.
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Old 08-08-2008, 11:09 AM
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For a charger get the Duratrax Onyx 230.
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Old 08-08-2008, 12:29 PM
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1. I need a new charger/chargers. For the longest time I've used a couple of DuraTrax IntelliPeak AC/DC Pulse chargers, $55 a pop, and they're plug-and-go. Just a button, a knob to set amperage, and 4 LED lights that go on to tell you what charge mode it's in. All but brainless operation, and I'd like to keep it that way. I really don't need anything like an ICE or a Turbo35 or a Pulsar, what I need is something I can set the amperage, plug the battery in, push a button, and it charges the pack. Bonus points for AC/DC and if it has a balance lead.

TRAKPOWER MAKES A VERY CHEAP IN PRICE DC CHARGER THAT WORKS GREAT. YOU WILL NEED A POWER SUPPLY. $59.99 FOR CHARGER. I RUN TWO OF THESE OFF OF A LRP 14AMP POWER SUPPLY AND IT IS FLAWLESS

2. If the charger doesn't have a balance lead, are there stand-alone LiPo balancers available? And how often should my LiPo pack be balanced?

YES THERE ARE STAND ALONE LIPO BALANCERS, COMMONSENSE RC CELLS 2 DIFFERENT TYPES OF BLINKY BALANCERS THAT CAN PLUG RIGHT INTO THE TRAKPOWER BC6 CHARGING HARNESS

3. I've heard LiPos don't trail off like nickel packs do as they discharge, they run at full power until they go empty and then just dump. I've also heard you do NOT want to take them past this point, but short of buying one of those LiPo cutoff modules or a new ESC does a LiPo pack give any kind of warning before it dumps (ex: all of a sudden you've got no top-end speed, etc.) and if so about how long can you keep driving without damaging the pack once you notice that warning?

LIPO FOR THE MOST PART WILL GIVE YOU CONSTANT POWER UNLIKE NIMH THAT WILL LOSE ITS PEAK PERFORMANCE AFTER THE FIRST COUPLE MINUTES. YOU CHOULD BE ABLE TO TELL WHEN YOUR LIPO BATTERY IS LOW BY THE WAY THE CAR FEELS, I WOULD NOT TRUST THIS METHOD AND WOULD GETA LIPO CUT OFF AND INSTALL IT IN YOUR ESC. YOU DO NOT WANT A LIPO CELL TO DROP BELOW 3V PER CELL.

4. I live in Wisconsin and race indoor electric in the winter, so how resilient are LiPo packs to very cold temperatures? I know whenever I would try driving one of my trucks in the cold with a NiMH the pack would drive almost as if it was in the process of dumping, but it would run like that for the full 5 or 6 minutes I'd normally get out of it. Warm it back up and it's just fine. But with the level of care people take with LiPos, would there be any real harm in leaving my LiPo pack with my toolbox in the back of my 1:1 truck while I'm at work?

LIPOS DO NOT HEAT UP LIKE NIMH DO, YOU DO NOT HAVE TO WARM UP THE CELLS PRIOR TO RUNNING. YOU DEFINITELY DO NOT WANT TO LEAVE THEM IN EXTREMELY HOT TEMPERATURES. LIPO TECHNOLOGY HAS COME A LONG WAY AND ARE BECOMING VERY PLUG AND PLAY BUT BE SURE TO NEVER LET VOLTAGE DROP BELOW 3V AND TO KEEP THEM BALANCED WHEN CHARGING

5. As far as electric goes, I race weekly offroad during the winter and on-and-off in the summer with my TC dirt late model. I always had a plan for my NiCd and NiMH packs when they weren't going to be run for, like, a month or more. Is there anything I should do before I shelf my LiPo pack for awhile? During the week between races in the winter?

If storing for a prolonged period, charge battery to about 4v per cell and they will be fine

6. I would think they've been around long enough for someone to know; assuming it's taken care of what's the typical life span of a LiPo before they go bad for good? And is there a way to tell, like how one dead cell in a NiMH pack would get noticeably hotter than the other 5 during a charge?

some companies are claiming up to 200 charge cycles and 100 race worthy charge cycles

7. For a pack like this, a 3 cell 4900mAh, what's a "safe" amperage to charge it at? I'm racing Stock Truck so I don't need to do anything like the crazy 10 amp charges guys were blowing up NiMHs with.
this all depends what brand of battery you are charging and what its rated to charge at. trakpower can be charged at 2C but i normally stay at the 1C mark so this would mean 4.9Amps

Hope this helps and you can find lipo info on my webpage that may help out some more.

http://www.BulldawgRC.com
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Old 08-08-2008, 12:34 PM
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Great info there, now I see how balancing works. I'm used to using trays to bring NiMH's down to the same level, but balancers use the charger to bring them up that way. Interesting

Both those chargers look good too, simple, functional, & easy on the wallet I'm just wondering, if I got the Onyx 230 could I use the TrakPower balancer with it, or is that a charger-specific thing?

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Old 08-08-2008, 01:46 PM
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the v-balancer is not a charger specific balancer. it can be used with any charger that has 4mm female bullet (+) (-) connectors. Otherwise you can remove the 4mm male connector on the v-balancer and use whatever connector you may want to use.
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Old 08-08-2008, 02:55 PM
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If you are running a 3 cell LiPo, you should have one FAST stock truck! It's like running a 10 cell NiMh!

Usually to be fair in stock only 2 cell LiPo packs are allowed.. Check with your track to make sure they allow it without cheating!

Bulldawg gave you a lot of good info!

Just be careful when charging.. make sure the charger you get is set on the correct profile for LiPo and amperage. You'll find them much easier to use and maintain than NiMh.


Have fun!

Jerome
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Old 08-08-2008, 05:43 PM
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Originally Posted by JeromeK99
If you are running a 3 cell LiPo, you should have one FAST stock truck! It's like running a 10 cell NiMh!

Usually to be fair in stock only 2 cell LiPo packs are allowed.. Check with your track to make sure they allow it without cheating!
Well it's a 2S1P, and they seem to be the hot setup in the oval field around S&N's Trackside and are run alongside the 6-cell NiMHs.

I built a new motor for my late model just before going racing last night, and at first I thought maybe something was wrong with it. The guy pitting behind me loaned me a charged NiMH for a couple laps, idea being if I used his pack and the car ripped, well then my battery was the problem. Sho' nuff, as soon as I set down for the second run the power was back. When I put the LiPo in and set down for the first time, the only real difference I could feel was the weight shift in the car now that it had a light little LiPo in it, the power felt about the same.

But yeah, thanks for all the tips & links guys, keep 'em coming! The more info the better
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Old 08-08-2008, 09:48 PM
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1. I need a new charger/chargers. For the longest time I've used a couple of DuraTrax IntelliPeak AC/DC Pulse chargers, $55 a pop, and they're plug-and-go. Just a button, a knob to set amperage, and 4 LED lights that go on to tell you what charge mode it's in. All but brainless operation, and I'd like to keep it that way. I really don't need anything like an ICE or a Turbo35 or a Pulsar, what I need is something I can set the amperage, plug the battery in, push a button, and it charges the pack. Bonus points for AC/DC and if it has a balance lead.

I know what you're saying, but going too idiot-proof on a charger usually leaves you with a lesser quality unit, and since you're going with high tech batteries I'd advise that it's time for a higher tech charger. The Duratrax ICE charger has been a fan favorite for a few years now, and its versatility of NiMH and LiPO charging makes it a good choice. It also has a programming section where you can log in seperate charging/discharing specs for up to 9 different packs if you have more than one different kinds and capacities of batteries. Once you have it set, all you have to do is plug in the pack and just push the button and go.

2. If the charger doesn't have a balance lead, are there stand-alone LiPo balancers available? And how often should my LiPo pack be balanced?

Yes, there are several different balancer options on the market. But I've found that LiPOs aren't near as sensitive to the need for regular balancing, as NiMHs are, and I only do mine once a month.

3. I've heard LiPos don't trail off like nickel packs do as they discharge, they run at full power until they go empty and then just dump. I've also heard you do NOT want to take them past this point, but short of buying one of those LiPo cutoff modules or a new ESC does a LiPo pack give any kind of warning before it dumps (ex: all of a sudden you've got no top-end speed, etc.) and if so about how long can you keep driving without damaging the pack once you notice that warning?

You're right, LiPOs don't trail off and generally have a constant discharge rate. But the problem is that you can kill one fast by over-discharging it and they really give no hint that you've exceeded the limit. A Low Voltage Cutoff module is pretty cheap, $25-ish, and keeps you from making the mistake and wasting the money a lot of people have.

4. I live in Wisconsin and race indoor electric in the winter, so how resilient are LiPo packs to very cold temperatures? I know whenever I would try driving one of my trucks in the cold with a NiMH the pack would drive almost as if it was in the process of dumping, but it would run like that for the full 5 or 6 minutes I'd normally get out of it. Warm it back up and it's just fine. But with the level of care people take with LiPos, would there be any real harm in leaving my LiPo pack with my toolbox in the back of my 1:1 truck while I'm at work?

Personally I've always kept my batteries in the house. That way they don't get too cold during the winter months or too hot during the summer months. While LiPOs don't tend to get as hot as NiMHs, they are a bit more sensitive and need a more stringent eye on care --- so that means the toolbox in the back of the truck is out. Checking one of my "spec sheets" they note "when transporting or temorarily storing in a vehicle, temperature range should be greater than 20 degrees F but no more than 150 degrees F."

5. As far as electric goes, I race weekly offroad during the winter and on-and-off in the summer with my TC dirt late model. I always had a plan for my NiCd and NiMH packs when they weren't going to be run for, like, a month or more. Is there anything I should do before I shelf my LiPo pack for awhile? During the week between races in the winter?

Most LiPOs come with some sort of instruction sheet that recommends maximum charge rate and storage voltage rate, and if not you can probably check the makers' website. Checking one of my "spec sheets" they note "do not store fully charged, best store at 3.8 to 3.9v per cell."

6. I would think they've been around long enough for someone to know; assuming it's taken care of what's the typical life span of a LiPo before they go bad for good? And is there a way to tell, like how one dead cell in a NiMH pack would get noticeably hotter than the other 5 during a charge?

I don't know because I've yet to kill a pack. Just like NiMHs they tend to be really fast when new, but once they have a few runs on them they level out and perform well for a long time. But considering a LiPO pack has only 2 or 3 cells (2s or 3s) per pack, the drop off in performance would be noticable enough to make a highly noticable difference.

7. For a pack like this, a 3 cell 4900mAh, what's a "safe" amperage to charge it at? I'm racing Stock Truck so I don't need to do anything like the crazy 10 amp charges guys were blowing up NiMHs with.

Most battery companies suggest different charge rates, so check with the manufacturer to make sure. Are you sure you bought a 3-cell (3s, 11.1v) or is it possible it was only a 2s (2-cell) 7.4volt model?

Originally Posted by OTE_TheMissile
Well it's a 2S1P, and they seem to be the hot setup in the oval field around S&N's Trackside and are run alongside the 6-cell NiMHs.
OK, it appears you have a 2s (2-cell) 7.4volt battery and not a 3-cell as you first suggested?
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Old 08-09-2008, 06:31 PM
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Originally Posted by ratherBracin
OK, it appears you have a 2s (2-cell) 7.4volt battery and not a 3-cell as you first suggested?
Yup (I guess). I highly doubt my ESC is capable of 11.1v (Futaba MC330CR) and I'm POSITIVE I would've noticed if it was

Like I said, these exact same packs are being used alongside 6-cell NiMH's at this track by other people for awhile now.
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Old 08-11-2008, 08:17 AM
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mike, for safety purposes a genera rule is charge at 1C for a 4900mAh, 4.9 amps. I have orion plats and tthey are 4800 and I charge them at 4 amps, although they could withstand 4.8amp charge rate.

return the bag, you wont need it unless you deliberately try to over heat the battery.

use a duratrax ice if you can afford it, they are liek 120-130 depending where you shop.

I charged my lipos before I closed shop last winter. I got back out there in march (maybe april) and topped one of them. it still had 8.4 volts in it and only charged for like, a minute. it was cold and the thing held the charge for 3 months. and no, im not kidding. lipo are faaaar superior to NiMH. and I guarantee youll never go back.

I have never balanced the cells, but if you built a simple comparator circuit, you could balance them yourself.

I saw the sliverado slammer in action when you ran both of PJs lipos in it on that one video.

it sure seemed to have more get-up than i had ever seen before.

for weight issues at Crackside when your racing, you can simply offset the weight difference with a 100g slab of brass plate in the bottom of your battery tray. Thats what matt sunderladge did, and I drove his losi desert truck with that setup, and it seemed fine.
in my trucks, I dont use additional weight. I just got used to the handling differrences.

When you come over again, you can review Erics Hyperion charger ( which is totally over the top) and also if you have lipos, but no chargers yet, we have about 7 ICEs in the house you can always heat up when you get there.

Pete
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Old 08-11-2008, 08:31 AM
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Originally Posted by RC Corral
return the bag, you wont need it unless you deliberately try to over heat the battery.
Good advice Pete, except for the "return the bag" part. After running lipos for a couple of years now, and watching a few other folks' go up in smoke and start quite a blaze, IMO it's an item well worth having if for no other reason than a safety precaution. Better safe, than sorry.
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Old 08-11-2008, 08:55 AM
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Yeah I think I'll hang onto the bag. I'd like to keep using the phrase "I'm on fire tonight!" strictly as a metaphor for my on-track performance
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