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Old 09-18-2008, 08:14 PM   #1
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Hey all,

Im sure its been answered somewhere on this forum, but i ran a search and couldnt pin-point anything.

I recently made the switch from nimh to lipos, i got two new ip3800 packs from trinity. There not really that main-stream in the us yet. Anyway, im new to lipo so i was wondering whats the point in the balancer? Do i have to use it everytime i charge, or does it only help balance the pack when your discharging? Also, i was told that lipos dont drain their voltage? I charged up a pack last night, around 11pm, and i checked it today around 8pm and the voltage was around 8.25, i have the team checkpoint tc1030, also i noticed theres no-repeak option? is it not possible to re-peak lipos or do i just re-charge them? when i did recharge them the voltage stopped at 8.50? seems low? I was also told that i should charge at whatever the pack rating is, ex 3800 charge at 3.8 however trinity said i could charge at up to 5amps? Just looking to get some real answers? and perhaps save my house from burning down.


thanks for the time,

tenpins77
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Old 09-18-2008, 08:30 PM   #2
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Are we talking about a 2 or 3 cell lipo?

ok, I'm just gonna go ahead and post this link to a post I made in another thread. Maybe it'll answer some of your questions. For the others I'd need additional info on your pack.

http://www.rctech.net/forum/nitro-of...ml#post4851420

Lemme know if you need more help.
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Old 09-18-2008, 08:42 PM   #3
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2 cell 4.8v
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Old 09-18-2008, 08:46 PM   #4
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LIPO is not NiMh. There is no repeak as lipo's charge differently then NiMh. 8.4v is the max on the ICE so 8.5 is not low. Lipo's are charged by the CC-CV method (Constant Current - Constant Voltage). This means that the first part of the charge the charger charges the pack at X amps, usually 1C i.e. 5000mah = 5amp charge rate. I personly wouldn't go higher than 1C. Once the lipo reaches 8.4v the charger switches to CV. The charger keeps the lipo's voltage at 8.4 and the charge current decreases to .1amp. Bell rings, lipo is done.
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Old 09-18-2008, 09:19 PM   #5
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Don't over discharge a LiPo (below 3 V per cell, so 6V for your Trinity packs), or they will swell up. Once this happens, pitch them. It's not safe to charge them after this happens. As soon as your heat is done, just throw it right back on the charger. The charging process helps the pack cool. LiPo also has a much lower self-discharge rate, so you can charge them several days in advance and they will be fine on race day. None of the maintenance of a NiMH pack.

You can balance charge them, but the Orion packaging states that after much testing, balancing is not needed. But it doesn't hurt. The Trinity packs should behave the same way.
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Old 09-18-2008, 09:50 PM   #6
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agree 100%..do not discharge below 3V...but the important is..do not keep play till the motor stop..i already experience that..just keep playing till no more response from esc..hehehe..then the lipos start to swallow...i try to figure out why that happen..then..try to charge..but the charger (b6) keep tell batt under voltage..cant charge..then i try to pitch that swallow par..and charge again without ballancer..set to 1.5a only..so..it happen..
and one experience that i never forget is..i forget to pin in the balancer port and keep charge...what i found is..the power is supply and peak is better than plug in the ballancer?..erm..maybe co-incident..but now..if my batt is too weak..i just use charge with ballancer plug in..

so..what is purpose the ballancer?..still counting on it..
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Old 09-18-2008, 10:19 PM   #7
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Quote:
Originally Posted by tenpins77 View Post
2 cell 4.8v
I assume that's a typo.

ok , well a 2 cell lipo is gonna be rated at 7.4 volts. Thats nominal voltage for a 2cell. 8.4v is going to be peak. First, any battery can drop voltage depending on its surrounding environment. Under normal circumstances your lipo probably would not drop much over nite. But how do you know it reached peak when you charged it? Did you leave it on the charger overnite? Was the pack hot or warm when you charged it? Was there a change in ambient temp? Is it terribly humid where you charged it? Was your dog licking the connector all nite long? There are a lot of factors that could have caused the perceived voltage drop. Also don't worry about a re-peak. Just charge to peak and go. I'm not familiar with your charger but if it's a decent one it will stop charging and signal (beep, whatever) if the pack is already at peak.

As for the balancer, because it's important not to over charge/discharge a single lipo cell, it becomes important to keep all cells in a pack balanced. Particularly when that pack will be charged as a pack.

For example, let's say you let a 2 cell pack become waaaaay out of balance. One cell reads 3.0 volts the other reads 4.0 volts. You charge the pack and the charger recognizes it as a 2 cell lipo, or you tell the charger it's a 2 cell lipo, and it will automatically set peak at 8.4 volts. One cell charges to 3.7 volts and the other to 4.7 volts. Peak voltage for a single lipo cell is 4.2 and you've just overcharged one of your cells by .5 volts. This can be a real bad thing with a lipo.

Now, same situation on the discharge side. Once you or your esc let(s) your pack run down to 6 volts, (presumably 3 volts per cell) you actually have one cell that reads 3.5 and the other 2.5. You've just over discharged and lost one cell.

In those examples I'm implying a straight charge/discharge curve for each cell. So, you can combine all that with the fact that the voltage charge/discharge curves (which are actually NOT straight) of each cell will move out of sync, and it's all sorts and kinds of bad.

You don't have to use a balancer every time you charge your pack but the pack MUST be kept in balance. Most manufacturers agree that the first 20 or so cycles are the most crucial for keeping the pack in balance.

Hope this helps.

Last edited by helibrian; 09-18-2008 at 10:50 PM.
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Old 09-19-2008, 07:08 AM   #8
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so i dont need the balancer to discharge
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Old 09-19-2008, 07:25 AM   #9
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Quote:
Originally Posted by tenpins77 View Post
Hey all,

Im sure its been answered somewhere on this forum, but i ran a search and couldnt pin-point anything.

I recently made the switch from nimh to lipos, i got two new ip3800 packs from trinity. There not really that main-stream in the us yet. Anyway, im new to lipo so i was wondering whats the point in the balancer? Do i have to use it everytime i charge, or does it only help balance the pack when your discharging? Also, i was told that lipos dont drain their voltage? I charged up a pack last night, around 11pm, and i checked it today around 8pm and the voltage was around 8.25, i have the team checkpoint tc1030, also i noticed theres no-repeak option? is it not possible to re-peak lipos or do i just re-charge them? when i did recharge them the voltage stopped at 8.50? seems low? I was also told that i should charge at whatever the pack rating is, ex 3800 charge at 3.8 however trinity said i could charge at up to 5amps? Just looking to get some real answers? and perhaps save my house from burning down.


thanks for the time,

tenpins77
I think your LiPo should stop at 8.4v
Please check your TC1030 that the Peak Charge % is only at 100%...I think the default is 110%, that would hurt your LiPo.



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Old 09-19-2008, 08:19 AM   #10
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Quote:
Originally Posted by tenpins77 View Post
so i dont need the balancer to discharge
Depending on the balancer, you can use it when you charge, discharge, or both. Personally I never discharge a lipo in anything but the device it powers. Theres really no need to cycle them, or run them flat, like there is with NiCd and some NiMH, unless it's for the purpose of balancing the cells.
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Old 09-19-2008, 08:24 AM   #11
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Quote:
Originally Posted by Mini Toink View Post
I think your LiPo should stop at 8.4v
Please check your TC1030 that the Peak Charge % is only at 100%...I think the default is 110%, that would hurt your LiPo.



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Absolutely. Like I said, I'm not familiar with your charger but, if it will allow you to charge a lipo to 110%, I would definitely consider using a different charger.
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Old 09-19-2008, 08:32 AM   #12
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ouch guys, i think the defualt was 120%, i can turn it down to 100 though. I guess im just having an issue trying to get the pack to discharge with the team checkpoint charger and balancer, whenever i go to discharge them, the charge just beeps giving me some error message that theres no pack hooked up to the charger.
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Old 09-19-2008, 08:35 AM   #13
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[QUOTE=tenpins77;4853625]Hey all,

Im sure its been answered somewhere on this forum, but i ran a search and couldnt pin-point anything.

I recently made the switch from nimh to lipos, i got two new ip3800 packs from trinity. There not really that main-stream in the us yet. Anyway, im new to lipo so i was wondering whats the point in the balancer? Do i have to use it everytime i charge, or does it only help balance the pack when your discharging? Also, i was told that lipos dont drain their voltage? I charged up a pack last night, around 11pm, and i checked it today around 8pm and the voltage was around 8.25, i have the team checkpoint tc1030, also i noticed theres no-repeak option? is it not possible to re-peak lipos or do i just re-charge them? when i did recharge them the voltage stopped at 8.50? seems low? I was also told that i should charge at whatever the pack rating is, ex 3800 charge at 3.8 however trinity said i could charge at up to 5amps? Just looking to get some real answers? and perhaps save my house from burning down.


thanks for the time,

tenpins77[/QUO

IMO, what I have seen trying 3 different types of cells is that the Orion type rarely go out of balance, it is a good idea to periodically check them. I ran the 3600 Race Spec for about 20 cycles and it was still even voltage using the Common Sense Balance Pro. The Reedy packs however, drift around and I now balance them every time they are charged. The Common Sense 4400's. while not ROAR approved are perfect for backyarding or club level and probably should be done every cycle as well as they are similar to the Reedy's. The guys here using SMC cells are typically checking them about every 5 cycles and balancing as needed. This, is of course for 2s 7.4V packs.
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Old 09-19-2008, 08:35 AM   #14
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Quote:
Originally Posted by helibrian View Post
You don't have to use a balancer every time you charge your pack but the pack MUST be kept in balance. Most manufacturers agree that the first 20 or so cycles are the most crucial for keeping the pack in balance.
The instructions that come with the Orion 3800 pack states that after a lot of testing, Orion determined that balancing is not necessary. I don't think that balancing is necessary on discharge (since using it in your car won't do that anyway), but it doesn't hurt to use one during charging. I wasn't about to buy a new charger just for that, so I use the Checkpoint add-on balancer. It is worth the $35 for peace of mind that a cell won't be overcharged.
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Old 09-19-2008, 08:49 AM   #15
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I just skimmed through this, so this may have been addressed and I missed it...but

MAKE SURE YOU USE A LIPO SAFE CHARGER - Never use a NiMh CHARGER...and ALWAYS Be 100% sure you NEVER Charge a LIPO w/ the charger set in NiMh MODE.

For balancing, w/ the ORION type packs that use the 4mm plugs, they have the 2 4mm plug holes and a 2mm plug hole. What I do is after a run I check the voltage from one 4mm to the 2mm plug hole, then to the other 4mm to 2mm. This will give you the voltage of each cell in the pack. If they are not the same - BALANCE it , I also do this check after the battery is charged.

I did see something about being a 2 cell 4.8 volts - I'm assuming that was backward, and should be 8.4 volts (Which really should be 7.4 volts)

Lipo cells are rated at 3.7 volts per cell. If they are hooked in Series (which is how they make their voltage) they would be 3.7 x 2 = 7.4v)

However, a 2 cell PARALLEL pack (some of the New 1/12th scale type) would still be able to be 2 cell, but they would only be 3.7v.

IMPORTANT: Do NOT Over Charge - and Do NOT Over DISCHARGE (beyond 6.0v) Both can be hazardous.
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