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Old 10-13-2008, 09:48 PM   #1
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Default my new lipo

bought a new hump cell lipo for my buggy, it came in the mail before my charger but according to my meter it had 7.1volts so i threw it in with a regulator to test it out. i ran maybe 60minutes total @6v with no problems and then it went completely dead. my meter still showed 5.6volts without the battery plugged into my reciever, but when i plug it in it wont power up. i take another measurement with it attatched to my reciever and it says
2.4v - hence there reason nothing powers up

im not too worried, im hoping its just dead (charger still not in the mail) but im not understanding why it would read 5.4v instead of 2.4v when not plugged in.... ? any help?
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Old 10-14-2008, 02:23 AM   #2
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A LiPo cell fully charged produce 4.2 volts. That means for a 2 cell LiPo battery fully charged is 8.4 volts and is not to operated under 6.0 volts. They are not to be run under 3.0 volts/cell or else the cells are permanently damaged. It's dead under 3.0 volts. Lipo batteries are not like Nimh or Nicd where you can draw it down to nothing and they can be recharged. You may try to charge it at .2A or .3A to see if it'll recover but it will never have it's full capacity
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Old 10-14-2008, 02:34 AM   #3
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It's call load brother, plug it in and the voltage drops because it cannot supply the load... unplug it no load and the voltage returns.
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Old 10-14-2008, 07:15 AM   #4
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I`m fairly new to lipo with my electric cars and want to go lipo rx pack in my nitros . Do the make a cut-off like they have for electric cars ?
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Old 10-14-2008, 09:23 AM   #5
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Default Idiot lights

The Protek regulator from Amain doesn't have an automatic cutoff but does have idiot lights...green is good (above 3.1V per cell), red is bad. I use it for my Lipo rx in both my nitro buggy and truggy.
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Old 10-14-2008, 07:05 PM   #6
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thanx for the info, hopefully its not damaged. so for the most part i have to check the voltage of the battery (2cell) after every time i pull the car off the track to make sure it stays above 6v?
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Old 10-14-2008, 07:57 PM   #7
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You shouldnt have to check volatge every time,depending on mah rating & electonics used.I have 2000 mah packs that go all day like 3/4 of a gal on a playday. leaving the switch on & running up the stand,waiting for marshals to get out so they let cars on the track,then warm up, then 5 min race then on walking back to the pits with the servos I'm using now = 250-275 mah on the 2/3 A cells I'm using now(dont have lipo that fit my present radio box yet). I wanna say the lipos in my last car actually took less like 175 mah in the same situation.Someone explained it to me before like actual pack potential or to do with the regulator,I dont really remember now but you will be able to get a whole standard race day from a 2000 mah lipo & not have to charge more than 1/2 the capacity when you get home.
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Old 10-14-2008, 08:06 PM   #8
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Quote:
Originally Posted by xyzyx00 View Post
thanx for the info, hopefully its not damaged. so for the most part i have to check the voltage of the battery (2cell) after every time i pull the car off the track to make sure it stays above 6v?
When you get your charger you need to charge the pack back up as SLOWLY as possible to get it back above 6.0 volts. If your new charger is adjustable set it on the lowest mah charge rate it will go. You need to keep an eye on it during the charge process and make sure it doesn't swell up. If it does stop charging immediately.

I've had a lot of luck recovering lipo's that have been run dead by charging them at about .10 amp/hr rate till they get back over 6.0 volts. Then I charge at normal 1C rating and keep an eye on it. My son has a habit of not turning off the receiver switch.
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Old 10-14-2008, 09:26 PM   #9
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thanx butch...

im deffinately gonna give it a try rob...

this is all new to me so im gonna ask another question. on normal instances i can allways recharge at the same rate, no matter what the remaining voltage on the battery is? its a 2cell, 1500mah so id want tocharge no more than 1.5a with a cut-off at 8.4volts ?
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Old 10-15-2008, 05:29 AM   #10
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thanx butch...

im deffinately gonna give it a try rob...

this is all new to me so im gonna ask another question. on normal instances i can allways recharge at the same rate, no matter what the remaining voltage on the battery is? its a 2cell, 1500mah so id want to charge no more than 1.5a with a cut-off at 8.4volts ?
You are correct. Under normal operating you would charge that pack back up at a rate of 1.5a with an 8.4 cut-off. Wouldn't matter what the voltage is as long as it is above 6.0 volts.
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Old 10-15-2008, 08:12 PM   #11
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for clarification, the battery is an orion SLPB hump, 2cell 1500mah

i got my charger today and hooked up the battery. i started with trying to charge at .1A to bring it up to 6v but the charger showed 6.09v to begin with so i stopped and reset the charger to .8c = 1.2a for a 2cell lipo. i also hooked up the temp monitor and set it to alarmat 120F. it took 88minutes and brought the pack to 8.4volts. i noticed that around 8.2volts the charger started dropping my charge rate slowly down to .1A before it completed. the pack wasnt hot at all, maybe a tad warmer at most. there was one number on the screen i wasnt sure of- it started at 0 and ended at 1364- maybe MaH?

this is all new to me, does this sound normal? i am going to keep a log of all my charges to compare in the future...
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Old 10-15-2008, 08:31 PM   #12
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Most chargers start dropping the amp rate as they approach the 8.4 volt setting. The number should be the amount of Mah you put back in the battery. Most manufactures say to get the most out of their packs you should never discharge more than 80% of the capacity. Since your pack is a 1500 Mah then ideally when you run your battery down you will never need to put more than 1200 Mah back in it since that is 80% of 1500.

You were just over that however some is lost in heat and resistance so you should be fine.

What make & model charger did you get? You never mentioned that.
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Old 10-15-2008, 08:32 PM   #13
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Yes, the number counting up from zero indicates the mAh you have charged into the battery. Are you sure you had the charger on a LiPo mode? I thought they didn't trickle charge, just constant voltage, constant rate?
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Old 10-15-2008, 08:37 PM   #14
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Quote:
Originally Posted by Turbine_au View Post
Yes, the number counting up from zero indicates the mAh you have charged into the battery. Are you sure you had the charger on a LiPo mode? I thought they didn't trickle charge, just constant voltage, constant rate?
As the charger senses the battery is close to full it reduces the charge rate . Even for lipo , either lipo specific chargers or a charger in lipo mode .
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Old 10-15-2008, 08:54 PM   #15
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yes, it was set to lipo-

I bought venom pro charger w/ power supply - pretty much because it was able to handle all the different batteries i have and it came with all the attatchments so i didnt have to spend a fortune on extras.

thanx for everyones help on this, so far so good. im curious to see how the battery lasts the next time i take the buggy out.

if anyone wants to help me on my other 2 batteries im all ears!

glow plug- single cell NiCD 1800MaH 1.2V it says to charge @ 180Ma for 15hours (ive just been plugging it into the wall with the supplied charger) the batt says fast charge possible. my charger charges at .1A incriments

starter box - 12v 7.2A Lead Acid (also been using the supplied wall charger)

I know im not soppose to discharge the lipo but whats the best options for the others?

Last edited by xyzyx00; 10-15-2008 at 09:07 PM.
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