Multistar lipo questions / issues / solutions

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amund7

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Sep 6, 2015
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Oslo, Norway
Hi all,

I've recently bought 2 10Ah 6S 10C Multistar Lipos from a friend (originally ordered from Hobby King).
I chose them to replace my 48V 13Ah li-ion 'unknown chinese quality' bottle battery, in the belief that the lipos would be smaller and lighter (they are) and that they would deliver at least a comparable amount of Ah's.
I have a cheapo GT Power wattmeter.
Magic Pie 4 pulling 31 ampere peak.

With the bottle battery I've gotten more than 9Ah on several occations, never had the patience to empty it completely.

With the Lipos (in series) they run completely out after usually 4,5 Ah. At this point my lipo alarms are going crazy, one cell in each pack is now falling off the cliff, while the other 5 are good.

If I ride with my wife, who has a manual bike, meaning I have to go slow, I have on one occation managed to get 6,5 Ah out of them.
When I recharge the charger says pretty much 10Ah.

Is this right ?!
At what ampere are you supposed to get 10Ah from these? 1C?
Does it sound right that I can expect less than half rated capacity when pulling 30 amps? 30 amps is what, 3C, on a 10C rated battery.

Are these batteries crap/wrong application for my use, or is this expected with any lipo?

Will it help to get more of these, i.e. buy 2 more and put them in parallell with the other 2, totaling 44.4V and 20Ah ? That will only load them 15 amps each, maybe that will get more Ah out?
Or are they crap and I should get another brand? Which?
 
Hi Amund7

I have HK turnigy lipo's 5000mah 6s 20c packs in my e-trike setup. They are wired parallel in bricks of 4's giving me 20000mah 25v each brick and then I series them to the controller giving me 50v hot of the charger 20ah which equal to 1000watt. In my old setup with a 900watt brushed scooter motor I would get 18-20miles @ 25mph. But then again I am a heavy set guy at 210lbs and trike is another 100lbs. Lipo's are very good for ebike because they are cheap you just have to baby them when charging and discharging. Maybe 10ah is to little for your setup 48v x 10ah = 480 watt while the magic pie 4 is 500 watt motor I believe. C rating is ah x C rating = amp, your lipo's are 10x10C= 100amp you can pull from it and burst at 200amp. What is your wattage on your wattmeter say? and how low do you have your lipo alarm set for? What I would focus on is your watt draw how much watt before you need to charge your battery that will help you determine your run time if that is what you are looking to increase.

Sorry if this makes no sense.
Simon
 
Used RC Lipo? That could be a problem. If they’ve been damaged or simply used enough that they’re reduced capacity. ‘Sounds like the ones you’re using have been degraded and/or something’s wrong which isn’t going to improve.

New RC Lipo in good shape is difficult to see labelled capacity without going to extreme voltages high/low. But generally speaking, they always tend to deliver close to labelled capacity.

If you really wanna know you’ll need to rig up capacity testing (I use old toaster oven element for load) and check IR of individual cells to get an accurate picture about the health of the cells in question.
 
The lipos were never used, they were ordered from hobbyking by my friend, then charged and tested once on my bike before I bought them.

IR pack 1: 2 2 2 2 0 1 m-ohm
IR pack 2: 2 2 0 1 0 0 m-ohm


Simonvtr, my magicpie now pulls almost 1600watt peak.
Lipo alarm is at 3,3v
What do you mean I should focus on watt draw, I suppose you mean watt-hours? I've been looking at amp-hours, I guess we're speaking the same language, just multiply by 50 or so volts.
 
after drive the e-bike til the lipo alarm goes on....wat numbers doe jou see @the lipo balanser? each cel must be very closse in voltage/mAh.
Maby a pack have some bad cells?

| drive with 3s packs and 5 of these 3s packs in serie...15s/2p that give me 9.2Ah 63volt.
after i take a ride of 20km i read al the cells in th 3s packs and the voltage is al the same numbers between 3.85v&3.87volt.
If there is one cell in a pack thats shows lower voltage like 3.4volt you have a problem and i will take out these pack direct!
 
Sorry I did not make myself clear I am also just learning all the lingo.
For me amp house (ah) is hard to measure in e-bikes due to not always running at a constant speed. Unless I am wrong, but my understanding is you take the wattage used and divide by the volt to get amp hours? Yes I did mean (Wh) so lets say in a 30min ride you burn 200wh and the multistar pack has 500wh (50vx10amp) then you should have more then half a pack. Unless the voltage sag is causing the buzzer to go off prematurely.

Joachim asked if all cells are around 3.3 when you hear that buzzer?
Unless you only hear the buzzer when the voltage sag that low but the pack still has some juice in it?
Are all cells in both pack read 3.3 when the lvc goes off?
So if the buzzer is going off due to voltage sag then maybe you need to add more amps (more packs in parallel) to increase the amps to reduce voltage sag?

Sorry I am also learning my limited knowledge of lipo was back during my rc racing days.
But in ebike its totally different.
 
Complex subject I am getting myself into :)

As you notice, I am new to ebikes, also lipo.

When the lipo alarm goes buzz, only once cell in each pack is falling off the cliff. Meaning, probably, one is 3,3 and free falling, the other 5 are 3,85 or something like it.

So if this is the answer - both packs are shot - brand new - what kind of warranty does hobby king have, how do you prove they are bad? I am guessing we are getting nowwhere with that, so I need to buy something else. Which brand, which supplier?
 
the voltage of one cel 3.3 the rest of the cels 3.8v in a 6s not ok!

check de end voltage of each cel. after you charge the 6s...must be between 4.19v&4.21volt.

I think you have bad luck...1 are 2 cels of the 6s are not in the 80/90% energie storage....maby they hold 60/50\% and the compleet 6s get out of ballans and this is
not good and dangerous!

you are lucky that you have 2 packs in paralel and just take a max 3c out of the 12 cels,on a rc big plane are car that takes a lot of amps the compleet pack wil burn after 10 minuts :lol:
 
If your charger says it puts 10ah in when it charges, then that's what was used. That's assuming you're charging the pack as 12s. If you've paralleled them to charge as 2 6s packs, then that's just 5ah used from both. Your 10ah 12s pack is 444wh. AH times nominal voltage = WH.
 
wesnewell said:
If your charger says it puts 10ah in when it charges, then that's what was used. That's assuming you're charging the pack as 12s. If you've paralleled them to charge as 2 6s packs, then that's just 5ah used from both. Your 10ah 12s pack is 444wh. AH times nominal voltage = WH.
Click to expand...

When I parallell charge I get close to 20 000 mah.
On the bike they are serial, 44.4v and 10 ah. But I only get 4.5 Ah from them, usually.
 
Joachim said:
the voltage of one cel 3.3 the rest of the cels 3.8v in a 6s not ok!

check de end voltage of each cel. after you charge the 6s...must be between 4.19v&4.21volt.

I think you have bad luck...1 are 2 cels of the 6s are not in the 80/90% energie storage....maby they hold 60/50\% and the compleet 6s get out of ballans and this is
not good and dangerous!

you are lucky that you have 2 packs in paralel and just take a max 3c out of the 12 cels,on a rc big plane are car that takes a lot of amps the compleet pack wil burn after 10 minuts :lol:
Click to expand...


Maybe they are 3,6, not sure. But I am sure that only one cell of each pack falls off the cliff.
Still, when I recharge I recharge close to 10.000 mAh.

Do you think it would help to do a full discharge on the charger? How low, 3.0 ?
 
Yes your charger can discharge them fine. I only suggested the medic so you can discharge 1 of the 2 pack while using the charger to do the other pack. Maybe 3.1? I know 3.0 is the limit and the way your pack is unbalance I don't know who low the bad cell will discharge to. But your charger can monitor each cell with the balance lead so I guess it would be fine to take them down to 3.0. Do that a few times to see if you can nurse the bad cell back to balance with the others.
 
you need more info and knowhow about these rc lipo cells before you ever put them on the e-bike!
Read and learn until the numbers and risks you have to take care of are in youre mind 4ever.

discharge is oke when the charger have this function?(not al have this function)
Discharge the packs to 3.2volt and charge the packs slow with a 1/2C so 2500mAh.

Dont try to discharge down the 3volt! best and max discharge i do is minimum 3.2volt.

I think maby a smart thing to do in this case:send the packs back and ask for good/new ones.
 
Obviously the packs need to be re balanced .
Easiest way is to just charge those single cells up to be the same as the rest using a singe cell charge setting through the balance connectors.
Then cycle the packs a few times on your Reaktor letting it finally balance for a while also.
If single cells still go out of balance .....then you have a bigger problem !
 
Hillhater said:
Obviously the packs need to be re balanced .
Easiest way is to just charge those single cells up to be the same as the rest using a singe cell charge setting through the balance connectors.
Then cycle the packs a few times on your Reaktor letting it finally balance for a while also.
If single cells still go out of balance .....then you have a bigger problem !
Click to expand...

Thanks, I've tried the charge single cell trick, I can't see it helped anything. But I will try more, including the discharge whole pack to 3.2 as Joachim reccommends.
 
if you have tried raising those single cells already, and they have again gone down below the others , then you are wasting your time..and risking way over discharging those bad cells... by trying to lower the whole pack voltage.
Try for a return to HK.
 
Hillhater said:
if you have tried raising those single cells already, and they have again gone down below the others , then you are wasting your time..and risking way over discharging those bad cells... by trying to lower the whole pack voltage.
Try for a return to HK.
Click to expand...

Tried this yesterday. I thought when I put 'discharge to 3.2V' in the charger it would actually balance each cell down to 3.2. But no, it ran until the bad cell hit 3.0, then stopped completely.

I did however balance charge both batteries from that state (1 cell at 3.0) at 5A (0.5C). One battery showed a bit over 10 000 mAh, the other a tad under. So at least they recieve the rated capacity when recharging. Isn't it a bit strange that I can stuff 10 Ah into them, but only get 4.5 out ?
 
You can't take a full gallon jug, only pour half of it out, and then put a full gallon back into it. I suspect you aren't getting a true reading of the energy used.
 
wesnewell said:
You can't take a full gallon jug, only pour half of it out, and then put a full gallon back into it. I suspect you aren't getting a true reading of the energy used.
Click to expand...

I agree, but I heard a theory that when discharging fast (30A) a lot of energy disappears through the batteries as heat, instead of as electricity through my watt meter.

The reason I have to believe the watt meter is semi-accurate is that is has showed more than 9Ah on several occations from my 48v/13Ah li-ion bottle battery (no-brand). And it didn't stop there, I just had enough bicycling for the day.

Also, we all know that you get fewer Ah at higher discharge rates - so how do you explain that? You still charged it a gallon, but you get less out?
 
You still get the same amount of energy out. But you lose efficiency to wasted heat. Test it at a .2C discharge rate and see what you get. Or 1C for that matter.
 
Sorry if I missed something but buying used or 'never used' Lipo from a friend sounds like a dubious situation if you ask me..
Maybe your friend dropped them, left them sit in the sun and they got hot or even if he merely charged them up to 4.1? volts and left them sit there for a good month or too it will make your lipo go shitty... Just like blowing up a rubber balloon with air to its absolute peak and letting it just sit there it will get all saggy and nasty over the weeks...
 
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