RC Lipo series charging tutorial

Batteries, Chargers, and Battery Management Systems.
cycleops612
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Re: RC Lipo series charging tutorial

Post by cycleops612 » Jun 17, 2016 9:14 pm

Ha. You thought you were rid of me.

I am not quite there?

discussion on lipo all seems about hardcore fussing about with RC sub paks that have to be laboriously and meticulously charged and balanced. Its not for those who have a life. Perhaps i have been misled. Hi drain also has limited appeal for ebikes, as per the goldenmotors link below.

I didnt know lipo came in pouch cell form.

i wasnt aware, & nobody explained, & i got the impression, nobody used

further, the chinese seem to make it a major puzzle finding out what exactly is in a pak; wrong/ambiguous terms (lipo/polymer/li-ion,cannister/pouch/bms/c-rate,,...???), vague, ...

eg.:

http://gebattery.en.alibaba.com/product ... _cell.html

"Product Description:
Dimensions: 8.7*150*180mm
Nominal capacity:20Ah
Nominal voltage:3.7V
Operation Voltage:(Charge)3.9V,(Discharge)2.5V
Charging ways:Constant-current/constant voltage
Max Charge Current:≤1CA
Max Discharge Current:(Constant Current)≤100A,(Impulse Current):≤400A
Standard Charge/Discharge Current:0.3 CA
Cycle Life:( 80DOD%)≥500Times
Operating Temperature:(Charge)0°C~45°C, (Discharge)-25°C~60°C
Self-discharge Rate:≤3%(Monthly)
Weight:less than 400g"

i like general rules of thumb, so the above means; a 36v 20ah, 5c (am happy with 2-3c, but 5c is good so its not straining) discharge using 10 x 3.7v nominal?? cells at 400g ea. for a total of 4kg for 20ah, or ~100amp (3.6kw) burst.

AND BMS

that is pretty awesome.

500 cycles - meh. hang the expense, tho i hear these numbers are optimistic.

A similar lipo pouch cell
http://gebattery.en.alibaba.com/product ... _3_7V.html

an example of a similar finished product:
http://www.alibaba.com/product-detail/F ... 0.0.Wfi9uF


So, is this as convenient as a bottle battery - is recharge as safe and simple? Whats the catch?

seeking wisdom on this. pls help?

incidentally, gary salo of goldenmotor expresses similar views to mine about lifepo4, but better:

http://www.goldenmotor.ca/news/184/LiFe ... M-ION.html

NB, yes, a 12x cell 36v lifepo4 is heavier than a 10 cell lipo 36v pak, but they are a very steady 38.4v vs 37v diminishing?.

OTH

am thinking, if the 15ah lifepo4 is too big and heavy, maybe its my estimate is the problem. Get a sturdy lifepo4, but smaller.

an hour and a half is all i want to be in the saddle, and am thinking 250w ph average use, a generous allowance w/o no pedaling on my mid-drive, - 25-30kph, with 500w on tap if needed.

10ah lifepo4 does that at a liveable ~3.5kg, tho 12ah (~4.2kg) seems sound for some wiggle room as it ages.

Pouch brands seem a well kept secret by pak makers. What gives? Ought one be wary?

all the fakes and lies of 18650s seem absent in the pouch world.

i have heard of crap quality tabs to work on, but not poor function or fraud or mislableing?

any advice?

ta in advance

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Re: RC Lipo series charging tutorial

Post by bionicon » Oct 17, 2016 2:13 pm

Don't know if i am right here :roll: I want to make a 12s 90ah pack out 3x ( 2x30ah) tattu lippo's. How can i balanced charge this as a complete pack......what do I need :?:
What kind of charger and balancer?

Thx

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Re: RC Lipo series charging tutorial

Post by MrDude_1 » Oct 17, 2016 2:52 pm

bionicon wrote:Don't know if i am right here :roll: I want to make a 12s 90ah pack out 3x ( 2x30ah) tattu lippo's. How can i balanced charge this as a complete pack......what do I need :?:
What kind of charger and balancer?

Thx
Theres only 2 ways to do it.

1. get a BMS that works for 12s... this makes it easy as the OEM stuff, just feed it a bulk charge.

2. split the pack balance leads into 8s groups or less. You can then monitor everything with RC vehicle tools... you can still bulk charge, but keep an eye on the balance and run it through an RC balancer when needed.

to do #1 you need a BMS and a bulk charger.
to do #2, you need a RC balance charger... but to bulk charge you need a bulk charger and some cheap cellogs or other cell monitor. They're a couple bucks and they let you see the voltages as it charges.
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Re: RC Lipo series charging tutorial

Post by neptronix » Oct 19, 2016 5:37 am

easy..

Buy a nice high quality 6s charger, use it to weed out the funky packs ( guaranteed you will get shipped at least 1 ), then bulk charge the pack for 99% of it's life. Charge to 4.15v average, discharge to 3.6v average ( or whatever the lowest common denominator is for all packs once you've created the graphs ).

With a little monitoring here and there, you can get away with this.. you just want to cut off the top 5-10% and bottom 5-10% of the pack's capacity. As long as the packs in question remain balanced over lots of cycles, this works.

If they don't remain balanced, you can always break apart the pack and do a balance on the 6S charger when needed.

12S BMS would certainly be a lot nicer though. If you can find one with the appropriate amperage output, that doesn't drain cell #1 and kill your battery early, and has the right voltage cutoffs etc.
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Re: RC Lipo series charging tutorial

Post by bionicon » Oct 23, 2016 7:10 am

....euh did a quick search and did not found a 12s bms that has a continue discharge of 350 amps. My battery's are 3X2 30000mah with 25C continue ...so 90X 25 =2250 AMPS continue!(tell me if i am wrong)
So can I use the bms just to charge the pack? And to discharge disconnect the bms?

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Re: RC Lipo series charging tutorial

Post by wesnewell » Oct 23, 2016 8:31 am

You don't even have to disconnect the bms to bypass it for discharge. Just use a separate main ground wire for the discharge and leave the bms connected all the time if you want to. But yes, you could just unplug the bms if you designed it that way.
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Re: RC Lipo series charging tutorial

Post by neptronix » Oct 23, 2016 10:20 am

If you do that, the BMS will not cut off when a cell goes too low though.

Which is one of the main things you wire up a BMS for, ya know. :)
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Re: RC Lipo series charging tutorial

Post by bionicon » Oct 23, 2016 1:53 pm

and if i will use regenerative braking.....wihout bms? Will that work?

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Re: RC Lipo series charging tutorial

Post by MrDude_1 » Oct 23, 2016 7:50 pm

bionicon wrote:and if i will use regenerative braking.....wihout bms? Will that work?
of course.
Just dont fully charge it at the top of the mountain and regen brake the entire way down.
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Re: RC Lipo series charging tutorial

Post by Wheazel » Dec 05, 2016 10:35 am

MrDude_1 wrote:
bionicon wrote:and if i will use regenerative braking.....wihout bms? Will that work?
of course.
Just dont fully charge it at the top of the mountain and regen brake the entire way down.
:D Sorry for no constructive post, but this was hilarious and put funny images in my head

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Re: RC Lipo series charging tutorial

Post by Dylancoffin » Dec 24, 2016 2:35 pm

Hi, I'm planning my first ebike. I have a 26 in steel frame bike and I'm thinking of a 350-500w front hub. My commute is a flat 5 miles. I have years of flying rc planes with lipos. These batteries from hk seem like a good fit:

https://hobbyking.com/en_us/multistar-h ... -pack.html

Huge capacity, light weight and a screaming deal. They are 10C, which is really low compared to my airplane lipos, but at 10Ah should be capable of 100 amps. The bike load should be more like 10 amps or only 1C, right?

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Re: RC Lipo series charging tutorial

Post by Ykick » Dec 24, 2016 3:05 pm

Dylancoffin wrote:Hi, I'm planning my first ebike. I have a 26 in steel frame bike and I'm thinking of a 350-500w front hub. My commute is a flat 5 miles. I have years of flying rc planes with lipos. These batteries from hk seem like a good fit:

https://hobbyking.com/en_us/multistar-h ... -pack.html

Huge capacity, light weight and a screaming deal. They are 10C, which is really low compared to my airplane lipos, but at 10Ah should be capable of 100 amps. The bike load should be more like 10 amps or only 1C, right?
3qty of those series wired for 12S1P would be a nice voltage for majority 48V systems. 500W @ 48V would be about 10A, plenty of headroom for those packs.

$/Wh is a very good deal although you may have to install different connectors or hardwired to series them. Have you checked prices on 6S packs? if similar price that would require one less series connection.
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Re: RC Lipo series charging tutorial

Post by Dylancoffin » Dec 24, 2016 6:35 pm

Thanks Ykick. The 4s 10 Ah are $37 and the 6S are $90. I don't know why the 4S are so cheap. Maybe they made a bunch. My experience with Turnegy batteries has been problem free, although I've never used these 10C packs. I like the XT connectors. It would be easy to make up a series connector.

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Re: RC Lipo series charging tutorial

Post by Ykick » Dec 24, 2016 6:49 pm

Pricing is just one of those HK mysteries. When they wanna move stuff they price it to move.

I believe these 10C packs are intended for AP multi-rotors? Slow and steady with long flight times but well within modest eBike needs.

I like XT’s and use them for all my aircraft but for series wiring packs 4mm Bullets have spoiled me. I’ve been using 4S Turnigy Hardcase with bullets for several years on my bikes. That was before these MS (multi star) packs became more prevalent.
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Re: RC Lipo series charging tutorial

Post by rguy56 » Jan 25, 2017 1:25 pm

I was measuring internal resistance in some packs I just bought. I believe that's measured in micro-ohms?

One cell was showing 3x the resistance of all other cells. I remeasured, and it's consistently off. I'm getting .001 in the other 63 cells, but .003 in that one cell.

Is that measurement meaningful enough that I should use that pack for "utility purposes" or spare cells, is it something I should be returning as faulty, or is it truly no big deal at all?

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Re: RC Lipo series charging tutorial

Post by MrDude_1 » Jan 25, 2017 9:50 pm

Dylancoffin wrote:Thanks Ykick. The 4s 10 Ah are $37 and the 6S are $90. I don't know why the 4S are so cheap. Maybe they made a bunch. My experience with Turnegy batteries has been problem free, although I've never used these 10C packs. I like the XT connectors. It would be easy to make up a series connector.
The 4s hardcase are so cheap because HUGE numbers of RC racers buy them. The non-hardpack ones are the same, except for the shrinkwrap instead of the case.. so the huge volume lets them be cheaper.
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Re: RC Lipo series charging tutorial

Post by CobraJet » Mar 06, 2017 11:33 pm

So what charger out there now does 14S Lipo packs and balances at the same time?

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Re: RC Lipo series charging tutorial

Post by Jon NCal » Mar 07, 2017 2:50 pm

CobraJet wrote:So what charger out there now does 14S Lipo packs and balances at the same time?
thunder power, adaptto

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