lipo noob questions

[dogman]

Unfortunately the RC market has no demand for 10 ah packs. Apparently the biggest ones are 5.8 ah. So you'd have to dissasemble two typical 5s 5ah pack to make a properly paralelled 10 ah pack. I suppose you could get 1p packs and paralell those, then do the series connections. Lots of wires to connect that way.

[chroot]

SOMEDAY!! RC market might sell 10 Ah LiPo, Just like they did it in past 1k Ah, then 1300 Ah, 1400 Ah then reached 5800 Ah nowtoday. I am believe that they will able reach 10 Ah in couple years ahead. Who knows!!!

You can see our ES member cell_man sells 15 and 20 Ah look like LiPo but it uses LiFeP04. That design almost same like
LiPo style.

[justadad1957]

darn i remember how hard it was to make run time in 1/12th scale rc racing 8 mins with sub c nicds 1200ma then 1400 and wow those 1700 sanyos where sweet
we used to rate cells with a 10 amp discharge to .9 v very few made the rated ma at 10 amp
and we would assemble the very best cells into our mains pack
then panisonic came out with some 2200's that would easily supply the rated ma at 10 so we started testing them at 20 amp
the rc car world is so fast now compared to back in the day

GEDC0096_1.JPG

gotta love tested and matched packs

(204.61 KiB) Not downloaded yet

30-40c * 4.5AH 135-180 amp good thing they use nice 10 ga wire
it does look kinda silly seeing the 10ga wires going to my control with what maybe 16 ga and crappy terminals
started out leaving all factory wiring intact and it is working fine but i know better conections mean better bottom end

so all this in mind and needed Ah for the death race i may have enough 18650 cells soon to make 2 16s9p packs that could be conected in series for ? 96 v system 3.3 * 32 105.6v nom
these cells are untested and may not developed my desired c rate
with a 3.6 to 3.7 per cell balance charge maybe hoc 118.4
totally nuked charged at 4.2 134.4 max volts hoc hopefully before they blow up maybe not a good idea as pack will most likely only last a limited number of these cycles but hey thats racing
because i will have a limited number of cells this might be the max volts i could make with enuf Ah for death race use also
as i could see my son and i each being able to use a 48v packs for some time if we dont damage them to much lol
oh ya this is an inexpensive form of transportation
i thought i was going to save money getting into an electric bike and for the few days i have been electricfied
all i can say is im hooked

my bike is legal on the street right now and its great for what it is

the bike we want to build is not and i fully understand that being said i will want it to be as safe as possible for my son and myself to "test ride" so with this in mind what speed controls / motors are you thinking about that could handle that kinda voltage !!!

or maybe 72v is enuf for now?

[kevo]

Gary / aka GGoodrum,
Could you post a description/jpeg of how to parallel Lipos using the balancing connectors? Also, I'm unclear how to hookup Schottky diodes for the same.
Thanks,
Kevo

[amberwolf]

This:
http://www.tppacks.com/proddetail.asp?p ... DLVC%2DHVC
if you need LVC/etc.

There used to be just a paralleling board available there but all that stuff seems to have gone away from both TPPacks and RechargeableLithiumPower.

This might parallel some:
http://www.hobbyking.com/hobbyking/stor ... arger_plug

But all of these are only to parallel for balancing; might not take the higher currents that could happen during high-rate discharge under the wrong conditions.

[justadad1957]

i dont think it its a easy thing to do way to many wires
batteries should be constructed that cells are unified into the pack as a whole battery unit
i am a newbe here but i think this is an important consideration for pack life
just think what might happen if you ganged a 10 Ah pack and a 5 AH pack that had even a slightly higher voltage
the higher voltage pack would discharge at a higher rate and could easily be damaged
as it would lose its capacity sooner
and then be like a flat tire dragging the total avg voltage down

darn i want my batteries to last for years

[dogman]

In general thats very true about too many wires and connectors. Every connector is a potential resistor. That's why the gold plated bullets.

But I don't think a 72v 10 ah lipo pack is going to be that complicated. Paralell connecting packs in pairs, then series connecting the 4 pairs of 5s lipo.

[chroot]

You can just use parallel cable from progressive RC online. Save your time. That's what im using it for my
15s2p set up.

http://www.progressiverc.com/index.php?option=com_virtuemart&page=shop.browse&category_id=5&Itemid=1

[Russell]

In general thats very true about too many wires and connectors. Every connector is a potential resistor. That's why the gold plated bullets.

But I don't think a 72v 10 ah lipo pack is going to be that complicated. Paralell connecting packs in pairs, then series connecting the 4 pairs of 5s lipo.

Look at this guy's LiPo set-up

viewtopic.php?f=14&t=10817&start=1035#p256133

-R

[dogman]

Drools on the keyboard...

Assuming those are 5s 5 ah blocks, that's impressive. 21 packs there. I'm contemplating an 8 packs x 5s 5 ah setup. For shorter runs, maybe even just run 4 at a time like for practice laps. Making plans for a stout container for them so they are crashworthy.

[moostrodamus]

Im thinking about 2X36v 10ah ping version 3 batteries for a 72v setup, mostly because i live in a house with 3 apartments, have no shop so cant afford to start any kind of lipo fire.... and of course you can just plug them in with no fuss...

[liveforphysics]

imo batteries should always be configured first to the AH needed capacity for correct cell balancing then series for the desired volts i do not think it is a good idea to pair packs for increased AH capacity
i was wanting to config a pack split on either side of bike and was thinking about possible problems with slightly mis matched packs

100% Wrong.

i dont think it its a easy thing to do way to many wires
batteries should be constructed that cells are unified into the pack as a whole battery unit
i am a newbe here but i think this is an important consideration for pack life
just think what might happen if you ganged a 10 Ah pack and a 5 AH pack that had even a slightly higher voltage
the higher voltage pack would discharge at a higher rate and could easily be damaged
as it would lose its capacity sooner
and then be like a flat tire dragging the total avg voltage down

darn i want my batteries to last for years

100% Wrong again.

[dogman]

How many amps of 72v do you want moosetrodamus? I'd say 72v 10 ah of ping would be good for about 12 amps continuous. Whatever the c rate of the v3 cells is divided in half.

You could just charge lipo in the oven, even apartments have one fire resistant place in them.

[moostrodamus]

How many amps of 72v do you want moosetrodamus? I'd say 72v 10 ah of ping would be good for about 12 amps continuous. Whatever the c rate of the v3 cells is divided in half.

You could just charge lipo in the oven, even apartments have one fire resistant place in them.

Is that how it is calculated? If so so much for that idea want to run a 30 amp controller. About the stove, that belongs to the landlord too...I suppose if I did have a fire i could always throw a piece of burnt chicken in there as a decoy.

At this point i'm just lurking waiting to see what you will do, you know a hell of alot more than i ever will...



Moo

[Russell]

Moo,

Check out this thread regarding the Ping V3;

viewtopic.php?f=14&t=12949&start=0

-R

[dogman]

Well, it depends on whether you want the full 1000 cycles or whatever, or if the pack is considered disposable.

There seems to be some consensus developing that whatever the c rate is, halfing it is a realistic number for continuous discharge, and getting some cycles out of it, and not exceeding 80% depth of discharge for not throwing the thing way out of balance every ride. I ran my ping v2.5 in a race recently, and got it pretty out of whack discharging a continuous 1200 watts. Less than 1c..... The kind of riding, alternating full on throttle with braking was pretty hard on it. About 20 cycles later, it seems to be gradually recovering. The packs resting voltage went from 56v to 52v in one afternoons racing. Now it's back to about 53.5v. The very brief spikes that afternoon could have been as much as 40 amps. It was a 48v 15 ah pack.

A realisitic pack size for running a larger controller would be aiming for a 1c discharge rate, so 30 ah of ping for a 30-35 amp controller. So that's aobut 40 pounds of battery. But a 72v 10 ah lipo pack of 20 or 30 c cells has a huge advantage, weighing a lot less since it can afford to be only 10 ah.

[justadad1957]

100% wrong ?

if you conect two packs together current will flow to the pack thats at a lower voltage
without any regard to cell voltage

old but still willing to learn more

[wasp]

i recently pounded the snot out of my lipo's hk 5s1p 5000mah x6 run in a 15s2p config
i ran without my turnigy meter hooked up and almost paid for it
i ran wot and when i returned the cells were all around 3.2v resting exept 1 was at 2.8...
when i charged them all together it took 29ah and was still going...btw they are 15c lipo's
they have about 30 cycles on them and they recovered nicely
i post this for the newbie's to lipo, i was a hair away from thermonuclearmeltdown and a 400 dollar loss
you should never run without somekind of protection...
i will reinstall my turnigy meter and order some of gary's toys to prevent this from happening again

[dogman]

Yeah, running with no bms, lipo users need to have some kind of monitor. I'm trying to figure out how to get started cheapest so I've been looking at the 3 buck lvc alarms. One alarm on each block, or pair of paralelled blocks. Looking at the turnigy meters, I'm not sure how you use one of those at 72v, wouldn't it cook it? Do the meters just hook to the balance wires? I think the lvc alarms do so they wouldn't see 72v, just the 18v of each block. To monitor a paired block of cells, I guess I'd have to parallel the balance leads, and then attach the lvc alarm, and the balance leads would allow both cells to equalize. Hopefully not too fast as Justadad is thinking of.

Re Justadad. yes paralelled batteries will charge each other. That's one of the reasons for using a lipo cell balancer. Don't be connecting any chemistry paralell without both batteries being at the same state of charge. Series connected batteries won't charge each other, that's why you can't charge a battery with a 3.5v charger hooked to the first cell.

[RTLSHIP]

What's the lifespan on lipos? Though they may be excellent for model planes and racing because of high density and light weight, they don't seem too attractive for urban ebike cruising.

[chroot]

@dogman - screw alarm!! It really no excuse for anyone is not buying LVC boards from Geoff or Gary. Let me tell you, One of my friend distracted and killed his 24s2p cause he did not pay attention the alarm due his area pretty heavy traffic lot noise masked the alarm's buzz. His LiPo got awful bad puffed and I told him dont charge these puffed LiPo anymore. It's no good! He lost nearly $400 dollars. TOO BAD!

@RTLSHIP - LiPo usually last 500-800 cycles depends how do you treat the LiPo. If you use LVC boards protected the LiPo, charging at 4.15v, never abuse such careless dent or damage LiPo cells and It probably will outlast with little mAh loss.

If you look El-Steak's thread somewhere, His LiPo over 100 cycle, He got few of the LiPo really dying faster and he abused it lot due he was lacking of LVC protection I.E. Gary or Geoff LVC boards.

[RTLSHIP]

chroot, 42 mph +. I'm scared at 25-30 mph. do you use special spokes and brakes? what about suspension

[arnie1]

Is a a low voltage cutout board necessary if you have a Cycle Analyst programmed with low voltage setting to protect the pack? Granted the CA can't protect individual cells...

[chroot]

I usually cruising around 20-25mph 99% all the time. No special brakes, I am using Avid BB7 caliper and 160mm disc. My hardtail frame with 140MM travel suspension front fork. That's why I stopped doing speed on my hardtail due too much bouncing on rear tire in high speed. My next 3rd MTB ebike building will be completely treat like an Motorcycle that has full suspension in front and rear end and travel suspension will be over 6" cause I wanted more plushy suspension comfortable on rough or bad roads.

My spokes on both front and rear uses 13g pretty strong enough as long as you readjustment and tune your bike. It pretty secured so far I built new 2nd ebike. Everything runs smooth.

I commuter my ebike to work and home sometime do errands. I saved so much money on gasoline! whoo hoo

@arnie1 The controller's LVC protect just only WHOLE of battery total voltage and NO protection on each cell. Only the one solution is get LVC boards from Gary or Geoff or You homemade the LVC boards that protect each cell.

I experimented the controller LVC set to 42v (15s2p), I discovered one of LiPo went cell 1 =2.73v, cell 2 =3.29, cell 3 =3.28, cell 4 =3.25 and cell 5 =3.28 Total 15.83v. Jesus I almost killed one of LiPo which it did not had balance proper and thank god I was very paranoid that time and felt instinct double check using LiPo monitor happened saw my own eye.

NEVER AGAIN! LVC boards are a MUST have! screw LiPo monitor or alarm and controller's LVC.

chroot, 42 mph +. I'm scared at 25-30 mph. do you use special spokes and brakes? what about suspension

[dogman]

I couldn't agree more, that the lvc boards are the best way to go. But far from mandatory.

What is mandatory is having some kind of way to monitor at least the total pack voltage. Even a simple 4 buck Harbor Freight voltmeter is better than nada.

After that, the pack size buzzers are ok, if you pay more attention to the led's and mount them where you can see them. no sound indicates, A , you didn't hear it. B it got disconnected, or C maybe you have power left. A combination of total pack voltage monitoring and the buzzers is not too bad, unless you ride further than your known range without paying attention. I don't often get suprised by the beeps coming when I haven't known they were coming by either the led's blinking blue, or the CA.

Obviously a real lvc can be better. But really, even with a reliable lvc, you still want to be aware of your pack voltage so you can slow down sooner if needed, and know what your range is on that day's weather, or hills, or temperature.