my first build, now with a shady m1 pack

[gestalt]

Indeed he does bzhwindtalker,

but he seemed a bit dubious as to whether or not 15ah at 48v would be enough batt for me :x he said that pulling 100a and 300a @ peak I would only have about a ten minute run time. could someone break down for me what kind of range I should expect with my motor combo?

motor is rated at 2000-7000w

controller is a 100a continuous 300a peak modded chrystalyte

rear wheel is 26" mtnbike wheel with a 5:1 ratio from motor to wheel

how far is 20ah going to get me maintaining city speeds? how far with 40ah get me?

I have about $1000 to play with now and I'm itching to make some real progress, but I still don't want to waste my time and money going down the wrong path. I cant afford 30ah of cell man, but could afford 40ah of lipo.

 

[gestalt]

In the night of bostons first heat wave I had many fevered dreams, one after another that continued a theme. I was traveling all over the country with my rickshaw courtesy of a traveling church that got my rickshaw from city to city. I was trying to find parts for my cruiser and I came accross methods at a store with big blinky lightscalled "spinning magnets". Then somehow mysteriosly Australia had replaced south America down there and I rode my rickshaw to visit aussiejester. I pulled Kim around the city while he drank, looking for hotties. Never ended up finding a battery though which is good yet because I would have been really dissapointed when I woke up if I had. Anyways I thought it was funny how this placehas started showing up in my dreams now.
I can't get away!!!

 

[AussieJester]

Australia had replaced south America down there and I rode my rickshaw to visit aussiejester. I pulled Kim around the city while he drank, looking for hotties. Never ended up finding a battery though which is good yet because I would have been really dissapointed when I woke up if I had. Anyways I thought it was funny how this placehas started showing up in my dreams now.
I can't get away!!!

Would of been a wet dream if you went lookin for hotties with me hehehe

KiM

 

[gestalt]

so....
I was really about to jump on that lipo bandwagon, but stoopid hobby king was sold out of the packs I wanted for who knows how long and I want to get this damn bike done. then a member posted this 27ah 48v pack made from a123 m1 cells for sale

granted now I'll have to learn how to install balance taps and find a decent bms but I think soon I'll be on my way to getting this bike running this pack may be a bit light on capacity for my application, but should still be able to jet me around the city quite well.

 

[liveforphysics]

27Ah of M1 cells makes for a battery that can laugh at 300amp discharge. Can only do it continous for about 5-6mins before its empty, but that's actually quite a lot of time to be at peak acceleration. I expect the controller will be the weak link. I think you will get at least 15 hard miles with that pack.

 

[gestalt]

15 hard miles sounds great luke! I plan on not running this bike that hard most of the time but want it to be available for showing off and other dangerous adventures. the three speed settings on my controller should work great for getting a bit more range out of my ride when I just feel like put-putting around the city and also not garnering more attention than I would like from the boys in blue, though from what I understand boston has some great laws when it comes to registration of experimental vehicles so I should be ok.

 

[gestalt]

I just came across this charger on craigslist, anyone think this could be a good onboard solution for my 48v pack http://boston.craigslist.org/nos/bik/1744050876.html

the guy also has 15ah 48v pack with a unused bms. I am interested in the bms not the battery, but seems like a decent price for the pack none the less. my question would be if it is a decent bms, and would that charger be compatable with it. http://boston.craigslist.org/nos/bik/1744055534.html

 

[amberwolf]

At a guess, the charger would probably work, but it does depend on the pack you're going to charge with it as to what voltage you end up with. a lead charger is going to be maybe 57-58V output for 48V nominal pack (4 batteries). What does your pack require?

As far as onboard...it looks pretty big.

EDIT: as far as I can tell, it's using a regular IEC C13/14 plug there for AC input, which is about 1.25" across. So that would make the charger about 7-8" wide, 10-12" long, and 3-4" thick. Metal case is not going to be all that light either, so at a guess 8-10lbs? Maybe more.

 

[gestalt]

it's a 12s4p a123 M1 pack, so 48v 27ah. Even after reading the care and feeding of a123 based packs thread I am still clueless to as how to charge the pack. what I need is a raging clue. I think what the guy means to say is that he has been using this charger on a 48v pack, the reason I like it is that it looks like a sturdy for being an on board charger

 

[amberwolf]

Well, if it's a 12s pack, then you can divide the voltage the charger puts out by 12 to see what each cell would have to take.

Since that's around 57-58V, we'll just go highest for experiment's sake and say 58 / 12 = 4.83V per cell.

I'd say that's a "no", you can't use this charger on your pack unless you can either add a few more series sets to your pack, to bring it up to 15s or 16s, or you can turn the charger voltage down about 10V or something.


Thing about "48V" or "36V" or "24V" is that it depends on the chemistry the charger is intended for as to it's actual full voltage. Some will be close enough they're ok to use.

But with 12s A123, that's 12 x about 3.3V nominal I think, meaning around 39-40V. It doesn't fit the 48V pack model, it's closer to 36V. So a 36V SLA charger might work, since it'd be about 43-44V or so.

 

[bzhwindtalker]

for me 12s4p of a123 m1 is 40v 8.8ah non?

 

[Anonymous]

yeah, that's what i figured, what gives? how is it 27ah?

for me 12s4p of a123 m1 is 40v 8.8ah non?

 

[gestalt]

yeah, that's what i figured, what gives? how is it 27ah?

well, now I have the pack in my possession we can start to sort that out. It came as two packs about the size of a small car batter and after cutting the wrapping off of one of them I got down to another layer

so.... each one of these packs has 8 groups of 12 cells, so that's 192 cells all together. now after opening it up I'm more confused than ever especially when it comes to wiring a BMS to this pack. so what is this 50lb monster? 12s 16p?

 

[amberwolf]

BMS balance taps go between each set of paralleled cells. So if there are 12 sets, that's 13 wires. One to pack negative, one to the cell above that, etc, until you get to the top of the last cell, which is pack positive.

If the BMS does the discharge control as well as charge control, then the pack positive and negative wires will need to be as thick as the rest of the supply wiring to your controller. If it only does the charge control, then they only need to be thick enough to carry charge current.

 

[gestalt]

well, I ordered two of the cell-log8s units from hobbyking today so that I could just monitor cell voltage myself and not use a bms for discharge, just for charge control. so if those 12 cell units are wired in series then the bms would just handle those 12 units and not the individual cells? would the 12 in each unit still be vulnerable to imbalance? and furthermore would ggoodrums "new approach to battery management" using hobbyking chargers be viable? or should I continue to wait for the 4.0 bms to be released someday. as I understand it the current goes strait to the load instead of going back through the bms.

 

[amberwolf]

As far as the pack goes, it looks like they are wired 8 cells in parallel straight across. Then 12 of those groups in series. Presumably both packs are the same.

Again, monitoring them is done the same way a BMS hooks up--one wire to each parallel group of cells, plus pack pos/neg.

For consideration here, all cells wired in parallel are essentially one single cell.

If cellog has 9 wires, most negative wire goes to pack neg, next to that cell's positive, next to cell + above that, etc, last wire ends up at pack positive.

Other cellog would monitor other pack, and then you can either parallel the two packs at their pack pos/neg, or series them, and the cellogs will work the same either way.

 

[liveforphysics]

Gestalt-

Your pack is 12p to make 27Ah.

Your pack SHOULD be 15S to make a 48v pack, but if you're only seeing 12 sections, then it's a 38.4v pack.

A real 48V pack(15s) just needs a 54.75-55v power supply to charge it. Make sure they are all in balance to start out, then just plug it in and forget about it. 27Ah of A123 is capable of being charged at 135amps... so it's not like you're going to have to worry about anything but cell balance.


If it's a 38.4v pack (12S), then you need a 43.8-44v supply.


A BMS really isn't a good idea for you... a 5,000w motor pulls 111amps at 45v, which makes a BMS more of a liability than an asset IMO.

 

[slayer]

from what i can see and having seen that pack for sale ...it is 4 block of 4 series 12 p ...like the picture you are showing each of these blocks are 4 x 3.3 volts = 13.2 volts wich mimics a very popular voltage system the old sla system, if you have 4 bolcks like that it would be 16s and you can take a 48 volts charger like a soneil 48 volts wich will bring them to about 3.6 volts each 57.6 volts total.

 

[liveforphysics]

If it's 16S, then just get a 58.4v power supply. I'm struggling to know how you can have the pack in your hands and not check voltage or count the series groups to know what you have.


A pair of these would give you 1hr charging:

http://cgi.ebay.com/D-C-POWER-SUPPLY-MODULAR-24-VDC-25AMPS-OUTPUT_W0QQitemZ260292051822QQcategoryZ58288QQcmdZViewItemQQ_trksidZp4340.m8QQ_trkparmsZalgo%3DMW%26its%3DC%26itu%3DUCC%26otn%3D20%26ps%3D63%26clkid%3D8206097541788712419

It claims you can only adjust them to 28.5, but just ad some series resistance with the V adj pot to get your extra volt. Cheap. Compact. Light. And 25amp charging means you can ride out somewhere, stop for lunch and opertunity charge, and have a full pack to head home.

 

[slayer]

Being french i took a look at the defenition in a online dictionary of shady

shady - not as expected; "there was something fishy about the accident";
Informal dubious or questionable as to honesty or legality
. full of shade; shaded
. affording or casting a shade

is that so.
because the pic you showed was not exactly like i expected anyway
are you not happy about the deal?

 

[gestalt]

If it's 16S, then just get a 58.4v power supply. I'm struggling to know how you can have the pack in your hands and not check voltage or count the series groups

well, it was advertised 12s 4p, which out of the gate had me suspicious but I made the leap anyways. Once it got here and I had a half day off first thing to do was take it to the shop and take apart one of the blocks to get a look at what was going on. The multi meter was missing so it was eyeball time. I suspected that the 12 cell packs were paralel cells but wasn't sure. Keep in mind this is the first time I have ever held an ev battery let alone disect one and try to understand it.

But this noob, with your sage advice will persevere. That charger looks great btw, mi gusta rapido charging! But I'll tell you one thing, I don't think there is going to be room in the frame for charging. I know it's been done over and over with cruisers like mine, but I see leather saddle bags in my bikes future.

 

[gestalt]

because the pic you showed was not exactly like i expected anyway
are you not happy about the deal?

no, I'm happy. It was a good deal and I think the pack will work out fine once I repackage it a bit. The wrapping melted around the bus bars is a bit unsettling but that's about it. I think it's a great pack for me to cut my teeth on.

 

[amberwolf]

melted wrapping there could be either from a busbar repair after wrapping or from really high current draw heating the busbar.

The latter might be nice to know that it's possible to draw that much current.

8p x 2.3Ah x 10C = 184A.... or 552A at 30C burst.

 

[slayer]

Amberwolf it is a 12 p that he has.
12p -27 ah x 10c =270 amps continuous 30c 810 amps burst... 810 amps x 48 vots = 38880 watts but of course with the sag it would be less than that

 

[amberwolf]

OK, I guess I got confused because he'd said it was 12s 4p, then something else later but still 12s. THen somehow when I counted I counted wrong and got 8 in each of those strings.

What I see in the picture is two packs, one in focus and one below that at a different angle. The one fully in frame appears to be 4 sets of paired parallel rows of 12 cells. Unless the cells are also stacked vertically so that I can't see the other half of the pack, that doesn't seem quite right based on what was already said?

Or, if the pack only partly in view is actually just the other half of the pack in view, and there is a whole other pack not even on camera. I'm so confused.... :?

So then really it is 2x 4s 12p? Meaning, total of 8s 12P? That would be only half of the 192 cells stated? I guess that does make more sense with the apparent layout of the busbars, but it leaves it very short in the voltage department, at only 26.4V nominal.

Sounds like they were basically built as two car battery replacements, as their individual pack nominal voltages would be about right for that, at 13.2V.

The way it's made it looks easy to cut the busbar between the paired parallel rows, so that each is only 6p. Then it could be reconfigured for 16s 6p, which would make more sense to me for a battery pack to drive a motor.