v28 Milwaukee Battery Packs

[Jay64]

Ok, this will probably turn out to be a stupid question, but...
Does anyone have the amp specs on these battery packs? I looked around and the only reference that I can find is that on the bottom of the packs it states 3.0 ah. Does anyone know the amps of these packs, or is there a way to figure it out from the ah? I guess I am still trying to get this amp vs. ah thing totally figured out. I'm running two packs in parallel and I am trying to figure out what my current would be.

 

[Link]

Without a datasheet, you can't really figure out how many amps you can get out of them unless you short them out and measure what you get (prolly not such a good idea). Generally, the bigger the battery, the more amps it can supply, but this can vary wildly.

Think about it, which can deliver more amps: a 5.0Ah SLA or a single A123? Even within chemistries it varies with manufacturer and even between individual batteries (albeit insignificantly).

If it has a BMS (I'm assuming it does), then you're still going to need a datasheet, which I can't seem to find, either. In any case, as long as you're not drawing crazy power, you _should_ be okay with two in parallel.

As long as something doesn't go wrong and the batteries are sized appropriately, the amps drawn is really a matter of the motor and controller.

 

[Rassy]

it states 3.0 ah. Does anyone know the amps of these packs

Jay, I am very non-technical in this area, so I'm going to try to answer the question I think you asked:

a 3 AH x 28 V battery can supply 1 amp for 3 hours, 3 amps for 1 hour, or 6 amps for 1/2 hour, etc. So it follows that two of these batteries in parallel would make a 6 AH x 28 V pack, which can supply 1 amp for 6 hours, etc. If two of these batteries were in series you would have a 3 AH x 56 V battery pack, which (at this higher voltage) could supply 1 amp for 3 hours, etc.

Of course, different chemistries have varying performance characteristics, the main ones being sag, which is the amount the voltage drops under load, and C ratings which indicate how fast a battery can be charged or used. Drawing 3 amps from a 3 AH battery would be considered a 1C rate, drawing 6 amps from a 3 AH battery would be considered a 2C rate, etc.

Hope this helps you. I don't really know any of this, but have learned it from this forum this year.

 

[TylerDurden]

Rassy's got most of the story. I'll try to fill in the rest:

The cells are made by E-one/Molicel. They are very safe LiMn (Lithium Manganese). The R/C folks loved everything about 'em except the weight... they are a bit heavier than LiCo. They are often called Emoli Cells, or Emolis.
View attachment IMG_2875sm.JPG

So... the question could be paraphrased as: "How many amps can these cells deliver? "

The specs boast about 20A. The folks in the real world say about 10A.
View attachment 2

Clearly, if you pull 10A continous, you will deplete a cell fast. So you might parallel more cells to split the load between the cells.

Things get more interesting when you go through the pack's BMS: You can't put more than two packs in series or the FETs in the BMS blow. But 2s2p will get you 56V 6AH, that you can pull 20A regularly and more in bursts.

Search the forums on "emoli" and see what fun some folks are having.

 

[Smoker]

I'm about to pull the trigger myself on the v28s. The only thing holding me back is how to charge these without buying a bunch of chargers. Any ideas? Could i connect 6 to the 1 hour charger and get a 6 hour charge time?

 

[magudaman]

Depending on how many cell you plan to use in series you could use a Hobby/RC charger setup for lithium charging. It is still a good idea to buy a balancer with that too.

 

[Jay64]

Thanks Rassy and Tyler. That did help me to continue to understand things better. So theoretically, if the packs can supply 20a from 3ah, then the C rating is about 6C for these packs? Jus trying to make sure I understand that correctly.

Tyler, you said that the packs can't handle more then 2 in series, is there any limits to how many in parallel they can handle. I am going to be using them just to get me started on my first build to keep every thing in as stock of trim as possible. My internal controller can't handle more then 30v, so I don't want to put them in series at all. I have four packs that I might want to put together just for a couple of test runs to see how far I can go with it. But once I understand things better I am going to change out the controller and then switch to the DeWalt packs that I have.

 

[TylerDurden]

6C is correct: it's the theoretical max according to some sources, but 3C is field-proven and will keep your cells alive longer.

Parallel discharge is no problem, since you aren't raising the voltage, but rather the total current (amps) your packs can deliver.

Series sums voltage
Parallel sums current.

 

[Jay64]

ok, so 1s2p (or would you just write that as 2p?) setup will give me 28v and 20a, right? So would that be 6C, or since it is 2 packs in parallel, would that stay as 3C? So, looking at 784w?

 

[TylerDurden]

I think it's standard to express it as 1s2p (usually referring to cells, but here in terms of packs).

The C rating applies to the batteries rate of charge or discharge. If you crack the throttle enough to draw 20A (current), you'll draw 10A from each of your two packs: each pack will discharge at a rate of 3C.

You might have enough headroom to draw up to a full 6C, but if you do that continuously, your packs won't last or live long.

At 3c, each pack is providing 280W, so when you goose-it (6C... 20A each pack), you can get 1120W total.

The more packs in parallel you add, the more you can crank the throttle without trashing the packs, since they share the load. I think ES member jondoh runs MilW packs in 2s3p.

 

[marty]

Think I finally hit the jackpot! Located 13,000 pounds of used Milwaukee V18 and V28 LITHIUM-ION battery scrap. Might these be desirable for building new batteries from the usable cells? Should I make a offer?

 

[pgt400]

wow, I would think so....how did you stumble on this?

 

[pwbset]

Located 13,000 pounds of used Milwaukee V18 and V28 LITHIUM-ION battery scrap.

Keep us posted Marty! Just remember that the Milwaukee packs don't have any "defects" like the Makitas so these emolis may be all trashed. I've yet to see a used emoli cell that will hold even 3C and 50-75% of it's original capacity. Milwaukee builds their packs tough! Having said that.. if you can get them cheap enough/free enough why not!

 

[marty]

....how did you stumble on this?

Top secret. If I told you I would have to kill you

 

[marty]

Look what I found:
http://www.swift-tuning.com/emoli.pdf
HOW TO REBUILD AN MILWAUKEE / EMOLI V28 PACK....INSTRUCTIONS
I will take a few packs apart and test the individual cells. What voltage should I look for?

 

[katou]

Everything is in the price. If you check out my recent testing of these cells:

http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=15044

You will see my conclusions regarding the Moli cells. Some the info will not apply because the cells you have may be 26650 size, and in addition, are being governed by a different BMS.

However, you will see that the failure rate of Moli cells can be up to 50% in some cases.

My advice would be to calculate the number of cells you would get, divide that in half, then multiply that by about 10c per cell.

You will only be able to charge (I'm guessing from my observing of sales here in the fora in the last year) about $2/cell for the little ones (18650 size) or perhaps $3-4/cell for the larger 26650 size, and that's only if you test them. Untested, I'm guessing that they'd fetch about 25cents each.

The bigger problem is separating the good from the bad. You need a way to process about 20,000 cells to find out their capacity. Now THAT'S a problem. I'd offer the guys 200$ cash and see what happens.

Don't forget you have to store these things too.

Katou

 

[katou]

You might make more money if you find a buyer for them sight unseen here on the forum. Then, you buy the packs from the dude you know, and ask if it's okay for them to stay there for a few days. The deal goes through on the forum here, and the truck picks them up at your "secret location".

You make a good bit of money, you have no risk, you aren't suddenly in the business of testing cells and developing testing equipment.

Might be a better deal for you. But, whatever you do, let us know how it goes hey?

Without exposing your secret location, whereabouts are you? Shipping is expensive.

Katou

 

[pwbset]

What voltage should I look for?

Anything under 3v I'd just toss right away. I think your best bet are going to be packs that got into a "bind" situation early in their life blowing the BMS, but keeping the cells relatively fresh.

If you go this route I'd very highly recommend calling Milwaukee direct and buy one of their service pack readers. If I remember right I was quoted like $145 for one. A very quick and easy way to check packs without having to disassemble them. You'd save TONS of time with one.

 

[katou]

Can you get the same thing for Dewalt packs? I did not know that such a thing existed for sale!

Katou

 

[pwbset]

Can you get the same thing for Dewalt packs?

Dunno. I've never heard of one for DeWalt packs, but never pursued it either. The Milwaukee one is cool as it shows individual cell voltages, # of cycles on the pack, max temperature the pack has reached and more.

You can barely see it, but this image shows it...

 

[marty]

Did some research on Milwaukee 18V and 28V LITHIUM-ION batteries. See results in detail area of images below. Note that M and V share the same model numbers.
48-11-1815_M18, 23Wh Li-ion, .91 pounds
48-11-1815_18V, 23Wh Li-ion, .91 pounds
48-11-1828_M18, 47Wh Li-ion, 1.50 pounds
48-11-1828_18V, 47Wh Li-ion, 1.50 pounds
48-11-2830_M28, 70Wh Li-ion, 2.30 pounds
48-11-2830_V28, 70Wh Li-ion, 2.30 pounds