Doctorbass: Single Cell Charger for M1

[Dee Jay]

I want to buy a fast single cell charger for my M1 packs.

You recommended a charger from web-tronics.com. I want the fastest available. As I understand it, the higher the amps the faster it charges?

Is this the fastest? 20 amps? http://www.web-tronics.com/103siouposup.html

Dumb question but I want to make sure: Will I need a separate power supply or do I just hook this charger up to plug/wires directly from a 100v AC power outlet?

Another dumb question: Can I plug this charger to 14 cells in series? Will this charge more than just one cell but slower?

Thanks in advance!

J

 

[Link]

That'll charge pretty quick. It's not the fastest, but will still get done in like 15 minutes (M1 cells are something like 2.somethingAh right?).

Dumb question but I want to make sure: Will I need a separate power supply or do I just hook this charger up to plug/wires directly from a 100v AC power outlet?

AC Input Voltage Range: 85-132/ 170-264VAC Selected by Switch
Input Frequency: 47-63Hz

Another dumb question: Can I plug this charger to 14 cells in series? Will this charge more than just one cell but slower?

You mean parallel? Cause series will blow it up.

 

[Dee Jay]

Thanks for the quick tips, Link!

15 minutes per cell? For *28 cells, this won't do. Can you recommend a faster charger at around the same price range? Or will I have to get exotic with a Soniel from France or something? :wink:

BTW, I know webtronics is based in Arizona. But any idea if their products are made/manucatured in the USA? I'm done buying junk from China.

* I may add one more cell to make it 15 cells per pack, A + B = 30 cells so I'll still be able to charge with DC9000 10 cells at a time. I just hope my controller can handle 15 cells.

Cheers!
J

 

[Link]

JSYN, that is not a charger. It's a power supply.

Problem is, single cell charging is not cheap. I don't even know if they make single cell chargers that go that high in amperage, let alone inexpensively.

Might help if we knew what voltage your pack is and how fast you want to charge, though.

 

[Ypedal]

Currently .. i charge my 12ah packs using single cell chargers from voltphreaks, 2 amp chargers.. so 12ah takes 6 hrs if i drain them flat ( wich i never.. ever.. do )

Yeah.. that's 16 individual chargers for a 48v pack !!!!!

 

[tailwind]

Dee Jay,

BTW, I know webtronics is based in Arizona. But any idea if their products are made/manucatured in the USA? I'm done buying junk from China.

I purchased a couple. The label on the outside says Made in China.

Info from the A123 ANR26650M1 datasheet

Recommended fast charge current......10A to 3.6V CCCV, 15 min

These powersupplies are rated as 20A at 3.3V.
The voltage is adjustable from 2.5V to 4.0V according to my voltmeter.

I think the question you are trying to ask is "How fast can I charge my A123 pack."

Here are two methods for charging a pack in 15 minutes.
Using your 14s1p pack as an example.

First,
Use a CCCV powersupply as a charger. Set the volts to 50.4V (14 times 3.6V), plug the battery in, set the amps to 10A. Should be finished in about 15min.
Problem with this method is that the cells wont be balanced.

Second,
Design your pack so that you can easily unplug the batteries from series connection and change to parallel connection.
Both A1234life and Beagle use this approach.
After unplugging series connections, plug cell 1 and 2 in parallel.
Problem with this method is if the cells dont match in voltage a current will flow from one to the other. If the voltages are far enough apart you could get a greater than 10A current flowing from one to the other.
Lets say you can restrict the current to under 10A via a resistor or pot or some other method.
So,
Plug cell 1 and 2 in parallel. Wait for cells to equalize. Plug in to the web-tronics powersupply (set to 3.6V).
Should be done in about 15 minutes.
By plugging two cells in parallel, each cell will charge at 10A from the 20A powersupply.
Buy seven powersupplies and you can do the whole pack in 15 minutes.

cell 1 - 2 - PS
cell 3 - 4 - PS
cell 5 - 6 - PS
etc

Greg

 

[Doctorbass]

Guys,

Avoid trouble please... :|

Avoid just charging lithium cells A123 or lipo only with one cahrger for multiple serie cells!

i'm SURE that if you do that, at the end of charge the voltage of first cell to be charged will increase and goes over 3.6 or 3.7V.. sometime more like 4 or 4.5V

let see:
using a 18V charger for 5 cells serie

cell 1 3.5
cell 2 3.55
cell 3 3.5
cell 4 3.95 <----- cell with the lowest capacity will overcharge
cell 4 3.45

if you charge 5 cells using a 18V charger (3.6V to each cells IDEALLY.. but not in fact!)

This this case, all cells share the 18V depending on their SOC.. and capacity.. but in the exemple, the total V is still 18V... but the V sharing is not like it is ideally sopposed to be!

What is happen as well in the dewalt pack is that a cell wil overcgharge like that and will be dammaged by that. the consequence is that it will lose capacity and will get worst and worst and the problem will just become worst...

Also, you will probably not be able to see that!.. why?... because at the end of cahrge, the voltage of the cell that goes higher will decrease and comebakc close to the others cells... sio it it goes to 4V or more, it will goes back to maybe 3.8 after few hours... but the bad thing is that you will only think that this cell had been charged to 3.8V.....

When the first cell become charged and that the voltage goes over limit, the current in serie will decrease very low and the rest of the cells will take much more time to finish their charge process... and... keeping the first charged cell at very high voltage....

be advised! :wink:

Doc

 

[steveo]

Guys,

Avoid trouble please... :|

Avoid just charging lithium cells A123 or lipo only with one cahrger for multiple serie cells!

i'm SURE that if you do that, at the end of charge the voltage of first cell to be charged will increase and goes over 3.6 or 3.7V.. sometime more like 4 or 4.5V

let see:
using a 18V charger for 5 cells serie

cell 1 3.5
cell 2 3.55
cell 3 3.5
cell 4 3.95 <----- cell with the lowest capacity will overcharge
cell 4 3.45

if you charge 5 cells using a 18V charger (3.6V to each cells IDEALLY.. but not in fact!)

This this case, all cells share the 18V depending on their SOC.. and capacity.. but in the exemple, the total V is still 18V... but the V sharing is not like it is ideally sopposed to be!

What is happen as well in the dewalt pack is that a cell wil overcgharge like that and will be dammaged by that. the consequence is that it will lose capacity and will get worst and worst and the problem will just become worst...

Also, you will probably not be able to see that!.. why?... because at the end of cahrge, the voltage of the cell that goes higher will decrease and comebakc close to the others cells... sio it it goes to 4V or more, it will goes back to maybe 3.8 after few hours... but the bad thing is that you will only think that this cell had been charged to 3.8V.....

When the first cell become charged and that the voltage goes over limit, the current in serie will decrease very low and the rest of the cells will take much more time to finish their charge process... and... keeping the first charged cell at very high voltage....

be advised! :wink:

Doc

Hey Doc

I totally agree with what your saying on this ...

the way i will be configuring my pack this weekend for each 5p 11.5ah pack on both the + & 1 end i will be using 45amp anderson connectors ...

i will series 30 of them for 99v @ 3.3v.. maybe later @ 133v...


To charge:

I will make 3 independent packs of 33v each @ 11.5ah & parrallel to be charged on my ebay 11.1amp 400w 36v cc/cv charger set @ 35v.

do you for see any problems if i use this method for say a dozen charges & then balance everything in parrallel @ 3.3v? keep in mind that i will have my dewalt a123 cells all matched as closely as possible.

-thanks
steveo

 

[Doctorbass]

Guys,

Avoid trouble please... :|

Avoid just charging lithium cells A123 or lipo only with one cahrger for multiple serie cells!

i'm SURE that if you do that, at the end of charge the voltage of first cell to be charged will increase and goes over 3.6 or 3.7V.. sometime more like 4 or 4.5V

let see:
using a 18V charger for 5 cells serie

cell 1 3.5
cell 2 3.55
cell 3 3.5
cell 4 3.95 <----- cell with the lowest capacity will overcharge
cell 4 3.45

if you charge 5 cells using a 18V charger (3.6V to each cells IDEALLY.. but not in fact!)

This this case, all cells share the 18V depending on their SOC.. and capacity.. but in the exemple, the total V is still 18V... but the V sharing is not like it is ideally sopposed to be!

What is happen as well in the dewalt pack is that a cell wil overcgharge like that and will be dammaged by that. the consequence is that it will lose capacity and will get worst and worst and the problem will just become worst...

Also, you will probably not be able to see that!.. why?... because at the end of cahrge, the voltage of the cell that goes higher will decrease and comebakc close to the others cells... sio it it goes to 4V or more, it will goes back to maybe 3.8 after few hours... but the bad thing is that you will only think that this cell had been charged to 3.8V.....

When the first cell become charged and that the voltage goes over limit, the current in serie will decrease very low and the rest of the cells will take much more time to finish their charge process... and... keeping the first charged cell at very high voltage....

be advised! :wink:

Doc

Hey Doc

I totally agree with what your saying on this ...

the way i will be configuring my pack this weekend for each 5p 11.5ah pack on both the + & 1 end i will be using 45amp anderson connectors ...

i will series 30 of them for 99v @ 3.3v.. maybe later @ 133v...


To charge:

I will make 3 independent packs of 33v each @ 11.5ah & parrallel to be charged on my ebay 11.1amp 400w 36v cc/cv charger set @ 35v.

do you for see any problems if i use this method for say a dozen charges & then balance everything in parrallel @ 3.3v? keep in mind that i will have my dewalt a123 cells all matched as closely as possible.

-thanks
steveo

Matched cells ONLY help preventing dammage or at least that ameliorate the cells life and discharge efficiency.

You will need to top each cells to the same voltage no more than 3.6 or max 3.7V to do a great charging job

Doc

 

[tailwind]

Thanks Doc,

I agree with what you are saying and you have done a good job of explaining the problem with the first method (series charging).

Because the powersupply is a dumb charger it will not cutoff when the voltage of any one cell rises above 3.6v. The lowest capacity cell will reach 3.6v first and then keep rising while the other cells catch up. Adding to the problem is that this cells voltage will rise rapidly.
Doing this over and over will preferentially weaken or damage the lowest capacity cell, compounding the problem.

So are there ways around this. I cant think of a one step, set and forget rapid charging for series connected battery packs that will leave you with a balanced pack at the end.

There are ways you can do it, but they involve more than one step or sitting by the pack and monitoring the voltages.

- Dont put more charge in than you have taken out.
Start with a balanced pack. Go for a ride. Note the Ahr used on your Cycle Analyist.
eg 1.92Ahr. Charge up the pack with a WattsUp meter inline. Terminate the charge when 1.92Ahr are put back in. Not perfect, not fully charged or balanced.
A variation on this is to stop the charge when the highest voltage cell reaches 3.6V.

- rapid charge to a lesser voltage. Then balance.
For example the 14sp1 pack. Charge to say 48v. Disconnect. Tap into each cell and rapid charge to 3.6v. Takes time and involves multiple steps but you finish with a fully charged and balanced pack.

- rapid charge to a lesser voltage. Connect Bob and Garys CMS.
For example the 14sp1 pack. Charge to say 48v. Disconnect. Connect the CMS board. Set charger to 50.4V and 1A. Wait for all the lights to come on.
Involves multiple steps and takes more time. The CMS will get too hot if you try to put 10A through it. The CMS is not for sale yet. You finish with a fully charged and balanced pack.

- rapid charge to a lesser voltage in series. Connect in parallel, charge and reconnect in series.
For example the 14sp1 pack. Charge to say 48v. Disconnect. Connect all batteries in parallel.
Charge at 3.6V. Reconnect in series.
Takes more time and involves multiple steps. Finish with a fully charged and balanced pack.

There are chargers with intergrated balances on the market, but generally they dont allow rapid charging and balancing.

All ideas welcome.

Greg

 

[Dee Jay]

Ok, so basically....


-you cannot use a 3.3v 20A charger to charge an entire pack of 50+ volts with the idea that it will only charge slower. It will blow up. Good to know, thanks again Link.

-Even if the charger's voltage is equal to the task, you'll risk over charging a few cells. Roger that, Doc :wink:

-The web-tronic charger is made in China. I guess there's no escape, we are owned! Thanks for confirming that, tailwind.

I will continue with my original idea which was to charge 10 cells at a time with the DC9000 and occasionally bump up low cells with a single cell charger

Ypedal's set up is awesome... I was thinking of using Voltphreaks' single cell charger too but that would be $200 for 15 chargers if I went that route.

Part of what I'm trying to achieve is developing the simplest, affordable charging solution that non-techies can follow. This is because I will be selling hub kits here in Japan. I will show different battery/charging configurations, the highlight being M1 14 cells series packs and DC9000 charger and a single cell charger for occasional balancing.

8) I'm also tinkering with an invention that safe calls a "rotating pulse charger". No, it won't have cell bypass system. It will be an electromechanical device that physically rotates or hops the single cell charger's power leads to each cell's tap leads, one at a time. The web-tronics 3.3v 8A charger is just what I'll need for my invention. http://www.web-tronics.com/253siouposup.html
FWIW, I will share my techniques as soon as I assemble the main parts. Hopefully, someone here would follow up and develop a solid state version and sell it *at a reasonable price*

safe, pulse charging: will 8 amps do? 20 amps?

Thanks for everyone's input!


Happy Friday!
J

 

[Link]

8) I'm also tinkering with an invention that safe calls a "rotating pulse charger". No, it won't have cell bypass system. It will be an electromechanical device that physically rotates or hops the single cell charger's power leads to each cell's tap leads, one at a time. The web-tronics 3.3v 8A charger is just what I'll need for my invention.

Whoa, damn. You thought up the exact thing as I did.

However, I went a little farther: I was going to use a CC/CV supply as a dumb charger to get the pack up to say 80-90% charge and then activate the "electromechanical device" (namely a PCB with a buttload of small relays on it) to top them all off. Much faster this way.

Regarding the relays, I could have sworn there was a link on here to a supplier of a bunch of random stuff. One of the things they were selling was a board with like a couple dozen relays (looked like the usual 5A ones) on it. Would have been perfect. Can't even remember the context the link was used in though, so I can't find it. :?

 

[Toorbough ULL-Zeveigh]

safe & his colorful names.
are you certain he came up with that?

http://www.kalikast.ca/rcp/rcp.html

 

[Dee Jay]

Whoa, damn. You thought up the exact thing as I did.

Cool, dude. I'm looking forward to seeing it! Yeah, it would take a buttload of relays if you choose to go that route.

I already bought most of the parts for my device. One major thing holding me back is the right thickness copper sheet.

The next challenge will be to incorporate it with the single cell charger. I won't be able to proceed until it arrives and learn how the charger works/behaves.

J

 

[Dee Jay]

safe & his colorful names.
are you certain he came up with that?

Wow, very interesting that others have been developing the same ideas.

I came up with the cell bypass discharging with no external influence.

Someone here confirmed my idea.

safe came up with the "rotating pulse charger" name after I proposed my cell bypass ideas.

But whatever . . .

obviously there's a need for an EV battery system. And since necessity is the mother of inventions, there's good chance that many of us here are thinking the very same things.


J

 

[swade]

What does everyone think of A1234Life's charging setup? This looks like a lot of work to build but once set up it should be perfect:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=3171&start=15

With this approach, every cell always gets the right voltage. If you want to charge faster, just add on more of the cheap power supplies. Pretty easy to alter the voltage and amp hours too.

Thoughts?

 

[Dr. Shock]

Regarding the relays, I could have sworn there was a link on here to a supplier of a bunch of random stuff. One of the things they were selling was a board with like a couple dozen relays (looked like the usual 5A ones) on it. Would have been perfect. Can't even remember the context the link was used in though, so I can't find it. :?

Link, I think Apex Surplus in Sun Valley, CA (google them) has the relay boards you're thinking of.

Just for the record, I'm also working (very intermittently) on a rotating charger. One of these days I'll get back to it.

 

[fechter]

What does everyone think of A1234Life's charging setup? This looks like a lot of work to build but once set up it should be perfect:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=3171&start=15

With this approach, every cell always gets the right voltage. If you want to charge faster, just add on more of the cheap power supplies. Pretty easy to alter the voltage and amp hours too.

Thoughts?

That setup works great from an electrical standpoint.
It's just a bit cumbersome to deal with all those connectors.

A rotating (sequential) charger could be done electronically using something that resembles a multiplexer. I can't think of a really easy way to implement it using FETs though. Seems like each cell tap would need two pairs of back to back FETs since the body diode will conduct in one direction. In addition to 4 FETs per cell, you need gate drivers and a sequencer to drive them. All the switching would need to 'break before make' to prevent shorts. It is definitely doable, but could be expensive.

Link's idea of bulk charging the string to 80-90% with a single charger and switching over for balancing has a lot going for it.

If the rotating charger was only used to top off and balance the cells, the current would be fairly low, and small surface mounted FETs could do the job. A fairly small 3.6v power supply would be adequate. As the cells are nearly charged, the charging current drops off quite a bit.

 

[Dr. Shock]

My thought is to use an scr to cut the current to a given parallel group of cells at the proper voltage, and have the cutoff signal a 4017 decade counter to advance the current to the next cell group, which would be regulated by an scr. This could either loop continuously, or could cut off after the last group of cells is charged.

I had the scrs cutting off current at the right voltage, and I got the decade counter to advance, but when I left the project, I had not managed to tie the two actions together. I was trying to use caps and/or inductors to send a pulse to the decade counter when the current out of the scr stopped. I've got to get back to work on that. Any ideas are most welcome.

I thought that if this could be made to work, it could be a very small onboard charger. It wouldn't be fast, but if you park your bike at work all day, it wouldn't need to be.

Alternatively, it could give the final charge after bulk charge, as Fechter suggests.

 

[Johnbear]

On a somewhat related topic, I recieved a 2 amp lifepo4 charger from YESA, it terminates at 3.9v. Does that sound right?

Thanks!

 

[Dee Jay]

tailwind, thanks again for your valuable input! I have a few more questions:

-Which charger did you buy?

-Is there an LED (like most single cell chargers) that indicates full charge? If so, will you do me a humungous favor and measure the LED volts and amps for me, please. Pretty Please? :wink:

-At the end of the charge, what happens at the charging leads? Volts drop to 0? Amps? It seems A1234LIFE bought the same power supply/charger. http://endless-sphere.com/forums/viewtopic.php?f=6&t=3171&start=15 He reports reading 20 miliamps at the end of the charge. And I do believe I spy me a green LED...

If it's too much trouble, it's all good, I can wait till my powersupply arrives.

I'm very excited about my project. If all goes well, I feel that "rotate charging" may benefit us poor hobbyists using affordable but precise single cell chargers! And I hope this simple electromechanical device of mine would trickle to non-hobbyists. 8)

Happy Friday!
J

 

[tailwind]

-Which charger did you buy?

I purchased both the 25w and the 100w versions.
One thing to note is that the label on the 25w model states 6A at 3.3v. The website has 8A.
So adjusting the voltage to 3.6v, the amps would be about 5.5A.

Is there an LED (like most single cell chargers) that indicates full charge?

There is a green LED. When you turn either unit on, the light comes on. Turn off, the light goes out . There is no change in the LED as you reach the set voltage. So there is no indication that you have reached the end of charge.
I did get it to flash by adjusting the voltage too low on the 25w model, less than 2.84v.

I charged a single cell last night with the 25w model and left it on for an hour after reaching the set voltage. The amps were almost zero on my analog ammeter , volts were 3.60v

Tonight I charged two cells in parallel with the 100w model to see how long it would really take. About 20 minutes.

Greg

 

[Dee Jay]

tailwind! Just a quick thanks! I'll get back to you tomorrow 8)

Cheers!
J

 

[Patrick]

Tailwind:

Quick question. Do those power supplies (25 and 100 watt models) have isolated outputs? That is, could I use a PS for each cell while the cells were still in series? Planning on a 16 cell LFP pack, and so $200 for a 6 amp charger that doesn't need a BMS doesn't sound so bad.

Thanks!

 

[fechter]

I'm sure it's isolated and you could use them in series.

Here's a similar 100w (20A) one http://www.mpja.com/prodinfo.asp?number=16010+PS

I'm not sure how this particular one will behave when the load gets too high.
SMPS tend to start pulsing rather than behave like a CC power supply.

Buy 10 for $26.49 each