# Single Cell LiFePO4 charger?



## ClintK (Apr 27, 2008)

ClintK said:


> Anyone know of an inexpensive charger for single cells of LiFePO4s (3.2V)?


Shoot nevermind, ebay prevails again!


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## gdirwin (Apr 7, 2009)

I also need help to get a single cell charger for Thundersky LIFePO4 batteries - the intent is for debugging and manual balancing cells during installation, or if I replace a cell.


There seem to be lots of chargers in the RC world, with many advanced features, but they seem to be meant for the A123 cells... For example, the ICharger can measure internal resistance (which would be good to identify bad cells):
http://www.progressiverc.com/index....category_id=1&option=com_virtuemart&Itemid=18

It lists the nominal cell voltage as 3.3V, and max charge voltage as 3.6V when in LiFe mode...

Has anyone used an ICharger or similar A123 cell charger with Thundersky LIFePO4 batteries?

Any suggestions?


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## RKM (Jun 9, 2008)

gdirwin said:


> I also need help to get a single cell charger for Thundersky LIFePO4 batteries - the intent is for debugging and manual balancing cells during installation, or if I replace a cell.
> 
> 
> There seem to be lots of chargers in the RC world, with many advanced features, but they seem to be meant for the A123 cells... For example, the ICharger can measure internal resistance (which would be good to identify bad cells):
> ...


Garth,

I suggest we share a charger between us! This should be the sort of tool that would be needed infrequently. I'm wanting to have access to one of these. I'll pm you.

Rob


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## MN Driver (Sep 29, 2009)

I personally have a Turnigy Accucell 8150, it's good, charges at 7amps, discharges at about 25 watts.

For larger capacity cells, if you are getting an R/C charger, the MRC SuperBrain 989 seems to be among the best from what I've read on RC forums using LiFePO4 and LiPo and among those on hybrid forums rebuilding their large NiMh packs. The power supply is built in, 10 amps charge and 10 amps discharge. A little google searching and it comes up with a steal of a price IMO, one that I wish I came across before I bought my Turnigy.

MRC Super Brain 989
http://www.modelrectifier.com/search/product-view.asp?ID=6863


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## AndyH (Jun 15, 2008)

https://p10.secure.hostingprod.com/...talog/product_info.php?cPath=3&products_id=28

The small VoltPhreaks 2A LiFePO4 chargers work well. The output is isolated from the input - they can be used in series or in parallel. I've used 13 chargers on a single cell 10Ah, and have used individual 2A chargers on a 21S TS60 pack. I cut the barrel connector and add alligator clips.

When using multiple chargers on a power strip, leave some airspace between them - like use every other outlet. They need a bit of airflow when running at the full 2A.

Andy


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## Voltswagen (Nov 13, 2008)

I plan on buying this Mastech once my Lithiums arrive.

http://www.mastechpowersupply.com/d...-voltage-over-current-protection/prod_70.html


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## dtbaker (Jan 5, 2008)

thats the same unit I am contemplating! I am wondering how much it will be needed though?! hhhmmm, perhaps a new thread....


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## frodus (Apr 12, 2008)

If people are interested, I have 3.7V power supplies with an AC front end, they're 74W output.... nice for charging larger cells. I'll throw one together this weekend and take some pictures.


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## dtbaker (Jan 5, 2008)

frodus said:


> If people are interested, I have 3.7V power supplies with an AC front end, they're 74W output.... nice for charging larger cells. I'll throw one together this weekend and take some pictures.


sounds interesting.... more specs available? i.e. how close is that 3.7v?

I am asking to get a feel for how much babysitting it would require. Lets say I have a low cell, and hook this baby up... could I walk away ad let it coast it's way up to 3.70 and hang there, or do I have to watch and disconnect after x amount of time to prevent over-voltage?


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## frodus (Apr 12, 2008)

dtbaker said:


> sounds interesting.... more specs available? i.e. how close is that 3.7v?
> 
> I am asking to get a feel for how much babysitting it would require. Lets say I have a low cell, and hook this baby up... could I walk away ad let it coast it's way up to 3.70 and hang there, or do I have to watch and disconnect after x amount of time to prevent over-voltage?


Its a 2-part system. One is a AC-DC converter that puts out 48V and 300W. The second part is a Vicor DC-DC 48V to 3.7V converter. It will put out high current as its loaded and as it gets closer to 3.7V current slows. It will hold at 3.7V.


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## dtbaker (Jan 5, 2008)

frodus said:


> Its a 2-part system. One is a AC-DC converter that puts out 48V and 300W. The second part is a Vicor DC-DC 48V to 3.7V converter. It will put out high current as its loaded and as it gets closer to 3.7V current slows. It will hold at 3.7V.


hhmmm, and how would this compare in price to a power supply that can be had for around $150 that has settable 0-30v/0-10amps ?

or conversely, a cheapo resistor to bleed some energy out of the high cells and bring everything back up with the pack charger?


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## gdirwin (Apr 7, 2009)

Voltswagen said:


> I plan on buying this Mastech once my Lithiums arrive.
> 
> http://www.mastechpowersupply.com/d...-voltage-over-current-protection/prod_70.html


They also have a 15V/20Amp model - 1/2 the voltage (but still good for 12V batteries) but double the current... 

I was confused how these things switch from constant current to constant voltage - there is a dial for current and for voltage... It auto-switches from one to the other - you would first start with an open circuit, and set the voltage to your max charge voltage (say 4V). Then you turn the current down, and connect it to the battery. Then you crank up the current - it will be in constant current mode until the voltage nears 4 V, then it will switch to constant voltage mode (and display the measured current).

In other words, if it is in current mode, then the current displayed is on the limit, and the voltage shown is the measured voltage (the limit is higher than this). If it is in voltage mode, then the voltage displayed is on the limit/set-point, and the current shown is the measured current (which should be decaying). Sounds perfect!

Make sure to get the EX models - they have OV (over-voltage) protection, and will not self-destruct if the voltage ever gets higher than the set-point (ie it cannot tolerate reverse current). Apparently this was a big problem in the E and D models - Mastech responded to customer complaints, suggested diode front-ends to help, but ultimately fixed it with the EX models.

The D models (linear power supply, not switching) have way less ripple, tighter tolerances etc... (and are much heavier and about $10 more) but also are not good for battery charging as they do not tolerate reverse current (ie no OV protection).


Rob (RKM) and I each got a 15V/20A EX model - will let you know how they work when they arrive (probably Rob first, as my TS cells are literally on a "slow boat from China").


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## frodus (Apr 12, 2008)

dtbaker said:


> hhmmm, and how would this compare in price to a power supply that can be had for around $150 that has settable 0-30v/0-10amps ?


Less than half the cost. With a few resistors you can set it to a lower voltage. Its by no means pretty, but it does its job well, many have used these same modules.


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## frodus (Apr 12, 2008)

Well, I put a few of them together, here are more details:
http://www.diyelectriccar.com/forums/showthread.php?p=167749#post167749


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## O'Zeeke (Mar 9, 2008)

gdirwin said:


> as my TS cells are literally on a "slow boat from China").


hi gd, are your ts cells from ev components? I am waiting on that boat too and haven't heard anything recently.


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## Voltswagen (Nov 13, 2008)

I emailed EvComponents yesterday about the Feb. Delivery for batts ordered before Dec. 15th
They said the container is in Seattle going thru customs. They expect to pick them up this week and begin delivery next week.


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## gdirwin (Apr 7, 2009)

My TS cells are from EVComponents, but were shipped directly from China to Canada - they are supposed to arrive in Vancouver on Feb 25, but then (wrongly) are to be put on a truck to Toronto - well Toronto is 2,200 kM past Winnipeg, so an extra 4,400 round trip by the time they come back to me... Dave at EVComponents is trying to contact TS in China to fix this, but it is Chinese new year, so no-one is available... Hopefully to be fixed in the next day or so...


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## O'Zeeke (Mar 9, 2008)

I emailed EvComponents yesterday about the Feb. Delivery for batts ordered before Dec. 15th
They said the container is in Seattle going thru customs. They expect to pick them up this week and begin delivery next week. 

Thanks Voltswagen





gdirwin said:


> My TS cells are from EVComponents, but were shipped directly from China to Canada - they are supposed to arrive in Vancouver on Feb 25, but then (wrongly) are to be put on a truck to Toronto - well Toronto is 2,200 kM past Winnipeg, so an extra 4,400 round trip by the time they come back to me... Dave at EVComponents is trying to contact TS in China to fix this, but it is Chinese new year, so no-one is available... Hopefully to be fixed in the next day or so...


Slow boat is bad enough, you dont need a slow truck too. Hope Dave gets it fixed.


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## PTCruisin (Nov 19, 2009)

frodus said:


> Well, I put a few of them together, here are more details:
> http://www.diyelectriccar.com/forums/showthread.php?p=167749#post167749



Hi Travis,

Do you have any of those left? I'd be interested in purchasing one.

-Ralph


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