GREAT DEAL !! Lot of 20 ARTESYN 3.63V at 50A max 75V input

[Doctorbass]

I seen this on ebay..

Great deal for those who want to stop bordering with BMS when charging!

199$ for 20 unit (20s capable)

http://cgi.ebay.com/ARTESYN-EXB250-...ageNameZWD1VQQcmdZViewItem?_trksid=p1638.m118

Doc :wink:

 

[vanilla ice]

$229.99 with shipping! He claims 90% efficiency on the 3.3v version...

 

[efreak]

Doc you r the best .

What is the verdict every one thumbs down to BMS?

I got me now 5 packs need 3 more yet undecided thye feeding process.
before i go buying chargers this method is like so awsome clean unintrupted it just require me to do dewalt surgery so to speak.

shed some weight and easier to mount so many benefits

efreak

 

[bobmcree]

it would be possible to adjust them to 3.6v and connect the outputs in series to charge a serial pack, since they are isolated, but there is no way to limit the current or terminate charge. i think 50A is an awfully high charge rate, and that you really want a way to terminate the charge when the current at 3.6v drops to a preset level

 

[Doctorbass]

it would be possible to adjust them to 3.6v and connect the outputs in series to charge a serial pack, since they are isolated, but there is no way to limit the current or terminate charge. i think 50A is an awfully high charge rate, and that you really want a way to terminate the charge when the current at 3.6v drops to a preset level

I've bought mine (the 150W 30A version) and they have a +sens and -sens to monitor and adjust the output. I will tri to built a circuit that use this control output tu limit the current using a shunt and some comparator...

The 3.3V +10% give 3.63V that is perfect. if people use Xs5p pack the 10A charge rate can be used if battery are coolled during charging)

Doc

 

[vanilla ice]

Would you even have to terminate the charge? Wouldn't the current draw drop off to nothing when the cells hit 3.63v? You can limit the input current to get a slower charge rate, correct?

 

[bobmcree]

Would you even have to terminate the charge? Wouldn't the current draw drop off to nothing when the cells hit 3.63v? You can limit the input current to get a slower charge rate, correct?

my experience is that the cells will continue to charge at 3.6v or wherever at a current in the range of 100 ma, and that for longest cycle life it is desirable to terminate charge at that point. nickel based batteries can turn extra power into heat so it does not hurt to overcharge them at c/10-20, but with these cells it is not desirable.

 

[Beagle123]

I'm also working on a circuit to terminate the power to the charger. I'm using a current sensor and a potentiometer to make a "cutoff point" in voltage. THen I'm using a comparator so when the current drops below a certain point, it turns off a relay that powers the power supply.

I'll be posting the complete circuit before you guys get this going. It should be pretty easy to build.

 

[steveo]

it would be possible to adjust them to 3.6v and connect the outputs in series to charge a serial pack, since they are isolated, but there is no way to limit the current or terminate charge. i think 50A is an awfully high charge rate, and that you really want a way to terminate the charge when the current at 3.6v drops to a preset level

I've bought mine (the 150W 30A version) and they have a +sens and -sens to monitor and adjust the output. I will tri to built a circuit that use this control output tu limit the current using a shunt and some comparator...

The 3.3V +10% give 3.63V that is perfect. if people use Xs5p pack the 10A charge rate can be used if battery are coolled during charging)

Doc

hey doc..

i've been following your posts on these things.. i would be interested in them .. could you provide pics .. or more explination on how to use them .. i'd like to make a setup for 30s2p or 20s3p pack..

-thanks
steveo

 

[Doctorbass]

When i will receive them from GGoodrum, i will work on that! :wink:

Doc

 

[Malcolm]

my experience is that the cells will continue to charge at 3.6v or wherever at a current in the range of 100 ma, and that for longest cycle life it is desirable to terminate charge at that point

Would it be practical to terminate charging using an SCR? http://en.wikipedia.org/wiki/Silicon-controlled_rectifier
I have one here with a holding current of 150 mA.

 

[Malcolm]

Found an answer here, also from Bob:

"the hold current of an scr is specified as Ih and is one of the standard parameters given for a device. the STNx10 family of 10A scrs have a max hold current of 30 ma., the STN2540 is 150 ma., the STYN640 is 75 ma. so you can pick the hold current you want and this looks like an excellent way to terminate fast charge on LiFePo4 with a constant voltage source, and when the pack hits the terminal voltage the charge will continue until the current drops below the hold current. Ih is the max current, so it might be less.

a simple control system like gary's board that cuts off the high rate when the first cell hits 3.7v could be used with the scr then supplying the rest of the charge at the desired lower rate.

good idea, oneeye! attached is an app note on scr hold current from ST

good simple tutorial on scr's at
http://www.americanmicrosemi.com/tutorials/scr.htm "

 

[fechter]

An SCR will have some voltage drop, so you would need to increase the voltage setting of the charger to compensate (~.7v?).

Beagle's current monitoring circuit has no voltage drop.