a DC-DC to charge li-ion... GREAT!!

[flip_normal]

Glad to see your converters arrived OK Doc, I'm still waiting on mine .

Very nice work on the power supply BTW.

I found this primer on DC/DC converters which gives some useful general info. One thing it mentions is that 240V AC gives 340V DC when rectified. Apparently the rectified DC voltage is about 1.4 times the AC RMS voltage. I then found a DC/DC converter with an input voltage range of 200～400V which gives 3.3V output (-10%～+20%) at 100A so that's ~300W output.

http://www.densei-lambda.com/products/sps/ps_pm/ph300_600s/indexe.html (PH600S280-3.3)

Here's the data sheet.

I haven't found anything which would be suitable for you guys with 110V mains, sorry, but what do you think? These could form the basis for a fast lightweight onboard charger/balancer for something like an electric moped or similar. I guess I'm just a bit amazed that these can take such a high input voltage and so it should cut out the need for a heavy transformer or bulky power supplies.

 

[Doctorbass]

Glad to see your converters arrived OK Doc, I'm still waiting on mine .

Very nice work on the power supply BTW.

I found this primer on DC/DC converters which gives some useful general info. One thing it mentions is that 240V AC gives 340V DC when rectified. Apparently the rectified DC voltage is about 1.4 times the AC RMS voltage. I then found a DC/DC converter which gives 3.3V output (-10%～+20%) with an input voltage range of DC200～400V at 100A so that's 330W output.

http://www.densei-lambda.com/products/sps/ps_pm/ph300_600s/indexe.html (PH600S280-3.3)

Here's the data sheet.

I haven't found anything which would be suitable for you guys with 110V mains, sorry, but what do you think? These could form the basis for a fast lightweight onboard charger/balancer for something like an electric moped or similar. I guess I'm just a bit amazed that these can take such a high input voltage and so it should cut out the need for a heavy transformer or bulky power supplies.

Great found!

how much they are each?

I agree with the size of my primary power stage of 15lbs! but the DC-DC modules I found was very cheap at 10$ each... that's the good point..

but with 240Ac V input directly, that's great! very simple and small

In fact, when converting the 240Vac to DC you need to multiply by sqrt of 2 (1.41) then if you rectify the voltage using full wave bridge each conducting diodes will take around 1volt on load... so the formula is:

VDC= (1.41 x Vac)-(2 x 1V)

so 240V ac will become 336.4Vdc

Doc

 

[flip_normal]

No info on price, probably not cheap and they may only sell in bulk. Never mind I'm still at the theory stage and anyways I'm going with the ones I've got on order, which will probably be better for the regen thing (with the 36-75V input range) if I can figure it out.

Thanks for the clarification on the AC/DC math BTW.

 

[flip_normal]

The two dozen DC/DC converters I ordered (same model as Docs) arrived today and I thought I'd test one just to check it was working. I connected the +Out to the +Sen pin and the -Out to the -Sen pin using some connector blocks and two short lengths of wire. I used a couple of croc clips to connect up the battery from the moped (53V) to the +In and the -In pins and expected to see 5V between the +Out and -Out pins but got 0.0V. I then tried another and got the same result. When I connect up the battery I get a very small spark but nothing violent. Am I just being thick and missing something obvious or does it look like I've gone and bought duds? Have I just blown two converters maybe?

 

[fechter]

I think there's an "enable" pin that needs to be connected before you will get output. It's designed for remote shutdown.

 

[Doctorbass]

.... Dont forget to read carefully the datasheet!!

The RC pin that enable the DC-DC need to be connected to the -IN pin

that will enable it and you should get around 5.00V at the output if using ani voltage between 35 and 75V at the IN+ and IN-

Also, if you want to trim the output voltage, you can adjust it bewteen 3.0 to 5.5V using the trim input. simply connect a 10k potentiometer between V adj and OUT -. in this mode it is a trim down mode. so you can adjust any voltage bewteen 5.00 and 3V. In trim up, that's from 5.00 to 5.5V

They highly recommand to add a fuse at the input + of max 20A but a 5 or 10A should be ok with the irush current at startup.

I can say that they are VERY accurate!!!!!!!!!!! i added a load of 0.15ohm at the output with a voltage set to 4.200 and it hold the 4.200 with our without the load!! the snese pins are very precise!!

Just dont forget to add a great heatsing on it to disssipate the 20% of heat :wink:

i am working on it now...

Tomorrow i will go to my friend Martin and we will use its CNC machine to prepare the heat sink in my charger.

there will be two heat sink of 120mm per 180mm face to face with the fines inside. i will put 6 DC-DC modules on each sides and will put a powerfull fan on one end of the heat sink to cool down. I should be able to get 3.0 degrees C per Watt so the max temp of the modules will never exceed 80 degree C at ambiant temperature of 40 degree C inside the metal box of my charger.

see the pics:

Doc

 

[Doctorbass]

The two dozen DC/DC converters I ordered (same model as Docs) arrived today and I thought I'd test one just to check it was working. I connected the +Out to the +Sen pin and the -Out to the -Sen pin using some connector blocks and two short lengths of wire. I used a couple of croc clips to connect up the battery from the moped (53V) to the +In and the -In pins and expected to see 5V between the +Out and -Out pins but got 0.0V. I then tried another and got the same result. When I connect up the battery I get a very small spark but nothing violent. Am I just being thick and missing something obvious or does it look like I've gone and bought duds? Have I just blown two converters maybe?

Oh.. I forgot...

How much did you pay eachone? did you bought those on ebay?

 

[flip_normal]

Cheers Fech, Doc; got it, thanks.

Just checked a couple of 'em, getting 4.97V and 4.98V (no load) on my cheapy DMM. 8)

Will get a trim pot today and do the Vout adjust.

I got these from this guy on ebay who ships worldwide. I paid $360 inc. shipping/insurance and £38 tax this end, so that's just over $18 (~£9) each, all in. He ships using USPS Priority Mail International but getting a tracking number from him is like getting blood from a stone, otherwise he's very helpfull and prompt with his replies. He quoted me $11.50 each on 100. But I'll pass on that for now, gotta get batts and PSUs.

Hey Doc, access to CNC machines and free components and heatsinks is enough to make a fella green with envy (only joking) and I'm well glad your here.

 

[Doctorbass]

6 Jan 2008

---UPDATE---

I finally changed my mind about the case i will use. I've manipulated it a couple of time the empty case only weight around 25lbs .. not very pratical i guess... previously i've planed to install it premanently on the wall in my garage.. BUT.. now i'm thinking about having the option to transport the charger with me on the bike for long runs... The transfo + capacitor + diodes +DC-DC +wires +connector weight around 11lbs that is acceptable with a 3lbs case for a 14lbs on the rear rack to allow me to recharge my 900Wh pack in less than hour!

There is another reason. it's because i got acces to many old chemical cooler power supply that look very nice! and that miraculously will fit PERFECTLY for my charger project!!! At my job, they wanted to put them on garbage since they was sleeping for a couple of years on the stock room...Like you know me, i toke 4-5 of those with me!.. the alluminium and case structure is premium quality!

I want to show you how i plan to built them:

Doc

 

[Beagle123]

Thanks for the pics Doc. It looks like a great plan. I can't wait to see it.

 

[efreak]

Thanks Doc, not wanting to go off topic but as i've read a lot of rc folks going with these mastech power supplies, but say for someone somewhat challeged as I ( with electronic details) is possible that I can get a mastech say 50volt 20A unit say for $200 $300 and use that for charging the m1s .

I have bought 5 packs and looking to get 3 more for 80 cells total. don't really want to mess around with dewalt bms and charger and later have to fix problems and what have you. The RC guys use various volts and amps for their set up but i figure for 66volt 9 ah set up i would need 50volt 20 amps mastech and then charge subpacks. what hapened to your mega chrger you like that? what do use to feed it?

pc power supply ? server power supply( cool)

I tellyou I am glad I am getting all this research done now because it is a very steep learning curb for me I really appreciate all that you and others contribute.
this is my college! there is a lot more info on the rc forums but not alot of it is helpfull for our application as i understand it.

I have to still get the cells out of their packs . How do you like gg's lvcs?
how do you connect one lvc to two packs i remember gary saying that he uses 1 for 2 packs and only the one board is populate d with parts

and then a charging solution that is not big headache . You know i bought these batteries the week before the big lifebatt packs announcement those packs are made for people like me but its ok since i have been learning a bit about a123 and they are better tested so far and if the lifebatts are good as advertised for the next bike project.

I am planning on a 66volt 9ah pack for a 5304 on 26" with the new controllers it is probably over kill i only need to go 20 km round trip each day maybe 40 if i go home for lunch!! (hmmm lunch )


thanks a lot

efreak

 

[Beagle123]

Hi efreak:

Doc is using bridge rectifiers to convert household 110v AC to DC, then he uses a transformer to reduce the voltage to the optimum voltage for the DC-DC converters (about 50v?). The big round thing is the transformer. These DC-DC converters are a great idea, but you're right that the problem is providing a 50v power source to them. The power supply you mentioned is a good way to do it, however you'd be charging each cell at about 40 watts. For example, if you used it to produce 50v, 20a, you'd get 1000 watts. If you have 20 packs, you'd get about 40 watts in the end for eack pack.

That's a little over 10 amps per pack, or about 1C for a 10AH pack. If you have a 20AH pack it would be only 0.5C (which is fine by me too).

 

[efreak]

here is a link regarding above


http://helifreak.com/showthread.php?t=40579


efreak

 

[Doctorbass]

Well, I dont want that this post turn out to ---a single charger to multiple cell---.. the Dewalt do that and any other common charger do that. My main idea about dc-dc is to use ONE dc-dc per 1s parallel group these DC-DC can be found for cheap price on ebay for around 10-15$ each. If you are lucky, you will fins dome that are AC-DC that do the same think at the output and avoid you the need to built a 500-1000W power supply to supply the DC-DC input like i am building. the reason why i use DC-DC is that i have acces to many powerfull component to built my own big power supply for few $.. i have the majority of the component stock in my lab that i accumulate since many years now when dissassembling electronic stuff...

I am tired about balancer and the need to care about the voltage balance when charging. Almost in case where you have cells in the pack that are lower than other and you need to use balancing tool to discharge to the same level the higher one...

The idea with DC-DC or AC-DC is to charge each individual 1s parallel group independently. with that , you will have no more problem about balancing step....


A SIMPLE MULTI-CHARGER DEVICE... that's it! :wink:

DC-DC have a extremely accurate voltage and you can use them as one big power supply anyway by connecting them in serie.

Think about that: 10$ per 1s parallel group to charge up to 30A !... Each 3p pack would recharge in 15min ! 6p pack in 30min...

buy 20 of them for 200$ and you can charge to 72V at up to 30A... if your AC outlet can hold it.. 8)

For any electric bike or CAR charger there are alot of advantages!

The charger i am building is capable of 1800W 43.2V at 30A (if i add an additional external aux transformer)... AND IT BALANCE THE CELL AUTOMATICLY ON CHARGE.... :wink:

Doc

 

[Doctorbass]

UPDATE 10 jan 2008:

-I've worked on the heatsink that are a part of the case.
-Did Many 6-32 tread in alluminium
-the DC-DC modules fit perfectly on the heatsink.. all the holes fo rtthe screw are at the right position... I used the CNC of my friend.

propblem to solve:
-this case that i've recycled from an old power supply may be a little bit too small for the transformer and the DC-DC inside for the inside width.
the transformer is 6. 1/8" diameter and the iside room for between the left and right side DC-DC pins is 5 7/8" .. but the room between the DC-DC case is 6 11/32".

What i am thinking to solve that is tocut the DC-DC pins just enough to allow tyhe transformer to fit and to use a PCB for each side of the case instead of wires.

I am working on that now.

Doc

 

[fechter]

Good, I see you went for a stable reference voltage for the comparator.

I think if you use a rail-to-rail output amp, you can drive the trim directly with the output of the op amp (just reverse the polarity of the inputs). This way you could eliminate the extra FET driver. The input impedance of the trim pin should be pretty high.


Efreak, I think Doc is just trying to stay on topic here. Your disscussion might be better under http://endless-sphere.com/forums/viewtopic.php?f=14&t=2498
Good questions, though. I want simple, cheap, and effective too.

 

[efreak]

My apologies, Thanks for explaining it clearly Doc, now I realize the difference, if fechter could kindly move my above post to the mentioned thread would very nice. so as to not get the proper discussion( and not here )

but staying on this topic; What could one use for a power supply in this set up if not able to build one like yours Doc? one of the bench testers?

thanks again
efreak

 

[Doctorbass]

My apologies, Thanks for explaining it clearly Doc, now I realize the difference, if fechter could kindly move my above post to the mentioned thread would very nice. so as to not get the proper discussion( and not here )

but staying on this topic; What could one use for a power supply in this set up if not able to build one like yours Doc? one of the bench testers?

thanks again
efreak

that's a grest idea to use multiple DC-DC converter and a bench power supply like that.. tou can fins alot of these on ebay for less than 200$ for 1000W. some a re fixed some are adjustable..

2 of these paralleled: http://cgi.ebay.com/500W-48V-10-4A-...ryZ48636QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


this one 48V 50A for 99+100$:http://cgi.ebay.com/La-Marche-A36-5...ryZ66995QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

paralleling 3 of thisone for 99$ http://cgi.ebay.com/350W-48V-7-2A-S...eZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem

Doc

 

[efreak]

I must say fascinating post really just that much more to learn for me....GREAT!!!! Gladly

ok what is the specs of the modules that I 'll need if I am to charge a 20s 4p pack of M1s?

they have the ones 3.3 volt that my understanding can be tweeked to operate 90%-%110 can get 3.65volts

not quite clear on the charging setup that would need!?

all of a sudden there aren't that many nice batches on ebay or I am not able to find them. these new converters some are said to be not in need of heatsink the newer models maybe but they are also list price at US$104

thanks
efreak

 

[Doctorbass]

I must say fascinating post really just that much more to learn for me....GREAT!!!! Gladly

ok what is the specs of the modules that I 'll need if I am to charge a 20s 4p pack of M1s?

they have the ones 3.3 volt that my understanding can be tweeked to operate 90%-%110 can get 3.65volts

not quite clear on the charging setup that would need!?

all of a sudden there aren't that many nice batches on ebay or I am not able to find them. these new converters some are said to be not in need of heatsink the newer models maybe but they are also list price at US$104

thanks
efreak

these are perfect!!! http://cgi.ebay.com/Lucent-DC-DC-66...oryZ4660QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


these too: http://cgi.ebay.com/Lucent-DC-DC-50...oryZ4660QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

charging to 3.65V is good but 3.60 if best fir cycles life

dc-dc that have 66W at 20A are ideal. at 3.6V they will give you 18.3A.. and for4p, that should be 4.6A each cells that is 2C charge.


On ebay, gp_trade seller seems to have 100+ 5V or 3.3V dc-dc availlable!
Doc

 

[efreak]

thanks doc In fact I did see those but was not sure whcih one is best for me. How is that 4p charging going to be done ? i am not sure what sort of wiring I ll need plus how many modules will i need ?

efreak

 

[efreak]

I was hoping I could just keep my dewalt packs as intact as possible and then a 2 packs in series times 4 in parallel to use these modules do i need to make 4 parallel cells first then sting them 20 in series? that would make sense i think
( forgive my lack of techieness in dc land)
also i ll need relay shipping thru us

UPS brokrage ouch

thanks again
efreak

 

[Doctorbass]

That's exact. you will need to make the parallel cell and then to serie these group for 20s.

You need one module per 1s so in your case it's 20 modules.

Doc

 

[Beagle123]

Hi Doc:

How's your project going? I saw this power supply on ebay. It would be easy to power all your dc-dc converters with this thing. 3000W!!!:

http://cgi.ebay.com/Compaq-3000W-48v-Hot-Plug-Power-Supply-for-P-253232-001_W0QQitemZ350006727186QQihZ022QQcategoryZ56090QQrdZ1QQssPageNameZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem

Here's another:
http://cgi.ebay.com/HP-3000W-48V-POWER-SUPPLY-BL-P-CL-ENCLOSURE-253232-001_W0QQitemZ150165133400QQihZ005QQcategoryZ56094QQrdZ1QQssPageNameZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem

 

[Doctorbass]

Hi Doc:

How's your project going? I saw this power supply on ebay. It would be easy to power all your dc-dc converters with this thing. 3000W!!!:

http://cgi.ebay.com/Compaq-3000W-48v-Hot-Plug-Power-Supply-for-P-253232-001_W0QQitemZ350006727186QQihZ022QQcategoryZ56090QQrdZ1QQssPageNameZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem

Here's another:
http://cgi.ebay.com/HP-3000W-48V-POWER-SUPPLY-BL-P-CL-ENCLOSURE-253232-001_W0QQitemZ150165133400QQihZ005QQcategoryZ56094QQrdZ1QQssPageNameZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem

Thanks Beagle123,

I've seen those last week.
They seems pretty powerfull.. I have 2x 12V 42A hp power supply similat to those.. but the disadvantage is that they are difficult to use without the rest of the HP enclosure. they have a &?$&(?$(&%!! multipin connector that need correct voltage applied to unknow pin to activate the output!... mine have 102pin rectangular connector !!!

The 3000W have this one:

maybe easyer to start..

I asked the seller if he could know how .

Doc