Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Apr 14, 2011, 09:45 PM
iCharger
junsi's Avatar
Joined Mar 2007
1,081 Posts
Quote:
Originally Posted by cleansho93 View Post
I am disappointed with a recent iCharger experience. I have a 106B+ that I purchased new a little over 2 years ago. It had been working very well until a few months ago. Cell #5 and #6 voltages (as seen by charger) have lost calibration. They show the cell's voltage as up to 0.05V lower than what they really are (when compared on digital multimeter or other charger). I have emailed Junsi (service@hillrc.com) 3 times now regarding how to fix this issue, and have still not received a response. It has been months now with no reply. I know that the charger can be manually calibrated with the newer firmware versions, but mine has the older firmware and I have not been able to get the software to detect the charger when connected. Here is a copy of the email sent to service@hillrc.com to which I have not received a reply.

"Hello.

I purchased a 106b+ charger about 2 years ago and have been very happy with it until recently. For some reason, the calibration is off on cells 5 and 6 when charging a lipo battery in balance charge mode. It will consistently read cells 5 and 6 to be up to 0.05V lower than they really are. I have verified this by hooking up several different 6s packs and then checking the cells of those packs with a voltage meter and also by hooking them up to one of my other chargers. So due to this the charger will actually overcharge cells 5 and 6. I just noticed this problem within the last week. I was getting ready to purchase another iCharger to increase my charge capability, but after this issue I am now concerned about the quality of the product. Can you please tell me if this is common or how I can fix the issue? My software version is 1.07, I have tried updating to the latest software that will allow me to calibrate charger, but I keep receiving an error "device not found" when trying to upgrade it. Please help."


I understand this charger is no longer under warranty, but can you please recommend the steps to fixing my charger's issues?
Dear Sir,

We are really sorry about this problem, there should have some misunderstanding, pls check the PM we have sent to you or you can contact us via another email address harrief111@hotmail.com, and our colleague will offer you the method how to handle this matter in time.

Sorry again for putting this trouble on you.

Regards,
Junsi
junsi is online now Find More Posts by junsi
Last edited by junsi; Apr 14, 2011 at 10:05 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 15, 2011, 12:21 AM
Registered User
Ipoh, Perak Malaysia
Joined Jul 2006
3,980 Posts
Quote:
Originally Posted by eecs View Post
I was forgetting the obvious solution to this, which is to give each MOSFET a resistor to allow the currents to equalize. This allows any number of (smaller and cheaper) N-channel MOSFETS to be connected in parallel to achieve any desired power sink:
Attachment 3761725

These FDA69N25 N-channel MOSFETs will dissipate about 176W each (assuming a 60 C heatsink and good thermal grease), so 6 of them will handle 1000W.

The drains are all connected in parallel, so they can share one heatsink. However, the heatsink will still be live, so watch for shorts!

Note, if it is not clear from the diagram, that the gates are all connected to each other, but each source is only connected to its own resistor and capacitor.

For the 208B and 206B this could be scaled back to four really cheap TO-220 MOSFETS:
Attachment 3761726

For the 106B+ it could be scaled back to two MOSFETS (logic-level ones this time, since we don't have much headroom):
Attachment 3761736

Again I have not built any of these myself, so if anyone tries any of these circuits then please post and let us know if they work!
Hi eecs,

Thanks for the circuit. I could not find the original FDA69N25 but found FDAF69N25

Is this ok? I see from the specs sheet that it can only dissipate 115W and not the 176W that you specified.

If I were to use the SUP75P05-08 p-channel mosfet as specified by beenflying in Post#9407, how would the circuit be different? Would it be too much to ask you to kindly provide the circuit diagram for that please. I think I have asked beenflying to show his mods, but he has not replied. Sorry to be so much bother, as I am not very knowledgable in EE, but am able to wire up a circuit once I have the diagram.

Thanks for your help.

chewy
chewytm is offline Find More Posts by chewytm
Last edited by chewytm; Apr 15, 2011 at 01:38 AM.
Reply With Quote
Old Apr 15, 2011, 05:07 AM
Registered User
Joined Dec 2010
58 Posts
Quote:
Originally Posted by chewytm View Post
I could not find the original FDA69N25 but found FDAF69N25

Is this ok? I see from the specs sheet that it can only dissipate 115W and not the 176W that you specified.
The problem is that the junction-to-case thermal resistance is 1.08 degrees/W, and the case-to-sink thermal resistance is 0.24 degrees/W, giving you a total of 1.32 degrees/W. Assuming your fan does a really good job and keeps the heat sink down around 40 degrees C, and noting that this MOSFET can operate at a maximum of 150 degrees C, you are left with 110 degrees C, which translates to 83W. How much power do you want to dissipate in total?

Quote:
If I were to use the SUP75P05-08 p-channel mosfet as specified by beenflying in Post#9407, how would the circuit be different? Would it be too much to ask you to kindly provide the circuit diagram for that please. I think I have asked beenflying to show his mods, but he has not replied. Sorry to be so much bother, as I am not very knowledgable in EE, but am able to wire up a circuit once I have the diagram.
Post#9407 describes essentially the original circuit that I posted:
Attachment 3759206
The main differences are:
  1. MOSFET (use SUP75P05-08)
  2. diode (use VS-40CPQ045)
  3. capacitor (use 220nF)

beenflying was also using a 24V power supply rather than a 12V power supply, which won't work for the 106B+ or 1010B+, and would be pushing it for the 206B, but is fine for the other iChargers. Which model charger are you using?
eecs is offline Find More Posts by eecs
Reply With Quote
Old Apr 15, 2011, 12:45 PM
Registered User
Ipoh, Perak Malaysia
Joined Jul 2006
3,980 Posts
eecs,

I am using the 106B+, so I guess those components won't work. Could you please recommend alternatives for this. My power supply is just a 12V computer PS capable of about 30A (probably less). A have some paired (parallel) schotky diodes rated for 30A each side.

I tried searching for IXTK90P20P, and some of its variations, but could not find anything at element14.com (farnell.com). Could you please provide a link to that?

Btw, would the SUP75P05-08 would with my 106B+ and the 12V ps?

Thanks for your help.

chewy
chewytm is offline Find More Posts by chewytm
Reply With Quote
Old Apr 15, 2011, 02:22 PM
Registered User
balistc1000's Avatar
Chandler, AZ
Joined Nov 2008
544 Posts
Quote:
Originally Posted by balistc1000 View Post
I have something really strange with my 1010B+. Only when I charge 6s packs, 4s-3s is fine, but a couple cells will be charged to 4.21-4.25v. I have my charger set to end at 4.19v and you would think it would be cells 5-6 that are off but it is cells 1-2 that get a little over charged. Anyone see this before?
Quote:
Originally Posted by everydayflyer View Post
Chargin a 3S or 4S balance is OK but charging a 6 cell cuases cells 1 and 2 to overcharge?

That does seem a bit strange.

Calibration how to from post #1

http://www.rcgroups.com/forums/showa...6&d=1293608349
Quote:
Originally Posted by balistc1000 View Post
Thanks Charles. I would just hate to mess up the 3s and 4s charging.
Junsi, any help with this?
balistc1000 is online now Find More Posts by balistc1000
Reply With Quote
Old Apr 15, 2011, 11:05 PM
Registered User
Joined Dec 2010
58 Posts
Quote:
Originally Posted by chewytm View Post
I am using the 106B+, so I guess those components won't work. Could you please recommend alternatives for this.
The 106B+ is limited to a maximum of 7A discharge current. It is also limited to 6s. During discharge, a LiPo will be delivering less than 4V/cell, so 6s means a maximum of 24V. 24V * 7A = 168W. So I would propose to aim for dissipating 168W.

We are aiming to run the 106B+ on at least 12V (higher during discharge) so the current in the discharger will be less than 168W / 12V = 14A.

The 106B+ is limited to 18V input, so at most the discharger needs to handle 18V.

So initially we are looking for MOSFETs that are rated for at least 14A, 18V and 168W.

I will assume your fan can keep the heatsink below 60 degrees C when dissipating 168W. Most MOSFETs can handle 150 or 175 degrees C. So you have at least 90 degrees C available to dissipate 168W. That implies a thermal resistance of 0.536 degrees/W junction-to-sink. That means either you rule out the cheap TO-220 MOSFETs, or else you use multiple MOSFETs. If you are willing to use enough of them, you can use just about any MOSFET. Here I will assume you would rather use just one.

Looking through the element14.com MOSFET list, the cheapest candidate I can see is the IRFP27N60KPbF [no good - too high a Vgs for the 106B+] STW45NM50FD:
http://my.element14.com/stmicroelect...fet/dp/1261468
which has a j-c resistance of 0.3 degrees/W and a c-s resistance of 0.24 degrees/W, giving a total of 0.54 degrees/W.

Quote:
A have some paired (parallel) schotky diodes rated for 30A each side.
Very good. You may as well connect both sides; it may save you a few mV!

Quote:
Btw, would the SUP75P05-08 would with my 106B+ and the 12V ps?
It would work, but you would need two of them to handle 168W, and they each cost more than half much as the STW45NM50FD, plus using two makes extra work. I can't see any advantage unless you already had the components spare.

Anyway, here is the kind of circuit you would need:
Name: dis1n.png
Views: 157
Size: 28.7 KB
Description: 168W discharger for 106B+

Note that the heatsink will be live (12V) and that you can't insulate the MOSFET from the sink because you can't afford the extra thermal resistance of the insulating washer.
eecs is offline Find More Posts by eecs
Last edited by eecs; Apr 16, 2011 at 08:23 AM. Reason: corrected bad transistor selection
Reply With Quote
Old Apr 16, 2011, 08:01 AM
Back to Pattern
kbtiii's Avatar
United States, TX, Cleveland
Joined May 2008
22 Posts
Thanks to all that sent me the info on epbuddy.com, it's why I love this place!!
kbtiii is offline Find More Posts by kbtiii
Reply With Quote
Old Apr 16, 2011, 08:39 AM
Back to Pattern
kbtiii's Avatar
United States, TX, Cleveland
Joined May 2008
22 Posts
I went to ebuddy's website and was looking at the Paraboard's but they don't list whether or not it will support the Sky Lipo...
I have an email into HobbyPartz to see if they can tell me which battery manufacturer uses the same balance plug as Sky, I can't imagine it would be their own, it must be an off the shelf product.
kbtiii is offline Find More Posts by kbtiii
Reply With Quote
Old Apr 16, 2011, 09:22 AM
Registered User
Nobert's Avatar
Tucson Avra Valley, Arizona, United States
Joined Jul 2002
1,454 Posts
Sky LiPo

The Sky LiPo uses JST connectors on the balance connector. You should be ok.
Neal
Nobert is offline Find More Posts by Nobert
Reply With Quote
Old Apr 16, 2011, 09:26 AM
Back to Pattern
kbtiii's Avatar
United States, TX, Cleveland
Joined May 2008
22 Posts
Thanks Neal, ordering the ParaBoard now.
kbtiii is offline Find More Posts by kbtiii
Reply With Quote
Old Apr 16, 2011, 12:48 PM
Registered User
Ipoh, Perak Malaysia
Joined Jul 2006
3,980 Posts
Quote:
Originally Posted by eecs View Post
The 106B+ is limited to a maximum of 7A discharge current. It is also limited to 6s. During discharge, a LiPo will be delivering less than 4V/cell, so 6s means a maximum of 24V. 24V * 7A = 168W. So I would propose to aim for dissipating 168W.

We are aiming to run the 106B+ on at least 12V (higher during discharge) so the current in the discharger will be less than 168W / 12V = 14A.

The 106B+ is limited to 18V input, so at most the discharger needs to handle 18V.

So initially we are looking for MOSFETs that are rated for at least 14A, 18V and 168W.

I will assume your fan can keep the heatsink below 60 degrees C when dissipating 168W. Most MOSFETs can handle 150 or 175 degrees C. So you have at least 90 degrees C available to dissipate 168W. That implies a thermal resistance of 0.536 degrees/W junction-to-sink. That means either you rule out the cheap TO-220 MOSFETs, or else you use multiple MOSFETs. If you are willing to use enough of them, you can use just about any MOSFET. Here I will assume you would rather use just one.

Looking through the element14.com MOSFET list, the cheapest candidate I can see is the IRFP27N60KPbF [no good - too high a Vgs for the 106B+] STW45NM50FD:
http://my.element14.com/stmicroelect...fet/dp/1261468
which has a j-c resistance of 0.3 degrees/W and a c-s resistance of 0.24 degrees/W, giving a total of 0.54 degrees/W.


Very good. You may as well connect both sides; it may save you a few mV!


It would work, but you would need two of them to handle 168W, and they each cost more than half much as the STW45NM50FD, plus using two makes extra work. I can't see any advantage unless you already had the components spare.

Anyway, here is the kind of circuit you would need:
Attachment 3945856

Note that the heatsink will be live (12V) and that you can't insulate the MOSFET from the sink because you can't afford the extra thermal resistance of the insulating washer.
eecs,

Thanks for the information. You are most helpful. I don't mind buying two of those MOSFET, if it would work better. If I use 2 of them, what would the circuit be like? Would I need to isolate them from each other electrically or can I share the same heat sink. Also, I will be leaving the circuit in during charging.

I see the resistor is missing from this circuit. Is it no longer necessary?

Thanks again for your help

chewy
chewytm is offline Find More Posts by chewytm
Reply With Quote
Old Apr 17, 2011, 01:12 AM
Registered User
Joined Dec 2010
58 Posts
Quote:
Originally Posted by chewytm View Post
I don't mind buying two of those MOSFET, if it would work better.
It won't work better or worse, it is just a trade-off between extra work (connecting up more components) and lower cost (high power MOSFETs are very expensive).

Quote:
If I use 2 of them, what would the circuit be like?
If you don't mind using more than one, I suggest you use three, and then you can get really cheap ones. For example, Futurlec sells the IRFZ44 for US$0.50 each:
http://www.futurlec.com/Transistors/IRFZ44pr.shtml

They only have a thermal resistance j-s of about 2.0 degrees/W, but they can handle a junction temperature of 175 degrees C, so (assuming 60 degrees C sink) and 168W design power you need a total thermal resistance of better than 0.685 degrees/W, which means better than 2.05 degrees/W each for three.

The circuit would then be something like this:
Name: dis3n.png
Views: 144
Size: 33.5 KB
Description: 106B+ discharger

Quote:
Would I need to isolate them from each other electrically or can I share the same heat sink.
They share the same sink. All the drains are at 12V.

Quote:
I see the resistor is missing from this circuit. Is it no longer necessary?
They are only needed to make sure multiple MOSFETs share the load equally, so you don't need them with only one MOSFET.
eecs is offline Find More Posts by eecs
Reply With Quote
Old Apr 17, 2011, 04:50 AM
Registered User
Joined Dec 2010
58 Posts
Quote:
Originally Posted by eecs View Post
The circuit would then be something like this:
Attachment 3947970
By the way, in this circuit the negative input of the iCharger will be at about -5V relative to the negative output of the 12V power supply. If your power supply has a floating output that won't matter, but if you have a power supply whose negative output is earthed, and if you are also connecting the iCharger to a PC, especially if you use a standard USB cable, you may have problems!

If you are concerned about this then you may prefer to use a circuit that has a common ground, such as:
Name: dis3n2.png
Views: 122
Size: 37.4 KB
Description: discharger with common negative
eecs is offline Find More Posts by eecs
Reply With Quote
Old Apr 17, 2011, 01:57 PM
Registered User
Ipoh, Perak Malaysia
Joined Jul 2006
3,980 Posts
Quote:
Originally Posted by eecs View Post
By the way, in this circuit the negative input of the iCharger will be at about -5V relative to the negative output of the 12V power supply. If your power supply has a floating output that won't matter, but if you have a power supply whose negative output is earthed, and if you are also connecting the iCharger to a PC, especially if you use a standard USB cable, you may have problems!

If you are concerned about this then you may prefer to use a circuit that has a common ground, such as:
Attachment 3948089
eecs,

Many thanks. I think I will use this circuit.

The SUP75P05-08 only cost less than USD10 each. Would 2 of them be okay with the above circuit. The problem is, I don't think they would be much interested in sending me 3xUSD0.50 items. There ain't no profit in it.

If the SUP75P05-08 works, then that price would be acceptable to me.

chewy

Ps. Btw, any specific types of capacitors required, or just any plain old ceramics of at least 30V?
chewytm is offline Find More Posts by chewytm
Reply With Quote
Old Apr 17, 2011, 09:10 PM
Registered User
Joined Dec 2010
58 Posts
Quote:
Originally Posted by chewytm View Post
The SUP75P05-08 only cost less than USD10 each. Would 2 of them be okay with the above circuit.
Yes.

Quote:
The problem is, I don't think they would be much interested in sending me 3xUSD0.50 items. There ain't no profit in it.
They have no minimum order limit. I presume they build some extra profit into the shipping charge. For orders up to US$29 your delivery charge would be US$5.00. So if all you wanted was three $0.50 MOSFETs you could get them for US$6.50 delivered.

I have done small orders with Futurlec in the past. They have been slow (orders seem to ship from Thailand), but after allowing for shipping they certainly have been cheap for small orders.

Places like Digikey have a much better range and ship very quickly, but for small orders the shipping costs are prohibitive if you live outside north America.

Element14 is a mixture - generally higher component prices, but middle-priced and fast shipping. I have used them for smaller orders where the shipping cost of places like Digikey dwarf the order value.

They all have their advantages and disadvantages, and I don't particularly recommend one supplier over another.

If anyone knows of a source with Digikey's range but with reasonable international shipping charges I would love to hear about it! If Digikey would send via USPS instead of insisting on using UPS/Fedex the price would be fine (the USPS is quite reasonable for small light packages).

Quote:
any specific types of capacitors required, or just any plain old ceramics of at least 30V?
Just a plain old monolithic ceramic - something like:
http://www.futurlec.com/Capacitors/C220UMCpr.shtml
for US$0.15 each.
eecs is offline Find More Posts by eecs
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Best charger/discharger $ can buy namancio Batteries and Chargers 30 Jan 31, 2010 02:52 PM
Power Pacer Battery charger/discharger ACE_McCOOL Batteries and Chargers 4 Oct 22, 2002 12:39 PM
NIB Hitec CG-325 Charger/Discharger/Cycler for 4-9 cells - $39! Jason M Aircraft - Electric - Airplanes (FS/W) 0 Oct 03, 2002 03:29 AM
WTB Good charger/discharger 10 + cells WickedFunRC Aircraft - Electric - Airplanes (FS/W) 0 Sep 05, 2002 08:55 PM