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Old 07-13-2007, 12:57 PM   #1 (permalink)
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Default How to use CCCV power supplies to charge LiFe (A123) packs

CCCV Power Supplies as A123 chargers

I have seen that some folk are using CCCV DC bench power supplies to directly charge LiFe (aka A123) packs at up to 10A or sometimes more. This is particularly useful for larger packs (8s and above) where typical R/C chargers are not powerful enough to charge at high currents or as a much cheaper option for charging two packs at once.

It would be great to hear from the folk doing their charging this way so we can learn from their experiences.

To kick things off I will describe my understanding of how it can be done and some links to examples of these lab power supplies.

Why do this ?
Amongst the advantages of A123 cells are their ability to be charged at up to 4C (10A) and their electrical robustness such that they tolerate overvoltage without damage or risk of thermal runaway. This opens the door to using high-power CCCV power supplies to achieve high charge rates at low cost.

The electrical robustness of the M1 cells and their good tolerance for over-voltage means that the 1-2% voltage tolerance on these CCCV supplies is not a problem so long as the packs are not left on the charger once they are done.

With the kind of power supplies we are talking about you can get very high power charging of high cell-count packs, well beyond what the current crop of high-end R/C chargers can achieve, at the same or lower cost.

How does it work ?
LiXx batteries are charged with a CCCV profile. That is Constant Current for the bulk of the charge and then Constant Voltage for the topping charge. These power supplies allow you to set the current and voltage limits and behave precisely as needed for a CCCV charge profile.

For example to charge a 10s pack of A123/M1 2300mAh cells at 2C you would dial up about 36.4V/4.6A. The power supply would start driving current into the packs in CC mode holding the voltage down so long as the current was at the programmed limit (in this case 4.6A). Once the voltage on the packs reaches 36.4 the voltage limit will kick in and the supply will go into CV mode, letting the current gradually drop off. You monitor the process and stop the charge (disconnect the pack from the power supply) when the current falls below 0.1C or about 250mA for A123/M1 2300mAh cells.

What's the catch ?
* No inherent safety. The R/C chargers have clever software that tries to ensure you don't try to charge a 3s battery on a 5s setting. Here you are on your own and must be very careful to set the voltage appropriately for your packs. Setting it too high won't start a fire with A123 packs but could easily kill cells. Also the chargers have total time and total charge automatic cutoffs so even if they fail to terminate the charge for any other reason, the safety net values will stop it anyway. These power supplies will just keep pumping current into the packs so long as they are connected.

* No balancing. Unless you use a charge-through balancer you are not getting any balancing. Most people find that A123 packs only need balancing every now and then. So you can simply cycle them through a standalone balancer from time to time followed by a slow charge cycle.

* No automatic end-of-charge cutoff. The power supply will keep pumping current into the pack so it has to be monitored and turned off or the pack disconnected when the charge current has fallen to 0.1C (or sooner, say 0.2C if you want quicker charge time). If you forget and leave your pack on overnight it won't start a fire but it could get ruined and some cells might vent and go open circuit. It might be a good idea to put a kitchen timer next to the power supply set for your expected charge time plus say 10 minutes.

* No data logging. The fancy R/C chargers all have PC interfaces that can let you log and review the details of each charge cycle including individual cell voltages over time.

* No total-charge-put-back data. Unless you put a WattsUp meter (or similar device) in line with your pack you won't know how much total charge went into it.

Examples
There are some really interesting options:

Mastech HY3005D, Single 30V/5A - charge a single A123 pack up to 8s at up to 5A (USD$97)
http://cgi.ebay.com/MASTECH-VARIABLE...QQcmdZViewItem

Mastech HY3010E-3 Dual 30V/10A - charge two A123 packs at the same time (up to 8s) or a single pack up to 15s at up to 10A (USD$278 + shipping)
http://cgi.ebay.com/MASTECH-TRIPLE-D...QQcmdZViewItem

Mastech HY5005-2 Dual 50V/5A - charge two A123 packs at the same time (up to 13s) or a single pack up to 26s at up to 5A (USD$230 + shipping)
http://cgi.ebay.com/NEW-MASTECH-DC-P...QQcmdZViewItem

Mastech HY5020E, Single 50V/20A - charge a single A123 pack up to 13s at up to 20A (USD$258)
http://shop.vendio.com/Evan2002/item.../?s=1184234402

=====================

OK so now over to you innovators out there that are doing this ? What have you learned ?

=====================

Reference links

2007 - All about A123 cells/packs/charging: http://www.rcgroups.com/forums/showp...01&postcount=2
Jan 2008 - Link to a demo video using a Mastech to charge A123 packs: Part 1
Charging A123 cells with HY5020E Part 1 (4 min 8 sec)
and Part 2
Charging A123 cells with HY5020E Part 2 (4 min 32 sec)


Apr 2008 - Link to an excellent thread on using an 3010 and how to build a reverse flow/reverse polarity protection circuit to keep the magic smoke inside your Mastech: http://www.rcgroups.com/forums/showthread.php?t=833118
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
* TRex450CF/430L/12t/CC45/HS65mg/L2100T/KP 3s 2200 25C or 4S LiFe
Previous rides: HX242, W5-4, TRex450(HDE), TRex450(SE), QJ-EP8v2, BCX2 ,Logo10, Hurricane550
SIM: Phoenix (previously also Reflex/XTR, ClearView, RF, FMS)

Last edited by kgfly; 04-09-2008 at 02:28 AM.. Reason: Updated video links and cross references
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Old 07-13-2007, 01:09 PM   #2 (permalink)
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NOTE - The technique described above is NOT safe for LiPo/LiIon battery packs as these packs are dangerous if over-charged and can explode as a result.

In theory the only way these CCCV power supplies could be used for LiPo packs would be by using an intelligent charge-through balancer like the FlightPower VBalancer between the power supply and the battery pack. Such a device will independently cut off the charge if any one cell gets over 4.21V.

However the lack of automatic charge safety features means that I would NOT recommend using this approach for charging LiPo/LiIon packs to anyone.

It is the inherent safety of A123 LiFe cells that makes it possible to use this technique safely and no other kind of battery should be charged this way.
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
* TRex450CF/430L/12t/CC45/HS65mg/L2100T/KP 3s 2200 25C or 4S LiFe
Previous rides: HX242, W5-4, TRex450(HDE), TRex450(SE), QJ-EP8v2, BCX2 ,Logo10, Hurricane550
SIM: Phoenix (previously also Reflex/XTR, ClearView, RF, FMS)
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Old 09-21-2007, 03:28 AM   #3 (permalink)
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I use the hy5020e from my car battery using a inverter,
to charge 12s2p a123 pack at 20A 43.2V with CCCV.
The 1000W inverter must generate sine wave 220V.
Use a 220V relay to cut output of hy5020e in case of 220V failure,
if not, a123 pack may discharge in hy5020e, causing damage.
Use the following procedure:
- inverter on;
- on hy5020e, set A and V to zero;
- hy5020e on;
- set V to 43.2V;
- connect a123 pack;
- set A to 20.0A;
- wait until A drops to 0.5A (12min);
- disconnect.
If car battery drops under 11V, inverter shuts down and relay disconnects a123 pack under charge.
Relay can be replaced with a 20A diode, but then take account on the voltage drop due to the diode.
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Old 09-21-2007, 09:01 AM   #4 (permalink)
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This all sounds great. I have been looking into A123 cells for my T-Rex 600. I have a TP1010 already, but I love to see alternative charging methods. An extra charging setup is always useful. Plus, if I ever want to go more than 10S on the T-Rex, I would be screwed with the TP1010

Ramboman - which inverter are you using? Is it a true sign wave inverter? Also, what relay are you using? Do you have any pictures of your setup. Like they say, a picture is worth a thousand words.

Great information. Keep it coming.

Steve
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Old 12-15-2007, 03:48 PM   #5 (permalink)
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I don't quite understand the fact with the Inverter. Can someone tell me which sort of inverter it has to be or can it be a standard Inverter from ebay, seeing a lot of them for round about 80$.

or whats the deal with those sin-waves?

Can someone show me a link what sort of inverter I need?

And are 1000W Inverter really enough power? I will have a kinda 100A Carbattery and then the inverter and then the Mastech on it.

greetings Daniel
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Old 12-17-2007, 03:26 AM   #6 (permalink)
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Default About relay and inverter

Relay is activated by presence of 220V (Europe) after the power switch of the MasTech. So "on" with MasTech "on" and 220V available.
Relay's contacts switch output "on" when MasTech can deliver power and "off" when not... so that the battery cannot discharge in the MasTech in case of power failure.

Any "good" inverter should work that can deliver 1KW. I use 4 lead gel batteries (38 Ah) in parallel.

Very heavy, so most of the time I use a "honda" generator.

Maintenance at home with a Robbe charger with a 12s balancer, both a123 aware.
But limited to 3.5A instead of 20A.
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Old 01-02-2008, 11:12 PM   #7 (permalink)
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I updated the first post with this link to a demo video using a Mastech to charge 5S A123 packs: http://www.youtube.com/watch?v=q-1fb...eature=related
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
* TRex450CF/430L/12t/CC45/HS65mg/L2100T/KP 3s 2200 25C or 4S LiFe
Previous rides: HX242, W5-4, TRex450(HDE), TRex450(SE), QJ-EP8v2, BCX2 ,Logo10, Hurricane550
SIM: Phoenix (previously also Reflex/XTR, ClearView, RF, FMS)
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Old 01-04-2008, 11:06 AM   #8 (permalink)
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I have been using a cccv bench top power supply now for the last 3 or 4 months on my 7 and 8s A123 packs. I picked up a cheap power supply on ebay for $35 it is only good for 6 amps and 50v but it does my packs in less then 25 minutes. and it real simple. you set your voltage, plug in the pack turn up the amps in my case to max. and I set a timmer and come back in about 20 minutes, when the voltage gets close to the target, the amps begin to drop, once the target voltage is reached the amps drop to 0 or almost 0 at this point unplug! My supply will stop charging when the target it reached, although I have heard some do not completely stop. I left 1 pack on the charger for about 1 hr and it did not overcharge. a 10 amp would really be nice but 20 minute charges on a $40 charger isn't a bad setup!
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Old 01-04-2008, 06:11 PM   #9 (permalink)
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Got a link ?
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
* TRex450CF/430L/12t/CC45/HS65mg/L2100T/KP 3s 2200 25C or 4S LiFe
Previous rides: HX242, W5-4, TRex450(HDE), TRex450(SE), QJ-EP8v2, BCX2 ,Logo10, Hurricane550
SIM: Phoenix (previously also Reflex/XTR, ClearView, RF, FMS)
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Old 01-05-2008, 09:57 AM   #10 (permalink)
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Default Another way...

For compatibility with my Schulze ESC's I reduced my packs to 10s2p.
Loading with MasTech at 36V 20A, or 10A with Robbe balancer.
36V is also 3 lead batteries
So loading in the field is straightforward, just connect
With appropriate wire lenght, current does not go higher than 20A,
and decreases to roughly zero when the pack is loaded.
I use three 38Ah gel batteries serially coupled.
Reloaded with the WasTech.
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Old 04-06-2008, 09:31 AM   #11 (permalink)
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Updated original post with links to some new videos and to a fascinating thread about using the HY3010-E3 which shows how to build a protection circuit to save your Mastech and you packs from being damaged if either you connect the pack with reverse polarity or if the AC power to the Mastech fails while a pack is connected to the output, an important consideration when using them off a generator at the field.
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
* TRex450CF/430L/12t/CC45/HS65mg/L2100T/KP 3s 2200 25C or 4S LiFe
Previous rides: HX242, W5-4, TRex450(HDE), TRex450(SE), QJ-EP8v2, BCX2 ,Logo10, Hurricane550
SIM: Phoenix (previously also Reflex/XTR, ClearView, RF, FMS)
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Old 04-12-2008, 12:09 PM   #12 (permalink)
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www.tanicpacks.com sells the wire needed for polarity protection if you dont want to do it yourself.


Here what I hook to my Mastech HY5020

First is a the Fused reverse polarity cable from Tanicpacks.com
Next is a standard watt meter
and next is a 15 timer I took from an old Hobbico 905 quick charger.

A full twist on the timer leaves my packs topped off and my mastech usually reading less that 1.0 amp by the time the timer pops. (14S @ 10amps)
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Old 04-12-2008, 06:55 PM   #13 (permalink)
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Nice setup. That lead from Tanic protects against reverse polarity but not against reverse flow. If the input power to the Mastech goes away while the battery is connected, power will flow from the battery back into the Mastech and this may cause damage. Using the design show here you can make up a full protection unit for the same or less than the lead from Tanic.
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
* TRex450CF/430L/12t/CC45/HS65mg/L2100T/KP 3s 2200 25C or 4S LiFe
Previous rides: HX242, W5-4, TRex450(HDE), TRex450(SE), QJ-EP8v2, BCX2 ,Logo10, Hurricane550
SIM: Phoenix (previously also Reflex/XTR, ClearView, RF, FMS)
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Old 04-12-2008, 10:31 PM   #14 (permalink)
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Not an electrical engineer, not sure why a high amp diode would not work.
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Old 04-12-2008, 10:40 PM   #15 (permalink)
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Quote:
Originally Posted by Cryofix View Post
Not an electrical engineer, not sure why a high amp diode would not work.
Not sure about your question. The lead from Tanic has a diode across the output terminals which will cause the fuse to blow if the battery is connected with reverse polarity. This diode does nothing to protect against reverse current flow, A high amp diode in series with the positive lead is exactly what is needed to protect against reverse current flow. The solution referenced above uses a cheap ($3.75) 25A diode bridge as a simple and convenient way to implement both kinds of protection.
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
* TRex450CF/430L/12t/CC45/HS65mg/L2100T/KP 3s 2200 25C or 4S LiFe
Previous rides: HX242, W5-4, TRex450(HDE), TRex450(SE), QJ-EP8v2, BCX2 ,Logo10, Hurricane550
SIM: Phoenix (previously also Reflex/XTR, ClearView, RF, FMS)
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Old 09-02-2010, 06:00 AM   #16 (permalink)
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Nice post... interesting !

Thank you very much for your efforts!!
Greatly appreciated!!!
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Old 09-02-2010, 12:32 PM   #17 (permalink)
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Wow, this is an oldie but goodie. While we're hear, are there any new ways to fast charge A123's (with a good price tag).
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Old 09-03-2010, 12:23 PM   #18 (permalink)
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Well there are now two 1000W chargers available (iCharger 3010B and FMA PowerLab8), both around $250+. The big problem for most folk is providing a 24V/50A power supply to be able to deliver the full 1000W/30A output. There are some relatively low cost approaches based around hacking two 12V PC server supplies in series to make 24/55A supply. That is not an approach for novices IMO.
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* MSH Protos Stock motor/15t/Align75/Align DS510/GL730+DS520/7s A123 2300
* TRex450CF/430L/12t/CC45/HS65mg/L2100T/KP 3s 2200 25C or 4S LiFe
Previous rides: HX242, W5-4, TRex450(HDE), TRex450(SE), QJ-EP8v2, BCX2 ,Logo10, Hurricane550
SIM: Phoenix (previously also Reflex/XTR, ClearView, RF, FMS)
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Old 09-04-2010, 01:15 AM   #19 (permalink)
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Quote:
Originally Posted by kgfly View Post
Well there are now two 1000W chargers available (iCharger 3010B and FMA PowerLab8), both around $250+. The big problem for most folk is providing a 24V/50A power supply to be able to deliver the full 1000W/30A output. There are some relatively low cost approaches based around hacking two 12V PC server supplies in series to make 24/55A supply. That is not an approach for novices IMO.
1. Use two 12V Pb batteries and reload them with a low cost 12V PSU.
2. Buy a 24V 1000W PSU... another $250+...
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Old 09-11-2010, 09:25 PM   #20 (permalink)
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I was thinking of using 2 12v car batts in series and a zip charger to charge 7s. anyone think this would work? I would of coarse monitor the charge with an amp meter.
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