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Post by Dillzio on Sept 3, 2009 7:10:17 GMT 1
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Post by ginginho on Sept 3, 2009 9:52:47 GMT 1
This looks to have the same functionality as my charger, this one.If it's the same under the covers then it's a good charger. I've been using mine for 10 months without a hitch. |
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Post by Dillzio on Sept 4, 2009 17:53:20 GMT 1
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Post by Dillzio on Sept 6, 2009 11:37:24 GMT 1
I got outbid on the one I was going for, so I just got one from the above link for the buy it now price. $40AU Delivered, or about 32ish US.
I'll post a review once I've tried it with my three new zippy 2200mah, my two crap ebay "1500mah" 1100mah cheapies, and maybe even my stock pack which is in about the poorest state imaginable.
I only use lipos so that's all I think I'll be using it for.
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Post by Dillzio on Sept 16, 2009 11:37:39 GMT 1
My charger arrived today. First impressions are very good.
Nice clear display, quite solid build quality, comes with lots of connectors, none of which I recall ever seeing before. There are however alligator clips for the input and output that make the unit pretty much universal.
I quite quickly cut the end off one of the adapters which had the oddest plug I think I've ever seen on it, and replaced it with a male deans connector.
It get's the batteries to hold a lot more charge than the stock charger. Each cell goes up to 4.20 volts, and no cell got above 4.21 during the charging/balancing process.
It has safety cutouts on it that can be manually set for temperature (if you have the probe), charging time, output capacity, and an automatically set voltage level cutout specific to the type of battery. Lipo charging options are charge, balance, discharge, fast charge and store. Charging voltage is adjustable between 0,1 and 5 amps.
I can't say I'm entirely sure what the difference is between choosing 'lipo charge' and 'lipo balance'. You can hook up the balance connector in both modes and monitor the individual voltage of each cell while it's charging, and I didn't notice any difference when I charged my two identical crappy ebay batteries which I know do not balance easily. The manual says that the balance port will also function in discharge and storage mode.
The manual is far from perfect, but I've seen much worse from Asia. The instructions are written in quite fluent Engrish. phrases like "Please get highlighted that Lithium battery packs can be wired in series or parallel" make for some entertaining reading, but other passages are just indecipherable. One of the indecipherable passages finishes in "This may cause fatal error". Fatal to the charger, the battery or myself is anyone's guess.
It seems to be identical in functionality to what I've read about the Accucel-6. It also has modes for charging other batteries (NiMH, NiCd, Pb) and has 5 programs you can save for the different types of batteries you have.
I think you'll find this charger very hard to beat for the price. I got it for $40AU delivered, which is about $32 US. So far I've got no complaints, and I'm very happy with the purchase.
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Post by patmatgal on Sept 16, 2009 12:26:02 GMT 1
dillzio
Thanks for the comprehensive review. "Fatal error", that's a good one.
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Post by ginginho on Sept 16, 2009 13:21:36 GMT 1
Does it also do LiFe (A123)? Likely to be useful in the future.
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Post by Dillzio on Sept 16, 2009 14:20:14 GMT 1
Yes, it does Li-Ion, LiPo and LiFe, with preset values for charge voltage, discharge voltage, and storage voltage.
Now I've been playing around with it a bit more I have some design faults to speak of.
Even though it says in the manual that you can use the charger to charge/discharge cycle your lipos to break them in and aid in balancing cells, the option can only be found in the NiMH menu, which is a bit weird. If I run it in this mode, it will ONLY work with the balance connector connected, so the mode definitely is intended for Lipos. I think the charger detects that it's a LiPo, not NiMH, and declares a connection error because the balance port isn't connected.
I'm concerned that while cycling in this mode, it may not employ the Lipo cut off of 4.2v per cell, and instead go by the delta peak voltage for the automated charge termination. I can set the value manually. According to the instruction manual "setting the trigger voltage higher brings a danger of overcharging, whereas setting it lower brings a possibility of premature termination." I'll have to watch it carefully the first time I try it to make sure it doesn't overcharge the batteries.
My other complaint is the extremely slow discharge rate. You can set it to 1 amp in the options, which is painfully low as it is, but on a 3S LiPo I don't think it can discharge at 1 amp without getting too hot because it doesn't have a cooling fan. Even though I had it set to 1 amp, the display only showed it discharging at half an amp, and the heatsink sticking out the base of it was getting about as hot as you'd want it too. My guess about 60 degrees C. If I want to discharge my batteries, I'll still be going with a 55w car light bulb and a low-voltage warning buzzer hooked up to the balance port.
The other design fault was that when you set the safety timer cut out, it uses the same value for charging and discharging. While 90 minutes is a reasonable cut off time for charging a lipo, my batteries would take over four hours to discharge at half an amp. You could get over this by simply increasing the value of the safety timer to about 5 hours, and relying on the other two cutouts to prevent overcharging - the cutouts for charge capacity and cell voltage/delta peak voltage.
Another odd mistake is that the manual says that "INPUT VOL ERR" means "Erroneous selection of voltage of Lithium pack, please check the voltage of the battery pack". I think this is wrong, because I saw that error message when I tried charging at over 3.3 amps with my 2 amp power pack, and I could cause the error message to come up at 3 amps by changing the input power low cut-off from 10.0 to 10.5. Seems pretty obvious to me that particular error message actually means "quit being such a tight-arse and buy a proper power pack", or "your power supply is too weak, you need to reduce your charging current".
I'll post again when I've worked out if this charger can be used effectively to charge/discharge cycle LiPos to break them in. Unfortunately, I don't use NiMH so I can't comment on how well this charger works on them, but I would recommend it none the less.
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Post by Dillzio on Sept 17, 2009 5:13:21 GMT 1
This charger does not discharge balance LiPos. I ran a battery down with a car light bulb, then put it on my charger to finish it off. It discharges to a final voltage of 9v, but if the pack becomes unbalanced it can discharge individual cells to less than 2.7v. This is particularly odd because it will only discharge lipos if the balance port is connected. Why does it require the balance port to be connected if it doesn't balance? It may work more effectively if discharging from a higher voltage, but at a 0.5 amp discharge rate I'm not patient enough to find out. As there is little need to ever completely discharge lipos, this should not pose an issue to most users.
If anyone wanted to discharge Lipos with this charger, you may want to do it in NiMH mode so that you can manually set the discharge voltage to 9.5 or 10 for a safety margin. The balance port must be connected to charge/discharge lipos in NiMH mode, but it will not monitor of display the individual cell voltages. It is not possible to charge Lipo batteries in NiMH mode safely, as it will not cut out when the battery is full. This excludes the possibility of using the charger to automatically charge/discharge LiPos.
While there doesn't seem to be any serious flaws with the balance charging mode, it seems that it may need a little external help to obtain perfection... I charged one battery that had been charged in storage mode, so it was previously balanced and each cell was at about 3.8 volts. After half an hour charging, the cells read 4.15, 4.20, 4.15 and they stayed on the same levels for almost an hour. I then took off the battery, and manually discharged the middle cell with my light bulb down to the same level as the other cells, then put it back on the charger. 7 minutes later it had finished charging and all cells were balanced to 4.20. This issue does not seem to present itself when charging batteries from flat, as I just charged an identical battery from flat (3.4 resting volts per cell), and all cells balanced perfectly to 4.2v
There also seems to be a few small bugs in the software. Yesterday, I could have sworn it didn't need the balance connector hooked up to charge lipos in "lipo charge" mode (as opposed to "lipo balance" mode), yet today it declares a connection error if I try to charge it in "lipo charge" mode without the balance connector. As a result, i'm not sure how effective this charger would be at charging lipos that don't have a balance connector. While it does seem to need the balance connector to start charging in "lipo charge" mode, I have established that in this mode it does not balance the cells, but it will display the cell's individual voltages. It does however balance cells quite well when in fast charge mode.
OK, so that's my comprehensive review. While the charger may not be perfect, it can certainly do everything I will need it for. The charger may not be up to the standard of the top of the line B6 chargers, but if you're looking for a cheap alternative this charger seems like a better choice than the Imax or the Mystery, but the Turnigy Accucel-6 may be better. The GE power brand on ebay seems like an identical charger but has a cooling fan, so that might be a good one too.
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Post by ginginho on Sept 17, 2009 8:04:25 GMT 1
Hmm, maybe not the same as mine as I don't see any of the odd traits you mention. You shouldn't really let any pack get below 3.7V at rest per cell, it will start deteriating. Check out the links Fly has posted lots of times for further info.
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Post by Dillzio on Sept 17, 2009 9:16:01 GMT 1
3.7? I thought it was 2.7 before they were damaged. Cheers for the tip, I'll have to check those links again :-)
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Post by ginginho on Sept 17, 2009 11:21:20 GMT 1
Hmm, shamelessly copying a post from Fly that raises it's head every couple of months that originated on RCG: I think I've posted this before (NOFLYZONE'S BLOG) and it is a working approximation that is useful: [http://www.rcgroups.com/forums/member.php?u=106813&page=2] ["Resting" Voltage per cell 4.20v = 100% of our battery's amp capacity remains. 4.03v = 76% of our battery's amp capacity remains. 3.86v = 52% of our battery's amp capacity remains. (A good voltage to store our Li-Pos at) 3.83v = 42% of our battery's amp capacity remains. 3.79v = 30% of our battery's capacity remains. 3.75v = 20% of our battery's amp capacity remains. (Where we want to take our Li-Pos to for long life) 3.70v = 11% of our battery's amp capacity remains. (Detrimental 'battery voltage dump' begins) 3.6?v = 0% In line with the above, we do NOT want our Li-Po's resting voltage to be less than 3.75v per cell, which would mean we had used about 80% of their capacity. [end of quote] I printed this table out and stuck it to my flight box for easy reference at the field. Any packs that you've taken to 2.7V are likely to be, erm, compromised. Maybe that's why you have various packs that range from "crap" to "poorest state imaginable".  |
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Post by Dillzio on Sept 17, 2009 12:02:20 GMT 1
My zippy battery packs are still in tip top condition as far as I know. I have two battery packs from ebay that I believe to be crap, but I haven't actually tried them in my plane yet. They may be as good or better than the stock LiPos. My stock LiPo is in the worst state imaginable, I'm planning on fully charging it then short circuiting it in a controlled environment for some home made fireworks :-) I think there are different guidelines for best practice and acceptable practice. I've just read through all of fly's references, and it seems that the extremes in voltage (2.8v and 4.2v) will damage the batteries if the battery is held at those levels for a prolonged period of time. At least two of the links links also say that "A charge state of 50% reads about 3.8V and 40% is 3.75V" The only hard figures I've seen for minimum voltage per cell is 2.7-2.8v before damage occurs, and 3 volts as a target for discharging, although it also says "Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for Lipos than one deep one". So, it seems that discharging below, say 3.5 is bad for the longevity of the batteries (not ideal), but will not necessarily damage them. Here are Fly's links again: rclovers.com/GetTheMostFromLipo.htmwww.maxamps.com/lipo-care.phpwww.batteryuniversity.com/partone.htm |
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Post by ginginho on Sept 17, 2009 14:11:22 GMT 1
My zippy battery packs are still in tip top condition as far as I know. I have two battery packs from ebay that I believe to be crap, but I haven't actually tried them in my plane yet. They may be as good or better than the stock LiPos. My stock LiPo is in the worst state imaginable, I'm planning on fully charging it then short circuiting it in a controlled environment for some home made fireworks :-) I think there are different guidelines for best practice and acceptable practice. I've just read through all of fly's references, and it seems that the extremes in voltage (2.8v and 4.2v) will damage the batteries if the battery is held at those levels for a prolonged period of time. At least two of the links links also say that "A charge state of 50% reads about 3.8V and 40% is 3.75V" The only hard figures I've seen for minimum voltage per cell is 2.7-2.8v before damage occurs, and 3 volts as a target for discharging, although it also says "Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for Lipos than one deep one". So, it seems that discharging below, say 3.5 is bad for the longevity of the batteries (not ideal), but will not necessarily damage them. Here are Fly's links again: rclovers.com/GetTheMostFromLipo.htmwww.maxamps.com/lipo-care.phpwww.batteryuniversity.com/partone.htmMy take on those low voltage figures in the links are when the pack is under load, not at rest. When a load of multiples of the C rating are put on a pack, the pack voltage drops. Some more that others on a set amperage (diff between good and bad packs). 3V with load can easily show as 3.7 without. The SC LVC (with jumper removed for lipo action) is too low really for Lipos, I can't remember what it is per cell but it may be as low as 2.9v/cell. Remember that this is under load though. I don't fly to LVC, not many lipo flyers do or recommend it. Even so, I set the LVC in my ESCs to the highest possible configurable option which happens to be 3.1v/cell in case I forget to set my timer. At least I've a chance of not totally stuffing the pack in this situation. When charging you should only be charging at 1C or less. A good charger will lower the input amps as each cell nears 4.2v (and balance) to put in the last few mA's. When a pack is being shown at 4.2V/cell (i.e. fully charged) it will quickly reduce to 4.15v/cell (or very very near) as the pack was under load (charge this time) during the charge cycle. I've seen that you've tried to charge at 3.3A, yet you've also stated that your biggest packs are 2200's. Are you parallel charging? If not, you are not doing the packs any good doing that either. The pertainant point is that you shouldn't discharge your cells fully. From the table I posted the lowest level (at rest!) without causing damage to a pack is 3.75v. The voltage of a pack will rise over a period following a discharge a bit so if you've ran a pack hard, leave it a few minutes to get it's true "at rest" ratings. I'm sure Fly will chip in when he's on and set us straight. |
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Post by Dillzio on Sept 17, 2009 14:45:19 GMT 1
Ah, thanks for the feedback. It seems I am being a little harsh on my poor little Lipos. I've never actually had the resting voltage on any of the cells below about 2.9 though (and that was only for a minute) so hopefully I haven't done them any damage.
My Zippy 2200mah 15Cs say on the label not to charge them at over 2C. I've set the charger up to charge them at 2.2 amps (1C) for the normal charge cycle, and 3.1 amps (1.4C) for the fast charge cycle. I though that since the specified maximum for the battery is 2C, 1.4 would be OK. Is this incorrect?
I have been discharging my packs/cells with a light bulb that's drawing 4 amps, I generally run the pack down until my battery alarm goes off (that's set to 2.8v as near as I can figure), which causes the lowest cell to settle on a resting voltage of about 3.4. If one or more cells are still too high, I drain them individually through the balance connector until the voltages are reasonably consistent. I was under the impression that this would be a good break in procedure?
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