MHC9000 & CCRANE?

[Al]

Hope this doesn't seem a foolish thread BUT ...

I don't have a C9000 (yet) but I do have a few CCranes'. Although not having near the versatility of the C9000 they do have option to select a conditioning cycle, have a digital readout battery check, and automatic "soft/fast" charging sequence followed by a top-off and then maintenance trickle. AAA, AA, C, D batteries and more if adapters are used.

Disregarding some of the mechanical problems some have experienced with CCranes', I wonder how the end result (charged batteries) compares with the new hi-tech chargers i.e. the MHC9000?

CCrane chargers pre-date most of the newer techie chargers by years. Someone was thinking ahead back then.

 

[SilverFox]

Hello Al,

I have not updated this thread with the C9000 information yet, but it comes in just above, but almost exactly the same as the C808M.

Tom

 

[Al]

Any info on what is going on during "soft start", "fast charge", and "trickle"
stages of charging? (CCrane)

 

[jusko]

The CCrane is a single channel charger. 4 cells are being charged in parallel, as a result that all 4 cells have pretty much the same voltage when charging terminates. Charging 4 cells in parallel, I think, is a good idea. But don't know why this idea is not popular among charger manufacturers.

 

[Al]

Charging 4 cells in parallel, I think, is a good idea. But don't know why this idea is not popular among charger manufacturers.

Me neither. Of course the cells should, I think, be in good condition and reasonably balanced to begin with. On the other hand, maybe the level of discharge might automatically regulate the charging process of 4 cells in parallel because of internal resistance differences.

I've noticed that my CCranes' will refuse charging if a bad cell is present.

 

[SilverFox]

Hello Al,

In general, it is not recommended to charge Nickel chemistry in parallel. It can be done, but special precautions are needed. I think the CCrane can get away with it because of the automatic discharge. It can be bypassed, but if your cells are acting up, I would expect an effort would be made to use the discharge function to bring cells back closer in balance.

The soft start feature starts the charge at a low current rate. The fast charge is the main charge current, and when you are charging in parallel, you have to stop the charge early. Peak detection and negative delta voltage detection is not reliable when charging in parallel. The trickle charge is used to bring the cells to a full charge. With parallel charging, an extended trickle charge is required to fully charge the cells.

Tom

 

[Al]

My experience with CCrane chargers exactly. I test cells with the "battery analyzer" feature, match cells, and do the conditioning if warranted. After charge termination I usually leave things in the "trickle" mode for a few hours.

I've got a set of 6 Energizer 2500's (a proven good set) used in a pair of Motorola FRS'.
At times this set of batts. waits patiently uninstalled for a month before use. Today I checked the set after 2 1/2 weeks. Each battery measured full at 1.37V.

Don't know how accurate the CCrane analyzer is, but I'd consider the above as good results.

 

[eluminator]

I've never had the CCrane refuse to charge a cell. Your cell must have been really bad.

The soft start allows charging cells that are in bad condition due to such things as over discharge. It ramps up the charging current slowly. Other chargers sometimes won't charge these cells, but my CCrane always does.

It doesn't use negative delta V to terminate the fast charge. Many chargers do, and they sometimes overheat cells. The fast charge is terminated earlier in the cycle by a more complicated way that looks at the shape of the volts versus time curve. They call it delta V square over delta t square.

After the fast charge, the charging current is reduced and it does the top off thing. Top off seems to be terminated by negative delta V.

Sometimes the CCrane doesn't fully charge my cells that have been abused. My digital camera likes to abuse cells. I can see that they aren't fully charged by looking at the voltage. I usually put them through a discharge/recharge cycle, but maybe just starting another charge would do the job.

The Saitek manual has a little more detail than the CCrane manual. It seems to be the same charger in a different package. The Saitek also has a simple 16 hour timed charge for 9 volt batteries, but it's no longer being sold.
http://www.hypercon.net/~blisscomm/Pictures/CPF/Saitek_CCrane_charger/Saitek_SmartCharger.pdf

 

[jusko]

Hi, Tom,
With 4 cells charging in parallel, will there be more current flowing through the cells with less capacity remaining ? Will the capacity of all 4 cells even out nearing the ending of charging ? I find that with the Saitek/CCrane charger, all 4 cells have quite even voltage after charge completion.

Best Regards
jusko

 

[Al]

The Saitek manual has a little more detail than the CCrane manual. It seems to be the same charger in a different package.

Are you sure? Seems like similar features but much different housing + 9V.

Thanks for the link

 

[SilverFox]

Hello Jusko,

In a parallel circuit, the voltages of the batteries will equal out, but not their capacities. In the extreme case, if one cell is full and the other is empty, and both are paralleled for charging, the full cell may trip the end of charge signal leaving the empty cell under charged. If it doesn't, the full cell will be overcharged as the empty cell is charged.

When you examine a voltage curve during charging, you will see a sudden rise in voltage at the very beginning of the charge, then the slope of the voltage curve settled down until the end of the charge. At the end, it, once again, rises to a peak, then drops down, slightly for NiMh chemistry, and more pronounced for NiCd chemistry.

The point at where the voltage rises near then ed of the charge occurs at roughly 85% of the full charge. This signal is rather large and the possibility of overcharge is minimal, even if your cells are a little out of balance. Now a top off charge is applied to bring the cells to a full charge and balance them. Unfortunately, warm chemistry and a reduced charging current make any charge termination signal very difficult to determine, so the top off charge is usually timed.

This charging method takes longer, and the completeness of the charge and the balance of the cells is dependent on the amount of time allocated for the top off charge.

Tom

 

[Al]

Going thru the info here:

http://www.hypercon.net/~blisscomm/...martCharger.pdf

Saitek mentions a variety of features employed during the charge process which apparently applies to the CCrane chargers as well. Among these are:

Negative Pulse
Negative Delta V
Delta V Square over Delta t Square.

Are these features the norm in most modern smart chargers such as the MH8XX series and the C9000?

 

[Al]

Interesting ...

http://www.rcbatteryclinic.com/burp.html

 

[jusko]

Thank you Tom and I appreciate your explanation.

But in practical use, I find the Saitek Smart charger never miss a termination and in very rare occasion does it refuse to charge a cell. Also, I always check the V of cells after charging and find that all 4 cells have almost equal voltage. It is a very reliable charger indeed.

Best Regards
jusko

 

[SilverFox]

Hello Al,

The only application that has shown "burp" charging as beneficial has been in the airline industry. On a twin engine plane, the battery is run down a lot while starting the first engine. The shore based charger recharges the battery in a very short time to enable starting the second engine. "Burp" charging allows a faster charge rate and is used in these shore based chargers.

At lower charge rates (5C or below) there is little evidence that "burp" charging offers any benefit. I don't think it does any harm, so don't be concerned if your charger uses it.

Tom

 

[SilverFox]

Hello Jusko,

It sounds like Saitek got it right.

However, in general, battery manufacturers do not recommend charging Nickel chemistry batteries in parallel. Can it be done? Yes. Is it recommended? No.

Another charger that does a good job with parallel charging is the RipVan Lightning Pack 4000N.

Tom

 

[Al]

Ok, guys, at the risk of belaboring this thread ... (I like my CCranes')

Battery analysis:

ZTS testers have been dealt with on CPF.
BC-900, MHC9000 and perhaps other chargers measure battery capacity AFTER charging.

CCrane has a "Battery Analyzer" feature. Place one cell (AA, AAA, C, D) in any slot, leave the lid open and press the button. 10 sec. later the LCD screen shows a digital readout (X.XX) of voltage and a bargraph display of remaining capacity. I believe the tested battery is subjected to a load for accuracy because if the process is repeated a number of times in succession, the values begin to drop.

I would like to see this capability, or know if it is available, in other chargers.

 

[eluminator]

Are you sure? Seems like similar features but much different housing + 9V.

Thanks for the link

The CCrane and Saitek chargers are certainly similar. The LCD displays show the same things. The switches have the same functions.

I'm not saying these are the best chargers, but they must be among the smartest. Consider that you can put anything in there from one AAA cell to 4 D cells. The charger just sees one cell because they are connected in parallel. There is no way for the user to tell the charger what's in there. The user can't specify the wrong charging current either, or any charging current for that matter. The charger takes full responsibility. There is no temperature sensor, possibly because that could be unreliable. There's no timer either. Somehow the charger figures it out and gets the job done.

 

[eluminator]

I don't know if the CCrane/Saitek charger burps, but it does charge in pulses, I think. I figure that's a fancy way of saying the power supply has poor filtering. , But I suppose there's no reason to filter it if it does no harm. It even pulses the trickle charge. A brief pulse every few seconds.

You can get some insight into its operation by powering it with a bench power supply and watching the current draw. You can see the current ramp up during soft start. You can see the current drop when it switches to top off mode. When I was watching, I think the current reduced to 1/3 the fast charge current. You can see the pulses during trickle charge. You can see that it charges with a different current depending on what cells you put in, and what their state of charge is.

I guess it has a switching power supply. It has two toroids on the board. I don't know how it dissipates the energy when discharging cells. I don't see any power resistors. Maybe it shoves the energy back into the grid and spins my electric meter backwards, but I doubt it.

Here's what the innards of the CCrane look like. The top board is the user interface. It has an LCD display and switches on the other side.

 

[eluminator]

I just found out that DBL 494 chip is a Daewoo designed for making pulse width modulated switching power supplies. I guess in this case the pulses are going straight into the cells.
http://www.ortodoxism.ro/datasheets/DaewooSemiconductor/mXuuyzs.pdf

I've noticed that the charger is silent when charging, but when discharging it produces a tone that can be heard up close in a quiet room. So what does that mean? Is it changing the electrical energy to acoustical energy and radiating it, or is it a byproduct of spinning my electric meter backwards?

And I also discovered there is a small power resistor on the back of the board. It looks like a .1 ohm 1 watt resistor. Well the color bands are brown-black-silver, and I'm not sure of the wattage. Possibly 2 watt.

The thing that amazes me is there seems to be no brain in this thing. I had assumed the one and only IC was a microcontroller, but apparently that's not the case. Maybe there's a chip hidden under the LCD display. I took one apart once, but I don't remember what I saw under there.