kgfly
08-09-2008, 10:12 AM
Review - Assan 6S Li Cell Monitor
Have you ever wanted to quickly check you pack voltage but didn't have a meter handy ? What about checking the cell balance before or after use ? Even with a meter that can be tricky as it is so fiddly to probe the balance lead and you have to take great care not to short a cell.
For some time now several vendors have been offering cheap little cell checkers that plug into the balance lead and report the cell voltages. I decided to get hold of a few and check them for accuracy. As I was investigating I came across an announcement from Assan that they were about to release and new 6S unit and they agreed to send me one to test.
Disclosure - I did not pay for any of these test units, they were all donated for evaluation and testing. Since they sell in the range of $5-$20 there is little financial incentive to bias my evaluation of any of the units and I hope you will take my word that this was an unbiased test and an honest review.
Summary
All the devices tested are useful as a quick check to see if a pack is charged or used and whether there is any gross imbalance. The Assan is more accurate than the others, living up to its 10mV accuracy specification, compared to 30mV claimed but not delivered for the others.
The Assan unit's low-power mode allows it to be used as a kind of in flight lipo alarm which many might find useful to try out to see how hard they are pushing their packs.
At around $10 they are useful to have in your flight kit so long as your packs don't have TP/FP balance leads which with their 2mm pin spacing won't fit any of the monitors without an adapter cable to match the expected 2.54mm (0.1in) pin spacing.
Recommendation
If you are going to get one of these then at the right price the Assan 6S Monitor stands ahead of the others for features, accuracy and presentation. The ability to be used as simple in-flight LV alarm adds to its appeal and value over the others.
Notes
1) The Assan unit is the largest and most professionally presented of the three. It comes in a hard plastic case with a fitted foam collar. The case contains a clear and simple instructions.
2) On the Assan unit the last digit would sometimes go blank. A little tap or squeeze would bring it back on again, indicating a poor solder joint in there somewhere.
3) Weights: Assan = 15g, HC6S = 6g, HC3S = 8g
4) Usability is fairly close. All are simple to use. All are protected against reverse polarity which is vital since you are bound to plug them in backwards now and then. The Assan provides more information since it has a 5-digit display rather than 3-digits on the others. This makes it quicker to cycle through the cells.
The HC6S has to display the label and then the value so for a 6S pack there are 14 steps to the cycle: Ttl, <value>, C1, <value> ... , C6, <value>
The Assan 6S has half as many since the label and value appear at the same time: A <value>, 1 <value>, 2 <value> ... , 6 <value>
The 3S unit does not display a total and simply moves the decimal point to indicate which cell. I found this is disconcerting at first and annoying in the end.
5) Only the Assan unit offers a low-power (15ma vs 70ma) mode where it can be left connected during flight as a low-voltage alarm. There is a small switch on the end of the unit which is used to select this mode.
In low-power mode it runs through the normal display cycle 3 times and then turns off the display but continues to monitor the cells. If any cell falls below 3.4V it will turn the display on and flash the cell number. You don't have to be able to read the display, if you notice it alive and flashing in flight (which you should, it is large and bright) then you know at least one cell has fallen below the threshold.
6) Both the 6S units are smart enough to display/cycle through only as many cells as are connected. The 3S unit still cycles through all three but displays "no" for any missing cells.
Here is a brief video showing them in action:
http://www.youtube.com/v/RMGUfYVbZ30
Photos to follow.
Have you ever wanted to quickly check you pack voltage but didn't have a meter handy ? What about checking the cell balance before or after use ? Even with a meter that can be tricky as it is so fiddly to probe the balance lead and you have to take great care not to short a cell.
For some time now several vendors have been offering cheap little cell checkers that plug into the balance lead and report the cell voltages. I decided to get hold of a few and check them for accuracy. As I was investigating I came across an announcement from Assan that they were about to release and new 6S unit and they agreed to send me one to test.
Disclosure - I did not pay for any of these test units, they were all donated for evaluation and testing. Since they sell in the range of $5-$20 there is little financial incentive to bias my evaluation of any of the units and I hope you will take my word that this was an unbiased test and an honest review.
Summary
All the devices tested are useful as a quick check to see if a pack is charged or used and whether there is any gross imbalance. The Assan is more accurate than the others, living up to its 10mV accuracy specification, compared to 30mV claimed but not delivered for the others.
The Assan unit's low-power mode allows it to be used as a kind of in flight lipo alarm which many might find useful to try out to see how hard they are pushing their packs.
At around $10 they are useful to have in your flight kit so long as your packs don't have TP/FP balance leads which with their 2mm pin spacing won't fit any of the monitors without an adapter cable to match the expected 2.54mm (0.1in) pin spacing.
Recommendation
If you are going to get one of these then at the right price the Assan 6S Monitor stands ahead of the others for features, accuracy and presentation. The ability to be used as simple in-flight LV alarm adds to its appeal and value over the others.
Notes
1) The Assan unit is the largest and most professionally presented of the three. It comes in a hard plastic case with a fitted foam collar. The case contains a clear and simple instructions.
2) On the Assan unit the last digit would sometimes go blank. A little tap or squeeze would bring it back on again, indicating a poor solder joint in there somewhere.
3) Weights: Assan = 15g, HC6S = 6g, HC3S = 8g
4) Usability is fairly close. All are simple to use. All are protected against reverse polarity which is vital since you are bound to plug them in backwards now and then. The Assan provides more information since it has a 5-digit display rather than 3-digits on the others. This makes it quicker to cycle through the cells.
The HC6S has to display the label and then the value so for a 6S pack there are 14 steps to the cycle: Ttl, <value>, C1, <value> ... , C6, <value>
The Assan 6S has half as many since the label and value appear at the same time: A <value>, 1 <value>, 2 <value> ... , 6 <value>
The 3S unit does not display a total and simply moves the decimal point to indicate which cell. I found this is disconcerting at first and annoying in the end.
5) Only the Assan unit offers a low-power (15ma vs 70ma) mode where it can be left connected during flight as a low-voltage alarm. There is a small switch on the end of the unit which is used to select this mode.
In low-power mode it runs through the normal display cycle 3 times and then turns off the display but continues to monitor the cells. If any cell falls below 3.4V it will turn the display on and flash the cell number. You don't have to be able to read the display, if you notice it alive and flashing in flight (which you should, it is large and bright) then you know at least one cell has fallen below the threshold.
6) Both the 6S units are smart enough to display/cycle through only as many cells as are connected. The 3S unit still cycles through all three but displays "no" for any missing cells.
Here is a brief video showing them in action:
http://www.youtube.com/v/RMGUfYVbZ30
Photos to follow.