Two Defective E902 Bantam Estation Chargers

[blueviewlaguna]

I purchased two E902 Bantam Estation Chargers and both have turned out to be defective. The second would not switch to the external load resistor (200w) when it was connected and smoked the internal one (50w). The (main) US importer sent a new unit to replace this second one and all was fine.

I also discovered that my first E-902 had been defective from day one – its been charging to 4.16 volts per cell on every battery (advises FULL and stops) It always showed a full 4.2/cell during the charge cycle on the display but the individual voltages from the balancer would be low. For example, charger stops charging a 6S with individual cell voltages at 4.16 volt, yet the display advises 25.2 volts. Upon measuring the actual voltage of the battery fresh off this charger, its only 24.9 volts (6S measures 25.1-25.2 with my other E-902 and displays 4.20 or 4.19 volts per cell at FULL. Upon further investigation, I discovered that the actual output voltage as measured at the Output One terminals during charges on this particular unit is 0.2 to 0.3 volts LESS than the screen display. For the defective charger 4.16 at full = 24.96. Basically, this charger does not charge at 4.2 volts per cell, whereas the second unit does charge at 4.2 volts and its Output One voltage measures exactly what its display reads. This explains why half of my 6S batteries are always 24.9 volts and the other half 25.1, also my 3S batteries are always either 12.48 or 12.57 off the chargers depending on which charger I use (the faulty one or the correct voltage one).

This was an easy diagnosis once I suspected that the display was wrong – I just measured the actual charge output and saw that the charger does not charge at 4.2 volts per cell. Here are some photos of the first and second units:

1/ First (Defective charger – 25.2 displayed, 25.0 actual (4.16 volts per cell)

2/ Second (Correctly operating) charger – 25.2 displayed, 25.2 actual (4.20 volts per cell)

Once working correctly, these are nice chargers, but with 2 out of 2 bad units, its a concern. The US Importer will not exchange my first one now and has advised that I deal directly with Bantam in Korea or send to him so he can send back and then wait for his next shipment of units to arrive - just him getting his next shipment in took one month last time (for the smoked resistor charger exchange) so now adding time for transportation to him in FL (I am in CA), then FL to Korea, then wait for Bantam to ship with his next shipment, well you get the idea - a lot of time without a 275.00 charger. As a side note, I handle several products (non-RC) through Asia, and would NEVER advise my customer to work directly with the factory - I service them from beginning to end, anyone can tender a sale - its the after-sale level of service that differentiates the various companies in my opinion.

Just a head's up for anyone with these chargers - measure the actual voltage to double check that they do, in fact, charge to 4.2V (not 4.16 V) - the danger here is one assumes that the battery is "FULL" per the E902 display, then uses (what they think is ) 80%, only to (unknowingly) over-discharge the battery to 90% because of the missing 10% from the undercharge. Combined with the long turnaround time (or faced with dealing with Manufacturer in Korea directly) and a seemingly high percentage of defective units, I am a little concerned here.

[RC Accessory]

I purchased two E902 Bantam Estation Chargers and both have turned out to be defective. The second would not switch to the external load resistor (200w) when it was connected and smoked the internal one (50w). The (main) US importer sent a new unit to replace this second one and all was fine.

I also discovered that my first E-902 had been defective from day one – its been charging to 4.16 volts per cell on every battery (advises FULL and stops) It always showed a full 4.2/cell during the charge cycle on the display but the individual voltages from the balancer would be low. For example, charger stops charging a 6S with individual cell voltages at 4.16 volt, yet the display advises 25.2 volts. Upon measuring the actual voltage of the battery fresh off this charger, its only 24.9 volts (6S measures 25.1-25.2 with my other E-902 and displays 4.20 or 4.19 volts per cell at FULL. Upon further investigation, I discovered that the actual output voltage as measured at the Output One terminals during charges on this particular unit is 0.2 to 0.3 volts LESS than the screen display. For the defective charger 4.16 at full = 24.96. Basically, this charger does not charge at 4.2 volts per cell, whereas the second unit does charge at 4.2 volts and its Output One voltage measures exactly what its display reads. This explains why half of my 6S batteries are always 24.9 volts and the other half 25.1, also my 3S batteries are always either 12.48 or 12.57 off the chargers depending on which charger I use (the faulty one or the correct voltage one).

This was an easy diagnosis once I suspected that the display was wrong – I just measured the actual charge output and saw that the charger does not charge at 4.2 volts per cell. Here are some photos of the first and second units:

1/ First (Defective charger – 25.2 displayed, 25.0 actual (4.16 volts per cell)

2/ Second (Correctly operating) charger – 25.2 displayed, 25.2 actual (4.20 volts per cell)

Once working correctly, these are nice chargers, but with 2 out of 2 bad units, its a concern. The US Importer will not exchange my first one now and has advised that I deal directly with Bantam in Korea or send to him so he can send back and then wait for his next shipment of units to arrive - just him getting his next shipment in took one month last time (for the smoked resistor charger exchange) so now adding time for transportation to him in FL (I am in CA), then FL to Korea, then wait for Bantam to ship with his next shipment, well you get the idea - a lot of time without a 275.00 charger. As a side note, I handle several products (non-RC) through Asia, and would NEVER advise my customer to work directly with the factory - I service them from beginning to end, anyone can tender a sale - its the after-sale level of service that differentiates the various companies in my opinion.

Just a head's up for anyone with these chargers - measure the actual voltage to double check that they do, in fact, charge to 4.2V (not 4.16 V) - the danger here is one assumes that the battery is "FULL" per the E902 display, then uses (what they think is ) 80%, only to (unknowingly) over-discharge the battery to 90% because of the missing 10% from the undercharge. Combined with the long turnaround time (or faced with dealing with Manufacturer in Korea directly) and a seemingly high percentage of defective units, I am a little concerned here.

Based on the amount of time that you have had the first one, it would need to be sent back to the factory for calibration. That is all that is needed. I gave you the option of either sending to me to send back or sending it back yourself. I'm sorry that either option was not acceptable for you. If you had sent it back to Bantam since you contacted me, it would have been returned to you by now. Bantam typically turns these around in 48 hours or less barring any Korean holiday's. Express mail delivery is 4-5 days each way. Most US based companies can't turn a repaired or updated product around that fast.

[blueviewlaguna]

Based on the amount of time that you have had the first one, it would need to be sent back to the factory for calibration. That is all that is needed. I gave you the option of either sending to me to send back or sending it back yourself. I'm sorry that either option was not acceptable for you. If you had sent it back to Bantam since you contacted me, it would have been returned to you by now. Bantam typically turns these around in 48 hours or less barring any Korean holiday's. Express mail delivery is 4-5 days each way. Most US based companies can't turn a repaired or updated product around that fast.
I stand by my statement that I would NEVER advise my customer to work directly with the Asian factory - I service them from beginning to end, anyone can tender a sale - its the after-sale level of service that differentiates the various companies in my opinion.

All of my return options with you were with an extended timeline (send to you so you can send back and then wait for your next shipment of units to arrive). If Bantam turns the units around so quickly (something that was not mentioned during our correspondence), then why couldn't you have handled the return?, this only deepens the mystery as to why I was told to contact Bantam directly. For your information, Bantam's first question to me was why I did not contact the distributor I purchased the charger from (I did).

Based on my experience in customer service, representing Asian manufacturers for 25 years and (on the other side) as a customer, I was disappointed with the level of service I received.

[RC Accessory]

I stand by my statement that I would NEVER advise my customer to work directly with the Asian factory - I service them from beginning to end, anyone can tender a sale - its the after-sale level of service that differentiates the various companies in my opinion.

All of my return options with you were with an extended timeline (send to you so you can send back and then wait for your next shipment of units to arrive). If Bantam turns the units around so quickly (something that was not mentioned during our correspondence), then why couldn't you have handled the return?, this only deepens the mystery as to why I was told to contact Bantam directly. For your information, Bantam's first question to me was why I did not contact the distributor I purchased the charger from (I did).

Based on my experience in customer service, representing Asian manufacturers for 25 years and (on the other side) as a customer, I was disappointed with the level of service I received.

I'm sorry that you feel my customer service was not up to your standards but you were given the options. You were not happy with the time frame for turnaround due to the holidays.

First, your purchase of the first 902 was on 8-28-07 when I was contacted by your dealer who purchased the unit, you did not purchase that unit directly from me. That does not make a difference as far my support, but important that you were not my direct customer.

You contacted me on 12-6-07 that the first unit was a concern after you had received the 2nd unit back. The 2nd unit that you exchanged was working fine, your concern was that when used with the external load resistor, that the unit was hot compared to the first unit. I exchanged the unit. Let me say it again, it was working fine.

Coming into the Christmas holiday, Bantam was going to be closed and that would effect the turnaround time if I sent it in. If you sent it in, the turn around time was much quicker, that was why it was given to you as an option. Normally, that would not have been given to you as an option.

If you would like to discuss this with me further, please contact me, you have my email address as well as phone number.

[WayneBrown]

I for one have always had an exceptional experience with Evan.
Evan is a hobbist first, and a vendor second, His primary concern is always that you get what you expect.
Bashing Evan and a product he distributes is in pretty poor taste.
If memory serves, Evan has been in the hobby about the same length of time as I have. ~30 odd years.

[RC Accessory]

blueviewlaguna,

Have you sent your 902 back in for an update yet? If you have not done so, send me your unit and I will send you my personal 902 charger to use in the mean time.

I did not offer this to you before because you have a second unit. If I know that a customers unit is going to be down for longer than normal period of time, I have given them my own unit to use. I know how hard it can be when your only charger is down. Since you did have a 2nd unit to use, I didn't think it was necessary.

Please contact me via email if you would like me to do this for you.

[RC Accessory]

I for one have always had an exceptional experience with Evan.
Evan is a hobbist first, and a vendor second, His primary concern is always that you get what you expect.
Bashing Evan and a product he distributes is in pretty poor taste.
If memory serves, Evan has been in the hobby about the same length of time as I have. ~30 odd years.

Thanks Wayne! :lol: Coming up on 32 years in the hobby. Man, now you make me feel old! I was one of the lucky kids that had parents that allowed such an expensive hobby. I started off flying single stick. OK, time for a nap.:rolling

[blueviewlaguna]

I for one have always had an exceptional experience with Evan.
Evan is a hobbist first, and a vendor second, His primary concern is always that you get what you expect.
Bashing Evan and a product he distributes is in pretty poor taste.
If memory serves, Evan has been in the hobby about the same length of time as I have. ~30 odd years.
My intent is to inform, not to "bash" - I have presented the facts of my experience and also my opinions (and so stated). Is sharing either of these in poor taste? We can only share our own experiences and let other members decide for themselves. If you have experiences with other vendors, I would hope that you would share them as well (good or bad) - its a crucial benefit of the forum. The first experience with Evan was great - fast exchange (and so stated in the post). It is a philosophical difference between us as to whether its acceptable to send a customer directly to the overseas vendor to resolve issues.

As far as the product, the facts are the facts - the Bantam chargers I received had issues. Period. I feel that knowing the issues beforehand will allow an informed decision - again shall I not share this information and let someone receive and use a bad unit when they could just perform a quick check with a voltmeter and return for a good one?

As stated, these are good chargers and I still use them exclusively. Almost all products have issues, the key is sharing them with others to work through them. Again, I would hope that you would do the same so I can either return or work around the issues.

[RC Accessory]

My intent is to inform, not to "bash" - I have presented the facts of my experience and also my opinions (and so stated). Is sharing either of these in poor taste? We can only share our own experiences and let other members decide for themselves. If you have experiences with other vendors, I would hope that you would share them as well (good or bad) - its a crucial benefit of the forum. The first experience with Evan was great - fast exchange (and so stated in the post). It is a philosophical difference between us as to whether its acceptable to send a customer directly to the overseas vendor to resolve issues.

blueviewlaguna, I'm sorry but I also believe it was your intent to bash. If it wasn't you could have simply said that you found the issue in one of your 902 chargers and that if anyone else had a 902 charger they should check them. Instead you went on and on about my customer service, or lack of. That I told you to go to the factory on your own. As stated before, due to Bantam being closed for the holidays, the length of time to turn the charger around would be longer than if you sent it yourself. I'll remember not to offer that suggestion anymore as it obviously has the wrong message.

My offer still stands to send you my own personal unit to use while yours is at the factory for a calibration.

[blueviewlaguna]

blueviewlaguna, I'm sorry but I also believe it was your intent to bash. If it wasn't you could have simply said that you found the issue in one of your 902 chargers and that if anyone else had a 902 charger they should check them. Instead you went on and on about my customer service, or lack of. That I told you to go to the factory on your own. As stated before, due to Bantam being closed for the holidays, the length of time to turn the charger around would be longer than if you sent it yourself. I'll remember not to offer that suggestion anymore as it obviously has the wrong message.

My offer still stands to send you my own personal unit to use while yours is at the factory for a calibration.
Thanks for the offer - let's chalk it up to a philosophical difference between us and move forward.

[WayneBrown]

AFAIK Evan is the only importer that I know, so to state that the importer would not satisfy you presents a skewed slant in the opening statement, implying that Evan would not stand behind his product(s), I know that to be untrue, as do many others.
I get beat up for standing up for those products and people I know are straight up and honest, so be it. :)
I know about 10 people with the same charger, and while we have not compared to a VOM, I'm comfortable that they are within a full volt, or .5 volt of each other.

[blueviewlaguna]

AFAIK Evan is the only importer that I know, so to state that the importer would not satisfy you presents a skewed slant in the opening statement, implying that Evan would not stand behind his product(s), I know that to be untrue, as do many others.
I get beat up for standing up for those products and people I know are straight up and honest, so be it. :)
I know about 10 people with the same charger, and while we have not compared to a VOM, I'm comfortable that they are within a full volt, or .5 volt of each other.
I am reporting my experiences, and its up to other forum members to decide the value of the information I have offered. You have stated your opinion as I have mine - both have equal weight.

As a side note - lipo chargers must operate within a very narrow voltage range (4.15 to 4.25) per cell. A full volt or even 0.5 volt is a major defect in a lipo charger. Imagine undercharging a 3S pack to only 11.6 volts or even 12.1 volts, then flying for (what is thought to be) 80% of its capacity, only to ruin the battery due to over-discharge. Or worse, overcharging the same amount. I bought a third E902 charger today and it measures within 0.01 volt of my other E902 - clearly the first E902 was defective. If you are comfortable with chargers that are within a full volt, or 0.5 volt of each other then I suggest a safe distance when charging!:flamedevil

[Mercuriell]

I started off flying single stick

You were lucky !! - I had two push buttons and reed relays driving non-propo actuators on rudder.

PS - I've had great experience with my 902 and PB6 balancers - checked my voltage output tonight and it was spot on. Only wish they'd make a 10S balancer!

[blueviewlaguna]

You were lucky !! - I had two push buttons and reed relays driving non-propo actuators on rudder.

PS - I've had great experience with my 902 and PB6 balancers - checked my voltage output tonight and it was spot on. Only wish they'd make a 10S balancer!
I just link up my two PB6's - they communicate with each other and work as a single 12S balancer this way.

The only other thing to watch for on these E902's is to check the internal temp reading to be sure that it switches to an external load resistor when discharging at a rate of over 50 watts, otherwise you will cook the internal load resistor which is only 50 watts. For example, if you program a discharge at 6.6 amps for a 6S (166 watts), press the display button a few times to be sure the internal temp is not rising. If it is, then stop and restart the discharge sequence.