Questions for R/C Charger for Li-Ion cells

Hi,

I've got a Tahmazo T-15 Power Up Charger. I've been using this charger for the past year for Nimh and LiPo battery packs => up to 11.1v and they are doing great.

However, this year when i started getting stuck into flashlights I'm getting more and more Li-ions and decided to connect them to the T-15. Thats where I'm having problems. Charging packs and the charger are great. But when charging Li-ion Cells, the v (display) went to 4.19 right away and after awhile its only "charging" less than 100mAh. When I unplug the battery, with the volt meter, theres only 4v in the battery but my charger reads them as 4.2 so its cut off from charging.

This happens to all my Li-ions - 5-6 RCR123s mixed brands, but mostly chinese, a few ultrafire and spiderfire 18650s, AW C cells. After this, I hooked up the charger to the lipo battery packs and its fine, it register the correct voltage and it charges correctly too..

Have any of you guys experience something like this? If so, any suggestions on what i should do/check? btw, the connection to battery is using bannana plugs, through 20awg silver coated wire to magnets (using silver epoxies)

Thanks,
Nicholas

Does it say it has completed charging?
The 4.19Volts will be the charging Voltage not the battery Voltage and if it is still showing 100mA then charging is not complete.
My hobby charger is slow but very reliable. You may needed to be a bit more patient
Norm

my new fma 4s works sometimes funny too, stating at 86% at fuel and tellls me that charging is complete ...

so what i did is, power off and on again, or also called 'reset', then it works!

does yr Tahmazo T-15 Power Up Charger has Li balancer install?
if no, maybe thats why all the errors are coming out.

lastly, can with Tahmazo if u can update yr firmware to support li ions ... ?

i have a hyperion 610 that i got for my rc needs, and i too started using it for my li-ion cells. what i noticed is when i select li-ion, it selects the cell as 3.6 volts, and lipo cells as 3.7. when i used the li-ion setting, it did basically the same thing you described, but when i switched to using the lipo setting, it seemed to charge and register the voltage correctly. one thing you need to do is make sure you have the charge rate at a correct rate of about .2C to .5C. i use .5C mostly on my larger cells, and .2-.4C on my smaller cells. not sure if this helps, but i just wanted to let ya know.:twothumbs

Norm said:

Does it say it has completed charging?
The 4.19Volts will be the charging Voltage not the battery Voltage and if it is still showing 100mA then charging is not complete.
My hobby charger is slow but very reliable. You may needed to be a bit more patient
Norm

Click to expand...

Yes, its actually "trickle" charge after that.. the voltage display is the current Voltage of the cells..

I've actually set the charger at 1-2A.. as per the 1C settings (2000ish for 18650 and 3000ish for C cells).. the 100mAh is the amount thats "filled" to the cell for the charge..

my new fma 4s works sometimes funny too, stating at 86% at fuel and tellls me that charging is complete ...

so what i did is, power off and on again, or also called 'reset', then it works!

does yr Tahmazo T-15 Power Up Charger has Li balancer install?
if no, maybe thats why all the errors are coming out.

lastly, can with Tahmazo if u can update yr firmware to support li ions ... ?

Click to expand...

Unfortunately my version is the older ones, so its not built in balancer. but I'm using the same thing for Lipos packs and its registering fine..

At first I thought that the "voltage meter" in the charger is faulty but with any other batteries, other than Li-ions its fine.. could this be that its "protected" cell? thus the charger are reading different datas?

I'm trying to contact the manufacturer, but they havent replied as yet, so I was wondering if any gurus can help me here hehehehe

i have a hyperion 610 that i got for my rc needs, and i too started using it for my li-ion cells. what i noticed is when i select li-ion, it selects the cell as 3.6 volts, and lipo cells as 3.7. when i used the li-ion setting, it did basically the same thing you described, but when i switched to using the lipo setting, it seemed to charge and register the voltage correctly. one thing you need to do is make sure you have the charge rate at a correct rate of about .2C to .5C. i use .5C mostly on my larger cells, and .2-.4C on my smaller cells. not sure if this helps, but i just wanted to let ya know.

Click to expand...

Crap.. I thought i can charge them to 1Cs... hmm But i did tried using smaller charge @100-200mAH and its still aint working.. The tahmazo is made from the same factory as Hyperion.. but I think they have different set ups.
Mine doesnt have different modes for Li-ions and Lipos.. Its using the same functions

Hello Nicholas,

Welcome to CPF.

I believe the problem you are experiencing is being caused by hook up wire resistance. The Schulze chargers are another brand that are very sensitive to lead wire resistance.

Of course, if your cells have developed higher internal resistance, they will cause the same problems...

Tom

SilverFox said:

Hello Nicholas,

Welcome to CPF.

I believe the problem you are experiencing is being caused by hook up wire resistance. The Schulze chargers are another brand that are very sensitive to lead wire resistance.

Of course, if your cells have developed higher internal resistance, they will cause the same problems...

Tom

Click to expand...

Tom,

Can you suggest me what kind of set ups to reduce the resistance?

At first I was hoping that the cells is the problem -cheaper to replace hehehe.. but seems that it happens to all the cells.... even those that is new and havent been used.

Thanks for all the feedbacks... but still trying to find a solution

Hello Nicholas,

If you look up CPF member cy, in his signature line is a link to the universal charging clamp. In addition to this you can go with heavy gauge wires and soldered ends on the wires. Also, keep the wires as short as practical. Another trick is to wipe the ends of the batteries with a cleaner to make sure you are getting a good connection. Don't forget to twist the cell as you clamp down. This helps remove any oxidation that may cause higher resistance.

To give you an extreme example...

I ran across someone at the RC air field that had a great hobby charger, but their leads were 6 feet long and 22 gauge. In addition, he was trying to charge an 18650 cell and was using magnets for the connection to the cell. Also, the ends on the leads were simply screwed down and not soldered. The complaint was that the cell would not charge to over 4.1 volts.

I let him borrow my charging clamp set up and my 36" 8 AWG wires with soldered ends and his problems went away.

Tom

Tom,

I've seen Cy's clamp method and its one of my "next" to do list ehhehe..

Will try them and let you all know the progress.

Thanks,
Nicholas

Just got reply from the factory. Seems that they program the li-ion to accept a minimum of 2 cells..

So.. my next question, whats the best way to "pack" 2 li-ion cells for charging? should i just used magnets between them? or should I get a pvc pipe, put the 2 cells inside and just use a clamp to squeeze them?

Thanks

Hello N1ch0,

You will get less resistance if you use a clamp.

When charging more than one cell at a time, you have to pay attention to the balance between the cells. When your charger finishes the charge, measure the voltage of each cell. They should be quite close.

If one cell shows a higher voltage, make sure it is not over 4.2 volts. If one cell gets higher in voltage, it can cause a "venting with flame" incident.

Tom

Ok.. thanks.

Dont worry, I'll try to just charge them to 4.1ish... well anything over 4v is already a plus for me, as I'm not very heavy user on any of my light

Thanks again