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TP5000 module review (and technical details)
#11
(03-26-2019, 01:37 AM)fannel Wrote: I wish I could figure out how to toggle the charge current between 300 mA, 500 mA and 1000 mA



Just take a 3-position toggle switch and 3 resistors and put in place of where Rs is at. Then you can toggle between the 3 charge currents. If you want to control this via an MCU, then you would need to add in some transistors that are controlled by the MCU.
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#12
(03-26-2019, 01:37 AM)fannel Wrote: Korishan, thanks for your reply and the link to the datasheet

"Looks like you could put an SMD switch on the board to switch between LiIon and LiFe. "

Thanks Geek for the reply. I wish I could figure out how to toggle the charge current between 300 mA, 500 mA and 1000 mA

You could use a resistor ladder. 2 50milliohm and 1 100miliohm resistor(s) in series. Then you could switch between  500, 1000, and 2000.

Edit: -Korishan beat me..
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#13
Geek has the better layout. I was thinking each leg of the switch went to each resistor. But the ladder is far better and easier to implement. And probably more accurate in the end, too.
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#14
Thanks Korishan and Geek. This is really helpful. The only things I know in electronics are stuff i learned in physics in high school 30 years ago. An MCU is above my capacity, but I could start something with the toggle switch or resistor ladder (new term for me; just learned it today, thanks Geek). I have 20 TP5100 units on the way from China to play with when they arrive
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#15
(03-26-2019, 02:08 AM)fannel Wrote: Thanks Korishan and Geek. This is really helpful. The only things I know in electronics are stuff i learned in physics in high school 30 years ago. An MCU is above my capacity, but I could start something with the toggle switch or resistor ladder (new term for me; just learned it today, thanks Geek). I have 20 TP5100 units on the way from China to play with when they arrive

I really like resistor ladders. If you don't need fine adjustment, they are far more reliable than POTs. I have heard some horror stories of POTs failing (on boost converters and CC/CV supplies) and blowing electronics up, or overcharging batteries. Using a resistor ladder, you have the advantage of being able to see what value is selected, without using a multimenter.
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#16
Looks to me like the big difference between the TP5000 and TP5100 is that the TP5000 can be set for either Li-Ion or LiFePO4, whereas the TP5100 can be set for 1 Li-Ion cell (4.2V Max) or 2 Li-Ion cells in series (8.4V Max) Which would explain the larger input Voltage range on the TP5100. If you want to charge 2 cells in series, you'd need at least 8.8V input.

Looks like the TP5100 is cheaper, but has 2 current control resistors in parallel. I'm not sure why that is, but I guess they could be replaced by a single resistor to get the desired current.
-Mike G
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#17
(03-26-2019, 04:01 AM)rebelrider.mike Wrote: Looks to me like the big difference between the TP5000 and TP5100 is that the TP5000 can be set for either Li-Ion or LiFePO4, whereas the TP5100 can be set for 1 Li-Ion cell (4.2V Max) or 2 Li-Ion cells in series (8.4V Max) Which would explain the larger input Voltage range on the TP5100. If you want to charge 2 cells in series, you'd need at least 8.8V input.

Looks like the TP5100 is cheaper, but has 2 current control resistors in parallel. I'm not sure why that is, but I guess they could be replaced by a single resistor to get the desired current.

That's interesting Mike. I was going to replace the Rs resistor with a resistor ladder based on suggestions from Korishan and Geek above to be able to select the charging current. Their suggestions are based on the TP5000, but what i have actually ordered is the TP5100. So, based on your statement above, I will need to replace two resistors instead, right?
Since they are in parallel, i will just need to duplicate the set up in parallel, bu then again, when resistors are in parallel, their resistance decreases, so it looks like more calculations are needed to get the proper values for the resistors to be used
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#18
(03-26-2019, 04:01 AM)rebelrider.mike Wrote: Looks like the TP5100 is cheaper, but has 2 current control resistors in parallel. I'm not sure why that is, but I guess they could be replaced by a single resistor to get the desired current.

Where are you seeing the 2 resistors?  In the datasheet for the TP5100 it only shows 1. If it's a PCB designed that way, they probably did that use existing resistors on hand and paralleled them to get a lower setting than what a single resistor would do.

https://cdn.datasheetspdf.com/pdf-down/T...pPower.pdf


Or are you referring to a design like this:


The circled resistors do appear to be in parallel. Not sure why they did that in that design, unless it's specifically to keep heat down. Each resistor would take 1/2 the heat generated. So if that's the case, fannel could still do a resistor ladder, but just run two parallel ladders, like a real ladder with 2 uprights and rungs at each step.
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#19
I thought I read somewhere that they did that so you could easily adjust the current by removing a resistor?
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#20
(03-26-2019, 12:35 PM)Korishan Wrote: Or are you referring to a design like this:


The circled resistors do appear to be in parallel. Not sure why they did that in that design, unless it's specifically to keep heat down. Each resistor would take 1/2 the heat generated. So if that's the case, fannel could still do a resistor ladder, but just run two parallel ladders, like a real ladder with 2 uprights and rungs at each step.

From what I've seen, those are the resistors that control the current. I have no idea why you'd want two in parallel, but then I'm still a noob at this stuff. All the boards I've seen for sale are configured like this. Another thing to note is that the TP5100 boards I've seen have no balancing feature, when configured for 2 cells. So another solution like a 2s BMS would be needed. Y'all probably know this already, but I thought I'd throw it in. Smile

I'm very interested in doing some kind of project with these boards in the future.
-Mike G
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