EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: BS3DP on April 09, 2017, 07:04:38 am
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Hey guys
I know I'm new to the forum and all but iv run into a bit of a small problem. I thought I would be able to work this out myself but I just find a better solution.
I'm currently building a custom Bluetooth speaker to take to work. The issue iv run into is that when using a TP4056
http://www.ebay.com.au/itm/10pcs-5V-Mini-USB-1A-18650-Lithium-Battery-Charger-Board-Module-TP4056-TE584-/172338310404?hash=item282029ed04:g:yYcAAOSwknJX1U~I (http://www.ebay.com.au/itm/10pcs-5V-Mini-USB-1A-18650-Lithium-Battery-Charger-Board-Module-TP4056-TE584-/172338310404?hash=item282029ed04:g:yYcAAOSwknJX1U~I)
Iv got the issue that the amp draws a little over the 1amp limit and starts losing power because the TP4056 board that's monitoring the battery pack (6 18650 cells wired in parallel) can't output more than 1amp.
Is there an alternative board similar and as cheap as the TP4056 board?
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You can try the 3amp version which is just what you have in parallel
http://www.ebay.com.au/itm/1PCS-TP4056-4-2V-3A-High-Current-Lithium-Battery-Charging-Board-Charger-Module-U-/302160585170?hash=item465a2ca1d2:g:MKgAAOSwEzxYSS~z (http://www.ebay.com.au/itm/1PCS-TP4056-4-2V-3A-High-Current-Lithium-Battery-Charging-Board-Charger-Module-U-/302160585170?hash=item465a2ca1d2:g:MKgAAOSwEzxYSS~z)
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See im not to sure because its not like i need faster charging but a higher output to allow the amp to draw enough power from the battery pack. Like is that a 3amp charging output or is that a bms that doesnt limit the appliance output.
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It is obvious you bought one of the more expensive charger boards that protects. Protects from what? You doing something stupid? If you are pretty sure you won't do that, just connect load directly to the battery. Protection We don't need no damn protection.
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See im not to sure because its not like i need faster charging but a higher output to allow the amp to draw enough power from the battery pack. Like is that a 3amp charging output or is that a bms that doesnt limit the appliance output.
That appears to be only parallel 4056's, so does not have the undervolt/overvolt/overcurrent protection.
The protection is handled by the DW01 (6 pin chip) and the 8205A on the pcbk, the DW01 is the protection IC, and the 8205A is a dual mosfet.
The DW01 circuits normally are configured to use the RDSon of the dual fet as it's current sense, when the current is sufficient to cause about 150mV drop across them it shuts them down.
To quote from the datasheet
3. Overcurrent Protection
In normal mode, the DW01-P continuously monitors the discharge current by sensing the voltage of
CS pin. If the voltage of CS pin exceeds the overcurrent protection voltage (VOIP) beyond the
overcurrent delay time (TOI1) period, the overcurrent protection circuit operates and discharging is
inhibited by turning off the discharge control MOSFET. The overcurrent condition returns to the normal
mode when the load is released or the impedance between BATT+ and BATT- is larger than 500k?.
The DW01-P provides two overcurrent detection levels (0.15V and 1.35V) with two overcurrent delay
time (TOI1 and TOI2) corresponding to each overcurrent detection level.
The two levels are used for normal overcurrent (150mV dropped, TOI1) which has a delay of 10-20ms, and short circuit (1.5v dropped, TOI2) which has a 500uS delay.
Anyway, the CS (Current Sense) is connected via 1k resistor to one side of the dual fets, and ground is connected to the other as you can see in the application circuit (M1 and M2 are both inside the 8205A IC)...
(http://i.imgur.com/8GAwPWw.jpg)
I see no reason that you could not therefore make a small hack to your existing board to instead have a dedicated current sense resistor which you can then size according to Ohm's law to produce the required voltage drop at your desired maximum current. The 8205A should be able to handle 3A of current OK physically.
(http://i.imgur.com/6t8hrlz.jpg)
I would use a sense resistor that can dissipate at least 1W.
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It is obvious you bought one of the more expensive charger boards that protects. Protects from what? You doing something stupid? If you are pretty sure you won't do that, just connect load directly to the battery. Protection We don't need no damn protection.
Using li-on cells should always be protected with a protection circuit because dead cells or over charged can be dangerous. Iv had cells blow up on me so of course i would use a protection circuit.
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You don't know enough to know what I said.
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I see no reason that you could not therefore make a small hack to your existing board to instead have a dedicated current sense resistor which you can then size according to Ohm's law to produce the required voltage drop at your desired maximum current. The 8205A should be able to handle 3A of current OK physically.
(http://i.imgur.com/6t8hrlz.jpg)
I would use a sense resistor that can dissipate at least 1W.
Hi sleemanj
thanks a lot for your great reply, I have added an R050 Current sense resistor as shown in the attached photo
I'm using a 9 cell 2600 mAh, the output pins of the charger module are connected to a DC-DC step up converter xl6009 module, after
the modification to the protection circuit, I'm able to get 1.37 A at 12v from the step up converter compared to 0.89 A at 12v which drops to 0
(when dw01 protection activates) before the MOD, thus while connecting a load of two 12v car bulbs each drawing 2.5A
I'm using the bulbs to determine the max Ambs I can get before the protection activates, the actual load is a router 12v 1.5A
but I noticed that while charging, the blue LED turns on while the battery is at 95% of charge, while when I connect another charging module (unmodified)
the charging process continuous until the charge percentage reaches 98%
what could cause that ?!, did I do the MOD correctly as you pointed out ?!
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If your app needs up to 2A you might want to have a look at this module i make TP5100FLEXADV-V2.00 (https://easyeda.com/catech75/TP5100FLEXADV_V2_00-99adcfd808554bc3ad45ced7558ab601)
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If your app needs up to 2A you might want to have a look at this module i make TP5100FLEXADV-V2.00 (https://easyeda.com/catech75/TP5100FLEXADV_V2_00-99adcfd808554bc3ad45ced7558ab601)
Thank you so much for your reply & help