LiPo chargers again

Preamble

Following on from GhettoVaper – an extended GhettoVape III, I thought that I would add, if possible, the ability to balance charge the LIPos via a micro USB port. However, as the battery configuration is 2P, and not 2S, it may not be possible.

This time we are looking at PCB chargers, and Battery Management Systems (BMS).

See also

Videos

Balanced 3S charger. These videos show the commonTP4056, as used byJulian Ilett, see:

Balanced 3S Lithium Cell Charger using the TP4056

More Details on the Balanced 3S Lithium Cell Charger using the TP4056

Two types of TP4056 PCB

Without over-charge protection:

 

With over-charge protection

 

I purchased the over-charge protection type, Hot Micro USB 5V 1A 18650 Lithium Battery Charging Board Charger Module 2PCS, C $0.56 (£0.34)

Other BMS PCB

I purchased a 2S3A over charge/discharge and protection circuit, 2S 3A Li-ion Lithium Battery 18650 Charger Protection Board BMS Module 7.4V 8.4V for £0.76.

2S 3A PCB
2S 3A PCB

Product features:

Main IC using original “precision” imported components. With over charge, over discharge, over current, short circuit protection function, for a variety of different shapes of 3.7V capacity lithium batteries. Sophisticated design, fine workmanship, comprehensive test. Compact size, suitable for many requirements of high integration, low cost occasions, can meet the performance requirements of many aspects, to ensure the absolute safety of the battery group.

 

Main function:

Over charging protection, over discharge protection, short circuit protection, over current protection function.

 

Technical parameter:
Overcharge Detection Voltage: 4.25-4.35V±0.05V
Over Discharge Detection Voltage: 2.3-3.0V±0.05V
Maximum Working Current: 3A
Transient Current: 5A
Operating Temperature: -40-50℃
Internal Resistance: Less than 45m Ω

 

Connection description:
B+ B-: The interface of battery core
P+ P-: The connector of battery board
MB: The connection point between the batteries
B+: Battery V+ Positive
B-: Battery V- Negative
P+: Output / Charging V+
P-: Output / Charging V-

 

from 2Pcs 3A BMS PCB Protection Board For 2 Pack 18650 Li-ion lithium Battery Cell 2S

Wiring diagram
Wiring diagram

 

From Lithium Ion 2S 7.4V 3A Over Charge-Discharge Protection PCB:

2S 3A LiPo PCB

Note the IMPORTANT in the image above:

IMPORTANT
In order to activate the protection module output, a charge voltage must be briefly applied to the P+/P- terminals after the batteries are connected to it. This must be repeated if the batteries are disconnected from the protection PCB.

This PCB does not balance charge, you need the following:

From 3A-15A-2S-BMS-PCB-Protection-Board-for-2-Packs-18650-Li-ion-Lithium-Battery-Cell:

 

 

 

Charging and balancing batteries in parallel

See Can I use multiple 18650 batteries in parallel with a standard MicroUSB 3.7V charger board?:

  • The use of 18650 LiPo batteries in parallel is risky business. Even if you have a perfectly matched pair to begin with, as they age, their characteristics will change and there may be complications that arise thereof;
  • If the batteries are charged individually, then the batteries will then require balancing. This circuit can be used to balance them, with the resistor values of 1kΩ
    Balance circuit
    Balance circuit

     

See also Balance Charging: Can you parallel charge?:

  • Batteries connected in parallel will balance by themselves, due to potential differences, and Ohm’s law, or should that be equilbrium, but a balance circuit should be used:
    • Big potential differences between cells will result in large discharge currents can cause fires, damage etc
    • Parallel balancing of LiPo packs (2S, 3S etc), will balance only the like cells, so the first cells of each pack will be balanced between themselves, and the second, and third and so on – but the first, second, third, and so on, cells in the same pack will not be balanced.
  • Charging cells in parallel may result in different charging currents to each cell, due to varying internal resistance of the cells:
    • So changing at nC x num cells, may result in one cell getting greater than nC and some less than nC – the charging current will not be equally distributed across the cells
  • Charging LiPo battery packs in parallel will result in the same voltage difference between their maximums and minimums.

How do you charge one 18650 cell with a SkyRC charger?

First Look: Turnigy Accucell-8150 150W 7A Balance Charger at @10.35

 

Balanced charger board

 

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