Battery charger testing - Page 1
Forum section: electronics / beginners

author: rakeshm55
author_rank: Regular Contributor
timestamp: August 22, 2019, 07:05:06 pm
content: I have a lithium ion battery charger used to charge a 14.4V battery pack. I want to test it's performance so hooked it up to an electronic load in CV mode. I was expecting charger to enter Into CC mode for charging.What I observed was error indication by charger.As I understand charger is using LM2677 for charging battery. It is capable of charging li ion battery pack to 15V max.How to test battery charger using a test equipment.?? Is there any standard battery charger circuit for LM2677

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: August 22, 2019, 09:06:09 pm
content: What about some battery pack made of super capacitors to get faster results? Eg:https://www.hackster.io/janost/super-capacitor-power-bank-e2f7cchttps://www.instructables.com/id/The-Forever-Rechargeable-VARIABLE-Super-Capacitor-/

author: ledtester
author_rank: Super Contributor
timestamp: August 23, 2019, 12:26:52 am
content: Quote from: rakeshm55 on August 22, 2019, 07:05:06 pmI have a feeling a battery is the best way to test a battery charger.QuoteYou could try adapting this LM2596 charger circuit:https://www.mpja.com/download/31562ps.pdf

author: radiolistener
author_rank: Super Contributor
timestamp: August 23, 2019, 06:43:15 am
content: 14.4V very strange voltage.Usual Li-Ion cell has nominal voltage 3.7 V. It should be charged max to 4.2 ± 0.05 V. Military grade should use max 3.92 V instead of 4.2 V. So, your charger should stop charge when voltage on one cell of Li-Ion accumulator is close to 4.2 V but should not exceed this voltage even for 0.05 V!Since you have battery pack, it looks like your battery has 4 cells. So, the charger should use 4.2 * 4 = 16.8 V limit.So, just connect the battery and make sure that your charger apply charging voltage to the battery and stops to charge it below 16.8 V.

author: MosherIV
author_rank: Super Contributor
timestamp: August 23, 2019, 06:51:29 am
content: Hi. Due to the growing market for LiIon batteries, you can now get battery simulators, a combined psu and electronic load.There are also electronic loads that have a battery simulator mode now.Standard electronic loads will not do the job because a battery changes as it charges. The terminal voltage rises.In order to use an electronic load to simulate a battery, it must be controlled externally and made to simulate a battery.Not sure CV mode is correct on the EL. The charger will be in CC mode which means it will vary the voltage to get the current but the EL will vary the resistance to try and maintain the voltage - in other words they are fighting each other.The charger is probably checking there is sufficient battery voltage before starting the charge. The EL will not have any voltage, it is not a voltage source.Edit: 14.4V good point. 3s is 12V and 4s is 16VI have the same problem with converting a 14.4V NiCad battery drill to LiIon.Sounds like the battery is NiCad or NickelMetalHydrideNot advisable to used LiIon charger for different chemistry unless it supports them

author: radiolistener
author_rank: Super Contributor
timestamp: August 23, 2019, 08:35:37 am
content: 14.4 V looks like lead-acid battery. I think this is not a good idea to use Li-Ion charge for lead-acid battery.

author: maukka
author_rank: Unknown
timestamp: August 23, 2019, 10:41:39 am
content: Quote from: radiolistener on August 23, 2019, 08:35:37 am14.4V would indicate it's meant for LiFePo4 batteries, which can be charged up to 14.6V, but provide almost all of the capacity anywhere from 13.8V upwards.

author: tunk
author_rank: Super Contributor
timestamp: August 23, 2019, 11:37:39 am
content: The nominal voltage of most 18650 li-ion cells are 3.6V: 3.6*4=14.4VOtherwise MosherIV is correct, you need something with a battery simulator mode.

author: radiolistener
author_rank: Super Contributor
timestamp: August 23, 2019, 12:27:16 pm
content: Quote from: tunk on August 23, 2019, 11:37:39 amLi-Ion cell has standard nominal voltage 3.7 V, and charge voltage 4.2 V.If this is really 4 x Li-Ion cells, then it's nominal voltage is 3.7 * 4 = 14.8 V and charge voltage 4.2 * 4 = 16.8 V.

author: Audioguru again
author_rank: Regular Contributor
timestamp: August 23, 2019, 09:44:10 pm
content: When you load a Lithium-Ion battery charger then it gives an error because it thinks that your loadproducesa voltage too low that is dangerous to charge. A voltage per cell that is less than about 2.8V causes metallic Lithium to form which causes an explosion or fire if it is charged.When some chargers sense a low voltage then it attempts a low current charge, But if the voltage does not rise then it stops the charge and gives an error indication.

author: David Hess
author_rank: Super Contributor
timestamp: August 24, 2019, 04:40:42 pm
content: Quote from: maukka on August 23, 2019, 10:41:39 amThis is what I was going to post and 4 cell LiFePO4 batteries are commonly used as drop in replacements for 12 volt lead-acid batteries.As to the original problem, try decoupling the charger from the electronic load by installing a large electrolytic capacitor at the charger's output. Unless the electronic load is designed to simulate a battery, it may not provide a low enough AC impedance.

author: thinkfat
author_rank: Unknown
timestamp: August 24, 2019, 06:08:35 pm
content: Multi quadrant power supply is what you want to use. Or a Communications power supply like a HP66309D.Gesendet von meinem Nokia 6.1 mit Tapatalk