Uneven battery charging in series charger.

[rj9923]

So the way I charge my batteries is through a series battery pack, connected to a charger set at 8.4 volts and 1.5 amps. I use my 18650 batteries in a single battery mod. I have two matching pairs of batteries (samsung and brillipower). Despite only using one battery at a time while vaping, I keep the pairs 'married' by ensuring they both drop to the same voltage (usually 3.6v) before charging the pair.
For some reason, even when both batteries are at 3.6 volts, they will emerge uneven after charging in a series. The one connected to the charger through the negative side will often end up at 4.4 volts, and the one connected at the positive side at 4 volts.
Do not worry. I understand overcharging batteries can be dangerous, so for now I am only charging the pair at 8 volts, so that the higher battery does not go above 4.2v.
Does anybody understand what is happening? The pairs of batteries have always had the same voltage as each other before charging, so therefore they should be receiving the same amperage from the series charger. What is wrong here? I will inform you one of the pairs of batteries are brand new. Thank you

 

[Zamazam]

That happens in series charging, one battery will charge quicker based on internal resistance (within the cell) being lower. The remedy is to get a parallel charger. They are cheap and will charge the cells to the correct voltage.

 

[rj9923]

That happens in series charging, one battery will charge quicker based on internal resistance (within the cell) being lower. The remedy is to get a parallel charger. They are cheap and will charge the cells to the correct voltage.

Thank you for clarifying. I suspected that was the issue as I've experienced the same with car batteries. I would go parallel with my current charger, but the lowest voltage is will put out is 7 volts, so that is not an option for 18650s. The charger I've been using is a homemade one connected to a broken IPV4 (with removed circuit boards) housing the batteries. I did recently spend 2 bucks on fasttech for what I thought was a 'proper' single channel 18650 charger, but the amperage is so low that it can remain charging for more than 12 hours and not even reach 4.2v... I'm considering the nitecore single 18650 usb charger if anyone has had a good experience with that one.

 

[Zamazam]

The Nitcore will be slow unless you have a port or wall wart that can put out 1 amp. I'd just get the dual one with the ac cord and be done with it. I used one for years, they work well.

 

[Stumpybaker82]

Wondering if anyone can help I'm using a xtar mc6 battery charger it's a 6 port device and when I'm charging 3 batteries in the centre ports 2 of them charge at 0.5 and 1 charges at 1.0 does this mean that the batteries are not married now

 

[Neunerball]

Wondering if anyone can help I'm using a xtar mc6 battery charger it's a 6 port device and when I'm charging 3 batteries in the centre ports 2 of them charge at 0.5 and 1 charges at 1.0 does this mean that the batteries are not married now

Welcome to VU!

The charger might have a maximum limit on the Ampere it can charge. The batteries charging at 0.5A will just take longer to be fully charged, where as the battery charging at 1.0A will be fully charged quicker. However, the healthier charge rate is 0.5A.

 

[Stumpybaker82]

Thank for the reply my concern though is that I used the 3 batteries in my rx2/3 and now I'm worried that they are no longer married because of the different amperage they charged at

 

[Neunerball]

Thank for the reply my concern though is that I used the 3 batteries in my rx2/3 and now I'm worried that they are no longer married because of the different amperage they charged at

Just switch the batteries into different charging ports, every time you charge them, so every time a different battery is charged at 1.0A. You can still consider them married.

 

[Vapin4Joy]

Wondering if anyone can help I'm using a xtar mc6 battery charger it's a 6 port device and when I'm charging 3 batteries in the centre ports 2 of them charge at 0.5 and 1 charges at 1.0 does this mean that the batteries are not married now

Read about your charger here, so you have a better understanding about it's operation.
https://www.lumensdirect.com/products/xtar-mc6-queen-ant-6-port-charger

 

[nightshard]

Why even bother with uneven charging, considering the fact that chargers are so cheap?
https://www.fasttech.com/products/0/10002304/2355101-authentic-xtar-vc2-2-slots-li-ion-usb-battery

https://www.fasttech.com/products/0...hentic-nitecore-i2-lithium-li-ion-ni-mh-ni-cd

 

[Jon@LiionWholesale]

As others have mentioned the charging setup you had would do that. Series charging is not a great idea.

It sounds like for some reason you're extremely budget conscious. We have a relatively new Efest 1 bay charger called the Pro C1 if you want a small USB charger that works well with no frills and is cheap. It also charges fairly quickly at 1A. But if it were me I'd just spend an extra few dollars for a Nitecore/Efest/Xtar with digital readout and 2-6 bays.