LiPo 3s - parallel charging using Schottky diodes

Thread Starter

jd96jack

Joined Apr 28, 2021
2
Hello! Probably it's a n00b question but I couldn't find much about LiPos parallel charging using diodes.
I am designing a charging station for 6 LiPo 3s batteries.
There are plenty of parallel charging boards in the market but it's common knowledge that if the voltage difference between the batteries is too big, the current flowing between them will damage them. In my application, the batteries will never have the same level because are used by different people in different times.
So I was thinking to a sequential charger controlled by a micro-controller that charges the battery one by one. However, this seems a bit of overkilling to me and I am thinking about a fully hardware solution. Could I just parallel charge the LiPos adding a Schottky on every line connecting the cells? It should prevent current flowing between the batteries. What are the drawbacks of this solution? the voltage drop across the diode?
Thank you in advance!
 

AlbertHall

Joined Jun 4, 2014
11,506
The charger will not know the actual cell voltage because of the diode drop.
The cells will not necessarily share the charge current equally and the charger cannot know the charge current for each cell.
 

Thread Starter

jd96jack

Joined Apr 28, 2021
2
Thank you for the reply :) So, I think it's better to stick with my previous idea: opening the conductive path from battery to charger one by one using relays controlled bu a micro-controller, unless anyone has better suggestions!
 

LowQCab

Joined Nov 6, 2012
1,110
You can use a single Power-Supply with 6-separate Voltage/Current Regulators.
Diodes will not work well.

There are many multiple output Battery-Chargers in the Radio-Control Planes and Quads Market.
Just search for "FPV" (First-Person-View) "Drone".
.
.
.
 

Juhahoo

Joined Jun 3, 2019
180
Series connected Lipo / Li-Ion cells needs to be charged with balancing mechanism, diodes would simply add voltage without caring the balance and eventually after few cycles some cells are charged to higher voltages than others causing those cells fail when others are not even full.
Search for ready made chargers and just parallel them to each battery from one power source. Balancing is necessary during charging !!!!! You may start from Aliexpress, HobbyKing had once 10$ balancing chargers..
 
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