Thursday, June 28, 2018

FAQ-6 Can Rechargeable and non-rechargeable cells be Mixed together?

They can be but it is highly inadvisable to do so.

There are many different types of Rechargeable and non-rechargeable cells so talking about all of them will not be possible in here but let me give you some ideas. If you have a device that takes multiple cells series, say an Infrared Remote controller for TV you might be okay with putting two types together but remember rechargeable NiMH has lower terminal voltage compared to non-rechargeable Zinc-Carbon/Zinc-Chloride/Alkaline cells, so the rechargeable one might get flat sooner and charged at reverse polarity which is not good for it plus Infrared remote controllers takes so little power there is not reason to use NiMH in them.

The process mentioned earlier will take a moderate amount of time to happen if it happen but if you have a device that has parallel cells, like the wall clock I have in my room, it requires 3 AA cells in parallel for it’s chime and in this case adding a NiMH with Alkaline might be catastrophic as the Alkaline with it’s higher terminal voltage trying to charge the NiMH.

In short not a good idea to do such a thing. 

Monday, June 25, 2018

FAQ-5 Does New Cell Phone Require 10 Hours of charge?

They Don't. 

The idea of charging for 8 hours came from the NiMH and SLA/LA type batteries. Lithium batteries charge at a much faster rate and 8 hours of charge might even stress it them a little(if it is charged at normal rate).

Here is the thing both NiMH and SLA are usually charged at a much lower rate, even at 1/10th(0.1C) of capacity so they often require 10+ hours of charge to be fully topped up. On the other hand Lithium batteries are charged at 1/2th(0.5C) of capacity to even more than 1C so they do charge up pretty fast.

The reason why new phones are to be charged is to simply have good capacity out of it, they often shipped at 40–60% capacity and during the time at inventory they goes down a bit so if you want to use it you have to charge it up to 100% and you are good to go. Time is not that important. If you think about a 20000mAh power bank and charge it at 1A, you will need 20+ hours of charge and it will be fine for it but if you have a phone and charge it for that long it might have small negative impact on the battery.