What is the simplest circuit for limiting charging of 1.5v batteries?

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Discussion Overview

The discussion revolves around finding a simple circuit to limit the charging of 1.5V NiMH batteries, specifically in the context of a wireless headphone charging base that lacks a cut-off mechanism. Participants explore methods to prevent overcharging and potential damage to the batteries.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses concern about the lack of a cut-off point in the charging circuit, which could lead to battery damage.
  • Another participant suggests that correctly charging NiMH batteries typically requires monitoring temperature or periodically stopping the charge to prevent damage.
  • There is a proposal that charging batteries very slowly (e.g., at 1/20 of their capacity) minimizes the risk of damage.
  • A question is raised about whether higher capacity batteries (mAh) mitigate concerns regarding continuous charging.
  • One participant recommends using a spare set of NiMH batteries with a slow charger to avoid damage, noting the specific capacity of AAA batteries.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method for charging the batteries safely, with multiple viewpoints on the necessity of monitoring and the implications of charging rates.

Contextual Notes

Participants mention various assumptions regarding charging rates and battery capacities, but do not resolve the specifics of the circuit design or the exact parameters for safe charging.

Who May Find This Useful

This discussion may be useful for individuals interested in battery management, electronics enthusiasts, or those looking to improve the longevity of rechargeable batteries in devices.

n0_3sc
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I have a cheap set of wireless headphones where the base unit supplies a voltage to the headphones to charge the 2 AAA NiMh batteries. However it has not cut-off point, ie. it'll charge indefinitely destroying my rechargeable batteries.

I'm looking for the least complicated circuit that will break the charge when the batteries are near or at max capacity.

Any ideas would help greatly.
 
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It's difficult to correctly charge NiMH batteries without either monitoring their temperature or periodically stopping, discharging at a constant rate and calculating the change in discharge rate.
The best and simple way to charge rechargables is to do so very slowly, it is difficult to damage batteries if you charge them at say 1/20 of their capacity (ie at 100mA for a 2100mAh AA)
 
ok so if i have a high mAh batt, I don't need to worry about continuous charge damage?
At the moment its using 500mAh and the batteries end up leaking acid after time.
 
I would get a spare pair of NiMH batteries and a cheap slow charger or one of these

(Sorry I didn't see the AAA part, the highest cap is likely to be about 800mAh - you don't have to worry about damage if you charge slow enough)
 

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