How long intelligent charger remembers previous cells?

- A
- Alex Coleman
  
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posted
17 years ago

Wed, Sep 13, 2006 7:53 AM

At home I charge my NiMH AA cells for everyday use.

I have an rapid "intelligent charger" which senses delta-V and it measures current/voltage/whatever.

Let's say I start to charge some cells. After an hour, they are not fully charged but I take them out and immediately replace them with some different cells.

(1) Would the charger still remember the first set of cells and seek to find delta-V based on its reading of the previous cells?

(2) How long should I leave an intelligent charger when swappig batteries like this to make it forget the previous cells?

(3) Would I need to actually disconnect the charger from the mains power to make it forget?

- P
- Palindrâ˜»me
  
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posted
17 years ago

Wed, Sep 13, 2006 8:19 AM

Sensible designs will detect the removal of the cells and reset the charger.

Many (most?) use standard chips that do this.

However, if you don't like assumptions, either take measurements, open the thing up and see what chip is used, or go for (3).

--
Sue

- T
- The Natural Philosopher
  
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posted
17 years ago

Wed, Sep 13, 2006 9:31 AM

No.

a millisecond.

No.

Chargers have no memory. Normally there is a 'fast charge' button, which initates the charge - the machine simply waits to see when the output voltage falls by a few mV instead of rising. Normally it then goes to 'trickle current' mode.

If you disconect the battery, it should sense that and go to trickle anyway when a new battery is connected. You normally restart the fast charge with a button.

In the case of a charger that is dedicated to a particular pack, (e.g. for a cordless) I suspect that there is a combination of voltage and delta V sensing..fast charge will be applied below a certain level,. otherwise its trickle charging. IN that sense its merely using the pack voltage to 'push' the notional 'restart button'.