With a starting point the year
2005, the basic NiMH 9V charger this appeared in the market, this using two specific charging technologies.
The version with charging current of
16mA, this does not include any
charge end control method.
According to NiMH handbook, an 9V NiMH it can handle constant charging current of 16mA as Non-stop charge, and no damage.
In theory after eighteen hours, the battery this is considered as charged.
The version with charging current of
25mA, this including timer control.
In theory after eleven hours the charger circuit this will stop the delivery of current.
At
2006 and later, Ansmann Energy introduced, ANSMANN Energy 8 and ANSMANN Energy 16.
Both at
70mA charging current, advanced micro controller, detection of defective batteries, DV cut-off charge detection, automatic switching to Trickle charge.
But such features they appear at high pricing.
Since 2008 and later there is no development of a better charger with advanced micro controller from another brand.
The latest offering of
basic smart charger, this were released at
2018 by ENERGIZER, with
30mA charge output.
This is a combination of DV cut-off charge detection and also with timer control.
In theory, the charge will stop as soon
DV cut-off detection activates, at a fully charged battery.
But there is also the function of
safety timer, this will stop the charge after
unknown time period.
Another severe downfall of the latest Energizer Universal 6-Bay, it can charge AA/AAA only in pairs.
Considerations: With exception the ENERGIZER UNIVERSAL CHARGER, all other chargers were developed in a period that
Always Ready / Pre charged NiMH they was not here.
If you do not expect using every single time, charged battery capacity in full, then Trickle charge this not of high importance.
From the other hand, they are applications as for example photography and external photo flash.
There, the Trickle charge its highly valuable, because the preferred type of AA for this application, this is regular high capacity NiMH.
Regular High capacity NiMH AA, this does not have a low self discharge rate.
Regular High capacity NiMH 9V 250~300mA, this also do not have a low self discharge rate.
The market place appears as full of 9V chargers, but most of them are clones of the ancient product design of 2005 or older.
You may detect the charging technology in use, only by reading the label of charging current.
I am very happy by owning both ANSMANN Energy 8 and ANSMANN Energy 16.
Charging bay this offers plenty of passive cooling (good ventilation), for its one battery cell.
The latest Energizer Universal 6-Bay this has also well designed charging bay, but the connectors for the 9V cells appears misplaced.
In contrast, ANSMANN energy models, both aloud an easy front loading for 9V cells.
In conclusion, anyone charging frequently NiMH 9V, he will be happier owning an ANSMANN charger.