Turns off, or fails to activate

I have exactly the same problems now with al gigasets S79H sets. It started with one but now all three have the same problem. I noticed that with new rechargeable batteries, they function OK, till after some time the problem repeats itself. I also have a different gigaset S68H and that one functions well but it has a different charging holder with similar adapter , thus I never tried to put the S79H sets in that charger holder because they do not fit. Now I noticed that all S79H chargers deliver without load a very high voltage and also the batteries are overcharged to a rather large voltage ( for both in series 2,95 volt which is excessive). Apparently the gigaset unit then decides to switch itself off to protect the telephone. My conclusion is that all 79H charging adapters have gone faulty after so many years and deliver a much too high charging voltage which causes the units to switch off to protect themselves. When new batteries are installed or batteries charged with an external general purpose charger the voltage per battery is much lower and the gigasets function normal till they are put in the chargers again. The adapter of that unit S68H which works OK , delivers indeed a much lower voltage without load . 5.73 volt versus 7.5 to 8 volts of the S79H adapters while the adapters are interchangeable . I am pretty sure that that is the problem because I have taken the S68H adapter out of the S68H charge holder and have put it in the S79H charger holder and now charging the S79H does not cause a switch off.

I have already ordered three new adapters.

In retrospect the problem with the non-lasting batteries in my gigaset dect sets, is that I used batteries which were not of the right quality. I am now using high quality eneloop batteries and I have no problems anymore. And strange enough also the Ikea laddo batteries also seem to work. They are apparently made by the same Japanese factory.

Dect batteries

Dect telephones like the gigaset telephones require low self discharge NiMH AAA batteries, because they do not seem to wear out by the continuously charge when they are placed in the charger like the cheaper brands.

Since I use these low self discharge batteries I do not have the problems discussed here. ( Showing battery empty sign and switching off after a short while)

Eneloop batteries ( original made by Sanyo but now Panasonic) are made in Japan.

Several other makes are made by the same the factory ( like the Ikea brand Ladda and also Fujitsu) and are obtainable for a lower price.  Also the Amazonbasics batteries exhibit a very low self discharge (after 24 month still 80% charge). If you check the rechargeable Battery brands advised by Gigaset or other Dect telephone manufacturers one wil find that they all have low self discharge specifications.

Eneloop is a brand of 1.2-volt low self-discharge nickel–metal hydride (NiMH) rechargeable batteries and accessories developed by Sanyo (later acquired by Panasonic), introduced in 2005.

Eneloop cells lose their charge much more slowly than the 0.5–4% per day loss by older-technology NiMH batteries, retaining about 85% of their charge for a year after charging.This allows them to be sold precharged and ready for use, unlike older types.

Because they can replace a large number of alkaline batteries over their life cycle, they are marketed as being eco-friendly.

Sanyo was acquired by Panasonic in 2009. In exchange for the US FTC's approval of the takeover, Panasonic agreed to sell Sanyo's portable NiMH battery business to Fujitsu subsidiary FDK in order to preserve competition,and later did so.

Following this, Panasonic retained the "Eneloop" trademark, but continued to source the batteries themselves from the same former-Sanyo factories (now owned by FDK).

Following the acquisition of Sanyo by Panasonic, a fourth generation was introduced in April 2013. The number of charges per cell was increased from 1800 to 2100 cycles for both AA (BK-3MCC) and AAA (BK-4MCC) models. In some countries the batteries are branded as Panasonic.

The eneloop type quality batteries with the extremely low self discharge do not seem to wear out when continuously charged like other brands and retain their quality for a much longer time.

Of course there are more mostly Japanese brands which exhibit more or less the same low self discharge properties which are also suitable for dect telephones. Do not select the types with more than 900 mA capacity. The lower capacity ones last longer and can have more recharge cycles.

I am having very similar problems, with older phones which used to really consider as suspect. Not lasting and constant resetting

However I am now suspecting the battery chargers. I have a mix of the originally supplied batteries, eneloops as well others. They all fail in the phones after a few months of use. I also have a state of the art battery panasonic battery charger and have always been confused when I insert perfectly charged batteries into the phones which the phone then reports as half charged. I do not feel that is right.

After reading this article I had a closer look at three of my four Gigaset charged. All well over 3 years old.

• C39280 C710 measured 7.53v(no load) yet label on charger said 4v 6.68v with 100Ω load

• C39280 C710 measured 8.0v(no load) yet label on charger said 4v

• S2181 measured 7.50v(no load) yet label on charger said 4v

I would love to know what a newish 4v gigaset power supply reads.

Anybody out there able to state what voltage a new gigaset 4v charger outputs?

The new charger arrived courtesy of siemens support. Its voltage was effectively identical to my own three chargers. So my assumptions in the previous post are either totally wrong or this new changer is also duff. I cut one of the gigaset charging leads to allow use of two multi-meters and tested two phones. The charger measured 7.534v on no load, ie. nothing in the cradle. I got to work with two DVMs and started monitoring the current and voltage going to the cradle, in the end I also used a scope.

placing bigroom C430HX phone on cradle (batteries almost fully charged)

* initially 4.744v and 150mA when first placed

* then 7.480v and 2ma after a few min

placing int3 C430HX phone on cradle very flat- battery icon red and empty

* initially 5.381v and 183mA when first placed 11:14am

* 4.745v and 178mA at 12:15pm

* 4.681v and 180mA at white empty icon 13:20pm

* 5.060v and 172mA one white bar 17:00pm

* by 22:00pm, battery icon reports fully charged and the DVMs are oscillating backward and forward between the following two states:

* 5.73V and 159mA

* 7.48V and 2mA

The batteries are eneloop 1.2v 750mAh so C/10 should be 75mA. These eneloops are equivilent to those recommended by gmkbatteries.co.uk for a C430HX, and from what I can tell the original gigaset batteries were 700mAh. So charging these at 170mA, is about C/4.4. I then looked at the first C430HX phone again. After it settled down I saw it also oscillating between the same two values. Using a scope, rather than DVMs, I was able to see a 600ms pulse charging with the battery getting a C/4.4 shot of current for 100ms of the cycle. I am not a battery expert so I cant comment on the effects of C/4.4 pulse charging fully charged batteries for months or years.

So I am wondering if it all comes down to the batteries ability to cope with the charging regime. I intend to try getting some of the original gigaset batteries - these super eneloop batteries may not be suited for this application.

Had the same. Just to try if your rechargeable batteries need refreshment - replace them with regular ones and try to switch handset on. For me it worked.

Thanks for your answer.

I did put in new rechargeable batteries, in both handsets, some months ago, but the problem remains: sudden complete shutdown of the handsets during a conversation or during the dialling.

Now I put in non rechargeable batteries and for the moment I do not have the problem anymore.

Thanks for the hint, I wonder how long the batteries will last….

Robert