PP9 Battery Life

[Jim - G4MEZ]

Firstly, I'm pleased to see the PP9 Battery remains quite easily obtainable and not too expensive... Be lost without them running a fleet of Hackers...

Strikes me that the modern versions of the PP9 seem to last a lot longer than they did back in the 70s when a wireless like a Hacker seemed to eat them for breakfast...

A set in my Herald, with almost daily use, has so far lasted a year and shows no signs of dying just yet...

Not had a flat one to break open and look inside yet but is this my imagination or do the modern versions really last longer?

[ukcol]

The original PP9s were zinc/carbon whereas now you can buy Alkaline PP9s. I think that explains the longer life.

Zinc/carbon PP9s are still available but presumably their life would be no better than the originals.

[Jim - G4MEZ]

The ones in use in the Hacker Hunter are Panasonic Zinc Chloride batteries. Not alkaline as far as I can tell. Those are the ones that have been doing sterling service for a twelve-month so far

I have a pair of Ever Ready Silver PP9s in the Herald. Looking at the Ever Ready batteries they do not say what they are...

[Herald1360]

They're not alkalines. In any case, if they were, they'd be boasting about it!

Gold was the Ever Ready alkaline colour.

[Tractionist]

The Ever Ready [plastic-bodied] 'Silvers' [currently £3.45 at Home Bargains] are the easiest that I've come across yet ..... to strip-out and convert into a rechargeable!!

[Jim - G4MEZ]

Now that's worth knowing Thanks!

[suebutcher]

I think Eveready/Ever Ready Silver batteries are zinc chloride. Isn't it Red = zinc carbon, Silver = zinc chloride, Gold = alkaline?

[emeritus]

According to a battery data chart in a 1981 "Allbatteries" catalogue, ZInc Chloride batteries have about 35% greater capacity than traditional Leclanché batteries on a watts per litre basis.

[Herald1360]

Surely that should be Joules per litre?

[Dave Moll]

Forgive me if I'm misunderstanding that document, but a number of things in it puzzle me. Just looking at the first section for the C-Zn batteries:

Assuming that "anode" means the positive terminal and "cathode" means the negative one, I thought that the zinc was negative and the carbon positive. Also, how can a carbon electrode be made of manganese dioxide?

Incidentally, by "electrode" I assume the document means "electrolyte".

[Dave Moll]

It seems my assumption was incorrect. A bit of further digging implies that the negative side of a battery is referred to as the anode (at least, according to Wikipedia) and conversely that the postive side is the cathode.

Also, I gather that the carbon rod is not the active part of the "cathode", which is a mixture of carbon and MnO2.

I stand, however, by my final comment about the electrolyte.

[60 oldjohn]

In January 1973 edition of Practical Wireless there is an article discussing the life of different batteries and different loads. For PP9 estimated service life for endpoint voltage 75% of normal.
10ma 4 hour daily =505hour ..15ma 4hours daily =330hours. ...25ma 4hour daily =175 hours. .... 50ma 4hour daily = 48 hours.

The chart list all the 1.5v 6&9v batteries available in 1973. with discharge rates from 0.5ma to 500ma and 30mins day to 12 hours a day of use.

John.

OT, But in same magazine "Going Back" there is mention of a Wireless preservation group being formed, BVWS I believe. Please don't comment.

[emeritus]

The Electrode/electrolyte confusion seems to be a typo: the same chart appears in their 1985 catalogue, where a discussion of the operation of a battery does say electrolyte. Allbatteries were/are a distributor, not a manufacturer, although they did offer to make up custom batteries from standard cells. The Watts per litre was my typo: the chart does actually say Wh/l.

A Vidor primary batteries catalogue of 1985 refers to the positiive terminal as the cathode [see lower part of the attached PDF].

I think the reason for the anode/cathode designation is that these are defined by the direction of electron flow rather than by potential difference. The upper part of the attached PDF (Fig 7) is from a 1942 book on accumulator charging, and shows that, during charge, the positive plate is an anode, and on discharge, a cathode.

[Nicklyons2]

AFAIK the Anode is postive & attracts Anions (negatively charged ions) and, conversely the Cathode attracts Cations (positively charged ions). Maybe it is this terminology which assists the confusion? of course I may be wrong...

As to the Zinc primary cell question; I myself for never really took much notice of the differences between the 'classic' Leclanche cells and the modern zinc cells - but there is quite a difference in construction. I think it was somewhere on this site where someone had looked into the demise of the Ever Ready company and within was described the improvements to the zinc cell chemistry & production which they hoped would save them from the onslaught of Alkaline cells.

[Jim - G4MEZ]

Originally Posted by 60 oldjohn

In January 1973 edition of Practical Wireless there is an article discussing the life of different batteries and different loads. For PP9 estimated service life for endpoint voltage 75% of normal.
10ma 4 hour daily =505hour ..15ma 4hours daily =330hours. ...25ma 4hour daily =175 hours. .... 50ma 4hour daily = 48 hours.

I must do the calculations and see how long a Herald would last using those figures..

Out of interest, and if not too OT, what else uses PP9 batteries nowadays for the likes of CPC Farnell to have over 400 in stock?

Surely users of old transistor radios don't make that massive a market these days or are there more still in use than we realise?

[turretslug]

Possibly, there's also a small but worthwhile demand for portable/field/lab equipment that uses PP9s- such stuff tends to be expensive and good stuff may be hung onto for decades (Radford DMS3 as just one example in one particular field), there isn't the renew, renew, renew sleeve-tugging endemic with consumer devices, so maintaining a residual demand. Professional organisations, as compliant-appliance users, may also be less keen on resorting to 6x AA holder retrofit-type solutions.

[Nuvistor]

I have an RP38A, bought new 1970's. 40 years ago it was the only radio we had and my wife would have the radio on 5 or 6 hours a day, the two PP9's lasted about 6 weeks. I bought the VP408? Hacker mains adapter, never needed another PP9 after that.

Frank

[broadgage]

I have a relatively compact Geiger counter that just about fits a large overall or coat pocket, it uses an internal PP3 battery.
The instrument was supplied with a jack socket and lead to use an external PP9 battery "in order to give extended battery life for lab or workshop use"

I understand that the armed forces use these Geiger counters and presumably need to keep a stock of reasonably fresh PP9s.