Advice: batteries for a digi-radio

[Another John]

I'm irredeemably clueless about electrical things (amps/watts/volts 'n' all that) -- sorry.

Sooooo: I have a John Lewis portable digital radio (30.00). The sound is *great*, and it has a nice simple unpretentious style about it (looks-wise and functionality-wise).

However I can't get it to work portably: my batteries won't power it. On checking the manual again, I find it requires 4x 1.5V AAs. (On checking the batteries) I find I've been using rechargeable 1.2V (2500mAh) NiMH AAs (which I suppose are quite old by now).

Sooooo: I've decided I need to buy some new batteries. Before I go looking for rechargeables that will give me 1.5V, are there any *types* that I should be looking out for? NiMH was all the rage when I last bought rechargeables, but I suspect there are all sorts of new types about these days.

Any advice gratefully received,

Thanks John

[Archibald]

6V or 4.8 shouldn't make a lot of difference.

Splash out on four AA's and if the wireless works with four, take one out and replace it with a link. If it still works, bin your nicads. If it doesn't then you have no choice but to use the correct Voltage batt's

In the olden days, one or two of those supersonic heterodyne devices wouldn't work if the batteries were slightly down, I seem to recollect that the manufacturers got the biasing wrong on the mixer- oscillator and dropping the value of the base feed resistor would allow them to function to the point of dry cell dribbling.

'Wouldnt even know if the digital devices oscillated any more :-(

AB

[Jeremy Nicoll - news posts]

Worse, even when new they'd only provide 4.8V, not 6. For some sorts of devices that doesn't matter, but for others it does.

You really might need an external box of five 1.2V batteries; whether that's practical may depend on whether there's a DC in power socket on the radio, or whether you're willing to create a connection into the existing battery compartment. And, of course, whether you can make a suitable 5-cell box etc.

There used to be a kind, known as RAM cells:

but they don't seem to be made any longer, and even if they were still available another problem would be if the radio (eg when running off mains) tries to charge batteries in it if it assumes they are NiCd or NiMH cells, as the charger needed for RAM cells is different from that for NiCd & NiMH.

[Jeremy Nicoll - news posts]

It will if there's 5V logic in the digital part...

What? You're saying if it works with 4x1.2V then let's try just 3.6 V?

Could you better explain what you mean?

[Vir Campestris]

Try four AAs. That's 6V.

Take one out and replace with a link. That's 4.5.

Better?

Andy

[Archibald]

I would have thought it reasonably obvious.

Re- read & think.

Your humble tranny even these days would be expected to work in a variety of temperatures using batteries that are not at their best.

An off the shelf AA can match a nicads Voltage after less than half it's capacity has been used.

Now I cannot see too many manufacturers producing goods that consume batteries so greedily.

TTL logic [I assume thats what you mean], functioned at less than 5V. Some of the more exotic equivalents went to 3V and lower. Somehow I would doubt that you'd find a few 7400's tucked away in the case though.

Now to s p e l l t h i n g s o u t

Four aa's from Asda or Lidl will cost peanuts

Use all four in the wireless [6V]

The wireless works [ go to step b]

The wireless doesn't work [ Fix it then try the old nicads]

step [b]

Remove one cell & link [4.5V]

The wireless works [buy fresh nicads]

The wireless doesn't work, use dry batteries, buy a long mains extention or build a battery box.

There we are- Comprehend now?

AB

[bert]

In message , Archibald writes

I can They're called digital radio manufacturers

[Uncle Peter]

When he wrote AAs, he should have written AA non-rechargeables, or Duracells.

[Uncle Peter]

The only piece of shit I've ever had that won't take rechargeables is a room stat for my central heating. One one of them I bothered to fit an extra AA holder inside it as there was plenty of room for one, and it ran happily off 3 rechargeables. The other I couldn't be bothered and just shoved Duracells in it. Quite why people are still making devices that use outdated battery technology only, I don't know. Domestic rechargeables were common in the 80s for f*ck's sake. If I spent 30 quid on a radio and it refused to take NiMH, I'd take it back to the shop.

I once had a charger that charged ANY battery, it would charge Duracells 10 times, but it didn't put that much capacity in them.

[A.Lee]

You havent tried a DAB radio using batteries have you? Mine uses 4 C cells, they last around 8 hours. The first time they died, I thought it must be poor quality batteries, so I put Duracells in. They lasted a day at work too.

I now use an FM radio, with 4 AA's, which usually last 2 weeks+

[Dave Plowman (News)]

It would be a very poor design if it ceased working when the voltage from

6v alkalines dropped below 5v.

[Dave Plowman (News)]

I have an elderly AM portable where the 9v battery lasts many months of heavy use. The speaker size is 7x4" and gives plenty level.

[meow2222]

Charge your nicd/nimhs, measure voltage of each one with a £2 multimeter. You may have a bad cell.

If theyre all good but the radio wont run on them, Maplin sell NiZn recharg eables that should do teh job.

NT

[Jeremy Nicoll - news posts]

That's interesting! I've never heard of these before.

The 5th review here is a little worrying though:

More info on the technology:

[Jeremy Nicoll - news posts]

And following that up, googling more generally for: NiZn performance, NiZn review, NiZn fail ... etc suggests that it's easy to kill these cells. There doesn't seem to be a vast pool of experience using them.

I've also read several accounts of people having problems (eg with torches) where the extra voltage has caused bulbs to burn out.

Someone (was it the Maplin site?) suggested that they have a slightly larger diameter than other AA cells, so might not fit in a tight battery compartment.

[Bill Wright]

A 3V torch battery connected for a minute imposes a load and thus gives a more realistic indication.

Bill

[RJH]

I have a Pure Radio with one of their rechargeable batteries (£15). Lasts a claimed 18 hours, which seems about right.

The bathroom FM radio used maybe 30 minutes daily, with 3 rechargeable AAs, seems to go on forever - maybe 6 months

[Brian Gaff]

Actually 1.5v batteries are usually of the dry cell type. Most rechargeable are a bit under this, but many pieces of modern equipment is fine on them. If you have recharged them a lot then yes, they will eventually die. Many in radio chargers seem to be very crude as well, so can knacker batteries faster than kind external chargers. External ones tend to charge the cells as separate cells, whereas radios do them in series, so if one of more is a bit dodgy it just tends to get hot instead of charging, or worse presents a resistance so the others never charge completely.

The newer versions of those you already have from Maplin and other places I find very good, but now try to remove them from radios when they go down and put them in a proper charger and this means if you are using it portably, you need two sets. Unfortunately, it is a known issue withed DAB that the dab chips are power hungry. they are not as bad as the first generation were, but still not good, hence people using rechargeable in the first place. Of course one could modify the radio to use other types of battery, but given your admission of not being electronically minded, this might be dangerous, literally, as Lithium Iron batteries can burst into flames if shorted out. Brian

[DerbyBorn]

Bill Wright wrote in news:lg5pcr$i01$ [e-mail]:

The ready to use Rechargeables are best IMHO as they don't self discharge. I once tried NiCads in a Vivitar Flashgun and they wouldn't work due to their lower voltage. I had to use ordinary non-rechargeables. I thik the radio is a poor choice and you should consider sending it back as not being suitable for battery use - but first check it with a new set of batteries so that you can provide some hard data.

In the meantime check this out (still 1.2v)

Personally - I would never consider rechargeables in low current devices such as TV Remotes, Wireless Thermostats, etc. Their "self discharge" rate makes it pointless.

[Brian Gaff]

Actually the worse things for not likening 1.25 v cells were portable tape recorders. they could wow, or sound like the speaker had a rattle due to crossover. Luckily, that seems to be a thing of the past and the only effect using rechargables now is slightly lower max volume as one might expect. Best not to mess with it, just replace like with like but see my long reply first. Brian