Battery for a "Pure One Classic" radio.

march.brown

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I bought a brand new "Pure One Classic" radio last year for about £50 ... It doesn't come with a battery pack although it will take six "C" cells ... I was considering getting six C cells (NiMh) and a suitable charger , but didn't really want to get yet another type of battery/charger system.

Battery packs (Pure C6L) are available that can be charged in-situ with the supplied mains cord , but they cost about £35 to buy and only have a one year guarantee ... I have read several reports that they fail shortly after the guarantee ends ... That seems a lot of money for a year or so's use ... Even my shaver battery and torch batteries last many times longer than this.

I can get a "compatible" non-Pure battery pack for £24-99 ... The seller also sells the genuine "Pure C6L" ... I asked him how long the packs generally lasted for and he said that it was about two years ... I'm not certain what batteries are in the pack , but the mains unit for the radio is 9 Volts ... Maybe there are six NiMh's in it ... The seller didn't know.

Is it going to be cheaper to buy six C-cells and a charger rather than use the battery pack and more to the point , will the C-cells last any longer than a year or perhaps two ? ...

Decisions , decisions !
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ChrisGarrett

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First of all, it runs on your AC mains, as well as their C6L proprietary pack, six regular rechargeable C size cells and/or 6xC alkalines, right?

How much of your listening will be portable listening, as this will be a deal maker for you? how many charges per week will you be applying to the pack, or rechargeables?

It states 40 hours per pack charge and 80 hours per set of 'quality alkalines'.

If you're only casually listening to it off your mains voltage, I'd just go with some alkalines bought in bulk, say a 20 pack, for cheap? Don't know what they cost in the UK, but it's simple math.

If the packs OEM/generics are 25L-35L or even up to 100L, that's a big spread. Since you didn't get a pack with the radio, you have to figure buying theirs is 35L, so that's money that will go to your charger/rechargeable, or regular alkalines if you're going to go that route.

What's a decent C/D size charger going to cost you? What are decent branded C cell NiCad/NiMH going to cost you per unit, in England?

How long of a life span will these rechargeable C size batteries yield, the same 1-2 years, or 5-10 yrs like Eneloops?

Lots of questions that need answers.

Chris
 

45/70

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Hi march. My best guess as to why the OEM packs, as well as the others, are only lasting a year, or two, is that radios (receive only) drain battery packs at a very low rate. Most likely, folks drain the packs down until the radio quits working. This would no doubt reverse charge (which I was just posting about in another thread:thinking:) some of the cells in the "battery". Regardless of the type of cells used in the pack, this will wear cells out prematurely. Even LSD cells will have a much shorter lifespan, if reverse charged.

If I were you, I would definitely look into some C cells and a charger. I wouldn't skimp here. It may cost you as much, or more than purchasing a pack, but I'm betting if you keep track of your usage habits, and charge the cells well before they are depleted, you will get several years out of a set of cells.

Of course developing this habit with the OEM pack, would likely extend the life of the pack as well. If you DIY with your own cells and charger though, when the cells do finally wear out, you will only have to replace the cells, not the charger.

One other point I'll mention, is that many radios that are designed to run on alkaline cells, loose some sensitivity, when run on NiCd, or NiMh cells. They still work, but signal strength is affected. Since this radio sounds like it is made to run on a rechargeable battery pack, it doesn't sound like this would be a problem.

Dave
 

Yamabushi

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Do you already have NiMH AAs? If so, have you considered getting C-adapters? You'd only get a fraction of the runtime, but it would be a minimal investment.
 

march.brown

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It states 40 hours per pack charge and 80 hours per set of 'quality alkalines'.

If you're only casually listening to it off your mains voltage, I'd just go with some alkalines bought in bulk, say a 20 pack, for cheap? Don't know what they cost in the UK, but it's simple math.
If I could get 80 ('ish) hours off a set of decent alkalines , that would be almost three months of listening ... This is based on my Wifes present evening radio useage when (or if) she can't get to sleep ... An hour or so of listening a few times per week ... I will possibly send off for 20 C cells for about £12 on Ebay , though I will look first in the local shops (Lidl or Aldi or even Poundstretcher) to see if they have any ... They tend to have Kodak batteries in stock ... I have just put some Proline cells in the radio and it seems to work well ... I think I paid about £12 for 20 cells delivered ... Working on that price , it would cost about £16 per year in batteries ... The radios display is showing "full batteries" so my Wife will be OK for a while ... I haven't checked for parasitic battery drain yet and will have to do it in the next couple of days ... I don't like leaving the set permanantly plugged into the mains as the 9 volt unit gets warm even when the radio is switched off ... Unfortunately the mains socket in the bedroom is behind a drawer unit and is not readily accessible to use that on/off switch.

Yamabushi Do you already have NiMH AAs ? If so, have you considered getting C-adapters? You'd only get a fraction of the runtime, but it would be a minimal investment.
I might try this as a cheap back-up supply and should still get a few hours out of my AA Eneloops ... It would give the Eneloops something to do , rather than sitting in storage waiting for their turn in a torch.

45/70 Thanks for your input about the battery packs ... I know that the radio works OK on Alkalines ... I just don't know yet how long it will work on the alkalines ... Time will tell.

If all else fails (too expensive on alkalines and too short a time on AA's) , I will revert to using the radio (again) as a "doggy" kitchen (mains) radio to keep him company when we are out of the house ... I would then buy my Wife a new radio that uses AA rechargeables ... DAB radios are readily available for the price of the C6L chargepak and I could use my existing stock of AA Eneloops.

There now seems to be too many options !
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march.brown

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Just checked the current drain on the Pure One Classic ... Parasitic drain is only 0.03 milliamps ... Radio switched on is 190 milliamps ... These figures are when using alkalines ... I don't know what milliampere-hour capacity an alkaline C cell has got , but whatever it is , that figure divided by 190 should give me the number of running hours that I can expect on this radio ... Six AA Eneloops in AA to C convertors should give ten hours of use ... I could charge the Eneloops every two weeks if she uses the radio for five hours a week ... I can justify buying a few more Eneloops easier than buying rechargeable C cells and another charger ... I would have to buy the AA to C converters too ... I think I can get eight of the convertors (they don't do sixes) for less than £8 from a UK dealer.

More food for thought.
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45/70

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According to wikipedia, alkaline C cells are 6000-8000mAh (and NiMH's are 6000mAh for normal ones / 4000mAh for LSD ones)

That sounds about right for alkaline cells, maybe a bit low. The problem is that alkaline cells, if rated (manufacturers generally do not rate alkaline cells, as their capacity varies greatly, depending on discharge rate), are usually rated at something like a discharge rate of C/30, whereas nickel based rechargeable cells are rated according to the IEC standard, at C/5.

I would guess though, that at a 190mA rate alkaline C cells would probably do a bit better than NiMh. At a higher discharge rate, say 500mA, the NiMhs likely would have the advantage. This is all speculation though. In my experience with AA cells, the break even point is somewhere around a 100-200mA discharge rate. This is not fact, but rather my experience comparing alkaline and NiMh AA cells over the years and is only a general observation.

Dave
 

march.brown

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According to wikipedia, alkaline C cells are 6000-8000mAh (and NiMH's are 6000mAh for normal ones / 4000mAh for LSD ones)
Many thanks for the information ... So , it looks like I can get 10 hours of use from AA Eneloops (in AA to C convertors) and 31 hours from normal NiMh C rechargeables and 21 hours from the LSD C's ... Since I already have AA Eneloops , to get double the discharge time , I would have to buy six C size NiMh LSD cells and the appropriate charger ...

If I use the AA to C convertors I would get about ten hours of use with my AA Eneloops ... I could keep a set of alkaline C cells for use when there are no spare (charged) Eneloops available ... A set of alkalines would last ages if only used once in a while ...

It looks as though (based on cost-effectiveness) it is better to use the AA Eneloops in convertors even with only 10 hours available use ... The only possible snag is that the lower voltages of the rechargeables might cause problems with the radio ... Is it worth £7 (for AA to C convertors) to find out ?
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march.brown

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Just tried the radio with six AA Eneloops and it works OK ... The battery indicator on the radio shows a full battery even though the Eneloops haven't been charged for several months ... I don't know how the Eneloops will perform after a few hours of use , but I can't really hold the six wobbly AA's in place for several hours to find out ... Based on this , I am going to invest in some AA to C convertors at £7 (for 8) and hope that it works well enough for my Wifes use ... I will tell her to watch the little LCD battery symbol and when it gets down low she can let me know.
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45/70

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... I will tell her to watch the little LCD battery symbol and when it gets down low she can let me know.

This is really important, March. With six cells in series, you run a much higher possibility of reverse charging a cell, than with say, two cells. As I mentioned in a previous post, I imagine this is why the OEM packs only last a year.

If it were me, and you calculate that the six eneloop AAs will last about two weeks, I would start a regimen of recharging them once a week. This will allow a bit of a cushion, adding some insurance to help prevent reverse charging from occurring in the "pack". I would definitely not wait until the radio's LCD display indicates that the "battery" is nearly exhausted. Depending on how well matched the cells are, what voltages are actually represented by the display etc, damage to one or more cells could occur, even though the radio still works.

Dave
 

Datman

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You could also use a little, cheap external lead-acid 12V battery, connected to the 12V input. It depends on the use you will do of it. You'll need a little lead-acid 12V charger. 12V is a common voltage, then you have a lot of choices.

Gianluca
 

march.brown

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This is really important, March. With six cells in series, you run a much higher possibility of reverse charging a cell, than with say, two cells. As I mentioned in a previous post, I imagine this is why the OEM packs only last a year.

If it were me, and you calculate that the six eneloop AAs will last about two weeks, I would start a regimen of recharging them once a week. This will allow a bit of a cushion, adding some insurance to help prevent reverse charging from occurring in the "pack". I would definitely not wait until the radio's LCD display indicates that the "battery" is nearly exhausted. Depending on how well matched the cells are, what voltages are actually represented by the display etc, damage to one or more cells could occur, even though the radio still works.

Dave

Hi Dave

Many thanks for your input on the Pure battery problem ... We have a small Sony VHF radio set in the kitchen which uses four AA Eneloop batteries and we just wait till the set stops playing or sounds distorted , then I put in another set of charged Eneloops ... Fortunately this radio set seems to keep working OK and the batteries seem to be OK too ... Perhaps they are balanced OK and have similar capacities , I don't really know as I don't ever do a discharge test to see what their capacities are ... I was just going to do the same procedure with the Pure radio ... Is there the possibility of an explosion by doing this or will it just cause the affected battery to die ? ... I have never worried about my misuse of NiMh cells used in any of my portable gear , though I am ultra careful with all my Li-Ion cells ... My use of LSD cells is usually in fours or pairs ... The Pure radio is the first with six cells.

All my chargers have four independant slots , so each battery is charged dependant on its state of discharge ... The Pure battery pack is charged with the six cells in series and with no check on individual cells ... In this case , I can see that eventually one or more individual cells will be in a lower state of charge than the others and this could eventually lead to a reverse charged cell.

There is no major problem with topping up the Eneloops every week or so , assuming that I remember to religiously do it ... Human nature will probably prevail and will possibly lead to occasional full discharge of these batteries ... Only time will tell ... If my 74 year old brain remembers to swop her radio batteries regularly , then all will be well ... I might buy some more Eneloops just in case ... You can't have too many Eneloops !
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Shadowww

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Is there the possibility of an explosion by doing this or will it just cause the affected battery to die ? ... I have never worried about my misuse of NiMh cells used in any of my portable gear , though I am ultra careful with all my Li-Ion cells ...
Nope, no danger of explosion, especially at currents so low - worst thing that can happen is cell venting. But battery might degrade noticeably in terms of capacity & self-discharge.
 

45/70

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Hi March. As Shadowww said, no, there is no real danger with NiCd/NiMh cells. You just may end up damaging one or more cells. Again, I suspect this is why the OEM packs only last a year.

When using cells in a series "pack", the more cells in series, the less noticeable (to the device being powered) a cell that runs out of steam will be. So, the more cells you have in series, the more likely cell reversal will take place if the device is "run down".

With two 1.2 Volt cells in series, for example, when one cell runs down, the voltage will drop ~50%. This will be rather obvious to the electronics in the device (or you, the user) and likely detected hopefully, before any reverse charging occurs. When six cells are used in series, if a cell runs down, the voltage drop will be ~17%. This comparatively small drop in voltage is much more likely to be overlooked, by the device's electronics. Therein lies the problem with running many cells in series.

Dave
 

march.brown

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Hi March. As Shadowww said, no, there is no real danger with NiCd/NiMh cells. You just may end up damaging one or more cells. Again, I suspect this is why the OEM packs only last a year.

When using cells in a series "pack", the more cells in series, the less noticeable (to the device being powered) a cell that runs out of steam will be. So, the more cells you have in series, the more likely cell reversal will take place if the device is "run down".

With two 1.2 Volt cells in series, for example, when one cell runs down, the voltage will drop ~50%. This will be rather obvious to the electronics in the device (or you, the user) and likely detected hopefully, before any reverse charging occurs. When six cells are used in series, if a cell runs down, the voltage drop will be ~17%. This comparatively small drop in voltage is much more likely to be overlooked, by the device's electronics. Therein lies the problem with running many cells in series.

Dave
Hi again Dave ...

If one of the six AA cells goes into "reverse charge" conditions , I thought that it acted as a "counter EMF" cell and reduces the five good cells by another 1.2 Volts , giving the effect of only four good cells ... I'm basing this on the way we used to control the large capacity 50 Volt telecomms batteries that we used on a charge/discharge system ... We took the short-circuits off the (series) counter-EMF cells when the battery was freshly charged and as the on-load voltage dropped during the day , we switched the short-circuits across the counter EMF cells as required to keep the DC volts within 1.0 volt of the 50V ... That was in the old days (in the early 1950's) when we used mercury arc rectifiers to charge the off-load battery ... In those days we always called them 50 Volt batteries then eventually they were called 48V systems as there were 24 cells and we then used duplicated high capacity float systems for security of supply ... Strange really as the float voltage was 54.0 volts (2.24V to 2.26V per cell).

Must be a sign of my old age , all this waffling on about totally irrelevant things !

I think my Wife is right.
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45/70

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I'm not sure how that worked with Telco batteries, but I can tell you that with a 12 or 13 "2/3 A" NiMH cell battery pack, such as used in my 2D M@g 623, the voltage drops 1.00-1.20 Volts (depending on the discharge rate) for each cell that poops out. I've seen this on my CBA's real-time graph, when checking for a bad/low capacity cell. It happens fairly suddenly, and while I have always intended to stop the discharge when the first cell drops out, I've actually accidentally let it go and seen a second cell drop out, as well. I wish I could post a graph from the CBA, but the computer those are on is kaput at this time.

Dave
 

march.brown

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I'm not sure how that worked with Telco batteries, but I can tell you that with a 12 or 13 "2/3 A" NiMH cell battery pack, such as used in my 2D M@g 623, the voltage drops 1.00-1.20 Volts (depending on the discharge rate) for each cell that poops out. I've seen this on my CBA's real-time graph, when checking for a bad/low capacity cell. It happens fairly suddenly, and while I have always intended to stop the discharge when the first cell drops out, I've actually accidentally let it go and seen a second cell drop out, as well. I wish I could post a graph from the CBA, but the computer those are on is kaput at this time.

Dave
Thanks Dave

So it seems that when a NiMh LSD cell "dies" in a multi-cell device , it just loses voltage completely ... Presumeably it turns into the equivalent of a series resistance device where the actual voltage loss is that cells normal voltage plus the loss due to the dead cells resistance ... I will have to think about that behaviour ... If you measured voltages across all the cells in the (on-load) battery , did the dead cells have a positive or negative reading or just a zero reading ?

By the way when your cells died , were they retrievable or were they dead forever ? ... I guess it would depend on how long they were reverse charged ... I might have to get a few more AA Eneloops in case that happens to me ... It's not that I would deliberately forget to top-up the AA cells , more likely that it would just get left for another day or maybe it would be pure laziness.


Thanks again.

George
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45/70

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Hi George. I never intended to run any of these packs down past where I could see that a bad/under performing cell did in fact exist. The one time that I did see a second cell crap out, it happened almost immediately after the first, and again, this was accidentally. I did not want to damage the packs anymore than necessary, just far enough to determine if indeed there was a bad cell.

... If you measured voltages across all the cells in the (on-load) battery , did the dead cells have a positive or negative reading or just a zero reading ?

I can't answer that question. Tom (SilverFox) suggested I monitor individual cells in the pack while discharging on the CBA II. The problem was that these packs are shrink wrapped and I would have had to puncture through and measure each cell with a needle, or something to take measurements. Since these packs are welded cells, I really could not replace the bad cells anyway, and as they still worked and ran about $60-$70 a pack, I didn't bother potentialy damaging the wrap, to find out. I have no doubt that at least sometimes, the weak cells were reverse charged. It would be almost impossible, considering the 10A+ load put on these diminutive cells.

By the way when your cells died , were they retrievable or were they dead forever ?

These packs still work, just not nearly as long as a new pack. The 14.4 Volt pack should run the M@g for about 9 minutes, and the 15.6 Volt pack for about 7 minutes. The 14.4V pack will only go for about 2 minutes or less, last I checked. The 15.6V pack fares a bit better and will go for about 5 minutes. Actually these are cumulative runtimes. At 140-170 Watts, the "2D" M@g gets way too hot after about one minute and needs a "rest".:)

Anyway, both packs have bad cells in them, but still work. No one makes packs for them anymore, either. This light isn't really all that useful anyway, although it is quite capable of illuminating a large pasture etc. and has been used for such. I have a FiveMega "2D" 12 x 2/3A cell holder (the light body is "tri bored"), that I've never used. When these packs finally die, I'll just use it, albeit it will only give me the lower 14.4 Volt output. Good 10A+ capable cells are hard to find also, adding to the problem.

Dave
 
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