Rechargeable batteries in Hacker trannies - UK Vintage Radio Repair and Restoration Discussion Forum

stevehertz · 25th Jan 2023, 1:07 pm

I've just read a post on the Facebook Hacker Radio Group page where a guy has put rechargeable PP3 Li-ion batteries inside the emptied out normal, large ones and it seems to work well apparently. It seems a great fix. However he does say that the battery is actually only 8V although it works fine with his Hunter RP38A. Is this likely to be a fix for most Hacker transistor sets? Any comments or suggestions?

paulsherwin · 25th Jan 2023, 1:15 pm

There are probably 2 cells in there, which would give about 8V when charged.

Most 9V sets will run perfectly happily on a couple of LiIon cells of any type, including 18650s scavenged from old battery packs and cells from disposable e-cigs. You just need to take them out and charge them every few months - they last for ages and don't self discharge. This has been discussed in previous threads.

stevehertz · 25th Jan 2023, 1:25 pm

Thanks Paul. I didn't know it had been discussed previously. But anyway, this guy has made a really neat job of doing it, and it's easy to just hook up a USB lead even while the set is running. The PP3s have the small USB sockets fitted to them.

paulsherwin · 25th Jan 2023, 1:30 pm

Yes, that would make life easier. I run my bathroom Party Boy on a couple of 18650s which I remove and charge externally every 6 months or so. USB charge controller modules can be bought on eBay for pennies.

Boulevardier · 25th Jan 2023, 2:01 pm

Quote:

Originally Posted by paulsherwin

Yes, that would make life easier. I run my bathroom Party Boy on a couple of 18650s which I remove and charge externally every 6 months or so. USB charge controller modules can be bought on eBay for pennies.

Presumably it needs an individual charge controller for each of the LiIon cells?
Mike

Katar83 · 25th Jan 2023, 2:17 pm

It does not if you keep an eye on them and don't forget to charge them when you should. You could put a small BMS across and that would do the trick and prevent discharging it too much.
I've put two used 18650 in my Panasonic radio(few post down the list from this one) and added a step up converter and it does work well. Step up converter just keeps the output voltage at 4.5V(which was what 3x C type batteries originally supplied). Two 18650 cells provide anything up to 4.2V(when fully charged) so without BMS I just need to make sure that I don't discharge the 18650 below 2.5V as that could cause damage to them.

paulsherwin · 25th Jan 2023, 2:19 pm

That's how I charge mine. The two cells are in holders and I remove them to charge them individually.

Actually, I have another pair of 18650s which I keep charged. Every few months I swap the cells over and charge the used ones. That way, the radio isn't out of use while the cells charge.

I don't use a BMS. I just charge the cells before they have the chance to discharge excessively. I do use a safety fuse though.

mhennessy · 25th Jan 2023, 5:58 pm

For anyone worrying about the 8V thing, just take a look at this graph:

https://commons.wikimedia.org/wiki/F...rent_100mA.svg

An alkaline cell doesn't sit at 1.5V for much of its life! Just a fleeting moment, really. It pretty quickly gets down to 1.3V, which is close enough to 8V for a 6 cell PP9, and there's still plenty of juice in the tank, as the picture shows. Well deigned devices will continue to work down to 1.1V per cell. The Hunter loses FM sensitivity as the batteries wear down, but will work well enough in a good reception area down to around 10 or 12V.

Lithium batteries tend to have much flatter discharge curves than alkalines, so if anything, they'll give better performance until it's time to recharge.

G6Tanuki · 25th Jan 2023, 6:03 pm

For my kludged '9V' battery-packs I use seven NiMH cells. I'm more worried about internal resistance causing the voltage to drop on high-volume peaks - but NiMH and Li-Ion cells have much lower internal resistances than a tired Leclanche primary-cell.

Boulevardier · 25th Jan 2023, 8:12 pm

Quote:

Originally Posted by G6Tanuki

For my kludged '9V' battery-packs I use seven NiMH cells. I'm more worried about internal resistance causing the voltage to drop on high-volume peaks - but NiMH and Li-Ion cells have much lower internal resistances than a tired Leclanche primary-cell.

I've been using 8 NiMH cells in my 9v Grundig Elite-Boy for years now without any apparent problems. Mind you, I do have a protective series-diode in the battery circuit. Perhaps I should also put in a series fuse?

Mike

saxmaniac · 26th Jan 2023, 9:14 am

I do the same, 8 NiMh but would always fit a series fuse, there's a serious amount of smoke waiting in the event of a short circuit

newlite4 · 26th Jan 2023, 6:05 pm

I used to run my Hunter on a pair of 6xAA battery packs fitted with Kodak zinc carbons which was fine until I had to replace the two lokfit transistors in the FM tunerhead. I did not have the exact types in stock so I fitted what I had. The audio had a tendency to warble if over run, following the repair it had become a bit supply sensitive. When I fitted a pair of Energiser PP9s (£5.99 here in Bath) the results were much more satisfactory.
Neil

25th Jan 2023, 1:07 pm	#1
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,831	Rechargeable batteries in Hacker trannies I've just read a post on the Facebook Hacker Radio Group page where a guy has put rechargeable PP3 Li-ion batteries inside the emptied out normal, large ones and it seems to work well apparently. It seems a great fix. However he does say that the battery is actually only 8V although it works fine with his Hunter RP38A. Is this likely to be a fix for most Hacker transistor sets? Any comments or suggestions? __________________ A digital radio is the latest thing, but a vintage wireless is forever..

25th Jan 2023, 1:15 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Rechargeable batteries in Hacker trannies There are probably 2 cells in there, which would give about 8V when charged. Most 9V sets will run perfectly happily on a couple of LiIon cells of any type, including 18650s scavenged from old battery packs and cells from disposable e-cigs. You just need to take them out and charge them every few months - they last for ages and don't self discharge. This has been discussed in previous threads.

25th Jan 2023, 1:25 pm	#3
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,831	Re: Rechargeable batteries in Hacker trannies Thanks Paul. I didn't know it had been discussed previously. But anyway, this guy has made a really neat job of doing it, and it's easy to just hook up a USB lead even while the set is running. The PP3s have the small USB sockets fitted to them. __________________ A digital radio is the latest thing, but a vintage wireless is forever..

25th Jan 2023, 1:30 pm	#4
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Rechargeable batteries in Hacker trannies Yes, that would make life easier. I run my bathroom Party Boy on a couple of 18650s which I remove and charge externally every 6 months or so. USB charge controller modules can be bought on eBay for pennies.

25th Jan 2023, 2:17 pm	#6
Katar83 Pentode Join Date: Feb 2021 Location: Thetford, Norfolk, UK. Posts: 133	Re: Rechargeable batteries in Hacker trannies It does not if you keep an eye on them and don't forget to charge them when you should. You could put a small BMS across and that would do the trick and prevent discharging it too much. I've put two used 18650 in my Panasonic radio(few post down the list from this one) and added a step up converter and it does work well. Step up converter just keeps the output voltage at 4.5V(which was what 3x C type batteries originally supplied). Two 18650 cells provide anything up to 4.2V(when fully charged) so without BMS I just need to make sure that I don't discharge the 18650 below 2.5V as that could cause damage to them.

25th Jan 2023, 2:19 pm	#7
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Rechargeable batteries in Hacker trannies That's how I charge mine. The two cells are in holders and I remove them to charge them individually. Actually, I have another pair of 18650s which I keep charged. Every few months I swap the cells over and charge the used ones. That way, the radio isn't out of use while the cells charge. I don't use a BMS. I just charge the cells before they have the chance to discharge excessively. I do use a safety fuse though.

25th Jan 2023, 5:58 pm	#8
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Rechargeable batteries in Hacker trannies For anyone worrying about the 8V thing, just take a look at this graph: https://commons.wikimedia.org/wiki/F...rent_100mA.svg An alkaline cell doesn't sit at 1.5V for much of its life! Just a fleeting moment, really. It pretty quickly gets down to 1.3V, which is close enough to 8V for a 6 cell PP9, and there's still plenty of juice in the tank, as the picture shows. Well deigned devices will continue to work down to 1.1V per cell. The Hunter loses FM sensitivity as the batteries wear down, but will work well enough in a good reception area down to around 10 or 12V. Lithium batteries tend to have much flatter discharge curves than alkalines, so if anything, they'll give better performance until it's time to recharge.

25th Jan 2023, 6:03 pm	#9
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Rechargeable batteries in Hacker trannies For my kludged '9V' battery-packs I use seven NiMH cells. I'm more worried about internal resistance causing the voltage to drop on high-volume peaks - but NiMH and Li-Ion cells have much lower internal resistances than a tired Leclanche primary-cell. __________________ I'm the Operator of my Pocket Calculator. -Kraftwerk.

26th Jan 2023, 9:14 am	#11
saxmaniac Heptode Join Date: Oct 2007 Location: Birmingham, West Midlands, UK. Posts: 618	Re: Rechargeable batteries in Hacker trannies I do the same, 8 NiMh but would always fit a series fuse, there's a serious amount of smoke waiting in the event of a short circuit

26th Jan 2023, 6:05 pm	#12
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,805	Re: Rechargeable batteries in Hacker trannies I used to run my Hunter on a pair of 6xAA battery packs fitted with Kodak zinc carbons which was fine until I had to replace the two lokfit transistors in the FM tunerhead. I did not have the exact types in stock so I fitted what I had. The audio had a tendency to warble if over run, following the repair it had become a bit supply sensitive. When I fitted a pair of Energiser PP9s (£5.99 here in Bath) the results were much more satisfactory. Neil __________________ preserving the recent past, for the distant future.