12v Li-ion to power 15v

[mulaz]

Many boomboxes run on 10 D cell batteries . what thoughts and info can be shared regarding running using a 12000MAH Large Capacity Long Battery Life DC 12V Rechargeable Li-ion Battery with a step up booster converter?

 

[Superduper]

Most 15v Boomboxes will run fine on 12v but if you want to step up to 15v, you can & the Boombox will have more power but the battery won’t last as long.

 

[Lasonic TRC-920]

Most 15v Boomboxes will run fine on 12v but if you want to step up to 15v, you can & the Boombox will have more power but the battery won’t last as long.

Hey Norm,

What are your thought's on these? If you add them up to 12v/15v


320mAh 3.7V 3.6V LiCoO2 Li-ion battery AAA size
Description
ICR10440 Li-ion battery
Rated Capacity: 320mAh
Nominal Voltage: 3.7V
Charge cut-off Voltage: 4.2±0.05V
Discharge cut-off Voltage: 3.0V
Slow charge current: 32mA
Standard charge current: 160mA
Quick charge current: 320mA
Slow discharge current: 64mA
Standard discharge current: 160mA
Quick discharge current: 320mA
Weight 9.0g (for reference only)
I.R. ≤120mΩ AC Impedance 1000Hz
Dimension: D: 10.00±0.2mm H: 44.00±0.5mm

 

[Superduper]

Chris, the magic number is 320mAH which is a minuscule amount. Let's compare to standard NiMH or alkaline "Duracell" type size batteries:

AA NiMH capacity can approach 2000mAH.
D cell NiMH or Alkaline batteries have 10,000 mAH.
Both AA and D are 1.5v cells when alkaline so you would need 10 cells in series to make 15v. The amp-hour capacity rating remains the same as single cell when run in series, only voltage changes.
NiMH cells are 1.2v so you would need 12 cells to make 14.4v. Of you could just run 10 of them to make 12V. Because they do not sag like alkalines, you may discover that 12v might be sufficient.

Now, the LiON batteries you shared are 3.6v so you would need 4 of them in series to make 14.4v. Since again, the amp-hour remains the same when run in series, you will get 320mAH @ 14.4v when you run 4 of these in series. To get capacity equivalent (close to but slightly lower) to 10 alkaline D cells, you will need to run 30 of them (times 4 in series) to get 9600mAH. That makes 120 cells run in parallel(30x)/series(4).

For perspective, 10x "D" alkalines will net you 10,000mAH @ 15V

So my opinion is that those cells are totally impractical as a replacement for D cell alkalines or NiMH cells. To be practical, you will need to acquire larger cells, probably of the sub-"c" size rather than these AAA size batteries.

You may get other opinions, but I'm just running the numbers you gave. AAA batteries are small but the numbers you offered seems low, even for AAA batteries. If per chance, the numbers are higher (maybe 3200mAH instead of 320), then you can reduce the number of needed cells by a factor of 10 (or 12 batteries).

 

[trippy1313]

Great explanation Norm. In understood 100% of it.

 

[hopey]

When buldiing power supply's or battery packs always consult ohms law which super duper has eluded to. Also note always make the input voltage equal to or slightly higher than the specification as Dc circuits are designed to handle twice the voltage. If you use lower input volts you can damage capacitors or reduce the life of the power supply or battery.

 

[mulaz]

Thoughts one one of these? 12000MAH Large Capacity Long Battery Life DC 12V Rechargeable Li-ion Battery


https://www.ebay.co.uk/itm/12000MAH-Large-Capacity-Long-Battery-Life-DC-12V-Rechargeable-Li-ion-Battery-HT/201936287179?hash=item2f045735cb:m:mADh9HS1eksctK4S54qkQKA

 

[Superduper]

Capacity "sounds" like it would be a good choice for boomboxes. 12000mAH compares well with standard D cell use. However, it's not really 12V. The specs are deceiving. It says 10.8v to 12v. That's not right, batteries are either 10.8v or 12v, not both. Then when you do the math (LiON cells are almost always 3.6v/cell), you will find that 10.8v conveniently equals 3x3.6. So in other words, these packs have 3 cells in series making it a 10.8v pack. 12AH is OK but again, I don't trust their specs and that is probably an optimistic number. Even if we lower it to 10AH, or 9, or 8AH, would probably still be a good enough but only for 12V boomboxes, not 15v boxes.

 

[mulaz]

Many thanks for the info and after reading old posts regarding batteries ( my main box is 15v ) and the pros and cons i have decided to go down the rechargeable D cells route
Now to find some at a sensible price?

 

[Lasonic TRC-920]

Chris, the magic number is 320mAH which is a minuscule amount. Let's compare to standard NiMH or alkaline "Duracell" type size batteries:

AA NiMH capacity can approach 2000mAH.
D cell NiMH or Alkaline batteries have 10,000 mAH.
Both AA and D are 1.5v cells when alkaline so you would need 10 cells in series to make 15v. The amp-hour capacity rating remains the same as single cell when run in series, only voltage changes.
NiMH cells are 1.2v so you would need 12 cells to make 14.4v. Of you could just run 10 of them to make 12V. Because they do not sag like alkalines, you may discover that 12v might be sufficient.

Now, the LiON batteries you shared are 3.6v so you would need 4 of them in series to make 14.4v. Since again, the amp-hour remains the same when run in series, you will get 320mAH @ 14.4v when you run 4 of these in series. To get capacity equivalent (close to but slightly lower) to 10 alkaline D cells, you will need to run 30 of them (times 4 in series) to get 9600mAH. That makes 120 cells run in parallel(30x)/series(4).

For perspective, 10x "D" alkalines will net you 10,000mAH @ 15V

So my opinion is that those cells are totally impractical as a replacement for D cell alkalines or NiMH cells. To be practical, you will need to acquire larger cells, probably of the sub-"c" size rather than these AAA size batteries.

You may get other opinions, but I'm just running the numbers you gave. AAA batteries are small but the numbers you offered seems low, even for AAA batteries. If per chance, the numbers are higher (maybe 3200mAH instead of 320), then you can reduce the number of needed cells by a factor of 10 (or 12 batteries).

Thank you for going through all that Norm. There really doesn't seem to be any short cuts to this battery game.

So, if we can find a battery solution that equals 10,000mAH, 15V, is in a packaged size we could use AND is priced better than 10 standard D's than we would be in business.

I really haven't done much searching, but you would think that with all this new battery technology going on we could find a small brick or something that would fit in the battery box, be dirt cheap, weigh less and handle the power.

I still have hope something is out there

 

[Superduper]

Chris,

Quality rechargeable battery technology is anything but cheap. And no, you won't find LiON or NiMH batteries at standard alkaline D cell prices. If you could, alkaline batteries would be out of business. If you go to the nearest Sams club or Costco, they sell those Duracell multi-packs like candy, which is a testament to how their price vs. convenience point vs rechargeables are still acceptable. Lithium or NiMH batteries are very costly vs the initial purchase cost of standard alkaline D's but since they are rechargeable, if used regularly, will end up being far far cheaper in the long run.

As for buying a rechargeable "brick", if exists, you would likely be talking about something out of China. Here's the problem:

In the early stages of rechargeable battery technology, there was NiCD (nickel cadmium cells). They were great but their greatest shortcoming was that you had to run them all the way down before recharging or else you would lose capacity because those cells had a memory effect. If you regularly charged when 1/2 drained, you will eventually lose 1/2 the capacity. So chargers were rather simple. They presumed that cells were completely drained when inserted and the chargers would do timed charges (18 hours, etc.) then shut down. Then came NiMH which was a fantastic development and basically wiped out NiCD technology since gone was the dreaded memory effect. You can now charge any time, rather than needing to completely drain a battery. But because you can charge any time, a "smart" charger is needed to ensure that the battery doesn't get damaged from overcharging. It's still a terrific and viable technology today. Nowadays, it's all Lithium Ion cells. The advantages of Lithium Ion cells is that they have a greater power density for their weight. Unfortunately, the technology is also more expensive and requires even smarter cells & chargers due to these cells tendency to catch on fire.

Going back to why pre-constructed packs are problematic.... how are you going to charge it? Chargers today are intended for "sized" cells and their voltages. A pack would need a specially designed charger to be safe and reliable. I'm not aware of anyone that offers them yet. Todays cells have sensors embedded within and molded together into the packs to ensure that they do not overheat due to excessive charge or draw. Lacking these, I would be afraid to embed such packs into a boombox, especially if the charger is a 2-wire charger since that guarantees that there is no provision for sensor monitors.

Hacking alternatives? The safest and most convenient way to go in my opinion is to design a pocket to allow use of current tool battery modules. The newest cells are up to 5AH and 2 of them together would yield 10AH. 18v packs would be perfect. You can then simply stick them into the tool chargers when they need it and can be recharged in as little as 1-hour. No need to redesign the wheel when someone already did the R&D to produce a reliable system. Unfortunately, this is in no way, a cheap affordable solution. That's because the newest battery packs are probably going to run you over $100/pack so 2 of them will set you back $200+ and you still need the charger and to create a mold to make yourself a pack receptacle pocket. On the other hand, once you've made your own pack receptors, the packs & charger are all off the shelf common parts. Your boombox can run forever! You can of course use standard D cell rechargeables as chargers are available for them, the only downside being that 10 cells is a lot and you'll need to have multiple chargers available or else you'll spend all your time making one charging run. Remember, putting in an off the shelf pack, sticking them into a boombox that are often plugged in long term can be dangerous without a properly designed charger.

 

[mulaz]

This could fit but you would need deep pockets as you also have to price in a charger
https://www.overlander.co.uk/10000mah-4s-14-8v-20c-lipo-battery-overlander-supersportxl.html

 

[Superduper]

This could fit but you would need deep pockets as you also have to price in a charger
https://www.overlander.co.uk/10000mah-4s-14-8v-20c-lipo-battery-overlander-supersportxl.html

That might work. Specs are OK. However, it's got 2-wire connector. That means no built in sensor/monitors. Suggest to charge this thing outside of the boombox. Even better if charger has a sensor designed such that the sensor can contact the pack during charge.

 

[mulaz]

This write up on Ebay 12v 6800mah li-po Batteries is interesting and i am glad i asked before i pressed the buy it now button
http://howiem.com/wordpress/index.php/2013/11/01/chinese-12v-6800mah-li-po-battery-mini-review/

 

[mulaz]

This are the batteries i finally decided on as good value for money 10 x GP Recyko D Size 5700 mAh Rechargeable Batteries NiMH for £37 off ebay
http://www.ebay.co.uk/itm/10-x-GP-Recyko-D-Size-5700-mAh-Rechargeable-Batteries-replaces-2600-NiMH-HR20/301210694809?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

also have a EBL Fast Smart LCD Display Battery Charger For 4 AA AAA 9V Ni-MH Ni-CD Batteries on its way for £13
https://www.ebay.co.uk/itm/EBL-Fast-Smart-LCD-Display-Battery-Charger-For-4-AA-AAA-9V-Ni-MH-Ni-CD-Batteries/253424611178?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

[T-STER]

These are only 1.2V instead of 1.5v, in a device expecting 15V i wonder if this is a significant enough drop to affect performance?

 

[Superduper]

Most 15v boomboxes will work fine on 12v, as long as the supply is stiff and stable. NiMH batteries can supply more current than standard batteries which have greater internal resistance and limits how much current can be supplied simultaneously. In fact, it is high demand use which causes voltage to droop or sag, and rechargeables are better able to deal with this. It's also why NiMH and LiON are so well suited for power tool use.

The JVC RC-70 is a 15v boombox but it's DC input specs states that the suitable DC input range is 12v ~ 16v.

Comment on the link for the 5700 mAh D cells; since most premium batteries are 10,000mAh or greater, it's reasonable to conclude that a 5700mAh cell is an economy type and probably won't last as long in run time, or life time.

 

[Reli]

These are only 1.2V instead of 1.5v, in a device expecting 15V i wonder if this is a significant enough drop to affect performance?

I use Tenergy Premium whites. I charged them last Friday and they reached 1.37 or 1.38V. I put them in a radio and played it for maybe 15 minutes, and then took the out. That was 3 days ago. Today they're down to 1.35V. So bottom line, they perform a lot better than the promised 1.2V.

However, once they fall below 1.2V, they start draining really fast. Much faster than an alkaline.

 

[Superduper]

These are only 1.2V instead of 1.5v, in a device expecting 15V i wonder if this is a significant enough drop to affect performance?

I use Tenergy Premium whites. I charged them last Friday and they reached 1.37 or 1.38V. I put them in a radio and played it for maybe 15 minutes, and then took the out. That was 3 days ago. Today they're down to 1.35V. So bottom line, they perform a lot better than the promised 1.2V.

However, once they fall below 1.2V, they start draining really fast. Much faster than an alkaline.

Reli, almost all batteries have a phenomenon known as "surface charge" after a fresh charge. Google it if you want to know what it is. It's not nearly as pronounced in NiMH batteries but on lead acid type batteries, it's enough to require that the batteries be used for a bit to bleed out the surface charge before testing or else you will get a false reading.

Your observation about draining is exactly right. NiMH batteries have a very steep ramp when depleted unlike Alkalines which steadily decline as they discharge. Actually, this is exactly the property that makes them so desirable as they provide a steady stream of power right up until they are depleted at which point, it drops off a cliff. That's the time to charge them. Although they can run out pretty suddenly, however, up until that point they will continue to output at a good clip making them useful until the end and ensuring you suck all the juice out of them. Alkalines however usually end up getting tossed when they still have some charge remaining because the voltage drop from use renders them unusable in applications that require higher voltage, even when they aren't fully discharged. If you have a device that isn't as voltage sensitive (flashlight perhaps), you'll often find that the batteries still will work for quite some time even when they are useless in the other device. The Lasonic i931 comes to mind. That boombox requires batteries with almost full charge in order to even turn on. When the battery voltage drops even a little, the unit won't power up anymore often confusing the owner who might think that the boombox is broken because they expect the set to power up, even if the batteries are semi-weak thinking that at worst, the volume will be weak.

Still, it's important to remember that you are talking 12V @10 cells vs 15V @10cells. This 3V discrepancy alone makes it appear as though the 12V cell is discharging faster at the end than a 15V cell, which after a 3V drop, is only just at the 12V level since by the time you get to 12V, the unit becomes far more sensitive to further voltage drops.

 

[mulaz]

For me who will run my box in the house most of the time on the mains extreme battery life is not so important and up to now these batteries are performing well
yes they are 1.2v as most rechargeable batteries are but for half the price of 10,000mha cells they should be fine for casual use