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12V DC 9800mAh Rechargeable Li-ion Battery Mod (Lasonic)

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#1 Alf

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Posted 23 April 2013 - 10:27 AM

YO guys!  


Recently I won a contest over at the Lasonic facebook page.  They sent me the new 931BT blaster.  I'm really digging it for several reasons. It was FREE and whats not to like there?  Haha!  It's pretty rugged and it's not rare or expensive so it's a great blaster to bring all over this summer and not worry about. It sounds pretty decent for what it is.  It's definitely LOUD! As BBB said, it does have better bass output than the earlier iPod Lasonics.  Also, despite not having chrome I think it looks awesome!  It's the tough guy of the current collection. 


So, I wanted to make this my hassle-free, always ready, beach/skate blaster of 2013!  That way I can keep all my vintage babies safe and sound under controlled conditions at home and unleash this beast when I'm out and about.  Lets face it.  I will still bring my other boxes out, but sometimes I just want to have some crankin' tunes without needing to obsess over a rare grail.   :D


Here's the plan.  I found this baby on ebay:  



Battery type: Rechargeable Li-on battery. 
Capacity: 9800mAh. 

Output voltage: 12.6-10.8V DC.


I did some tests with a smaller capacity lead acid battery and everything went fine so I'm assuming this Li Ion should be ok.  Think this'll work out?  


The box already has a 12V DC jack on the rear panel as seen below:




My goal, is to wire the battery pack inline with the 12V DC input.  Therefore I'd be able to charge her up using the stock jack.   I will just be able to switch the existing power selector from DC to AC to take any load off of the battery.  This will allow for a totally easy solution for keeping this thing juiced up without having to worry about about alkalines all while keeping the appearance oem.


This should be pretty straight forward as far as I can see.  Am I missing anything?  WHat are your opinions?  As Norm will tell you, I use the common sense approach to this kind of thing.  Any type of "actual" electrical theory is beyond me.   :blush:  :-D





#2 blu_fuz

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Posted 23 April 2013 - 01:44 PM

The i931 Lasonics eat battery power OVERNIGHT even when the boombox is OFF and switched to AC!


Congrats on the win! I was shooting for that too but just wasn't as creative with my picture :-/

#3 Alf

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Posted 23 April 2013 - 08:50 PM

It's true!  The new Lasonics DEVOUR batteries for some reason.  Thats what prompted me to look for a solution.  Think this should do it?  I'm just not sure how this particular battery will perform.  I need the tech guru's to chime in.  :D

#4 redbenjoe


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Posted 23 April 2013 - 08:58 PM

that 10 AH battery should run hard -ALL DAY ...plus the next day

#5 Superduper

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Posted 23 April 2013 - 09:36 PM

That Lasonic wastes battery capacity because it will refuse to power up when the battery voltage drops even a little, even though there is plenty of capacity left. When that Lasonic appears stone dead, the batteries still work in flashlights or other devices -- even other older analog boomboxes. That's why many owners think their machine is broken or no DC. I'm not sure what is the low voltage shut off threshold but 10.8 volts is probably close. Another thing to be careful about is that dedicated chargers are supposed to have overcharge protection circuit built in. Chinese one probably lack it. Guess I'm saying be careful about overcharging if you are connecting inline. LiOn batteries will catch on fire when overcharged. No kidding.

#6 Alf

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Posted 24 April 2013 - 07:42 AM

Wow... Imagine how epic my profile picture would be if I were holding a FLAMING LASONIC!!!!   :chris920:  :chris920:  :chris920:


Norm, this battery does in fact have overcharge protection... Well thats what the listings say. lol.  What about using a higher voltage?  I know 10 D cells produce 15 volts, in theory.   :hmmm:  

#7 Lasonic TRC-920

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Posted 01 May 2013 - 10:44 AM

interesting thread.... :popcorn: 


Congrat's on winning the Lasonic....I'm glad it went to our crew and not some loser nobody, non collector  :lol:  :lol:

#8 Superduper

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Posted 01 May 2013 - 12:02 PM


Norm, this battery does in fact have overcharge protection... Well thats what the listings say. lol.  What about using a higher voltage?  I know 10 D cells produce 15 volts, in theory.   :hmmm:  




Yes, a higher starting voltage will definitely be helpful but that battery pack you mentioned is rated at whatever it's rating is....  how will you increase the voltage?


Like I said, most batteries will lose voltage as they discharge.  Analog devices like boomboxes of old will continue to run until the battery voltage drops to almost nothing (or at least much lower than compared to the late model lasonics) thereby using up almost all the capacity of the batteries.  The issue with the later lasonics is that the digital components have a minimum operating voltage threshold so if the voltage drops to a certain point, it will refuse to power up at all, even though the battery might have plenty of life remaining to power other things.  This is quite wasteful since the control circuitry is the digital portion.  The amp itself is probably analog and probably could continue working fine if only the control circuitry would allow the system to start.  Starting with a higher voltage will provide more operating range before the low threshold is reached.


8 batteries @ 1.5 initial volts = 12 volts.

8 batteries @ 1.2 volts = 9.6 volts.


10 batteries @ 1.5 initial volts = 15 volts.

10 batteries @ 1.2 volts = 12 volts.


As you can see, a 10 cell pack that drains down to 1.2 volts per cell still provides the same voltage as a fresh 8-cell pack which might, at this time, already be at the low threshold of powering up.  I'm pretty sure that the Lasonic only needs 12.6 volts on the DC input circuitry because it expects that power to come from a stable source such as a car lighter adapter or a DC wall wart.  From  such a source, the voltage would never drop below the low threshold.  On batteries, you would likely need to start at a higher voltage to give enough range.

#9 Alf

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Posted 02 May 2013 - 07:53 AM

Very helpful info Norm!!!  Thank you!  I think I'm going to alter the direction of this project and look more towards stuffing a reliable lead acid type battery in there... If I pair that with a smart charger I'm sure I'll have better results.