Li-ion

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panserv
Posts: 13
Joined: Wed Dec 26, 2001 4:00 pm

Li-ion

Post by panserv »

Has anyone made a saber battery by fitting two 18650 li-ion cells inside a used battery housing?
Will the slightly higher voltage, 3.6 to 4.2 V each cell, matter much ?
I was looking at what looked like a good buy of x2 Panasonic 3400mAh cells for $ 18.7 and liked the potential http://www.fasttech.com/product/1341105 ... -protected.
A usefull Saber battery an inch high, should be interesting.
Thoughts?
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nukedude
Posts: 59
Joined: Fri Apr 16, 2010 9:40 am
What radios do you own?: Many Motorola's

Re: Li-ion

Post by nukedude »

I have been contemplating this, since all of my Saber batteries are starting to wear out. Only one of my batteries that fit my vehicle adapter (due to length) still work. The plan was to use a power resister to try to shed some of that excess voltage and see if it still kept the heat down. If I break down and attempt it, I will post result here. Need to find where I put the old batteries first.
panserv
Posts: 13
Joined: Wed Dec 26, 2001 4:00 pm

Re: Li-ion

Post by panserv »

If the saber power circuitry can take the x2 Li-ion max of 8.4 volts, then maybe there is no need to reduce the voltage.
Possibly sabers have a supply regulator that can take this max.
If it cant, then rather than a resistor, perhaps a small linear regulator inside the battery case will do.
The voltage drop needed will be about 1 volt so not much power will be dissipated.
Maybe someone better knowledged than myself about astro saber architecture can chime in.
panserv
Posts: 13
Joined: Wed Dec 26, 2001 4:00 pm

Re: Li-ion

Post by panserv »

Does anyone know if Astro Saber will run with no damage on x2 LI-ION cells at 8.4 Volts ?
On batlabs astro page, I read that it should run at up to 9V, but it don't know if this is a cutoff absolute max.
I mean, perhaps the extra volt will cause the pa stage to run too hot or some similar effect.
I am about to buy cells and charging stuff, so will appreciate a little help before I spend any money and blow some radio.
Thank you in advance.
N9LLO
Posts: 788
Joined: Sat Sep 08, 2001 4:00 pm

Re: Li-ion

Post by N9LLO »

well considering a fully charged nicad cell is about 1.43 volts times 6 =8.58v for the standard pack I would say a definite maybe
RFI-EMI-GUY
Posts: 51
Joined: Fri Jun 02, 2006 7:23 pm

Re: Li-ion

Post by RFI-EMI-GUY »

I have done it, it works great! I had to find a proper Li-ion charger chip and modified a pocket charger to work with my new 8.4V 2 cell Li-ion batteries.
TV DINNER BY THE POOL, IM SO GLAD I FINISHED SCHOOL. FZ
RFI-EMI-GUY
Posts: 51
Joined: Fri Jun 02, 2006 7:23 pm

Re: Li-ion

Post by RFI-EMI-GUY »

I used a two cell protected pack from Tenergy about 2200 mAh 18650 cells. No need to step down the voltage as it is a good match. Because Motorola uses a diode to isolate the charging pin and I could not afford the voltage drop from the Microchip 2 cell charger, I used a reed switch and put a strong magnet outside the charger pocket so the charging terminal has no potential unless it is in the charger. The hardest part is getting the Motorola battery pack open and stripped of cells and Kapton PC. You will need to solder the terminals of the battery pack. I used a 25 watt iron, some low temp solder. I also lined the inside of the battery case with aluminum foil two layers so I wouldnt melt the sides. When you solder a terminal, quench it in a shallow pan of water. I prewired the battery case and installed the lithium ion pack and reed switch as a final step. Use hot glue to put the battery bottom back on.
TV DINNER BY THE POOL, IM SO GLAD I FINISHED SCHOOL. FZ
RFI-EMI-GUY
Posts: 51
Joined: Fri Jun 02, 2006 7:23 pm

Re: Li-ion

Post by RFI-EMI-GUY »

31003 is the Tenergy part number. I used a medium sized NIMH Intrinsically safe battery case. The weight is now several ounces lighter . Obviuosly no longer IS Rated, but works fine. The particular charger Chip is available on a development PC board and starts charging when the battery is down below 7.4V. That means you cant "top it off", but really I am pleased. I think this could be the solution for all those ruggedized sabers that need batteries.
TV DINNER BY THE POOL, IM SO GLAD I FINISHED SCHOOL. FZ
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