# SLA battery dead...best ideas for a battery pack?!?!



## black_z (Jan 23, 2015)

It's a Black and Decker with an H3 bulb. 6V and 75 watts. 

The battery was a 6V 4.5Ah

Should I do a LiPo, AAs, 18650s? Cordless tool battery?

Open to all suggestions!!


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## LightningJack (Jan 24, 2015)

Lipo isn't good for cold temperatures.Depends on how much space you got,too.Maybe 2s1p lifepo4 in 26650 or a lipo 2s1p if you don't use it in cold conditions.The easiest would be to just replace the battery to a new one.But if you got a charger for lipo lifepo4 and liion why not upgrade since they don't need to be charged once per month.
Iwould search for a fitting battery at hobbyking.com in the almost same shape.
But think of if you got 2 Li Ions or 2 lifepo4 cells that they need to be balanced at charging or you put them in a battery shell so you can take out the single cell to load them in a charger.


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## black_z (Jan 24, 2015)

I just don't wanna hassle with it going bad again if I don't keep it charged all the time. It's didn't last two months when I bought it.

If replacing it is the BEST option, then that's what I'll do...


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## black_z (Jan 24, 2015)

That's also gonna be 12.5 amps...will other batteries do that besides an SLA?

Well, I've seen AAs do 3 amps, so I guess they will.


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## gofastman (Jan 24, 2015)

I vote LiFePO4


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## chaosdsm (Jan 25, 2015)

I also vote LiFePO4 which is even starting to replace SLA in cars and motorcycles due to longer life span, smaller size requirement, higher AH capacity, higher CCA. Only real drawback that I can find at this point is price. 

Not an apples to apples view, since motorcycles & flashlights have vastly different power delivery requirements, but as an example: my motorcycle takes a Yuasa YTX9 SLA battery with following specs: 120CCA - 8AH - 5.4lbs - 150mm X 87mm X 105mm - average stated battery life 3 years (1year pro-rata*) $58. 

Shorai Power now has two LiFePO4 batteries available for my bike, specs on the "cheap" one: 210CCA - 14AH - 1.98lbs - 148mm X 86mm X 88mm - expected life span 6 years (3 years pro-rata*) $160 - while the Shorai "recommended" battery has 270CCA - 18AH capacity - 2.19lbs - 148mm X 66mm X 105mm $190

*pro-rata details: YTX9 pro-rata = 6mo replace + 6mo 50% - Shorai Power pro-rata = 12mo replace + 12mo 50% + 12mo 25% 

NOTE: the YTX9 is the factory activated & sealed version, not the more common "-BS" version that you have to add acid to & seal yourself. 

Huge price premium for the LiFePO4, but YTX9 is too weak for headlight on high (dims at idle with brakes &/or turn signal on), and I've just put the 5th battery in it late November after 10 years ownership (10 years + 5 weeks actually) The previous 4 YTX9's all died less than 2 months after the 2nd year in the bike. Sadly, after 16 months unemployment, I could not afford a LiFePO4 for the bike when I needed a new battery  But if things continue to go well with the new job, maybe in a few months I'll get the "cheap" one!

While it won't make a noticeable difference on the bike, the weight difference (for any Lithium tech) will be huge in your flashlight!


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## black_z (Jan 25, 2015)

Thanks for the info so far!


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## black_z (Jan 25, 2015)

I have a cordless drill that I dont really use. Battery pack has 14 NiCd batteries. Would 6 of them @ 7.2 volts be too much for the bulb? That'd be 86.4 watts. 

The rating stamped on it says 6V 75W

The resistance I've been getting with the bulb lit is .6 Ohms...meaning it looks like it's only gonna do 60 watts at 6V, versus 75.

I'd guess by the time voltage dropped with the load, it'd be in the mid 6s somewhere. What do you guys think?


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## gofastman (Jan 25, 2015)

black_z said:


> I have a cordless drill that I dont really use. Battery pack has 14 NiCd batteries. Would 6 of them @ 7.2 volts be too much for the bulb? That'd be 86.4 watts.
> 
> The rating stamped on it says 6V 75W
> 
> ...


bulb lifespan drops
exponentially to the power -13 with voltage rise.


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## black_z (Jan 25, 2015)

But shouldn't voltage sag put the voltage about where it needs to be when under a load? Ought to drop it from 7.2 down into the mid 6 range, right?


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## gofastman (Jan 25, 2015)

black_z said:


> But shouldn't voltage sag put the voltage about where it needs to be when under a load? Ought to drop it from 7.2 down into the mid 6 range, right?



7.4v is the nominal voltage for 6 cells, probably right where it's gonna stay under load. if the cells are full the pack would be about 9.3v


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## black_z (Jan 26, 2015)

I thought they were 1.2v?


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## gofastman (Jan 26, 2015)

black_z said:


> I thought they were 1.2v?



They are, nominally. When they come off the charger they are about 1.55v


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## black_z (Jan 26, 2015)

Whats nominally mean?


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## gofastman (Jan 27, 2015)

black_z said:


> Whats nominally mean?



I don't know to be honest. I think it may be voltage under rated amperage draw?
take a car battery for example, it's called 12v, but when 100% charged it's about 14.7v


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## black_z (Jan 27, 2015)

Actually, 12.6 is a fully charged 12v car Battery.


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## thedoc007 (Jan 27, 2015)

The nominal voltage is what you see on the packaging. Every cell has a range of voltages that are "safe", and the nominal voltage is somewhat arbitrary. Usually the nominal voltage is somewhere in the middle of that range. For example, a typical twelve volt (nominal) car battery is a little over 10 volts when near dead...and during some parts of the charge phase, it might be 14 or even 15 volts. Just because it isn't at exactly twelve volts, doesn't mean there is a problem. Lithium-ion cells typically have a range of 2.5 to 4.2 volts, and the listed (nominal) voltage is 3.6 or 3.7 volts (for most types). NiMH cells are nominally 1.2 volts, and the reasonable range is 0.9 to 1.5 volts or so. You get the idea.


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## black_z (Jan 31, 2015)

Gotcha!

Regarding overpowering this bulb. If 12V auto stuff regularly sees ~14.5V, shouldnt a 6V bulb take roughly half of that and be okay? At least 7?


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## BVH (Jan 31, 2015)

Been a long time since I worked on 6 Volt automotive systems but if memory serves, charging systems put out 7 to 7.5 Volts so 6V lamps should take 7+ Volts


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## more_vampires (Feb 1, 2015)

BVH said:


> Been a long time since I worked on 6 Volt automotive systems but if memory serves, charging systems put out 7 to 7.5 Volts so 6V lamps should take 7+ Volts



I think you're right, IIRC. I wanted to say 7.3v or 7.4v though. I have an old 6v bike that would boil a lead acid at 7.5 and above.

YMMV.


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## black_z (Feb 2, 2015)

I'll shoot for something in that range, then!


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## more_vampires (Feb 2, 2015)

Warning! Thread drift now in progress!


black_z said:


> I'll shoot for something in that range, then!



FULL STOP! :shakehead Story was about a (now) antique motorcycle. Not a currently available flashlight. "Just saying," ladies and gentlemen.

You can't necessarily without precaution slap just any battery upon just any device. Haven't you even considered amp hours versus your amperage draw requirement? Did you mis-hear some words and are now falling for the Dark Side? I hope not. Judge a battery by it's size, do you?

Ask a question. Is your device and combination safe?


black_z said:


> It's a Black and Decker with an H3 bulb. 6V and 75 watts.
> The battery was a 6V 4.5Ah
> Should I do a LiPo, AAs, 18650s? Cordless tool battery?
> Open to all suggestions!!



*It is a flashlight.* It's starting to become a complex system, what bulb... what battery? What of the wiring and such in the way?


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## more_vampires (Feb 2, 2015)

I fear for your charging system and your cell protection. Does the device have a voltage cutoff or more likely rely on protection upon the pack. If you figure out to hotwire just anything in there, will it be safe?

Sometimes, maker suggested power packs and power supplies really are just the thing.

Just a thought. I'm not saying "don't do it." I'm saying "What is this going to take?"


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## black_z (Feb 3, 2015)

more_vampires said:


> You can't necessarily without precaution slap just any battery upon just any device. Haven't you even considered amp hours versus your amperage draw requirement? Did you mis-hear some words and are now falling for the Dark Side? I hope not. Judge a battery by it's size, do you?




Oh, I definitely have...as soon as I noticed how fast it'll drain a couple AA cells! haha

Dark side?!


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## more_vampires (Feb 3, 2015)

LOL!  Oh sorry, drain a couple of AA alkalines? Meant to say "The Mcnair Side." :laughing:


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## black_z (Feb 3, 2015)

Mcnair? I'm still lost! lol


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## more_vampires (Feb 4, 2015)

Keep talking about alkalines and he'll show up.


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