# replacement battery for gemini duo 1500



## seamarsh (Mar 5, 2012)

my battery pack for my Gemini duo cracked and is no longer holding a charge.. I bought in 2015.

replacement is 70$ https://www.action-led-lights.com/products/gemini-5200mah-hardshell-battery-pack

Was hoping someone might steer me to an eBay replacement that works with this light.. not really wanting to spend the 70$ Id rather buy a cordless light for that $

Does anyone have any good alternative battery links??


----------



## bme107 (Jul 23, 2008)

I've bought from this seller 3x over the course of 4 years. Use them with both Gemini and Gloworm light heads.
https://www.ebay.com/itm/Pana-sonic...on-battery-for-Bike-Light-2S1P-U/221320143805
They also make 4 and 6 cell packs if that's what you need. No fancy case though so you'll have to devise something yourself.


----------



## seamarsh (Mar 5, 2012)

bme107 said:


> I've bought from this seller 3x over the course of 4 years. Use them with both Gemini and Gloworm light heads.
> https://www.ebay.com/itm/Pana-sonic...on-battery-for-Bike-Light-2S1P-U/221320143805
> They also make 4 and 6 cell packs if that's what you need. No fancy case though so you'll have to devise something yourself.


Thanks, Do you get decent runtime with gemini and this battery.. its 3200 vs 5400 of the standard battery... my rides are under 2 hrs


----------



## patski (Dec 12, 2005)

bme107 said:


> I've bought from this seller 3x over the course of 4 years. Use them with both Gemini and Gloworm light heads.
> https://www.ebay.com/itm/Pana-sonic...on-battery-for-Bike-Light-2S1P-U/221320143805
> They also make 4 and 6 cell packs if that's what you need. No fancy case though so you'll have to devise something yourself.


Pretty sure it's the old Hunk Lee, I've had great luck with their batteries. 
These batteries Ship from New Jersey

If you're like a lot of us on here, you've bought too many crap batteries and have plenty of cheap battery bags laying around, if not: https://www.aliexpress.com/i/4000044175196.html?spm=2114.12057483.0.0.4fe03502cLD8q6


----------



## xcandrew (Dec 30, 2007)

I recently got a two-cell battery pack from fasttech. They have a 4-cell pack as well, probably linked from the two-cell listing. I don't know if it's the same battery pack that someone reviewed in this forum about a year ago as decent for the money, but the plastic shell looks the same. Inexpensive, but fasttech took their sweet time mailing it. (The quoted capacity is obviously nonsense... I just ignored that part.)

https://www.fasttech.com/p/9638360


----------



## seamarsh (Mar 5, 2012)

seamarsh said:


> Thanks, Do you get decent runtime with gemini and this battery.. its 3200 vs 5400 of the standard battery... my rides are under 2 hrs


Thanks, bought the one from first link.. ill post back after I receive it.


----------



## Ivan87 (Oct 30, 2012)

these have been very good

http://kaidomain.com/S024751-KBP-18...n-Battery-Pack-with-10cm-Cable?search=3500mah


----------



## lemke (Feb 13, 2015)

Yep, second the "kaidomain" battery packs. They use Panasonic cells, and are inexpensive. I have 2 packs for my Gloworm lights that are going on 5 years now.


----------



## seamarsh (Mar 5, 2012)

bme107 said:


> I've bought from this seller 3x over the course of 4 years. Use them with both Gemini and Gloworm light heads.
> https://www.ebay.com/itm/Pana-sonic...on-battery-for-Bike-Light-2S1P-U/221320143805
> They also make 4 and 6 cell packs if that's what you need. No fancy case though so you'll have to devise something yourself.


First ride with this battery pack you linked and unfortunately it sucks! Lol only made it 1hr 10 minutes on low for 75% of ride...bummer.. would steer clear of this for Gemini duo


----------



## patski (Dec 12, 2005)

seamarsh said:


> bme107 said:
> 
> 
> > I've bought from this seller 3x over the course of 4 years. Use them with both Gemini and Gloworm light heads.
> ...


That's a bummer, I get 2ish hrs with that battery(bought in '17) on my Gloworm XS. Hopefully you bought from the new jersey shipper so it's an easy return.


----------



## Cat-man-do (May 16, 2004)

seamarsh said:


> First ride with this battery pack you linked and unfortunately it sucks! Lol only made it 1hr 10 minutes on low for 75% of ride...bummer.. would steer clear of this for Gemini duo


You're the first person posting on this forum that has bought a Hunk lee battery that has had problems. ( I own a 2 cell HLee battery and it is still going strong after many years ). Could be you just got a bad one. A two cell with good Panasonic 3400mAh cells should run several hours if being run on a low ( < or ~ 200 lumen ) mode. If I were you I'd contact him through his web store and see if you can return and get a replacement.

To be fair though I have to admit that I've never put the HL 2 cell I own to an extended run time test. I only use mine for momentary High beam duties used in combo with my Gemini Duo. When I get a chance I'll set my Duo on low and see if it runs more than three hours. Not sure what my low setting is because I programmed mine years ago so likely it's more than 200 lumen.


----------



## bme107 (Jul 23, 2008)

Yes I think you guys are right, was HunkLee and now a new seller name. Hadn’t noticed that when I posted. I’ve got that 2s pack on permanent watch so I can find whatever I’m looking for in their store. 

Sorry it didn’t work out. I’ve bought 2,4,6 cells packs from them depending on what application was needed. Sounds like other’s have too with success. 

My oldest is probably 4 years old and newest 2 yrs. I don’t recall the mAh of each but they are lasting about the same as they always have. 

Had you made sure it was topped off with a charge or did you run it straight out of the box?


----------



## MRMOLE (May 31, 2011)

I did a runtime test (indoors cooled with a large fan) on my older 1100 Duo last night with that exact battery (less than 1 yr. old) and got 1:55 run at 100% power. I also checked the current draw which showed 1.75A so battery capacity seems OK. Current draw readings for the OP's Duo should be similar so should last longer than 1:10. It could be the battery is not fully charged for some reason but more likely there's just something wrong with the battery IMO.
Mole


----------



## Davide (Jan 29, 2004)

MRMOLE said:


> I did a runtime test (indoors cooled with a large fan) on my older 1100 Duo last night with that exact battery (less than 1 yr. old) and got 1:55 run at 100% power. I also checked the current draw which showed 1.75A so battery capacity seems OK. Current draw readings for the OP's Duo should be similar so should last longer than 1:10. It could be the battery is not fully charged for some reason but more likely there's just something wrong with the battery IMO.
> Mole


Which battery are you referring to? (there are a few in the thread).

I need new batteries too (my 2013 are going legs up, and last about 30' with my duo 1500), but I am tempted to buy new Gemini. I backpack and they can come handy to keep electronics running. Does anybody know if they come with USB cables and if they need a USB adaptor/charger? (Gemini has one on the web site.)


----------



## MRMOLE (May 31, 2011)

Davide said:


> Which battery are you referring to? (there are a few in the thread).
> 
> I need new batteries too (my 2013 are going legs up, and last about 30' with my duo 1500), but I am tempted to buy new Gemini. I backpack and they can come handy to keep electronics running. Does anybody know if they come with USB cables and if they need a USB adaptor/charger? (Gemini has one on the web site.)


The 2 Panasonic cell 3400 mAh one (Hunk Lee). I guess I'm not sure when Gemini switched to the 1500 lumen model (I thought it was 2016). Current draw readings I've seen posted for the 1500 were 2.5A so runtimes would be shorter than my model (more like 1:20 @ 100%). The newest Gemini battery uses 21700 cells so capacity is higher (4000mAh/2 cell, 8000mAh/4cell) which will increase runtime and definitely a better fit for the 1500 and newer Duo's. I.m not familiar with USB-C but the Action-LED-Lights site (linked below) makes it sound like it comes with one cable and others are available for different applications.
Mole

https://www.action-led-lights.com/products/gemini-usb-c-cables


----------



## Davide (Jan 29, 2004)

MRMOLE said:


> The 2 Panasonic cell 3400 mAh one (Hunk Lee). I guess I'm not sure when Gemini switched to the 1500 lumen model (I thought it was 2016). Current draw readings I've seen posted for the 1500 were 2.5A so runtimes would be shorter than my model (more like 1:20 @ 100%). The newest Gemini battery uses 21700 cells so capacity is higher (4000mAh/2 cell, 8000mAh/4cell) which will increase runtime and definitely a better fit for the 1500 and newer Duo's. I.m not familiar with USB-C but the Action-LED-Lights site (linked below) makes it sound like it comes with one cable and others are available for different applications.
> Mole
> 
> https://www.action-led-lights.com/products/gemini-usb-c-cables


Thanks for the info, I ordered two Gemini batteries. My order from Dec 2013 says 1x "Gemini DUO 1500 lumen LED light System" so it looks like it is a 1500 (or at least nominally so). Nice lights, tonight I was going around with the 50% setting (because the batteries are not holding much charge) and it was pretty good even in the deep of the forest.


----------



## MRMOLE (May 31, 2011)

Davide said:


> Thanks for the info, I ordered two Gemini batteries. My order from Dec 2013 says 1x "Gemini DUO 1500 lumen LED light System" so it looks like it is a 1500 (or at least nominally so). Nice lights, tonight I was going around with the 50% setting (because the batteries are not holding much charge) and it was pretty good even in the deep of the forest.


 :thumbsup:


----------



## Davide (Jan 29, 2004)

MRMOLE said:


> :thumbsup:


Got them yesterday, no USB cables but of course they do charge with the standard charger.A bit larger and heavier than the old Gemini 2013 (to the right in the photo, 190 vs 136 grams). More capacity is actually a good thing because with the old ones I was often a bit too close to empty at the end of a longish night run, and having the peace of mind is nice. The USB port will come handy backpacking.

The Helmet light battery used to be on my night helmet, but now the added grams convinced me to carry it on my Camel Back. It actually works great, just drop the battery in the top pocket of the Camel Back with a longish extension cable and off you go :thumbsup:


----------



## RS VR6 (Mar 29, 2007)

xcandrew said:


> I recently got a two-cell battery pack from fasttech. They have a 4-cell pack as well, probably linked from the two-cell listing. I don't know if it's the same battery pack that someone reviewed in this forum about a year ago as decent for the money, but the plastic shell looks the same. Inexpensive, but fasttech took their sweet time mailing it. (The quoted capacity is obviously nonsense... I just ignored that part.)
> 
> https://www.fasttech.com/p/9638360


I got the same battery from Aliexpress...but it was labeled as "Vastfire". After a two hour ride...the indicator light on my lamp was still green. It's half the size of the battery it replaced. Only thing is the connector isn't as snug as the original battery.


----------



## xcandrew (Dec 30, 2007)

RS VR6 said:


> I got the same battery from Aliexpress...but it was labeled as "Vastfire". After a two hour ride...the indicator light on my lamp was still green. It's half the size of the battery it replaced. Only thing is the connector isn't as snug as the original battery.


I dug up the review of the RockBros battery pack, which I kind of referenced as looking the same as the "fasttech" battery that I linked. Same hard case, both sold at one point on fasttech.

https://forums.mtbr.com/lights-night-riding/rockbros-2-cell-battery-pack-review-1079861.html

I've been using it nightly for several weeks for 1 to 1.5 hour runs in the cold (both above and below freezing), mostly on low/limited med and high on a Yinding. That's not testing the run time limits at all for a 2-cell pack, but it's enough use to say it's well worth the $11.54 shipped.

I like the hard case of the "fasttech" battery better than the Gemini one for sure - have had the end caps of the Gemini battery crack on all three of my 2-cells from them (though the cracks didn't affect function, just wrapped tape around them).


----------

