11 x high current AA NiMh = what Lithium Ion?

Minimoog · Dec 5, 2018

I have a USL Maglite, had it for years and it uses the Elite high current 2000 mAh AA batteries built into a pack by CheapBatteryPack - an excellent company but now closed.

This light uses a bored Mag host, 12V 100 Watt bulb with axial filament and uprated switch and bulb holder. It gives a wonderful bright and clean light.

Is it possible to drive this light from Li-Ion cells instead of NiMh? Anyone done it? Maybe I need to swap the bulb to something else as it does not like being overdriven too much.

Thanks for any thoughts.

Thetasigma · Dec 5, 2018

3 Lithion Ion would net you 12.6V fully charged. Your NiMH presumably were 13.2V charged.
Next closest thing would be 4 LiFePo4, which would be 14.4V.

Could of course take some of the excellent Eneloop Pros and try to build them into a series pack.

alpg88 · Dec 5, 2018

Minimoog said:
I have a USL Maglite, had it for years and it uses the Elite high current 2000 mAh AA batteries built into a pack by CheapBatteryPack - an excellent company but now closed.

This light uses a bored Mag host, 12V 100 Watt bulb with axial filament and uprated switch and bulb holder. It gives a wonderful bright and clean light.

Is it possible to drive this light from Li-Ion cells instead of NiMh? Anyone done it? Maybe I need to swap the bulb to something else as it does not like being overdriven too much.

Thanks for any thoughts.

It depends what bulb you use, some can take 5 cells other will flash with 4
see destruction tests in inc. section. to see what level of overdrive your particular bulb can take. just saying 12v 100w does not say much, there are several different ones, all rated at 12\100

i build about a dozen of hotwires, the best bulb is 90w bulb that can be over driven to 200w with no issues, look for Phillips 64458 . use 5 cells with it. for the first minute you'll have 10klm light

Minimoog · Dec 5, 2018

Thanks. The bulbs I have are the Osram 62138 - 12V, 100W, 50 Hour. Probably something more suited to LiIon now now but that is what I am using as I bought them way back. 3000 Lumens.

alpg88 · Dec 5, 2018

http://photobucket.com/gallery/user/pike444/media/bWVkaWFJZDoxNzg2NTkzNA==/?ref=

3 cells will be ok at first but as cells discharge and drop below 12v you'll be under driving the bulb most of the time. nominal voltage of 3 li ion is lower than nominal voltage of 11 nimh. 11.1 vs 13.2

edit, i was wrong to claim it can take 4 cells, my bad, it will flash immediately, i looked at different number.

looks like the easy option is using 3 cells, but it will be dimmer than it was running on 11 nimh. you can go 4 li feo4 cells that are 3,2v.

alpg88 · Dec 5, 2018

Thetasigma said:
3 Lithion Ion would net you 12.6V fully charged. Your NiMH presumably were 13.2V charged.
Next closest thing would be 4 LiFePo4, which would be 14.4V.

.

not quite. you are comparing max charged voltage of li ion to nominal voltage of nimh, fully charged nimh cell typically 1,4-1,5v fresh off charger. and runs at 1,2v till it's almost empty. li ions otoh have usable voltage range is from 4,2 to 3

Thetasigma · Dec 5, 2018

alpg88 said:
not quite. you are comparing max charged voltage of li ion to nominal voltage of nimh, fully charged nimh cell typically 1,4-1,5v fresh off charger.

In which case the bulb could be seeing a spike of up to 16.5V off a fresh pack.

alpg88 · Dec 5, 2018

Thetasigma said:
In which case the bulb could be seeing a spike of up to 16.5V off a fresh pack.

yes. according to the destructive test table it was supposed to flash. the bulb flashes at 15. unless it uses in rush current limiter, or some kinda resistance trick.

alpg88 · Dec 5, 2018

if you have 4D maglite, you may use 12 aa cell adapter with 1 dummy cell, (if you can still find elite cells, you need 10A cont. draw, no eneloop will handle that for long),
li ion3 cells and 62138 is not a good combo, it will be dimmer than it was with nimh, 4 regular li ion will instaflash the bulb, 4 li fepo4 will be about what nimh cells put out.

fivemega · Dec 6, 2018

Combination of 4 large IMRs with Osram 64623 is better than 3 large IMRs with Osram 62138
3 large IMRs with FM1909 is perfect match. It's 50 watts with much longer run time and whiter beam.

Minimoog · Dec 6, 2018

Thanks for the input. With NiMh cells I can charge at 0.2C and they are pretty sure to be balanced - never had any issues. When using IMR or li feo4 cells, is it right that they cannot be charged as a pack without balancer? Just that as is, the USL has no internals - its all hard wired and soldered so holders cannot be used - unless I rig up something on extending wires perhaps.

Timothybil · Dec 6, 2018

I would suggest a 14.7v LiPO pack, but it would be hard to find one in a cylindrical form factor.

Question: In a LiPO pack, is 14.7 the charging voltage or the nominal voltage?

Minimoog · Dec 6, 2018

Its hard for me to find out in the UK - but does anyone know if the Elite AA's are still in production?

alpg88 · Dec 6, 2018

i found few sites that sell them, but whether it is old stock or new production, unclear. not sure how long can such cell sit before it discharged to the point it wont charge no more,

alpg88 · Dec 6, 2018

Minimoog said:
Thanks for the input. With NiMh cells I can charge at 0.2C and they are pretty sure to be balanced - never had any issues. When using IMR or li feo4 cells, is it right that they cannot be charged as a pack without balancer? Just that as is, the USL has no internals - its all hard wired and soldered so holders cannot be used - unless I rig up something on extending wires perhaps.

you can, but you should not, once or twice is ok, but if you keep doing it, cells will dis balance more and more.
your best bet would be removing them and charging in a separate charger as individual cells. thou it is not as easy and convinient as pluging a charger in the pack itself.,

11 x high current AA NiMh = what Lithium Ion?

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