How short is SF MN61 bulb life with 3X 18650 setup?

[tntsl]

In MD's Lithium-Ion>Incandecent Guide, for a 3X 18650 SF turbo head setup it says...

SF MN61: 32W, 760 - 455 lumen in 40 minutes (bulb life very short, but incredible)

How short is the bulb life?

I have the LF HO-M6R and that's pretty awesome, the SF MN61 must be amazing!

 

[DM51]

It's the luck of the draw.

Some people have had their instaflash, which at $31 per millisecond is very painful on the wallet.

Others (I am one) have had more luck. Mine hasn't flashed yet, but I don't think it is likely to last very long. I haven't racked up much time on it yet, so I don't know. I measured it at 3 amps on 3x17670s, and the cells weren't even fully charged. In stock configuration with 4x CR123A primaries it is only 2.5A. That is a BIG increase in current.

MN61 + 3x Li-Ions will outgun a MN21 + primaries, so yes, it is very bright. But not very reliable, as it could go at any time.

The HO-M6R is an excellent LA for 3x Li-Ions.

 

[Patriot]

I tried the MN61 and flashed it in a late model Guardian on 1 week rested batteries.

With the cost of MN61's and the amount of light increase gained, it's hard for me not to see the obvious mod answer in the 1111 or 1185 with bi-pin. When mdocod finishes the 2 x 18650 set-up it will make an easy 900+ bulb lumen option. I'm guessing that if the MN21 on new batteries is within the 750 lumen mark that the MN61 is approaching 900-1000 lumens, which is where the 1111 is at anyways, but with no risk of flashing.

 

[DM51]

In output: HO-M6R/3x Li-Ions < MN21/primaries = WA1111/2x Li-Ions < MN61/3x Li-Ions < WA1185/3x Li-Ions.

 

[tntsl]

So how would I use a WA1185 in a SF M4? I'll do a search on this.

 

[tntsl]

Does anyone know (or have an educated guess) what the runtime is with three 18650 cells and a WA1185?

 

[DM51]

2,200mAh / 3.3A, so in theory, 40 mins from full to empty. However, it is never a good idea to run Li-Ions down to empty, so best advice would be not to exceed 30 mins.

 

[tntsl]

2,200mAh / 3.3A, so in theory, 40 mins from full to empty. However, it is never a good idea to run Li-Ions down to empty, so best advice would be not to exceed 30 mins.

Thanks for the info DM51! I plan to use the light for short (less than 5 minutes) durations at a time so I should be able to recharge the cells long before they are empty but I wanted to know the approximate limit anyhow. Thanks again for the info.

 

[Tessaiga]

There's been repeated posts for and against running a MN21 on 2 X 18650 cells...

so is the MN21 + 2 X 18650 an advisable / good setup?

 

[Patriot]

So how would I use a WA1185 in a SF M4? I'll do a search on this.

I don't think there is a battery combination which would allow this to work.

Tessaiga
There's been repeated posts for and against running a MN21 on 2 X 18650 cells...

so is the MN21 + 2 X 18650 an advisable / good setup?

It's another borderline combination that pushes the MN21 to the max and sometimes beyond. Once an 18650 set up is available then all you need is a bi-pin to run a WA1111 which would be more solid.

 

[Patriot]

In output: HO-M6R/3x Li-Ions < MN21/primaries = WA1111/2x Li-Ions < MN61/3x Li-Ions < WA1185/3x Li-Ions.

Don't forget the last one:

< WA5761 + 2 X AW C cells .... oo:

 

[DM51]

… is the MN21 + 2 X 18650 an advisable / good setup?

Don't forget the last one:

< 5761 + 2 X AW C cells ....

I really don't recommend either of these. I've tried them, and they work, but these are both very power-hungry 2-cell bulbs (by 2-cell, I mean 2x Li-Ions).

They should really only be used with 'C' Li-Ions – the current draw is way over 2C with 18650s. The MN21 draws ~5A, the 5761 5.5A. Even with 'C' Li-Ions, you will bump up against the high current protection on the cells and you will need to double or triple-click/twist to get them going, which with an M6 is a PITA.

You will also need the FM extender for the M6, which adds ~18mm to the length of the light and unbalances it IMO.

The MN21 is driven very hard at the higher voltage, and although the output is spectacular – noticeably brighter than on primaries - the bulb life will be short.

The Philips 5761 is a larger-size bulb, and dimensions seem to vary slightly from one batch to another. Some people have found 5761s won't fit through the hole in the KT4 reflector. The batch I have do happen to fit; however there is an additional nuisance in that the bulb "sits up" higher, even when pushed right home into the FM MN bi-pin adapter. You will need to adjust the filament height with shims (provided by FM with the adapter) but you need at least 1mm of them.

The WA1111 is the best high-output bulb for 2x Li-Ions. mdocod's 2x18650 adapter will suit it perfectly.

For 3x Li-Ions cells, the biggest output is with the WA1185 and 3x 17670. I have not had any problems with instaflashing the WA1185.

Do not forget the HO-M6R! It is a very good bulb, not far behind the MN21 in output and very economical, meaning good run-time with 3x17670s (theoretical 40 mins, but better not to exceed 30 mins to keep cells from discharging to empty). It can also be run on 3s2p RCR123s in the stock MB20 holder, although some RCR123s are a tight fit.

 

[brighterisbetter]

I really don't recommend either of these. I've tried them, and they work, but these are both very power-hungry 2-cell bulbs (by 2-cell, I mean 2x Li-Ions).

They should really only be used with 'C' Li-Ions – the current draw is way over 2C with 18650s. The MN21 draws ~5A, the 5761 5.5A. Even with 'C' Li-Ions, you will bump up against the high current protection on the cells and you will need to double or triple-click/twist to get them going, which with an M6 is a PITA.

You will also need the FM extender for the M6, which adds ~18mm to the length of the light and unbalances it IMO.

The MN21 is driven very hard at the higher voltage, and although the output is spectacular – noticeably brighter than on primaries - the bulb life will be short.

The Philips 5761 is a larger-size bulb, and dimensions seem to vary slightly from one batch to another. Some people have found 5761s won't fit through the hole in the KT4 reflector. The batch I have do happen to fit; however there is an additional nuisance in that the bulb "sits up" higher, even when pushed right home into the FM MN bi-pin adapter. You will need to adjust the filament height with shims (provided by FM with the adapter) but you need at least 1mm of them.

The WA1111 is the best high-output bulb for 2x Li-Ions. mdocod's 2x18650 adapter will suit it perfectly.

For 3x Li-Ions cells, the biggest output is with the WA1185 and 3x 17670. I have not had any problems with instaflashing the WA1185.

Do not forget the HO-M6R! It is a very good bulb, not far behind the MN21 in output and very economical, meaning good run-time with 3x17670s (theoretical 40 mins, but better not to exceed 30 mins to keep cells from discharging to empty). It can also be run on 3s2p RCR123s in the stock MB20 holder, although some RCR123s are a tight fit.

thanks DM51 for your post, very informative.