Mag85 Problem - Gradual start

I built a Mag85 about a year ago and I've been very happy with it. I don't use it too often, I'd say maybe a dozen battery cycles. After sitting dormant for a few months, I recharged the cells and after waiting for them to settle I fired it up. The bulb does not reach full brightness for maybe 20 sec, or possibly a little more. It starts out very dim and grows gradually. Any idea what could be causing this? My battery pack voltage checks out as normal.

Take the mag apart and clean it. You may have some hi resistance contacts from sitting.

Ctechlite said:

Take the mag apart and clean it. You may have some hi resistance contacts from sitting.

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I finally got around to doing this but I was not able to figure out how to get the switch assembly out. I cleaned the bulb pins, the bipin adapter, and all of the contacts on the battery adapter. Unfortunately there was no change in the performance. How do I get the switch out? Any other ideas?

To remove the switch take off the rubber switch cover and you'll see a hole in the centre.

Use a 5/64ths hex key to unscrew the grub screw at the bottom of that hole. You should then be able to slide the switch assembly down and out the bottom. Note that the switch should be 'on' to slide it out.

After that it is a bit more obvious how to further disassemble.

Try searching on here, there are some very good step by step guides with pics showing the mag switch taken apart.

Sorry, I'm at work at the mo so can't view pics otherwise I would dig some up.

Hope that helps some.

I don't know that much about the 1185 bulbs, but this sounds like a good thing, i know surefire builds "soft start" into a lot of it's lights. The slower start with the super powered bulbs is supposed to make them last longer.

Although quite far fetched, on thing that came up in my mind was that some high-current RC-cells needs to be run hot before they can deliver full current. 20 seconds could very well be the thermal time constant for a battery when run hard.

What happens if you try another bulb?

winny said:

Although quite far fetched, on thing that came up in my mind was that some high-current RC-cells needs to be run hot before they can deliver full current. 20 seconds could very well be the thermal time constant for a battery when run hard.

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Umm...yes, SubC NiMH cells need to warm up before they deliver 30+ amps.

But I don't think his Mag draws that much current.

Toshi

TMorita said:

But I don't think his Mag draws that much current.

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Precisely!

Thanks for the suggestions. I'll try cleaning the switch. As for the "soft-start" being a feature, the light didn't used to behave like this. It would reach full brightness easily in under a second, but now it's more like 20s. The same thing happens when I change the bulb. Is it possible that one or more of my cells are damaged? I haven't tried replacing them yet.

Which batteries are you using?

BigusLightus said:

Which batteries are you using?

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9x Sanyo 2700

Whiteknight said:

9x Sanyo 2700

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sanyo are good batteries, but I suggest to replace them becouse if a year ago your mag worked well must work well today (there are't any parts in a cleaned flashlight that lost their characteristics during the time, exept for the batteries)

NiMh cells, unless they are the new hybrids like the Eneloop, don't like to sit around for months without being used. You probably need to do a forming charge or two on the cells to bring them back up to speed.

A good voltage reading isn't enough to determine that they are fine. That's just one parameter that affects current flow.

Hop over to the battery forum and look for SilverFox's threads on NiMh cells. A lot can be learned from his info on keeping cells in tip-top shape.

sounds like a combination of over-loaded battery and corroded/contaminated switch contacts. one of the 50-watt MR16 light I built exhibited similar symptoms until I swapped the stock switch for a 15-amp rated rocker switch and it not only solved the problem but also made the light much brighter.

the high-amp-hour rated(like 2600-2900) batteries are typically not suited for being driven over 2-3 amps. the batteries you should be using are the high-drain ones like the 1650 from CBP. trust me you will see a HUGE difference in brightness if you used the RC batteries rather than consumer NiMh AAs.

Since the 1650s don't seem to be stocked any more, I picked up some Eneloops and put them in the torch. Problem solved. I guess it's time for a refresh cycle on my BC-900 for the Sanyos.

I had a similar problem with one of mine, It just needed to be taken apart
and cleaned out, also check the batteries