Phillips 5761 Resistance is my friend

[icantsee]

I just got my first Phillips 5761 light put together today. It uses a 3C Mag host with a KIU switch mod and all switch contacts Pro-Golded. (Is Pro-Golded a word?) I'm using 2 E-Moli 26700 batteries. The voltage reads 3.85 on each cell. They are new cells with the factory charge. I'm using a MOP camless reflector and borofloat lens. It worked fine. I only tested in the house during daylight , but it seems whiter than my ROP high. I don't think it is enough different to notice if the lights weren't side by side. The ROP is in a 5C mag with a home modded tail cap to accept 6 subCs and the tailspring is resistance fixed. (Same reflector and lens in both lights.) I decided to further improve the 5761 by doing the tailspring resistance fix. Put it back together and the bulb flashed in about a second. I put in a new bulb and regular Mag tailcap and spring and we're back in business. I don't know how much the resistance changes with the tailspring mod or how to do the math to determine the voltage drop if I did know the value of the change. Does anyone know of a soft start circuit that would be a diy project, or is available as a package? Thanks.
John

 

[larryk]

Hi John, have you charged those cells yet ? If not you may have found an enemy. Those cells fully charged will be at around 4.1 to 4.2 volts with little voltage drop at 5 amps. I am using the same bulb in a 2 D Mag with 2 D sized Li-Ion batteries. I left the tail cap and switch stock just for added resistance. The 5761 is very bright and white, and blows away the ROP high using the same set-up. Yes resistance can sometimes be your friend.

 

[icantsee]

Thanks for the reply. No, I haven't charged them yet. Just took them out of the Milwaukee pack a couple days ago. I'm looking at a cellpro charger, but haven't bought anything yet. I'd like to get a voltage reading at the bulb, but am not exactly sure how to do it. I thought about getting the wire leads off the flashed bulb and plugging them into the KIU socket along with the new bulb. I'm not sure if that is sensible or if there is a better or safer way to do it.

John

 

[missionaryman]

Thanks for the reply. No, I haven't charged them yet. Just took them out of the Milwaukee pack a couple days ago. I'm looking at a cellpro charger, but haven't bought anything yet. I'd like to get a voltage reading at the bulb, but am not exactly sure how to do it. I thought about getting the wire leads off the flashed bulb and plugging them into the KIU socket along with the new bulb. I'm not sure if that is sensible or if there is a better or safer way to do it.

John

I just hook aligator leads to the pins of the bulb and to the pins of my DMM then just put the shiny end in a box or something so I don't go blind or get a bulb explosion in free air. Works fine but if you want the pins on there for more than a few seconds then you'll need to take the plastic off the aligator clips.

 

[mudman cj]

I just wrapped some fine gauge Teflon wire around each pin. It gets partially held in by the bulb when seated.

BTW-what is the capacity of those Moli cells?

 

[icantsee]

I believe that the manufacturer says 3ah. I've seen reports of 2.9 ah. I sent 4 cells to Silver Fox, but I haven't seen his results yet. He did say that the cells got hot at a 20 amp draw, "but had more in them." I've read posts on the R.C. forums stating that they're not much good above 9c discharge rates. I can live with considerably less than 9c. I bought a Milwaukee pack off eBay for $88.00 inc. shipping, (7 cells in a pack.) There's a lot of good info on the RC sites showing how to dismantle the milwaukee packs. Thanks for the vbulb info. (ROP works excellant in this setup.)

John

 

[icantsee]

Actually I just checked the Li-ion shootout thread in the battery section and Silver Fox has the data uploaded. He found 2900 as well.

John