cree R5 drop-in at 1.9 amps

[Edgy]

I just recently received my cree r5 drop in from dx and installed my 3 mode solarforce driver inside. This driver drives an R2 at around 1.4 amps so I assumed that it would do the same with the R5. I tested the tailcap current with the R5 and was getting around 1.9 amps which eventually settled to around 1.8. I have no idea why the driver drives the R5 harder than the R2. I did my best to heatsink the drop-in using the aluminum can trick to snug up the gap between drop in and battery tube, but I'm still afraid that I might be overdriving the led too much. I have used the drop-in for a day or so and the head of my L2 gets warm after only a couple minutes so at least i know the pop can is working out for now. Anyone know if this is safe for an R5 or should I go with a less powerful driver?

 

[copperfox]

Current at the tailcap =/= current at the LED

 

[Fichtenelch]

You should measure the current directly at the led. maybe your driver is not running efficient and wastes 20%.
I'm looking for a 1xLi-Ion driver which has 3 modes and drives the led up to 1.5A in High.
Cree has updated the official specs of the xp-g and supports now up to 1.5A drive current.

 

[kramer5150]

I have noticed this as well with my DIY P60 builds.
My XRE-Q5-WC pills using 1.4A-7135 boards draw 1.25A.
My XPG-R4 pill, draws 1.4A using the same DC board, host and reflector.

Can someone explain why the current draw changes between the XRE and XPG?
:thinking::thinking:

 

[Justin Case]

Your XR-Es probably have a high Vf at the drive current of interest and combined with battery voltage sag, your 1xLi-ion source isn't delivering enough voltage to keep the 7135 driver in full regulation. If you have a bench power supply, send the driver say 4.5V and I bet you'll get 1.4A current draw.

The datasheet spec for the XR-E is 3.7V at 1000mA drive. At 1400mA drive, the XR-E Vf could be 4.0V or more. You need 120mV voltage overhead to run in full regulation, but your 1xLi-ion is probably going to sag below 4.1V pretty quickly. Even if it doesn't you aren't going to stay in full regulation for very long. Basically, you have a mismatched LED Vf/driver/battery combination.

In contrast, the XP-G datasheet shows a Vf of about 3.5V at 1500mA drive current. 1xLi-ion is well-matched to the LED in this case when using a 4x7135-based driver.