Overheat Protection

Speedlite Overheat Protection

Speedlite overheat protection is a really useful function to have – just because your flash may say it can recharge quickly at full power doesn’t mean that you can shoot continuously without giving it a break to cool down. Better quality speedlite are usually designed to dissipate the heat better. Continuously firing your flash at high power will generate a lot of heat and if you don’t take care or have a speedlite that will automatically shut down when it detects it is starting to overheat then your speedlite might actually start to melt, smoke or catch fire. Apart from the obvious health and safety risks you won’t exactly look professional when you set the fire alarms off.

Many speedlites will have a feature that detects that it’s getting too hot and automatically shut down for a period of time (20-30 minutes). If you plan on shooting long continuous bursts of flash or you use high speed sync flash a lot outside then this is a very useful feature to have. It can save you a lot of money.

Icon for level 1 overheating on the Canon 600EX II-RT
Level 1: Firing interval reduced to approximately 8 seconds. Icon lit red.
Icon for level 2 overheating on the Canon 600EX II-RT
Level 2: Firing interval reduced to 20 seconds. Icon lit red and blinking

How to avoid overheating your flash

The obvious advice to avoid overheating your flash is not to use your flash continuously on high settings such as full power or even half power. If you can’t avoid it then do it for short periods and then give your speedlite a chance to cool down. Using your flash at 1/4 power and below is recommended. Not only does it reduce the chance of overheating but it will also extend the life of your flash. Your speedlite manual will usually give you advice on maximum continuous flash settings and usage.

If 1/4 power isn’t powerful enough for you then use two or more speedlites together. Two speedlites at 1/4 power is the same as one speedlite at 1/2 power. Four speedlites at 1/4 power equals one speedlite at full power. Using 1/4 power will not only reduce heat output but it will considerably speed up flash recycle time and give you a much quicker flash duration which is useful if trying to freeze action (dance / sports photography).

As mentioned previously in our section on batteries try to avoid using AA lithium batteries as they overheat quicker. Even alkaline or NiMH batteries will get warm or hot with heavy use. Eneloop Pro rechargeable are highly recommended and don’t appear to heat up as quickly as some other brands.

Another way of avoiding overheating problems is to use an external battery pack. The heat will be generated away from the speedlite and save it from damage if things start to get hot. Battery packs are usually better at dissipating the heat than a speedlite.

The Canon CP-E4N battery pack holds 8 AA batteries but if you delve into the speedlite custom functions you get a option of selecting between putting it in a mode where all 12 batteries (4 internal + 8 external) work together OR a mode where the internal batteries run the electroncis, communication, etc. and the externals only power the capacitors to do the firing.  This is the better mode to use because it means the internal batteries won’t get as hot.  It also means your distributing the load across 8 batteries instead of just 4…. so you’re halving the load on each battery.

Extract from Canon 600EX II-RT manual Custom Function C.Fn-12
Extract from Canon 600EX II-RT manual Custom Function C.Fn-12

The Godox PB960 lithium-ion power pack is also recommended. Again you can use the speedlite custom function to instruct the speedlite only to draw flash power from the external battery and leave the internal batteries to run the electronics and communications.

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