I have chosen for a Lanparte V-mount plate in combination with Rolux batteries. (Yes, Doug, it's all Chinese;-) ! And why not- even when it's not Chinese, it's still Chinese these days...)

I did not buy the V-mount plate via eBay though, but at a reputable AV-shop in Amsterdam so that I knew I would get support.

After some research, I opted for the Rolux batteries. Rolux is a solid, longstanding manufacturer of batteries.(whose products are sold under many different, top of the line names.)

Anyway, I bought the battery on eBay for around $130 for a 130Wh version. I noticed that the more powerful batteries have a steep increase in price. A 160Wh model is around twice the price of the 130Wh model. Why is that? And what would be the difference in runtime?

I'm tempted to get a few more 130Wh models. I don't use external monitors and use them exlusively to power the camera and an occasional on-camera light.

I noticed that the more powerful batteries have a steep increase in price. A 160Wh model is around twice the price of the 130Wh model. Why is that? And what would be the difference in runtime?

Any ideas, anyone?

I guess there are no V-mount users on the forum... or they're all Chinese and don't speak English...

Jeroen ~

Yes there are some V-Loc users out here. What I've learned over the years having had a number of cameramen working for me who seemed to go through batteries like there was no tomorrow might throw some light on the subject.

I now use Beillen 150Wh batteries that enable the best part of about 4.5hours plus. I find the 150's life span is better than the 160's over a number of years. The internal packs aren't 'tweaked' quite as hard. I believe they use the same battery packs but their internal charge monitoring chips have their charge maximum reduced.

Also with Li-ion V-Loc batteries consider cycle life as a function of DEPTH OF DISCHARGE. A partial discharge reduces stress and prolongs battery life. Elevated temperature and high currents also affect cycle life.

DOD Re CYCLES

100% DoD 300–500

50% DoD 1,200–1,500

25% DoD 2,000–2,500

10% DoD 3,750–4,700

In 4K on the FS7 the BPU-60 (genuine Sony ones) claim to give you about two hours, and three hours on the BPU-90s. On Sony's figures of 30Wh per hour I guess with a 160 your theoretical would be 160Wh divided by 30Wh should give you around 5.5 hours run time. I think pretty safe at 5 hours but I have never run the FS7 to end of battery.

From experience though I learned that If you do run V-Loc batteries via external cable you need to re-set your FS7 external DC Low Voltage #1 and #2 settings. By default these are set to 11.5v and 11.0v by default. These levels are okay for external power supplies but if these voltages are applied to a 14.8v V-Loc battery you will end up with problems. Virtually no warning before the camera cuts out. Not nice in the middle of a shot. On top of which you can drastically reduce the life expectancy of your batteries as you would be going well past their recommended minimum depth of discharge.

14.8volt V-Loc batteries are often built around 4 x 3.6 volt Li-ion packs. 4 x 3.6 = 14.4 volt. Each pack fully charged come up to 4.2 volt. 4 x 4.2 volt = 16.8 volt. A voltage you are likely to see from a battery straight off the charger. So as not to damage the batteries and to ensure you don't go below the minimum battery levels you will need to re-adjust the two Low Voltage levels in the FS7 "System/Camera DC In Alarm" menu.

Seeing that most of the V-Loc batteries use 3.6 volt cells that are nominally considered discharged at 3.0 volts one can take it that 4 packs x 3 volt each means a V-Loc pack is "dead" at 12 volts. If we give this figure a 10% safety margin we can say each pack is flat at 3.3 volts. 4 x 3.3 = 13.2 volts. On that basis Low Voltage Alarm #2 could be set at 13.2 volts. If we now calculate a 15% level for Low Voltage #1 this would be 3.45 volts per pack x 4 giving us 13.8 volts.

Battery Voltage Information ? Battery University (http://batteryuniversity.com/learn/article/confusion_with_voltages)

I have mine set at 14 volts for Low #1 and #13.5 volts for Low # 2 and find I am getting plenty of warning time to enable me to pick the best time for a battery change.

The reason for the price difference I think comes down to the fact that 2250mAh batteries are much cheaper than 2700mAh batteries. If I want to buy them in small batches I have to pay somewhere around twice the price or more for the higher mAh batteries:

4 x 2250mAh = 9000mAh divided by 14.8 volt = 133.2Wh around $5.00 each = $20.00 per 4 packs

4 x 2700mAh = 10,800mAh dived by 14.8 volt = 159.84Wh around $13.00 each = $52.00 per 4 packs

https://milliamps-watts.appspot.com/

I guess the battery pack manufacturers face a similar price difference hence have to charge a lot more for the higher Wh rated packs.

I hope some of this info is useful.

Chris Young
CYV Productions
Sydney

Now that's what I call an informative response! Kudo's to you mate! The fact that you can get a low battery warning on your screen with V-mount was completely unknown to me! Really very helpful.

If I can run my camera off the 130wH battery for a good 4 hours, that's plenty for me.

Thanks for taking the time to write this up, Chris- I think many others will benefit from this info as well.

Glad it was of some use Jeroen :)

Chris Young
CYV Productions
Sydney

I've just bought couple of 130Wh Rolux batteries with LCD screen. They're V-mount type, RLC-130S.
At first glance, the quality of plastic is not bad. No "Сhinese smell" if you know what I mean. :) The housing is assembled on screws, not glued as some brands used to do, thence it will be relatively easy to re-cell packs in the future.
LCD screen is essentially a voltmeter with a specific indication. I found it pretty practical. Voltage data on screen is the same as my multimeter shows.

As for battery life and reliability, I can not say anything certain now .

The drawback is the LCD screen hasn't backlight, so You must carry a flashlight to watch battery information in the dark.

I have mine set at 14 volts for Low #1 and #13.5 volts for Low # 2 and find I am getting plenty of warning time to enable me to pick the best time for a battery change.

Thanks a lot. These are the numbers I was looking for (but was to lazy to obtain by myself).
I already noticed that the default numbers a way too low on the FS7.

My advice to others: MAXOAK batteries (no connection to this company) do have a chip and communicate with the FS7 if you use them on the XDCA-FS7. This way you get minutes/percentage instead of voltage (and it seems to be quite accurate -> when I connect the Atomos Shogun Inferno additionally then the left time drops to about half of the time before).

Cheers,
Alex