Cheap 12V External Battery

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Cthe47

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Cheap 12V External Battery

PostSun Feb 25, 2018 6:46 pm

Hi

Has anyone used car battery chargers as external battery with the BlackMagic cameras?

Would the following charger work with BMCC? These batteries are really cheap.

ae235.jpg
ae235.jpg (19.11 KiB) Viewed 1121 times

Specs of the battery in the picture:
Battery Power: 4 Ah
Charging Current: 4 A
Current Type: DC
Voltage: 12 V
Voltage Supply: 240 V
Weight: 1.2 kg
Price: £10 ~ £15
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Kim Janson

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Re: Cheap 12V External Battery

PostSun Feb 25, 2018 6:52 pm

Not a good idea to ruin an expensive camera with cheap power supply, that is not even a power supply. That kind of chargers lack any kind of regulation and provide much higher voltage than 12 V when not loaded.
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Denny Smith

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Re: Cheap 12V External Battery

PostSun Feb 25, 2018 7:58 pm

A very good way to burn up your camera, and like Kim said, a very Poor way to power your camera.
Get a used Sony Studio Camera power supply, it is regulated and outputs the correct voltage.
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Re: Cheap 12V External Battery

PostSun Feb 25, 2018 9:32 pm

OK. Thanks for the responses. I know nothing about batteries. I thought it might work as it is 12V.

How about these:

Sealed Lead Acid Battery
The one in the picture: 12V - 4.2Ah

12V Sealed Lead Acid Battery 4.2Ah.jpg
12V Sealed Lead Acid Battery 4.2Ah.jpg (12.47 KiB) Viewed 1044 times

If good, what connectors to use it with the camera?

There are very cheap batteries on ebay (below) listed as replacement for Sony BPU batteries (new, for £50). Very confusing! Are they useful?

s-l1600.jpg
14.4V - 7800mAh
s-l1600.jpg (22.12 KiB) Viewed 1044 times

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Jeff Brass

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Re: Cheap 12V External Battery

PostSun Feb 25, 2018 10:30 pm

sealed lead acid are a bad idea. There is a reason camera batteries are lithium . SLA batteries voltage and wattage will drop way more then a lithium battery as the power runs low.

remember the old battery drills. as soon as you used it a little bit they got slower and slower until they stopped. Newer ones with lithium batteries keep the speed constant until fully depleted.

seriously, I'm not sure why risk so much for the sake of saving a few dollars on a battery, that you'll need to muck around with to get it to connect etc.

plus, you'll have no way of knowing how charged or flat the battery is until the camera just stops.
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Anatoly Mashanov

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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 2:34 am

1. Lead acid batteries would work with BMCC, BMPC4K, BMPCC and URSA without problem.
2. Lead acid batteries are extremely heavy so generally you don't want to use them unless your family name is Schwarzenegger. And anything less than 7AH is too weak for the camera.
3. Lead acid batteries contain some amount of acid so they could be unsafe for your eyes, skin and clothes, and for your camera too.
4. Sealed lead acid batteries (differently from flooded lead acid batteries) require strict compliance of charging regime to specifications. If you use a car charger your battery will be fried in less than 1 year.
5. The batteries should be stored fully charged.
6. Don't forget that the wrong polarity fries your camera immediately.

And the last:

NEVER power your camera from charger. NEVER attach the camera to the battery while the charger is attached to it. Doing so could fry your camera immediately.

Also: The 14.4 volts GOOD-BPU60 batteries could most possibly work. At least, I use 14.4V battery with my BMPCC without problem. But they are Lithium so:

1) You should use a specified charger or universal drone charger for them. Use of unspecified charger could cause a firework.
2) They stop working abruptly when discharged to 3 volts per cell. It's not a problem for cameras with backup batteries such as BMPCC but for URSAs you should use some voltmeter.
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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 3:12 am

Thanks for the detailed response.

I will probably get one of those GOOD(!)-BPU60 batteries or maybe a CCTV battery like the one in the following picture, to get started with my new camera. I think they will work similarly. Later, I'll get a real "GOOD" one.

72W 100WH 12V/8300mAh 9V/11000mAh 5V/20000mAh CCTV Camera Power Bank
CCTV_Battery.jpg
CCTV_Battery.jpg (9.79 KiB) Viewed 1013 times


Have you had those GOOD(!)-BPU60 batteries or CCTV ones? I just wanted to know how long they last.

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Craig Marshall

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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 4:10 am

You could always build one of these like I did. Simply re-charges in the field from any phone charger or a portable solar panel:

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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 8:05 am

I most definitely would not use a battery charger for a power supply. Some are simply brutal with spikey waveforms coming through on the DC. Others have interpretive electronics which may interact badly with the camera's own power regulator with fatal results for your camera.

For similar reasons, you should not use a mains powered regulated supply to the camera when there is a HMI lamp or heavyduty switchmode power device connected to the same mains power source.

These may also do brutal things to the mains power waveform and cause weird voltage levels on neutral mains lines which may get at your camera's own power supply destructively. I found this out the hard way with the SI2K which spontaneously shut down and forgot its user settings when its power supply shared its mains power source with a 1.2K HMI lamp. Fortunately the onboard automatic file repair utility saved the camera file which was affected.

For a backup, I have used older style lead-gel jump-start batteries for camera power with the SI2K. They are convenient to carry around and with an XLR standard four pin power socket added become fairly reliable. These are not designed for slow deep-cycling and fast recharge but for intermittent very heavy duty and prompt slow recharge. They may not live long in constant use for camera power.

Do not ever make adaptor cables with a cigarette lighter plug on one end and four pin XLR on the other for connection between them and camera. The electrical connection of the cigarette lighter plug is unpredictable at best and often resistive.

The 12VDC batteries did not have any longer endurance than the correct lithium batteries which have a higher initial voltage. As the 12VDC batteries expended, the voltage fell below the cut-off point where the camera would load-shed and shut the monitor off. Yet there remained considerable life in the batteries at lower voltage.

The cable from the 12VDC battery also had to be kept short. The power drop over more than about three metres of cable length would trigger load-shedding by the camera. Longer runs did not work at all.

The Sony clone batteries from China I would avoid. You would need to carry several of them for the same endurance time you would expect with single AB or V-Mount clone batteries from China. A cost advantage is unlikely. The Sony clone batteries and AB or V-Mount clone batteries usually have a check button on them which lights up a row of LEDs to indicate battery state.

The complication of wiring in a voltmeter is not needed. The voltmeter could be handy in telling you if the Sony clone batteries are being overextended and should not be used. By then of course you would have wasted your money buying them.

The Sony clone batteries may also live shorter lives in this application. At worst, constantly overdrawing the small Sony clone batteries may cause them to burn your house, your car or your camera to the ground.
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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 6:17 pm

Thanks Robert. Useful information!

I had no knowledge on how batteries work. Researching on the internet and following this thread, I am now convinced to buy proper batteries from the beginning.

What batteries would you recommend in the range of £150 to £200 which are reliable and possibly with the longest run time among others in that price range?
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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 7:43 pm

If you do end up using a high wattage battery like the sealed batteries shown, make sure you put an appropriate sized fuse (slightly larger than the camera draw) in line on the cable before using it. You can get any good AV tech shop to do this for you.
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Craig Marshall

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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 9:01 pm

Good suggestion as these batteries can deliver a lot of current in a short circuit situation. I put an 8amp in-line circuit breaker in my battery belt-pack details of which are linked in my earlier post. Saves carrying fuses in the field and Auto re-sets with virtually no resistive load at the rated current.

DSC04284_HD.jpg
12-15 volt DC, high current universal camera battery
DSC04284_HD.jpg (290.53 KiB) Viewed 948 times
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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 9:05 pm

Craig Marshall wrote:Good suggestion as these batteries can deliver a lot of current in a short circuit situation. I put an 8amp in-line circuit breaker in my battery belt-pack details of which are linked in my earlier post. Saves carrying fuses in the field and Auto re-sets with virtually no resistive load at the rated current.

DSC04284_HD.jpg


Nice!


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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 9:10 pm

I’ve done many tests of 12-volt Sealed Lead Acid batteries with the Pocket.

When I got frustrated with $15 internal 800mAh EN-EL20s lasting as little as five or ten minutes, I began to wonder about cheap SLA batteries. Looking at the Pocket specs, seemed like they would work. I started with an eight-dollar 1.3-Amp-Hour SLA. I made a cable with the Pocket connector on one end and two F2 connectors on the battery end, being sure to match F2 positive and F2 negative with center pole positive and outside pole negative of the Pocket connector.

Naturally, I was terrified the Pocket would fry, but when I hooked up that first 1.3AH battery, it worked. Run time with mostly continuous recording: About 28 minutes with the 1.3AH SLA alone and 80 minutes with both the fully charged (12.65 volts) SLA and fully charged (8.2 volts) internal EN-EL20. With dual batteries, the camera quit recording when the external SLA battery ran down to 8.2V and the internal EN-EL20 ran down to 7.4V.

I tested the SLA alone to see if it made a difference in noise; a theory was going around that when the internal battery heated up the camera, you’d get more noise. My testing was inconclusive. But with the SLA alone, the camera quit recording sooner, when the SLA discharged to 10.8 volts, rather than 8.2V. I decided that the longer run time with an internal battery present, 80 minutes vs. 28 minutes, might outweigh any extra noise. But I also had a couple of internal batteries that started to swell over time and were difficult to remove. That was a reason I later leaned toward using an external SLA alone, despite the shorter run time. My theory (never tested) was that if I left an internal battery in place, continuously being charged for eight hours by an external SLA, it might heat up and swell. My recurring nightmare: A dead, swollen battery stuck inside the camera.

That first 1.3AH SLA gave me a taste; it was my gateway battery. Next experiment: a 5 Amp-Hour SLA for about $10. It worked. Then I mainlined a 9AH SLA for $20. It worked. Bigger batteries, longer run times. It was pleasant. But I continued to be terrified and thought I should check myself into Anton Bauer rehab. Becoming ever more paranoid, I constantly monitored the voltage of these batteries with a multi-meter. My testing showed that all these batteries were similar: They would be "fully charged" at around 12.65 volts, they would self-discharge to around 12.3 volts over a period of a couple of days if you didn’t use them, but stabilize at 12.3V. When I later began powering the Pocket with them, they would run the camera (in recording mode) until they discharged to around 10.8V and the camera would quit (Note: This is with no internal battery). The camera would remain powered up in standby and play clips back at 10.8V or less, but not record. Conclusion: Higher voltage is required for recording.

One thing I never understood is why an internal EN-EL20 will run the Pocket until it discharges to 7.4 volts, but an external SLA that discharges below 10.8 volts will not. Could the Pocket have two “baseline” recording voltages, one for internal power and one for external? I’m guessing Denny could answer that.

Further testing results: I found that when you have an internal battery present, the 12-volt SLA will discharge deeper, to 8.2V, as it continues to charge the internal — but that's a bad idea. The nice thing about having the 12-volt SLA quit working at 10.8 volts is, that’s about as far as you should discharge an SLA, to give it longer life. Simple rule: When using an SLA by itself, it’s time to recharge when the Pocket quits recording — that means the SLA is down to 10.8 volts. And to prevent overcharging, recharge the SLA with a “float charger” that regulates the “full charge,” which seems to be around 12.65V. Another recurring nightmare: Exploding batteries!

Big negative with SLAs: Weight. The 9AH weights 5.5 pounds. So I made a fanny pack that I carry this battery in, and a longer cable to reach the camera for hand-held stuff. On a tripod, I mount the 9AH on the sticks. Big positive: the 9AH will run the Pocket for a long time. My guess, based on rate of discharge, would be eight hours of continuous recording if you also had an internal battery present. But I have not tested this on a continuous "record" cycle because I'm terrified the Pocket might get tired and fry. Or hit a wall in the land of physics. I like to test, but I'm not willing to fill up cards running the camera continuously for eight hours pointed at a physics wall.

Anatoly nicely lays out the risks of using SLAs. I agree with everything he says. I would add one more: With a cheap SLA battery, you are always terrified your camera is going to fry. It hasn’t happened to me in two years of using them, and my Pocket is now going on four years old, but I expect it to happen the next time I power up. Probably tomorrow. If I had an extra $284 lying around, I would check into Anton Bauer for the peace of mind.

FULL RIG.JPG
FULL RIG.JPG (120.59 KiB) Viewed 945 times
SCREEN.JPG
SCREEN.JPG (92.29 KiB) Viewed 945 times
BATTERY.JPG
BATTERY.JPG (130.53 KiB) Viewed 945 times
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Craig Marshall

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Re: Cheap 12V External Battery

PostMon Feb 26, 2018 9:16 pm

We powered an entire TV network of $50K Sony Betacams with 7AH SLAs and they worked well for years. You just need to make sure you use the correct charger as they are very sensitive to overcharging which cooks them. We equipped every belt pack with it's own permanently wired mini 240VAC charger so crews could safely leave them plugged in overnight whenever they were not in use. Each camera crew was equipped with three or four battery packs.
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Re: Cheap 12V External Battery

PostTue Feb 27, 2018 12:19 am

Jim Braly wrote:I’ve done many tests of 12-volt Sealed Lead Acid batteries with the Pocket.

When I got frustrated with $15 internal 800mAh EN-EL20s lasting as little as five or ten minutes, I began to wonder about cheap SLA batteries. Looking at the Pocket specs, seemed like they would work. I started with an eight-dollar 1.3-Amp-Hour SLA. I made a cable with the Pocket connector on one end and two F2 connectors on the battery end, being sure to match F2 positive and F2 negative with center pole positive and outside pole negative of the Pocket connector.

Naturally, I was terrified the Pocket would fry, but when I hooked up that first 1.3AH battery, it worked. Run time with mostly continuous recording: About 28 minutes with the 1.3AH SLA alone and 80 minutes with both the fully charged (12.65 volts) SLA and fully charged (8.2 volts) internal EN-EL20. With dual batteries, the camera quit recording when the external SLA battery ran down to 8.2V and the internal EN-EL20 ran down to 7.4V.

I tested the SLA alone to see if it made a difference in noise; a theory was going around that when the internal battery heated up the camera, you’d get more noise. My testing was inconclusive. But with the SLA alone, the camera quit recording sooner, when the SLA discharged to 10.8 volts, rather than 8.2V. I decided that the longer run time with an internal battery present, 80 minutes vs. 28 minutes, might outweigh any extra noise. But I also had a couple of internal batteries that started to swell over time and were difficult to remove. That was a reason I later leaned toward using an external SLA alone, despite the shorter run time. My theory (never tested) was that if I left an internal battery in place, continuously being charged for eight hours by an external SLA, it might heat up and swell. My recurring nightmare: A dead, swollen battery stuck inside the camera.

That first 1.3AH SLA gave me a taste; it was my gateway battery. Next experiment: a 5 Amp-Hour SLA for about $10. It worked. Then I mainlined a 9AH SLA for $20. It worked. Bigger batteries, longer run times. It was pleasant. But I continued to be terrified and thought I should check myself into Anton Bauer rehab. Becoming ever more paranoid, I constantly monitored the voltage of these batteries with a multi-meter. My testing showed that all these batteries were similar: They would be "fully charged" at around 12.65 volts, they would self-discharge to around 12.3 volts over a period of a couple of days if you didn’t use them, but stabilize at 12.3V. When I later began powering the Pocket with them, they would run the camera (in recording mode) until they discharged to around 10.8V and the camera would quit (Note: This is with no internal battery). The camera would remain powered up in standby and play clips back at 10.8V or less, but not record. Conclusion: Higher voltage is required for recording.

One thing I never understood is why an internal EN-EL20 will run the Pocket until it discharges to 7.4 volts, but an external SLA that discharges below 10.8 volts will not. Could the Pocket have two “baseline” recording voltages, one for internal power and one for external? I’m guessing Denny could answer that.

Further testing results: I found that when you have an internal battery present, the 12-volt SLA will discharge deeper, to 8.2V, as it continues to charge the internal — but that's a bad idea. The nice thing about having the 12-volt SLA quit working at 10.8 volts is, that’s about as far as you should discharge an SLA, to give it longer life. Simple rule: When using an SLA by itself, it’s time to recharge when the Pocket quits recording — that means the SLA is down to 10.8 volts. And to prevent overcharging, recharge the SLA with a “float charger” that regulates the “full charge,” which seems to be around 12.65V. Another recurring nightmare: Exploding batteries!

Big negative with SLAs: Weight. The 9AH weights 5.5 pounds. So I made a fanny pack that I carry this battery in, and a longer cable to reach the camera for hand-held stuff. On a tripod, I mount the 9AH on the sticks. Big positive: the 9AH will run the Pocket for a long time. My guess, based on rate of discharge, would be eight hours of continuous recording if you also had an internal battery present. But I have not tested this on a continuous "record" cycle because I'm terrified the Pocket might get tired and fry. Or hit a wall in the land of physics. I like to test, but I'm not willing to fill up cards running the camera continuously for eight hours pointed at a physics wall.

Anatoly nicely lays out the risks of using SLAs. I agree with everything he says. I would add one more: With a cheap SLA battery, you are always terrified your camera is going to fry. It hasn’t happened to me in two years of using them, and my Pocket is now going on four years old, but I expect it to happen the next time I power up. Probably tomorrow. If I had an extra $284 lying around, I would check into Anton Bauer for the peace of mind.

FULL RIG.JPG
SCREEN.JPG
BATTERY.JPG


Thank you for sharing your experience. Very helpful!
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Re: Cheap 12V External Battery

PostTue Feb 27, 2018 3:43 am

I read through the forum and noticed that many people have used tablet/phone power banks with their BMCC successfully. They've all used Anker power banks. However, it seems Anker has discontinued those powerful versions! But there are other brands available.

For example, will this battery work? According to the spec, it can power the BMCC for several hours, right? That's strange! It's only £75.

23000mAh Multi-Voltage (9V 12V 16V 19V 20V) Portable Charger External Battery
Battery Type: Li-polymer Battery
Capacity: 23000mAh/85Wh
Input: DC 15~24V/2A
Output: DC 9V/12V/16V/19V/20V 4.5A(MAX)
USB1: 5V, 2.5A
USB2: 5V, 1A

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Re: Cheap 12V External Battery

PostTue Feb 27, 2018 3:52 am

My camera Battery uses 3 x Apacer 6000ma power banks (made in Taiwan) wired in series and they are about $15 each. Your multi-voltage lithium solution looks ideal.
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Re: Cheap 12V External Battery

PostWed Feb 28, 2018 2:25 am

Jim Braly wrote:One thing I never understood is why an internal EN-EL20 will run the Pocket until it discharges to 7.4 volts, but an external SLA that discharges below 10.8 volts will not. Could the Pocket have two “baseline” recording voltages, one for internal power and one for external? I’m guessing Denny could answer that.

Just because the lead acid keeps supplying the juice being discharged below limit, but Li does not. So the internal battery should have enough juice to stop recording, safely close the files and power off, while the external battery is good while it's voltage is at least higher than the voltage of internal battery + some spare so the internal battery is being charged.

Also, 7.4 and 10.8 volts are nominal voltages, real voltages are 6.0-8.4 and 9.0-12.6 correspondingly. The battery dies if the voltage is below 3.0 and explodes above 4.2 per cell so the controller ensures that the voltage is in these limits and disconnects the battery if not.

For lead acid the nominal voltages are from 10.8v under load to 13.5v under float charge and 14.4 volts under fast charge for 6 cells.
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Cheap 12V External Battery

PostWed Feb 28, 2018 4:37 am

Is powering the camera on the same circuit that supplies power to the lights (let’s say 2000 w lights) harmful? If yes, would that be a good suggestion to use extension cables to bring power from another circuit (for example another room) to power the camera?


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Kim Janson

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Re: Cheap 12V External Battery

PostWed Feb 28, 2018 6:34 am

It is really best to power cameras from power suplies dedicated to that and keep power cables short. Long DC power cables have inductance and that can cause voltage pikes that burn electronics, when the connector is connected.

In any case connect and disconnect power cables when the power supply is unpowered.
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Denny Smith

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Re: Cheap 12V External Battery

PostWed Feb 28, 2018 7:43 am

Most studios have separate circuits in the Studio for lights and camera power supply connections. Control room board is also on separate circuits.
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Re: Cheap 12V External Battery

PostWed Feb 28, 2018 9:29 am

We will be shooting in an old house, second floor, with no dedicated power supply for camera. This is not a professional film and it is not going to make money. Budget is very limited.

The lighting needs about 2000 W. What would you do for powering the camera if taking power from other rooms/floors using long cables is not a good idea?

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Kim Janson

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Re: Cheap 12V External Battery

PostWed Feb 28, 2018 9:59 am

It is ok to use long cables on 240 AC 50Hz, 110 V AC 60 Hz etc what ever houshold power network you are using, but the cables between the camera and power suply should be kept short.
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Re: Cheap 12V External Battery

PostSun Mar 04, 2018 8:09 am

the reason the camera stops when the SLA is around 10.8 volts, vs the internal Li battery going down to 7.2v before the camera stops, is that at 10.8 (approx) volts the SLA can no longer supply enough current (amps) to run the camera. Voltage is determined by what the components need to be safe (the voltage they are designed to run at), current is what is need to actually make things work. AS a battery drains, voltage and current go down. The difference is as an SLA voltage goes down, so does the current - quickly. Li batteries can keep the current up higher almost to the very end.

As for the "more noise when internal battery gets hot" - more then likely its a case of as the battery gets hot, so do the camera internals, sensor etc. Heat equals noise. An external battery would help minimize that.
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