Building a Battery-Pack for the HV20

[TheDingo]

Hi All,

Last January I bought a Zoom H4 portable recorder ( to record HQ audio for the videos I shoot ), and have been very happy with it's performance. After reading a few posts on a Zoom H4 forum ( http://www.2090.org/zoom/bbs/viewforum.php?f=15 ) I built an external battery-pack for it. The results of battery-pack have been great. 28 hours of recording with one 48v phantom powered mic using just 6 alkaline C-cells, versus 2 hours of recording with the normal 2 AA batteries. ( the battery pack connects to the Zoom H4 using the external AC PS connector )

Now that I own a HV20, I am thinking of building a simillar battery-pack for it. It will be nice to be able to leave the HV20 screwed down on the tripod-head during a long shoot if I can find a way to power it with an external battery-pack.

I was able to buy an identical connector to the HV20 AC adapter for just $5 at a local electronics supply store. The HV20 AC unit puts out 8.4 volts at 1.5 amps. Any ideas on what type of battery I should look at to power the HV20 ?

Thanks!

[dasbin]

I believe they are 7.4v Lithium-Ion batteries.
LiIon batteries contain some built-in circuitry and need to be approached differently from an electronic perspective. Notice how the battery has more than just 2 contacts?
My advice is, don't do it unless you know exactly what you are getting into (and it sounds like you don't). It's going to be really impractical.

You could just get a bunch of spare batteries, and if you want to leave the cam on the tripod, perhaps build some kind of adapter that simply provides an identical contact mount for the battery a few inches behind (or below, or wherever) the cam, so it can be accessed.

[TheDingo]

I believe they are 7.4v Lithium-Ion batteries.
LiIon batteries contain some built-in circuitry and need to be approached differently from an electronic perspective. Notice how the battery has more than just 2 contacts? My advice is, don't do it unless you know exactly what you are getting into (and it sounds like you don't). It's going to be really impractical.

Hi Dasbin,

Actually I don't want to build my own on-camera battery, but rather I want to use the DC connector that the AC-adapter uses. This is a lot simpler, as the battery pack only has to supply 8.4 volts DC at 1.5 amps to match the Canon AC adapter.

What I am looking for are some ideas on 8.4 volt batteries that might be suitable. Off the top of my head, I am wondering if 6 nickel metal hydride C cells might do the trick. In series they would put out 8.4 volts, though I am not sure about the amperage. ( I would definitely check things out with a digital multimeter before connecting to my HV20 )

I was amazed at how simple it was to build a 28 hour battery pack for my Zoom H4 digital recorder using 6 alkaline C cells. The recorder works flawlessly, and beats the standard AA battery pack by a mile. ( 28 hours while powering a 48volt phantom mic versus just 2 hours from the normal AA's )

[bluegrass]

Hi All,

Last January I bought a Zoom H4 portable recorder ( to record HQ audio for the videos I shoot ), and have been very happy with it's performance. After reading a few posts on a Zoom H4 forum ( http://www.2090.org/zoom/bbs/viewforum.php?f=15 ) I built an external battery-pack for it. The results of battery-pack have been great. 28 hours of recording with one 48v phantom powered mic using just 6 alkaline C-cells, versus 2 hours of recording with the normal 2 AA batteries. ( the battery pack connects to the Zoom H4 using the external AC PS connector )

Now that I own a HV20, I am thinking of building a simillar battery-pack for it. It will be nice to be able to leave the HV20 screwed down on the tripod-head during a long shoot if I can find a way to power it with an external battery-pack.

I was able to buy an identical connector to the HV20 AC adapter for just $5 at a local electronics supply store. The HV20 AC unit puts out 8.4 volts at 1.5 amps. Any ideas on what type of battery I should look at to power the HV20 ?

Thanks!

I respectfully disagree with dasbin. I wouldn't be afraid to figure out how to package together 5 rechargeable "D" size batteries (approx. 7.5 volts) in a series format that you can remove and put in a charger as needed. If you want it to last longer you could even put two of these packs in parallel but I bet a pack made up of 5 "D" cells would keep that "twenty" goin' for a bunch of hours.

I personally am thinking about pluckin' down a car battery under my tripod with a 300 watt inverter, puttin' the cam on auto-pan and zoom and going to sleep after an all night jam. I know your thinkin' how on gods green earth is he gonna carry that car battery. Above the battery will be my cabinet with XLR cables, mics, and a mixer. I already bought a portable fold up dolly that can handle up to 200 pounds.

Another method I'm going to try in a couple weeks is an 800 watt UPS I bought from Best Buy for abut $100 just to use for field power. I already hacked the dam beeper off the circuit board with a razor. This baby should also keep my mixer, DVD-monitor/player, & my camera going for hours. It's not much bigger than a brick and I can easily carry it. I'm going to benchmark it to see how long it will keep a 60 watt bulb burning bright.

Anyway I like your "can do" attitude. Just like messin' with all the controls & settings on our camcorders, there are more ways than one to skin a cat. A friend of mine always said "If you can dream it, you can do it". There is a lot of truth to that. I'll post some pictures of my setup when I'm camped out. I always pitch my tent where I can run an extension cord into it for recharging stuff and my pod coffee maker.

Update: TheDingo. You have the right idea. K.I.S.. I would personally like to see you attach a couple wires to that connector and run them to the exact connections on the battery pack than plug your new plug into the camcorder, and with a DVM, measure the voltage. It may very well have dropped to about 7.5 volts. I suspect that votage given may be under no load. It would be interesting to see what it is under load with the camcorder turned on and doin' it's thing. Don't do what I suggest unless you are good at messing around with wires and plugs. It would be very important to keep the polarity correct when you setup this temporary adaptor. I personally thing it's gong to be fine with 5 cells but it wouldn't hurt to put a 6th cell in there.

[TheDingo]

Another method I'm going to try in a couple weeks is an 800 watt UPS I bought from Best Buy for abut $100 just to use for field power. I already hacked the dam beeper off the circuit board with a razor. This baby should also keep my mixer, DVD-monitor/player, & my camera going for hours. It's not much bigger than a brick and I can easily carry it.

Wow! That's a very cool idea, and it's pretty much ready to go once you've amputated the beeper.

[ardo]

Hi Dasbin,

Actually I don't want to build my own on-camera battery, but rather I want to use the DC connector that the AC-adapter uses. This is a lot simpler, as the battery pack only has to supply 8.4 volts DC at 1.5 amps to match the Canon AC adapter.

What I am looking for are some ideas on 8.4 volt batteries that might be suitable. Off the top of my head, I am wondering if 6 nickel metal hydride C cells might do the trick. In series they would put out 8.4 volts, though I am not sure about the amperage. ( I would definitely check things out with a digital multimeter before connecting to my HV20 )

Not making an on-camera battery makes things much easier. I built one for my old Sony PC100 a couple of years ago. I used a 'dead' laptop battery. When these die, only one or 2 cells go, the rest is fine. Each cell is rated for 3.6V (actual 4.2 when fully charged), so 2 cells in series gives you the desired 7.2V (8.4V). I've had 3pairs of cells connected in parallel, giving me a total of 5,400mAh. The best part is, you can use the same camcorder charger, just get the right plug. Contrary to popular belief, Li-Ion batteries are safe to handle, just don't burn or puncture them. One more thing: your camcorder does not draw 1.5A, that's the charger rating to charge depleted batteries.

BTW, I never heard about Zoom H4 until I saw your post. I have a great condensor mike, so H4 with phantom power & balanced inputs would be ideal. The price tag of $300US is another story, however.

Where did you get the power connector to fit the HV20? I'm building a battery for it as soon as I get my camcorder in about a month.

[TheDingo]

Where did you get the power connector to fit the HV20?

I scrounged through a big bin of AC power-supplies at a local electronics remainder store here in Toronto. It cost me $5.

...I am really curious to see how long 6 C cells would power the HV20. I suspect I would get at least 8-10 hours out of them.

[dasbin]

I respectfully disagree with dasbin. I wouldn't be afraid to figure out how to package together 5 rechargeable "D" size batteries (approx. 7.5 volts) in a series format that you can remove and put in a charger as needed. If you want it to last longer you could even put two of these packs in parallel but I bet a pack made up of 5 "D" cells would keep that "twenty" goin' for a bunch of hours.

It wasn't the building-the-battery part that I was referring to, which is definitely as simple as you mention, but rather interfacing it with the back of the cam, which I believe expects some amount of data flow between the battery and the cam (the two bits of information I'm 99% sure about are the charge-state and the battery's serial number - the serial number is how eg a laptop will know that you've inserted a different battery and can always tell you what it's charge level last was, even if it's not on the device at the time).

Anyway, I'm getting a bit off-topic here; the point is now that he's looking to use the DC-in plug rather than attaching a custom battery to the back of the cam. Yeah, that should be quite simple.
There is the possibility that the cam will do something funky when the charge starts to go and the voltage drops. I guess there's only one way to find out, though.

I was going to mention the thought of using a UPS as probably being the simplest solution, but you beat me to it
The only concern that way is that you lose a heck of a lot of efficiency because of the DC-AC-DC transformation, so if you are concerned about getting the most from a given cell size it might be better to interface the DC directly.

[ardo]

Car and UPS batteries are not really designed for deep discharge, so I wouldn't use those. The only lead-acid battery that can deep discharge would be a marine battery. However, these cost roughly twice as much as car batteries.

[bluegrass]

Car and UPS batteries are not really designed for deep discharge, so I wouldn't use those. The only lead-acid battery that can deep discharge would be a marine battery. However, these cost roughly twice as much as car batteries.

Actually when I said car battery I am really using a deep charge marine battery. Yes they're more expensive but so is this hobby.

[tom chang]

I respectfully disagree with dasbin. I wouldn't be afraid to figure out how to package together 5 rechargeable "D" size batteries (approx. 7.5 volts) in a series format that you can remove and put in a charger as needed. If you want it to last longer you could even put two of these packs in parallel but I bet a pack made up of 5 "D" cells would keep that "twenty" goin' for a bunch of hours.

I personally am thinking about pluckin' down a car battery under my tripod with a 300 watt inverter, puttin' the cam on auto-pan and zoom and going to sleep after an all night jam. I know your thinkin' how on gods green earth is he gonna carry that car battery. Above the battery will be my cabinet with XLR cables, mics, and a mixer. I already bought a portable fold up dolly that can handle up to 200 pounds.

Another method I'm going to try in a couple weeks is an 800 watt UPS I bought from Best Buy for abut $100 just to use for field power. I already hacked the dam beeper off the circuit board with a razor. This baby should also keep my mixer, DVD-monitor/player, & my camera going for hours. It's not much bigger than a brick and I can easily carry it. I'm going to benchmark it to see how long it will keep a 60 watt bulb burning bright.

Anyway I like your "can do" attitude. Just like messin' with all the controls & settings on our camcorders, there are more ways than one to skin a cat. A friend of mine always said "If you can dream it, you can do it". There is a lot of truth to that. I'll post some pictures of my setup when I'm camped out. I always pitch my tent where I can run an extension cord into it for recharging stuff and my pod coffee maker.

Update: TheDingo. You have the right idea. K.I.S.. I would personally like to see you attach a couple wires to that connector and run them to the exact connections on the battery pack than plug your new plug into the camcorder, and with a DVM, measure the voltage. It may very well have dropped to about 7.5 volts. I suspect that votage given may be under no load. It would be interesting to see what it is under load with the camcorder turned on and doin' it's thing. Don't do what I suggest unless you are good at messing around with wires and plugs. It would be very important to keep the polarity correct when you setup this temporary adaptor. I personally thing it's gong to be fine with 5 cells but it wouldn't hurt to put a 6th cell in there.

Car batter is overkill, you can get smaller motorcycle type batteries, gel-cel
that will do the job, run for hours.

[bluegrass]

Car batter is overkill, you can get smaller motorcycle type batteries, gel-cel
that will do the job, run for hours.

What about powering my 500 watt haogen's?

[bluegrass]

Car batter is overkill, you can get smaller motorcycle type batteries, gel-cel
that will do the job, run for hours.

Thanks for the tip Tom. Do I need to go to a motorcycle store to buy one?