battery info

[jason porter]

Hi All,

I am using a 7.2V lith-ion battery to power my ENG bag and it is great, lasts forever.(SD302 & 2 X UCR201's...35 hours straight)

My question is, do I have a "maximum draw" from these little batteries?  I can't seem to find any info.  I am currently drawing about 400ma, but I want to add another 400ma (approx, probably a little less)

Am I correct in assuming I have a limit to how many milliamps can safely draw?

The gear is this-

SD302-130ma

UCR201-120ma

UCR201-120ma

UCR401-120ma

Stereoline Tx (older version)- 200ma??

So that totals about 700ma.

Anyone have any experience in these matters??

Thanks

-JP

[carbonhobbit]

      I run three lectros, a 442 and a 744T all thru a BDS system and can go about seven hours plus. My battery is an IDX 14.8V/ 71 watt hour lithium. Without the 744, I can go about three days. Since your using a battery of one half this size, I would guess you would only go half as long. I tried to use my older metal batteries (50 watts) and they would poop out in twenty minutes or so, so I never even tried to use them with my 744 package but they work fine without the recorder. So yes, you do have a limit. Seven volts shared thru five units that normally run on 9 volts each would make me nervous.

      Scott L

[Eric Leonard]

Jason,

I'm not sure what the maximum current-draw specs are for the Sony 7.2s, however, their highest-draw camcorders using this battery (HVR-S270/Z7) pull about 730 milliamps at 7.2 volts (7.3 watts, per Sony specs). This may be why a new generation of battery was designed for the XDCAM-EX cameras, but I don't know and haven't investigated.

But -- it seems like you have at least another 300 mA to draw with no problem - 800 total is probably fine. I don't know enough about Li chemistry and the battery design to know what the limits are or should be, or what the consequences are for pulling too much too quickly.

I have a customer who uses these batteries to run a mixer and some Audio Ltd radios. To err on the side of caution (and because the batteries are so cheap for their performance) I'm using two batteries -- one for the wireless RX and TXs and another for the mixer and a few other gizmos. Even with two top-capacity Sony batteries - the rig is still lighter than a single NP-1.

The SD stuff (other than the recorders) will run at full performance well below 9 volts, and the Audio Ltds only need 6 volts. Lectro radios typically want to see 10 volts minimum, but I haven't tested them with lower voltage. Larry?

Hope this helps -- Eric.

[jason porter]

Thanks for the info.

Just for the record...the UCR 201's will run down to 6V when I use a 9V battery dummy!  the UCR401 needs 6V via the external power input (according to the manual...haven't actually tried it yet!)

I looked at adding another small capacity battery for the Zaxcom (2000 mah), I'll look closer

-Jason

[studiomprd]

it is mostly about the capacity, in MAh, of the battery.

As noted, with their modern circuitry and DC-DC converters, the devices all function fine down to about 6 volts.

if the chosen battery can deliver 700MAh of voltage before falling below 6 VDC, then you can draw 700MAh for almost one hour, or 350MAh for about 2 hours; note these are approximate figures, as exact capacity may vary (many factors!), and the entire capacity can not be actually used without damaging the battery.

safety margins (and appropriate wiring) are advised!

[jason porter]

Thanks Senator,

Very helpful info, as usual!