SD 7XX Powering Question

[stevetoney]

I know that the Li-ion batteries used on the back posts of the SD-7XX units are 7.2V, but the voltage at the Hirose connector is higher.  Has it ever been determined if those posts can take anything other than 7.2V and, if so, what is the acceptable range of voltages?

[Ultfris101]

Just last night I was browsing through the Cables forum and I came across a post where somebody had gotten some battery stand-ins and had hacked an RC connector to let him connect RC batteries through it to power a 7xx of some kind. I can't find it at the moment, but I'm guess that was getting him above 7.2 volts. I recall it being from at least 4 or 5 years ago.

I was thinking he might have made some comments about voltage ranges but I don't recall for sure, thus I was looking for it.

[stevetoney]

Just last night I was browsing through the Cables forum and I came across a post where somebody had gotten some battery stand-ins and had hacked an RC connector to let him connect RC batteries through it to power a 7xx of some kind. I can't find it at the moment, but I'm guess that was getting him above 7.2 volts. I recall it being from at least 4 or 5 years ago.

I was thinking he might have made some comments about voltage ranges but I don't recall for sure, thus I was looking for it.

Thanks Ultfris101.  Yeah, after getting the 744 recently, I made myself one of these 'dummy cells' for the back of my 744.  I did same thing when I had a 702 a few years ago.  What I did was I bought a cheap li-ion battery pack off ebay for like $12 and cut it open.  Then I pulled out the guts leaving just the shell and the contacts.  Soldered it up with wires to the dummy cells terminals and epoxied the wires so there would be some stress relief.  Finally glued the shell back together.  On the other end of the wire, I installed a Tamiya connector, which is the connector that Remote Control car batteries use.

So now I can use 7.2V RC car batteries now to power my 744 through this dummy cell as an option to the expensive Sony L style Li-Ion batteries, which of couse are also 7.2V.   The reason I was asking about other voltages is I also have a bunch of high cacapacity SLA batteries that would power my 744 all day at a festival.   So, I was wondering if I could put a different voltage on these battery terminals than 7.2V.  I haven't got that answer yet.  Might inquire directly with Sound Devices.   

I know that I can buy a hirose connector and do this through the external battery conector though, but I was just trying to avoid spending $50 on another cable if possilble.  I know for sure that the 744 will take anywhere from 10 to 18V through that connector.  Probably should just break down and do that anyway...would be a nice cable to have.

[Ultfris101]

I just ordered a couple third party AC adapters with hirose 4-pin connectors for SD devices. Going to cut at least one and insert an RC connector in there and then make a RC > DVD batt cable so I can interchange with this mixpre I'm playing with. Avoiding soldering the hirose which seems tough. Not avoiding spending $50 but will have both wall power and battery option.

Ted could easily do this too but I want to give it a try.

I'm sure others will be interested to hear what you learn from SD on this topic.

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I swear the max range is 8.1v to 6.7v for the bottom battery ports. I remember freshly charging a battery and it registering around 8 or 8.1. Wasn't for long, but I swear thats what it was. Remember, those camera batteries didn't/don't have voltage regulators so you have to account for the full charge level. I also remember reading that there is a gap between the external and bottom inputs of a volt or two (so you can use like 10-18 externally, but nothing between 8-10 anywhere and then under 8 in the bottom battery) cause I had a time during the the 9v dvd battery craze that I wanted to use something else and couldn't.

[stevetoney]

I swear the max range is 8.1v to 6.7v for the bottom battery ports. I remember freshly charging a battery and it registering around 8 or 8.1. Wasn't for long, but I swear thats what it was. Remember, those camera batteries didn't/don't have voltage regulators so you have to account for the full charge level. I also remember reading that there is a gap between the external and bottom inputs of a volt or two (so you can use like 10-18 externally, but nothing between 8-10 anywhere and then under 8 in the bottom battery) cause I had a time during the the 9v dvd battery craze that I wanted to use something else and couldn't.

Thanks.  Your response summarizes the conclusion I reached from my limited research.  I never checked directly with Sound Devices though.  The reason I asked the question initially was that I have a ton of high capacity 12V SLAs that I'd like to use to run it for summer festivals and since I already had the dummy cell I wondered if I could use the SLAs off that.  My 7.2V RC batteries are getting old and it would be nice to use the SLAs since I already have them rather than buying a new batch of RCs (I could also use the 3300 Tekkeons that I just bought a bunch of, but I'm dedicating those to power my preamps). 

Anyway, I opted to just put together a cable with a hirose connector and use the hirose for this purpose instead since it's specs are 10-18V.

[stevetoney]

I ended up posing the question to Sound Devices.  First my question, followed by Sound Devices response.

+++++++744T Powering Question-----------

The specifications on the 744T provide a range from 10-18V from the hirose connector. Understandably, there is no range specified for the rear battery pins. I have a dummy cell that allows for the use of 7.2V Remote Control car batteries as alternatives to the Sony L or M battery, but I was also curious if this connector is limited to strictly 7.2V or if there's also a voltage range associated with that connector. I have some 9V and 12V batteries that it would be handy to use off of this connector if that's an option, though of course I won't even try without hearing back from you first. Thanks in advance for any response you could provide.

+++++++++++++++++++++++++

Hello Steve Toney.

This L-Mount battery connection has an operating range of 8.5-6.5V which is the average operating range of the 7.2V L-Mount batteries. You may be able to get away with the 9V batteries, but I wouldn't use this connection for the 12V batteries. 

Casey Luft
Sound Devices, LLC
(608) 415-6144