[SOLVED] Powering a portable recorder with an SLA through the AC adapter port

[djamie]

Hi,
I have a portable recorder namely a TASCAM DR680. It runs on 8 AA cells which last for an hour. I read on some forums that They power the same recorder with a LI-ion or SLA of 9-12V 7000mah batteries.
The AC adapter provides 12v DC at 2.5A. i.e 30W max power.
If I power it up with an SLA or Li-ion battery of 7A or more, wouldn't that fry my recorder?
Is there anyway I can regulate the current going into my recorder?

I have tried using a 12v 7000mah SLA. It has worked fine. But I am not sure whether the recorder can handle such power on the long run?

any suggestions?
Thanks!

 

[tpetar]

Will not fry your recorder. You can use free this battery, until this battery get empty, then recharge it, and go again.

 

[djamie]

Thanks a lot tpetar, I am relying on your answer and going to use the SLA for my recorder.

 

[tpetar]

Use freely, and whatch just that SLA battery dont go under 10,5V, its low level, after that recharge it. You can use even car lead acid battery 12V 55Ah or bigger without problems. Just look voltage to be adequate (12V). If battery have more Ah this means that this device will work longer.

 

[djamie]

Thanks again! that makes a lot of sense!
u saved me a lot of headache!!

 

[bobstay]

In general, the current ratings (e.g. 2.5A) on devices are the maximum current the device will ever need to draw. As long as you match the voltages, it doesn't matter if the supply (in this case your battery) can supply more current - the device will not draw current unless it needs it.

Also, I think you are confusing the battery capacity rating (7000mAh = 7Ah) with current (e.g. 2.5A). The battery capacity is in amp-hours (Ah), whereas the current is in amps (A). A 7-amp-hour battery (7Ah / 7000mAh) can supply 7 amps for 1 hour, before it is drained. Or, it can supply 1 amp for 7 hours. Or 14 amps for half an hour. Or 28 amps for a quarter of an hour. Or 3.5 amps, for 2 hours, or anything other combination that multiplies together to give 7.

This lets you calculate the minimum time your recorder will be able to run from your battery: 7Ah / 2.5A = 2.8 hours (2h48m). Note that because the current rating of the recorder is a maximum rating, this time is the minimum time you will be able to run it. Practically, it's likely to run for much longer, probably at least twice as long. If you measure it with an ammeter in normal operation, you'll be able to make a better estimate.

 

[tpetar]

A 7-amp-hour battery (7Ah / 7000mAh) can supply 7 amps for 1 hour, before it is drained.

This battery cant give that current for that time, its lead acid battery and capacity of 7Ah is given for /10 discharge time. ;-)

 

[bobstay]

This battery cant give that current for that time, its lead acid battery and capacity of 7Ah is given for /10 discharge time. ;-)

You're right, I was simplifying to theory for explanation's sake ;-)

 

[djamie]

Thanks a lot Bobstay!
I was confused about the battery capacity and current. Your explanation helped!