External Battery Recommendation?

Hi, Folks,

I'm looking for an external battery to power my UMID M1 MBook.

The rub is, I need 9.5v. I have an external battery that will do 9.0v, but I'm getting a weird sound from the device which says at the very least, it's undervolted.

The M1 is an old device, and non-usb (meaning a need for the proper adapter) external batteries are few and far b/w.

As always, any advice would be much appreciated,
Jake

If you are looking for only a power supply, then the ASUS EE PC power supply should work well, you will just need to solder on the correct plug. If you are looking for a battery only to make it portable, then the cheapest way to go would be a simple 12v batter that you could wire a variable POT in series to reduce the voltage to 9.5v...you'd waste some power to heat on the POT...but it would work fine...

Hi, Rich!

Many thanks for the quick post. Man, I dunno: dumbing down a 12-volt battery sounds above my pay grade. You're much more the master at that stuff than me, with all your batt rebuilding.

Any actual ready-built battery come to mind?

Jake

There used to be nicad 9.5vdc batteries for portable power tools...but you would need a special charger then.

Another option would be a series-parallel configuration of nicad batteries. Most are rated at 1.2v, so 8 of them in series would be 9.6v. Probably 3 rows would be enough to supply a funtional current source to power you handheld for an hour. But you would have to recharge the cells...and that would take a while.

Somewhere here I posted my AAA battery adapter for a MP880 that worked great! Same idea really...

If you had a car adapter for your handheld, then hooking that up to a small 12v motorcycle battery would give you juice for all day! I see them on ebay for about $35...

Very intriguing. I actually have seen a car adapter sold for this device. Lugging a motorcycle battery might be prohibitive, but I wonder if something smaller might work. Many external batteries out there, but they only have 9v setting.

Jake

Actually any 12V battery would work. For instance, search eBay for "ADT 804302 CASIL 1240"

It's a 12V battery that is only 3"W x 4"L x 4H" and supplies 4000mAh of current. But it is a dry cell battery needing an electrical charging circuit with overcharge protection to charge it.

A typical small 12V wet cell battery measures about 3"W x 6"L x 4"H...but supplies a whopping 8500mAh of current and can be charged with any cheap $10 trickle charger.

Also there are a ton of 9.6V ni-mh batteries with chargers for sale on eBay. 9.6 is a standard for R/C cars and helicopters...

Ah denotes capacity for a given voltage, not current.

Don't get all technical on me Alt Bass. The voltage for a battery is fairly constant. In my post above, a 8500mAh battery will supply 8.5 amps of current for 1 hour. So if your handheld draws 1 amp of current, you can operate for 8 1/2 hours before recharge...ideally.

I might be wrong...Ah has never been a component of voltage directly...at least not in my training...

Rich, with these 9.6v chargers you've suggested, how would a user connect the proper adapter tip? Do they have a universal slot that can take a variety of tips? I remember that being the case for the old Radio Shack a/c adapters.

Jake

Almost all the time the tip or center core is positive voltage....but you need to find a compatible tip, and then using a multimeter figure out which is the positive lead...

This looks like something that even the hard-of-thinking like myself could manage, and it's a battery pack specifically for the M1 MBook:

http://www.pocketables.com/forum/showthread.php?t=2415&page=3

I have not found this hardware (other than the batteries) on USA Ebay and Radio Shack is no more. Where might I look for an 8-AA battery pack that would have a variety of available tips?

Happy Thanksgiving to anybody celebrating it today,
Jake

Actually they are pretty common, you are just using the wrong eBay search criteria. Now you can buy a 8 cell holder which is even better.

8 x 1.2V NiCad batteries = 9.6V total if in series. Alkaline are nominally 1.5, so 8 x 1.5V = 12V which might be too much.

Anyways, check out THIS auction...it would be just what you need I think based on that post you listed.







Attachments
----------------
snap.bmp (504KB - 0 downloads)

I think that's it. Rich, thanks! Just bought it. Rummaging around, I found a 4-aa Radio Shack battery pack with a universal female end (instead of the bare leads). Lo and behold, the male tip I had placed on it (to power an Oregon Osiris, a Psion Series 5 knock-off) is the same tip for the M1 Mbook.

I'll try to upload a picture of the 4-aa pack I have because I don't know the search terminology for finding an 8-aa pack with universal female end.

Thanks again,
Jake

Edited by Jake 2015-11-26 6:44 PM






Attachments
----------------
2015-11-26-002_1.jpg (71KB - 0 downloads)

As far as I know, only Radio Shack sold those things with the universal female sockets, mainly because they sold the tips individually. However, you can go anywhere and buy a cheap universal a/c adapter and get a variety of plugs to fit that socket. Just a matter of cutting off the cable and splicing it onto your AA battery holder.

Tips by themselves are available as well. Check out eBay and search for "universal 2 pin tips"

Many thanks for your clear explanations. I think I'll just cut off the cable for my 4 aa holder and splice it on the 8 aa holder.

To do this, I would just need wire strippers and electrical tape, no? I'll double-check, but the white-stripped wire of the 4 aa holder connects to which color of the 8 aa holder, black or red?

Jake