BU-303 ! I have found the problem for all!

**stevieg** · 02-22-2005, 12:09 PM

I have suspected something like this for a long time...

I found that if the BU303 is left for a few weeks it took me ages to get the satellites to lock, until days and days after hooking it back up - and it had reset from SIRF or whatever back to NMEA 4800.

I just figured the battery needed time to warm up.. I'll be trying this for sure though!

**Grayscale** · 02-22-2005, 02:16 PM

Originally Posted by westscape

Well last time I looked I was sure the "battery" inside the BU-303 is not a battery but is actually a super capacitor. Not sure what soldering a battery in would have though!

I'm almost positive it's a battery, not a capacitor. Anyone wanna back me up on this?

**mox** · 02-22-2005, 06:03 PM

I popped open my BU-303 to check out this "watch battery". Actually it is NOT a battery, but a 0.22F capacitor ("SuperCap"). Think of a supercap as a small rechargeable battery with a very short charging time. Replacing it by a non-rechargeable kind of (watch-)battery is definitely a bad idea.

Older BU-303s are known to contain badly soldered or otherwise badly mounted supercaps which come loose due to a car's vibration. This might be an explanation for the problems you guys are having.

Should the BU-303 have contained a regular battery, the manufacturer would have mentioned so, or would at least have made it user serviceable.

- Erwin

**Grayscale** · 02-22-2005, 06:12 PM

Interesting. So I didn't know capacitors started going bad like that. Any insight on where to get one? I don't think I need one, since I still have my old one, I'm just asking for anyone else. Mouser.com or Digi-key.com? I just searched and it looks like they have some specifically labeled "super backup capacitors" that have the specs we need for a minimum of 1500.

Mox (or anybody) would a typical .22F electrolitic cap with a max voltage rating of like 35 work?

**Scouse Monkey** · 02-22-2005, 06:15 PM

Originally Posted by Grayscale

Interesting. So I didn't know capacitors started going bad like that. Any insight on where to get one? I don't think I need one, since I still have my old one, I'm just asking for anyone else. Mouser.com or Digi-key.com? I just searched and it looks like they have some specifically labeled "super backup capacitors" that have the specs we need for a minimum of 1500.

Mox (or anybody) would a typical .22F electrolitic cap with a max voltage rating of like 35 work?

Yeah caps can die with a lot of use - especially high capacity ones like that.

**mox** · 02-22-2005, 06:24 PM

I guess so, but don't expect to find a .22F/35V capacitor that will fit. Remember, .22F is 220,000 microfarad!

**Grayscale** · 02-22-2005, 06:31 PM

Originally Posted by mox

Remember, .22F is 220,000 microfarad!

I know, it took me a sec to figure out why you were calling it a supercap and then I was like OH, its not 22uF! Well I guess I'm safe for now. So putting a watch battery in would be bad...hmmmm. I will have to test out if putting my "SuperCap" back in will make my GPS lock faster.

**naveedh** · 02-22-2005, 06:45 PM

ok looking on this advice, my Rikaline 6010 started playing up as well. So i thought i open it up and had a look and it is a battery. If you search for PCB mounted batteries you will find what your looking for, i have. The price i found was $4.

The Rikaline Has a Battery not a supercap.

**Pilt** · 02-24-2005, 10:57 AM

Couldnt you just use a 12v to 3.3 LDO regulator from the car battery to where the cap went. Then you would always get a quick satalite lock.

Of course you would need a diode on the output so the gps doesnt try and charge it.

Obviously you would have to look at the circuit to see if its possible, but its an idea

**Goddy** · 02-24-2005, 01:31 PM

To avoid all these bu303 problems (there are also problems with this gps unit in combination with lcd-screens) are there any good alternatives? I have the bu303 too and i have to put the unit on the airbagunit (it has a metal underground) so the lcd wont interfer with the gps unit (i have tried all Hz', none working fine).

Is the Rikaline a good alternative?