Akom's Tech Ruminations

Various tech outbursts - code and solutions to practical problems
Hardware Hacks

Replacing Garmin C330 Li-Ion battery on the cheap (with whatever is onhand)

Posted by Akom • Sunday, December 21. 2008 • Category: Hardware Hacks

I have a hand-me-down Garmin C330, the el-cheapo, no-text-to-speech teletubby-looking GPS unit that every online store was liquidating a few months ago. Mine also has a dead battery, and while it used to run for 1-2 minutes on it, now it barely runs 5 seconds. I can live with that, after all - you generally use it while plugged in, but it is oh-so-handy to be able to hand it to the passenger for co-pilot... co-piloting.

So, I had to do something...

To make matters more difficult, I was departing on a 2000 mile road trip... the day after. So drastic measures had to be taken. I cracked it open to check out the battery up close (screws are under the pretty silver trim on the front, remove with fingernail).

The battery is a Lithium Ion LR1865AF cylindrical cell (metal case), about 2X the size of a AA, and takes up a bit of room inside. After some testing, the battery is indeed totalled - I ran it through my Mystery B6 charger on a charge/discharge a few times, and it could hold maybe 6mah total! I looked around for other 3.7V lithium batteries I had on hand, and even considered a spare Ipod Nano battery, but as the original is something like an 1800mAh, the 340mAh ipod battery seemed a little... underwhelmed.

The Parts At Play

Then I noticed the Blackberry battery... it was a C-S2, the blue flat square from the old 7130e I used to have. A 3.7V, 900mAh battery which was still quite decent. The battery has 4 terminals (1 or 2 are for temperature and ident, I am guessing), but the outer 2 are the + and - ... so I soldered right to them - there is nothing that a little flux and solder can't do!

The Fit

To fit the odd-shaped battery, I clipped the structural ribs inside a little to make it slide in, and it fits just fine. The unit works... and in field testing I accidentally ran it on battery for almost 4 hours - and it was still alive. The 2000 mile trip was a success and the GPS worked as expected, lending plenty of opportunities to be handed over to the co-pilot, and operate on battery.

I did confirm that the unit charges the battery normally and does not overcharge, but that was expected since proper Li-Ion/Li-Po charging technique is basically the same - do not exceed 4.20V per cell. All in all I'd say that the hardest part is figuring out where the antenna board used to sit before you opened the case - so if you open this thing up - make sure you open it slowly and memorize how that fits together. If you don't - don't blame me.

Finally, I'd guess that a large variety of Li-Ion and LiPo batteries could be used for this device, but the ones that most people have sitting around are probably from old cell phones that we forget to sell before they become worthless. Here is one way to use them. (Hmm... here is another way - build them into RC aircraft battery packs)

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  1. Your writeup 'Replacing Garmin C330 Li-Ion battery on the cheap' got me wondering something. Could a portable GPS such as a c330 be modified to connect to an external LCD via RCA for example. Portables are much less expensive than integrated units such as Garmin GVN 53.

  2. Not to be negative, but I don't think so. It is highly unlikely that an embedded device manufacturer would include unused extras like an analog video interconnect. Audio - yes, but that's used (the speakers are analog in the end, eh?). In any case, a larger screen won't really give you any more detail, so you could probably achieve the same result with a big glass magnifying lens (like the early TV's did). If you want navigation on a big screen - either shell out for an overpriced nav system, or dedicate an old laptop :-)

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