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Just a heads up, but if you need a battery for your ULTRA. Batteryhookup.com (no, I'm not affiliated) has a 4.5Ahr cell for $0.99 ea. Size is 755275 and yes it fits like a glove. That'll give you 50% more power than the 3Ahr presently installed. Buying the cell singularly will cost the same as 20, so buy many. That's about the min to stay within the shipping minimum w/UPS. Yes, they are new cells. I've bought many with no problems. It'll work out to $1.61/cell (shipping included)

Mike C. Sand Mtn GA

This has a three wire connector.

Larry

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Nope, here's the link:? Look carefully at the picture, it's there. They did give the dimensions but in English units.

Mike C. Sand Mtn GA

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The yellow wire can just be clipped,i.e. not used. 2nd thing is unsolder the the existing wires and use the plug from the 3000mahr cell and use it on the 4500mahr cell, simple, yes.

Mike C.

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Yeah, that's the same cell that Batteryhookup.com is selling for $0.99 each (like I said, the shipping is the killer, you can order more to stay within the shipping limits and you'd still be CHEAPER than that one on ebayism.)

Mike C.

My question would be can the charging circuit in the TinySA handle the bigger battery?

The charging circuit of tinySA ULTRA is designed for a 3.7V battery and will stop charging when the battery is charged to 4.2V. If you plug in a 3.8V lithium battery, you can only use about 80% of the power of this battery because the charging circuit cannot charge to the full voltage of 4.3V of a 3.8V battery, so you will not get much improvement in battery endurance by replacing the battery.

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Hi,

I don't think so. All usual LiPo chemistries have a normal charging voltage of 4.2V. Some can be charged a little higher up to 4.25 or 4.35V. But this doesn't make a big difference in capacity, it mostly affects the charging time, because the charging current stays higher when the charging is coming from the constant current to the constant voltage part of the charging process. SO the charging time to full capacity can be shortened. But even this is in most cases not that important, because the normal constant current part charges a LiIon battery up to round about 80 to 90 percent.

But all this isn't important for this little unit, because it don't work with currents in the range of 1C or more. So you can use nearly every LiIon chemistry with the same result regarding the capacity. There are some chemistries out there optimized for high current and/or low temperature, they have sometimes higher self discharge currents or are more sensitive to over discharge.

So a normal LiPo cell, like the one delivered with the Ultra or the one linked at batteyhookup.com should work nicely.

The bigest advantage of such batteries specified up to 4.35V is that they don't die immediately in case of little overcharge. So they are more tolerant to little unbalance in a pack or tolerances of the charging regulator.

A classic 4.2 volts simple cell can blow up if charged with 4.35V.

But please don't use such cells like this one for high current applications.

All the Best,

Isidro