Replacing a battery with a higher mAh rating one

[Dannyx]

Good day folks. This may seem like a completely and utterly idiotic question that's been asked a thousand times, but please hear me out: let's say I got a device, doesn't matter exactly what, since the principle is the same and I want to "upgrade" its battery. By upgrade I mean install one with a higher mAh rating. Now this is nothing new: plenty of people have asked this before and I'm sure there are many reads out there on the subject, but another person's opinion never hurts, plus I'm not really interested in knowing whether the device will actually run longer...that's not really the point of the project.

I'm interested in the charging process of a larger-than-intended battery...this is where it gets a bit confusing. I have watched Dave's video on how Li-Ion batteries charge and I kinda know about the constant current and constant voltage modes of a charge IC, but I think these differ from device to device depending on the charging ICs they've got in them. The way I see it, and please don't quote me on this because I'm not an expert, is if the device has a 450mAh battery and I replace it with a 4500mAh battery from a tablet, the charging circuit will not be able to fully charge it because it's a constant current source and the more the battery charges, the more current it requires to charge it any further, so if the battery wasn't intended to be larger than 450mAh, the circuit is "tuned" for that and the maximum charging current will not be enough to push the larger battery past that threshold.....I might be completely wrong though, but it's a bit confusing to be fair. What do you guys think ? Cheers.

[budm]

Re: Replacing a battery with a higher mAh rating one

Lower charging current = longer time to fully charge the batteries.

[sam_sam_sam]

Re: Replacing a battery with a higher mAh rating one

Not all USB cables are the same and not all USB power supply are not the same
Have you checked the voltage on the USB charger if it is not above 5 volts it might charge at a slow rate and if your USB uses very thin wire will cause a very big voltage drop that can cause it to charge slow

The reason I mentioned this is IPad Pro has this problem with long USB cables the power supply that I use has voltage adjustment so I can over come the voltage drop

To go in to fast charge mode

The charging board on tablet are a little different than your normal protection board in that it let charge at faster rate however be careful with this thought in that you charge it faster (or hard ) it may not let the battery to fully charge because once it hit 4.2 volts it shut the charging off

[petehall347]

Re: Replacing a battery with a higher mAh rating one

temp sensors might have fun if large capacity battery is well low on charge . try and keep circuits cool .
p.s i know nothing about this circuit . all i know is other charging circuits .