Does Recharging a portal have an internal "hidden" cooldown?

Lately I've started to do a lot of recharges on friendly portals, and I've noticed that after two or three succesful attempts, all subsequent will silently fail for a while: ADA will say "Resonator recharged" as if it went through succesfully, my XM will drop, but I'll regain them immediately after and no green "+x%" will appear on the screen. This has happened to me more than once, with portals not completely charged and with nobody else operating on it: in fact after a few minutes I've been able to completely recharge the remaining resonators.

Is there some kind of hidden internal cooldown, or am I just experiencing some weird glitch?

If you are moving too fast the recharge will silently fail. I believe "too fast" is about 60 km/h (was higher before 70 km/h). It takes a while after you slow down for the recharging to start again.

I have not seen any internal cooldowns on recharging.

One possible answer is - maybe portal is already recharged to 100%, but your scanner has not yet updated?

Synchronization when more then one person is operating on a portal can take a while (even half a minute is frequent for me).