I am using busway on daily basis, so there is no surprise when I finally decided to use e-ticket. You may look at this posting if you wish to know a bit about e-ticket.
The most practical e-ticket to be used is this one: JakCard and card from mini market : Indomaret. If your JakCard have no balance then you can have it top up at the busway stop. But note, not all busway stop able to top up the card.
While if you have e-money card from Indomaret then you can top up at Indomaret or top up at Bank Mandiri. Assuming you have registered account at Bank Mandiri. And since there are many Indomaret here in Jakarta, you will have no worries. For JakCard you may top up with nominal IDR 20.000,- minimum. While for Indomaret card, you will need IDR 50.000,- for minimum top up. Using these two e-tickets, you may use it until there is no balance in the card. As long as last balance sufficient enough to cover the busway fare. So. if you have balance about IDR 1.000,- then you can't use it. But if you have balance IDR 3.500,- then you can use the e-ticket.
And then there is FLAZZ card from BCA (Bank Central Asia). Having this, you need to have registered account at BCA. You will be able to top up the balace at several busway stop. But you still need to have ATM card from BCA to top up the FLAZZ Card. The great thing about having FLAZZ CARD is that you can use it for busway and also train aka commuter line.
The thing that you need to be aware that if you are using FLAZZ card to buy ticket for train, then please ensure you have balance more than IDR 10.000,- Perhaps IDR 20.000,- will be sufficient enough for you just in case. It's different when you are using it to buy ticket for busway. You may use all the balance until there is none. You may check the balance at several busway stop and top it up there.
For Flazz Card and all other e-ticket for busway, the fare will be deducted once you swipe the card before you begin the journey. However, if you are using it to go around by train then the balance will be deducted at the destination station. That is why one card can only be used per person and can't be used together with others.
Also be aware that if there the light is off at the busway station or system error, it means we all have to lining up again to buy the ticket manually. I don't know the situation if it happens at train station.
Hopefully this information will be usefull.