Recharge Battery with Multiple Chargers
Connecting battery chargers in parallel is not a good idea. They can interact with each other, e.g. if they momentarily switch off the charge current in order to monitor the battery voltage. This can lead to a charger thinking the battery is fully charged, when it is not, and stopping the charge process.

If your chargers are very crude, with no sensing electronics, then it might work. You'd have to use chargers that were little more than a transformer and a rectifier, though.

Much better to get a bigger charger.