battery charger problems

[Jusp]

For my 48V battery pack (8 x 6V Interstate lead batteries) I ordered the following charger: https://www.ebay.com/itm/113187182950

Hooked it up for a test today. The batteries were new, except for some drain while running a few motor tests, and still measured 52V unloaded, so I expected minimal charging activity.
Instead the charger panel claimed to provide 22 Amps, at a voltage that was steadily increasing beyond 58 V until I unhooked it because I could clearly hear my new batteries boiling,
with a vague sulphur smell. Checked the charger polarity, the plus of the charger was connected to the positive battery pole, same for negative.

I have little experience with battery charging, but this sounds wrong to me. Hope I did not damage my batteries. Am I correct in thinking this?

Thanks for any input,

Juul

[Bikemad]

I doubt that the batteries were actually boiling, it is usually just the sound of the bubbles of hydrogen and oxygen being produced by the electrolytic action during the normal charging process of a "flooded" lead acid battery.  Check out this site for further information on the bubbling batteries which should put your mind at ease.

Your charger should stop the bulk charge completely(or switch over to a trickle charge) when it reaches ~58.8V (2.45V per cell), as this is typically the maximum recommended charging voltage for a 48V lead acid battery, but some chargers can go as high as 60V (2.5V per cell) if they have a equalisation charge function.

I have also read that some inverters used for charging lead acid storage batteries from solar panels will actually go as high as 61.2V (2.55V per cell).

It might be worth checking the resting voltages of each of the 8 batteries, just to confirm that they are all at a similar state of charge.

Further general information on charging lead acid batteries can be found here.

Alan
 

[Jusp]

Sorry, was busy elsewhere for a while. Yes, after reading the helpful links that Bikemad posted and trying again the batteries charged normally.
Not sure what happened the first time.