Charging batterys

[bassodav]

My on board charger has stopped charging my question is do I need to unconnect the cross terimanls before charging with portable charger the other day I left them hooked up and it charged both batteries at the same time? didn't know if this would harm them thanks in advance

 

[digitalcb]

I don't claim any expertise but I have done this many times and never had any issues with my batteries just take twice as long.