Forum Discussion
landyacht318
May 04, 2015Explorer
A hydrometer will tell you if those 'interstate recommended' voltages are necessary. The deeper the discharge then the more likely it is that they are required. If you are just doing shallow discharges then it is likely that you do not need 15's to return SG to near maximum
Isn't Johnson controls now making Interstate gc-2 batteries?
I thought their recommended voltages were lower, and it was when US battery was making their GC2 that the 15.3v was documented. Can you find a date on that documentation as to interstate recommendations?
I've got a group31 USbattery that requires rather extreme voltages to get the SG into the green daily. Now it has at least one cell which no longer gets above 1.255 no matter what, after about 450 cycles.
I still hammer it overnight, but have reduced my charging voltages to 14.4v and it stays there all afternoon, and the 15.3v I used to let it stay at all afternoon has not been applied for a while now. Kind of just waiting for a cell to short but the thing easily meets my overnight needs so I will keep it under the hammer.
Isn't Johnson controls now making Interstate gc-2 batteries?
I thought their recommended voltages were lower, and it was when US battery was making their GC2 that the 15.3v was documented. Can you find a date on that documentation as to interstate recommendations?
I've got a group31 USbattery that requires rather extreme voltages to get the SG into the green daily. Now it has at least one cell which no longer gets above 1.255 no matter what, after about 450 cycles.
I still hammer it overnight, but have reduced my charging voltages to 14.4v and it stays there all afternoon, and the 15.3v I used to let it stay at all afternoon has not been applied for a while now. Kind of just waiting for a cell to short but the thing easily meets my overnight needs so I will keep it under the hammer.
About Technical Issues
Having RV issues? Connect with others who have been in your shoes.24,363 PostsLatest Activity: Mar 05, 2026