roadtrek17 Report post Posted June 22, 2012 I just purchased a used roadtrek and need to replace the weak batteries. They are two 6 volt batteries in series. Any thoughts on what I should be looking for in replacing them. Stay with 6 volt or go to 12 volt? Capacity of battery? Should I charge the batteries before installing them into the Roadtrek or just let the inverter/charger do it? I didn't know if my charger was adequate to do the proper job. Also is there a recommendation on what voltage level where the batteries should be charged without relying on the crude battery indicator in the Roadtrek? Share this post Link to post Share on other sites
shields Report post Posted June 22, 2012 Welcome to the FMCA forum. Your issue is remarkably similar to the one posted recently as Assumption - The Mother of All Screw-ups (Coach Batteries) If you can take a few minutes and look through that post, I believe you'll find your questions covered and a lot of good information to help you on your way. Yes, the batteries should be charged before installation. When fully charged, they should show about 12.7 volts. Good luck and happy travels, Tim Share this post Link to post Share on other sites
RVerOnTheMove Report post Posted June 22, 2012 Generally, when you buy new batteries they will already have a pretty good charge on them. Assuming the charger in the RV is working properly and putting out 13+V to your batteries you should be able to install them and let the charge do its work. Hopefully, you have a multi-stage charger and it will charge quickly, cut back the voltage a bit and then do a float charge to keep them topped off. Share this post Link to post Share on other sites
wolfe10 Report post Posted June 22, 2012 Good advice. Stick with golf cart (6 VDC) batteries if you want the most battery (deep cycle battery) for the money. Install them, no need to charge before installation. We really can't comment on the adequacy of your converter or charger in the Roadtrek unless you tell us what converter or charger you have. As mentioned, best are the "Smart" ones that charge at a higher voltage (14.0-14.5) in BULK mode and ABSORPTION MODE and tamper off voltage to 13.2-13.5 in FLOAT MODE. Very difficult to tell state of charge from voltage level when the converter or charger is on, as very quickly voltage will reach the above figures if a smart charger and should be in the 13.2-13.5 range from the beginning if "not smart". An ammeter would be better for telling charge rate. Voltage is a reasonable indicator of state of charge IF the batteries are in a "state of rest" (no charging and no discharging for at least an hour). Brett Share this post Link to post Share on other sites
