Yes David, and same condition as well, meaning age. I think you and I have discussed that maybe brand isn't that important, but if they are not similar amp/hour, size, and construction, one battery could dominate the other. It is a big no no in series, but it just isn't a good idea in parallel either. Because an older or smaller battery will not get the same treatment as the newer or larger when charging, and the older/smaller could end up sulfated. Now, if you have dual charging on shore power, you may avoid all of that, and just use the ACR for supplement on the water. But the reality is that we have guys that don't shore charge...ever, and battery condition is questionable. That is certainly going to not let the larger, more expensive bank get fully topped off. That will gradually degrade that bank. So keeping everything equal is even more important. I am not saying you can't do it, I am just saying that unless you maintain them both on and off the water optimally, you may find yourself spending more money than you have to. I used one pulse tech on my batteries for several years, with an ACR allowing shore power to charge both banks at home. That too is a bad idea, even though it works. Because the smart charger is not only a charger, but it is optimized for polarity as well as battery condition. It may never see that one battery is bad if it sees a good battery between the two of them...and then it can and will charge a bad battery. I won't do that again, and will use a dual bank charger at home on my two battery banks.