Please do an archive search on
"Guest Battery Charger" and "Newmar." w/o the quotes, of course. Then look for posts that I made regarding this very subject. I, too, have a 340 and HAD a Guest charger. If you will read these posts, I think I can save you a lot of frustration, and in the long run, money. I would not suggest you shop for a cheap charger. You'll likely give the money back in fried batteries. I did, as explained in my posts.BTW, my Newmar charger is performing beautifully and has continued to maintain my batteries in top notch condition.Below is a URL to take you to the Newmar web site.Good luck,Wynn FerrelS/V Tranquility