One of the two banks on my Guest 2 bank shore charger has quit.  Leaving my 2 Group 27 Deep Cycles running in parallel deader than a hammer this weekend.
I could replace the Guest with it's new model 26106 (I believe is the part number), 12 amp, 2 bank ...
OR
I could spend a bit more and get the modular Battery Tender system.  
http://batterytender.com/marine/power-pro3-bank-pack.htmlAdvantages (as I see it):
1)  It's modular.  One bank goes out, replace the module (less than 5 minutes work) not the entire thing which results in rewiring, etc.  This is a biggie for me.  I don't like doing the same job twice.  Spend extra $$ and fix it for life or at least make it less painful if something goes wrong.
2)  I have had nothing but good luck with Battery Tender products.  
Disadvantages:
1)  Cost.  The BT system will cost about $200 more.
2)  BT's are 5 amps each as opposed to 12 amps on the Guest, resulting in longer bulk charge times.
Any experience?  Good or bad?
Craig C.
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2003 Vista 248, VP 5.0 GXi-C, DP