vacuumed,
Roger that Sir. Picking the right charger for this particular application can be a bit confusing. There's only about a thousand battery chargers out there. On the SDFD for 30 years, I was involved in research for types and styles of battery chargers for those fire trucks. We tried many. Some would over charge, some not enough, and some were too large to fit in the possible places we had in mind etc.
We finally settled on this one, if it shows up here on this site:
Well, I copied a picture of one on the NAPA site that's very similar to the one I installed in my rig but, for some reason, it didn't paste over to this site. It's about a foot high, about 7" wide and about 3.5" deep. I don't have the model number right now but, I'll get it if you desire it. Good luck.
Scott
