[C320-list] Newmar HDM50 Battery Charger

[Warren Updike]

Dave, it's been a while, but if memory serves, the Newmar is the original charger. It is a ferro-resonant type, and as such it will produce more heat than newer digital types. The biggest issue is it is not a 3-stage charger and will not float the batteries. That is to say, it cannot completely charge the batteries, and should not be left on once the absorption stage has been completed. I learned this lesson the hard and costly way. My advice is to replace the charger at once with a digital, 3-stage charger. As for the Newmar, attach a shackle and line and use it for a dingy anchor.
I replaced our Newmar with a Xantrex 40A charger, and it has performed well. There are a couple other boats in our marina with the same charger. It's not the best constructed; but, for the price is a good value. How you manage your batteries depends somewhat on how you use your boat and if it is kept in a slip with 24/7 power. 
Most modern chargers will charge 2 or 3 batteries at once; but, there are differences on how they accomplish this. If you will connect the charger to both batteries, be sure to understand how this is accomplished and that the method works for you. 
Be sure to search the 320 Google Archives for prior threads. There is also a ton of info on the internet about lead-acid batteries. 
Finally, I'm not any kind of an expert on battery management, so don't take my word as gospel. What I know I learned by solving problems, making mistakes, and listening to people on this list that know far more than I. 

Warren and Pattie Updike
1994 C320 "Warr de Mar" #62
Middle River, Chesapeake Bay

-----Original Message-----
From: Dave Hupe [mailto:hoopdtwo at yahoo.com] 
Sent: Saturday, April 29, 2017 7:47 PM
To: C320-List at Catalina320.com
Subject: [C320-list] Newmar HDM50 Battery Charger

I just bought this boat and discovered one bad battery of the two (both are Deka 904D lead acid, but one was about 5 years old and the other bought just last season).  The older battery cells had gone dry and would not hold a charge after refilling the cells.  I noticed the old battery and charger were both hot after I had left the charger on for an extended time.  The newer battery was not getting hot. As a result, I turned off the shore power and have just replaced the old battery. 

I will now try charging again and monitor if the charger gets hot. 

Is the existing Newmar HDM50 charger (12 volt DC, 50 amp, 3 bank) likely the original for my 1994 boat?  Does anyone have experience with this charger and have any input about if it typically runs hot (or was this likely because of the bad battery)?  Obviously, I'll watch carefully for a while and will know better if the charger temperature was due to the battery.

If it continues to run hotter than seems good, what is a good comparable replacement charger?  We will use the boat occasionally, but will want to leave the refrigerator running.  

Dave Hupe
1994 (hull 32)
Holland, MI