The Mechanics of Battery Equalization

amelliahona <no_reply@...>

Hi All:

My 50 Amp Dolphin Battery charger (original Amel) suddenly died upon re-commissioning the boat after our hurricane repairs.  Having an electronics background I contacted Dolphin for schematics and a parts list which they promptly provided for this 17 year old product, (wow, I was impressed, and when I have a moment I will post those items in the files section).  As usual the failed parts were two capacitors (that seems to be the most common failure mode for all things electric on our boats).  The exact part number was available and I obtained those and installed them and voila, the beast is alive.  The LED indicators also went at the same time, so I found replacements for those cute little rectangular LEDs, replaced them, and checks show everything is working as prior including the multistage charging etc.  Total cost about $16.00 US and a day's labor at my exorbitant shop rate of $0.00 per hour.  If you actually paid someone to render this repair it would probably be cheaper to buy a new charger.

My chargers don't have an equalization mode so I have been using a DC power supply to equalize pairs (4 pairs) at 31 volts at 5 amps.  This is laborious (2 day) process but forces me to carefully watch the process and monitor temps, water levels, specific gravity etc.  I also isolate each pair from the boat during the process to avoid any damage to any boat items. 

As I considered a new charger (just in case I couldn't fix the Dolphin 50 A), I found that I couldn't find any marine 28 volt DC, 50-60 amp output, input 220-230 volt, 50-60 hertz chargers that have an equalization mode.  Blue Sea makes one but it is a max 40 Amp DC output,  Mastervolt and Victron don't have any with an equalization mode (at least that I could discover in their literature).  So I have two questions for the group:

1.  What charger do you have that has an equalization mode?  

2.  When you do the equalization, how do you isolate the house bank batteries from the boat? (I know that turning off the two large red handles in the quarter-berth companionway turns off most of the power to the boat, but I wasn't certain if there are "sneak, hot battery bus" type circuits that are wired (e.g. inverters, solar panel regulators etc).  The chargers do NOT go thru the large red handled shut off switches.  

Your thoughts and experiences would be most welcome. 


Gary S. Silver

s/v Liahona

Amel SM 2000 #335

Puerto Del Rey Marina - Puerto Rico

Join to automatically receive all group messages.