Re: Battery bank problems SM with 13 batteries

Alan Leslie

Any battery charger, if it's big enough, will only supply the current that the battery can accept (otherwise its limited to its max output). Providing there is not some mechanical / electrical defect with the charger, the fact that it is a 100A charger only indicates the maximum current it can provide. It is the state of discharge of the batteries and their acceptance rate that determines the actual current flow. So in terms of maintaining the batteries at the dock there is little or no difference between a 30A and a 100A charger (except our 100A charger frequently trips the shore power breaker on the docks if the battery bank is down)
In bulk mode the voltage increases to the absorption this case 28.8V...when it reaches that it is in Absorption mode...bulk charging is finished...voltage is held at that level and current tapers off over time.
AGM batteries for example have a high acceptance rate and so the bulk charge current will be much higher than for so called calcium or flooded they can charge faster and therefore a high output charger is beneficial...but if your battery bank will only ever accept say 40Amps, there's little point in having a 100A charger.

Its interesting to hear these comments about Dolphin chargers that have failed...not that many I guess in hundreds of Amel boats out there...I wonder if the failure rate is any different to other brands.

We have Dolphin 30 and 100...they've been in the boat since 2004 without problems as far as I know.

Elyse SM437

--- In, "drew_gaffney" <drew.gaffney@...> wrote:

When we went to NZ to see about buying Revelation SM390, we found the battery compartment full of acid and 12 dry Trojan batteries. The Dolphin 30 A charger had cooked them having remained in bulk charge mode. The charger had been replaced once and repaired a second time. It was no longer being serviced by Dolphin.
The owner replaced the batteries and I added a Xantrex Freedom inverter charger which has worked well. It delivers approximately 40A. The Dolphin 100 A charger PCB failed, was not repairable, and was replaced with a Victron Centaur 100A Charger. It failed after 1yr, was replaced, and a year later, was not charging properly. The dealer in Phuket changed the program to provide 28.8V bulk charge and it's worked well for the past 6 mo's. Who know's what's next.
You will need some a lower Amp charger for use in the marina... I would not buy Dolphin again.
Revelation SM390
On the hard, Krabi Thailand

--- In, Sailorman <kimberlite@> wrote:

Thank you Roque.
I was wondering if anyone else has had similar problems.
Fair Winds
Amel Super Maramu #376 Kimberlite

-----Original Message-----
[] On Behalf Of Roque
Sent: Wednesday, May 22, 2013 5:10 PM
Subject: Re: [Amel] Battery bank problems SM with 13 batteries


1. Even the so called sealed maintenance free batteries need to be checked
from time to time, if they have a way to top the water (as most do). They
are in fact ¨low maintenance¨ ;

2. If you have a voltage regulator, it doesn´t matter if the charger is
small. In fact, the trouble is when you have a charger that is too big for
the bank (about 20 to 25% of the total amperage would be ideal). I guess
you have at least a 600A battery bank, so both the 100 charger and the 175A
nominal alternator would be fine

3. If you do have a voltage regulator, maybe it was set to charge a
different kind of battery. The alternator could also be a suspect, if the
voltage it delivers is out of range, (but it sounds like you don´t use it a


Atica Amel 54
currently in Benalmádena- Spain

2013/5/22 eric <kimberlite@>


On our trip home from St Martin last week, we discovered that most of the
liquid in all the sealed maintenance free batteries had boiled off. I did
not realize that under the labels there are plugs where water can be
In any event all the house (12) batteries
have to be replaced.
We have a 175 amp alternator and 30 and 100 amp Dolphin chargers.
I spoke with Dolphin and they said that the 30 amp charger is too small
for the bank and it probably cooked the batteries as it saw the bank as
always needing a charge. I plan on having the alternator checked and then
speak again with Dolphin when I install the new batteries.

Kimberlite usually is in a marina somewhere and plugged in with the 30 amp
charger running.
Any thoughts on my problem?
Fair Winds
Amel Super Maramu #376 Kimberlite

[Non-text portions of this message have been removed]


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