Should older battery chargers be replaced?

You may not need to replace the chargers, just add a desulfinator circuit to maintain the battery plates. Since I've started using them, my various battery lives have gone from the customary 2-3 years to 7.

Your charger may have a upgrade panel available,it may now only monitor one of the banks and could overcharge the other banks. Contact the manufacture of your charger with the model and serial number on hand. Let us know how you make out.

The technology of the vintage of your charger was ferroresonant. Essentially a constant voltage output with circuitry that tripped output voltage to a lesser float voltage when the battery bank would accept little current as it reached full charge. Neither the charge voltage or the float voltage were settable and therefore could cause the batteries to excessively gas, with concurrent loss of water, if the battery manufacture did not get it right. In this day and age, these units are considered battery warmers.

Absolutely contrary with the stated experience of CaptJ, I have replaced literally dozens of these battery warmers with the new smart charging battery chargers that utilize switching technology and a three stage charging algorithm to provide an efficient charge in the shortest period of time. I have had no failures with any of these chargers. Zero. None.

Regarding desulphanators: I have put an o'scope across the output of units from three different manufactures expecting to see the pulses. I have seen nothing but battery voltage. I no longer recommend these units to my clients.

I have worked on several yachts in the last 5 years, all with a lot of batteries and a lot of chargers as well. I have probably replaced less than 4 8D's in that time. New Chargers=good stuff and long battery life (think 8+ years for gels).

Now jetskis, keep plenty of those batteries on hand! I think they should just go to a bunch of Duracells in a watertight box, I think they would last longer!

Capt J? Who knows, lots of variables in any problem.

Your 87 Viking 44 should have come with a Sentry model G-160-3NL charger by Marine Development Corp (Cruisair)
Viking at that time installed Sentry... All parts are still available for that model...It was built like a tank, and if setup & used correctly...It will not boil or sulfate batteries.

The Sentry charger has a control circuit that can sense up to 4 banks of batteries...But it came with all sensor wires on one output because MDC did not know how many outputs would be utilized at installation...It was the installers job to connect sensors to outputs that had batteries connected.
The control circuit would shut the charger off completely when all banks reached a preset voltage (switch in auto position on front panel) Usually 13.9 volts for 12 volt banks (which is where 12v batts start to sulfate & boil)

Thing was at that time...Viking was using Delco "Freedom" batteries which required a 14.25 cut off to assure full charge...MDC started installing boards calibrated for that voltage cut off just for Viking/Freedom.

If you still have the board calibrated for that voltage and have changed to standard wet cell or gel batteries...It will over charge them.

There is also the possibility that someone has set the switch on the front panel of the charger to manual, or that the board could have failed by now...In either case...The charger will never shut off but will taper back to a trickle...Still overcharging & boiling the electrolyte out of the cells.

Cruisair went the route of offering the newer Switch Mode chargers & warranty ate them up badly enough that they stopped offering them...The only replaceable part was the main board...It was the only part except for the box that housed it.
They have never stopped building the Sentry ferroresonant charger and I see models that are still working well (and don't boil batteries) that are over 30 years old...I have a 30 year old 20 amp model installed my service van that charges the engine battery as well as a inverter bank I use for power tools & a refrigerator when working...That bank of 6v golf cart Trojans is now 7 years old and I have only added water twice in their lifetime.

Steve~

Dear Steve,

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I have had fantastic results with Charles chargers. The one that I did have go bad (several years out of warranty) was sent to Charles who repaired it at no cost and sent it back as new.

You can do a couple of things...

If the existing board is good...It can be re-calibrated for a 13.9v cut off or...
Due to it's age & the chance that the potentiometer's (adj pots) might have internally corroded by now, and may not hold an accurate re-calibration...
You can replace the board with a new one that is already calibrated for 13.9 volt cut off.

The Sentry part number is G-12-NX...Any Sentry/Cruisair dealer should have access....If you can't find one close...I can have a G-12-NX shipped to you.

No real need to pull the charger...That is unless access is terrible like on the 44 SF...but I seem to remember on the 44 MY...The charger was located behind a removable panel behind the couch ?

Steve~

After replacing 6 batteries that were getting cooked by the original ProMariner, I replaced it with a Charles and no issues since.