Gel batteries, signs of imminent death?

[meirriba]

I have 4 x 120 gel batteries as housebank.
Usually adequately charged (shore, alternators - 2 units on a L400cat, solar).
Never dropped under 45% capacity, usually not under 70%, more at 90%-100%. Batteries always (until recently that is) kept nice voltage, around 12.5V under load with no charging (e.g. sailing at night when solar does not operate, but autopilot and fridges load the system)

Recently, if total amperage drops under 80% it corresponds with voltage drop to around 10.8-10.9V and warning on meters (there are 2 separate meters, both showing similar info).

Batteries are 4.5 years old.

Are the batteries on their way to the morgue?

[Catopia]

I am interested to see the answers you get. We are having the same issue with the 3.5 year old gel batteries on our L450.


Sent from my iPhone using Cruisers Sailing Forum

[btrayfors]

Gelled batteries -- NOT AGM -- are among the longest lived batteries on boats, provided they are not abused. High charging voltages will kill them quickly.

The only sure way to tell their actual capacity is to do a 20-hour controlled discharge test AFTER they have been fully charged. DO NOT BELIEVE THE AMP-COUNTER BATTERY MONITORS -- they are often way off for several reasons, many of which have been detailed by MaineSail in his excellent articles.

Bill

[belizesailor]

OP: what charge profile/max volts are you using (for all charge sources)? Brand & model of batteries?


My venerable old gels are going on 12 years old and still quite serviceable. But, gels are also among the easiest to destroy if not maintained properly.

As the saying goes: batteries don't die...they are murdered. If you are getting under 5 years life in normal cruising boat usage then somethings not right.

[Emerald Sea]

I too am quite interested in this thread. Our 6x 1.5yr old Exide gel house batteries aren't holding their charge and showing the same signs as Mark/merriba's above.

A few months ago, after a good discussion with folks at AmplePower, I did a 'rejuvenation' whereby I discharged the batteries down to 10.5V (measured with Fluke directly on the batteries, not the electric panel voltmeter), recharged with bat chargers to 100%SOC and repeated the exercise again. It worked, the results were good with greatly prolonged life as they were before (new). However, 5 months later they are again loosing charge quickly and questioning whether I need to buy new ones. Ive since test the voltage drop on each of the 6 batteries and temperature and there are no anomalies here.

Im not a electrical or battery engineer and still get lost, or confused, by all the technical reading out there but one thing has come up a few times that may be the culprit: were the new batteries broken in properly? In my case its quite possible they were not as I took possession of a new boat, after being shipped for 6 weeks with battery powered up (or not). Im unable to get any info from the agent or Lagoon on this.

Reading with interest...

[Andina Marie]

Stage 1 is to just use one battery at a time to test if they are all degrading or there is one perpetrator.

[meirriba]

Originally Posted by Andina Marie

Stage 1 is to just use one battery at a time to test if they are all degrading or there is one perpetrator.

Good idea. I may try it the other way around i.e. using three out of four, disconnecting one at a time.

[Cheechako]

Charge them all, disconnect them all. Measure voltage next am on each. You will find the culprit.

[Lokiyawl]

I have found that there are gel batteries and then there are really excellent gel batteries. I have an 8D German made Prevailer in my boat that is plus 15 years old now that seems to perform close to new. I have 5 other 8ds of the same make that are a similar vintage that I did a capacity test down to 50 percent and they were within 5 percent of spec. I have several of the US made Prevailers that aren't as old that vary between dead to barely useable. I have only used one other gel brand that was sold by West Marine years back and despite careful charging those all died over the course of 3-4 years. I have yet to kill one of the German Prevailers. Sometimes you can actually get what you pay for... Btw, I recently replaced a 3 year old set of Dynasty AGMs. At least one of the AGMs had leaked out the electrolyte and it ate up the wooden battery shelf despite the epoxy coating, corroded the egine etc. Big mess. My Dad is still using a Prevailer that he drilled a 1/4" hole right through the case...nothing came out so he put caulking over the hole. I have yet to have anything nasty come out of a gel battery. James

Originally Posted by meirriba

I have 4 x 120 gel batteries as housebank.
Usually adequately charged (shore, alternators - 2 units on a L400cat, solar).
Never dropped under 45% capacity, usually not under 70%, more at 90%-100%. Batteries always (until recently that is) kept nice voltage, around 12.5V under load with no charging (e.g. sailing at night when solar does not operate, but autopilot and fridges load the system)

Recently, if total amperage drops under 80% it corresponds with voltage drop to around 10.8-10.9V and warning on meters (there are 2 separate meters, both showing similar info).

Batteries are 4.5 years old.

Are the batteries on their way to the morgue?

[GrahamHO]

My Optima AGM batteries are still going strong after 12 years. (as someone mentioned there is now a new owner of the company) They are always fully charged on solar except in use overnight. Being fully charged and at the correct rate is important for any type of battery we might use. I also have a built in mains charger which has an optional setting for gel batteries as they are sensitive to overcharge. I imagine the alternator setting should also be set for gel batteries. A small disadvantage with AGM batteries is that if they are ever completely discharged they need another good battery (any lead acid) put in parallel to trick the charger into starting the charge. I once experienced this with an AGM battery in my car when I left the headlights on...to go sailing. No type of battery is perfect and each has special needs.

[mitiempo]

Originally Posted by GrahamHO

A small disadvantage with AGM batteries is that if they are ever completely discharged they need another good battery (any lead acid) put in parallel to trick the charger into starting the charge. I once experienced this with an AGM battery in my car when I left the headlights on...to go sailing. No type of battery is perfect and each has special needs.

This is not because of battery type but due to the charger. Many chargers will not charge a totally dead battery, some will.

[belizesailor]

Originally Posted by mitiempo

This is not because of battery type but due to the charger. Many chargers will not charge a totally dead battery, some will.

Between boats, cars, and an off grid house, I've got loads of chargers...some very sophisticated...some not. Having a dumb charger, or one with a manual mode, is handy sometimes to get it to do what the smart ones wont...of course that assumes the operator has a brain. ;-)

Anything smart should have a dumb mode switch.

[meirriba]

I am not on the boat but will be in a few days - will certainly try some of the suggestions and bring more info.
Thanks to all who answered!

[GrahamHO]

Originally Posted by mitiempo

This is not because of battery type but due to the charger. Many chargers will not charge a totally dead battery, some will.

On the Optima Battery web site there are instructions for recharging a completely flat Optima AGM battery by paralleling another already charged lead acid battery to start the process. My at home charger will charge a completely flat flooded cell lead acid. It would not charge my completely flat Optima AGM until I looked up and followed those instructions. Perhaps there are more sofisticated chargers that automatically provide that load but I don't know about that.
I have wondered if instead of using an additional charged battery to start the charging process, a resistance such as a 12 v light bulb could be paralleled. Perhaps you can advise me?

[mitiempo]

As far as I know it is not resistance that is needed, but voltage. If the charger sees zero voltage it remains inactive. By paralleling another battery you are providing that needed voltage.

I fail to see why an Optima or any other lead acid battery would be different as far as charging one with zero voltage is concerned - regardless of which form the acid is in.