Gel Batteries Charge

[ukrsindicat]

Whats going on, Guys?
I have recently picked up couple of 12 v gel batteries. I am not sure if I can replace my old wornout starter cranking batteries with the gel batteries. I am affraid to burn and over charge my gel baterries with the alternator(picture atttached). Also, while they are out, can I charge them with this portable charger( http://picasaweb.google.com/yuriytymo/GelBatteries#5540245588940470818)?

Thank you!

 

[Steve Dion]

I do not believe that using a "car charger" is recommended or wise. You should be charging them with a multi-stage smart charger that is designed for Gel Cell batteries. If you had purchased AGM batteries, you can use these chargers, but they would probably not give you the full benefit of the AGM technology either.

 

[Rag Bagger]

I am in the process of changing batteries on my 1984 Cat 30. After many questions, reading and asking, I have decided to stay with the wet cell design battery. Much of the battery choice comes from the type of sailing you do and the use you apply to the battery. The charging requirments are different between each battery type and do require different charging sullpies and controls. This is one reason I choose to stay with wet cells. The cost was not necessarly a fact but there is a hugh difference. The charger you show was probably designed for wet cell batteries and may not charge a gel cell to its' full capicity. It would have a selector swith or specify gel cell charger. It won't fry the battery, it just won't charge it completely. Not sure of the alternator, but I didn't want to go there with mine. Hope this helped and good luck.

 

[Maine Sail]

Gel batteries need very specific charge parameters or they can easily be ruined. Treated well they can be some of the longest lasting but they are a pain to manage.

The "gel" is an addition of silica which makes the electrolyte about the consistency of thick jelly. If you over charge these batteries you can ruin them in short order. Most gels like to charge at a max of about 14.1 volts where wet cells and AGM's can be charged at higher voltages. It is best to check the charge parameters of your specific battery chemistry with the manufacturer. Some can take higher charge voltages than others and some lower.

Using a car charger on gels can ruin them. That alternator regulator is likely factory set to 14.4V so it too would not be a suitable charger for gel batteries if you want to get your money's worth.

For instance here is what the Deka Dominator Gel's need for charge voltage:

From Deka/East Penn:

"For 12-volt batteries, charge to at least 13.8 volts but no more than 14.1 volts at 68°F (20°C)."


Most any "dumb" shore charger will put out more than 14.1 volts and usually more like 14.4-14.6 volts. Some older alts may have low enough voltage for gels but this should be confirmed.

 

[Ed Schenck]

My gel batteries(4) were still going strong after eight years of being "improperly" charged. My Heart inverter/charger did have a gel setting. So no problem at the dock. But I was warned that my 55-amp Hitachi alternator might fry the batteries. If you look at the charge curve for that alternator there is no way it could hurt the gels. Nor would it ever fully charge the gels. I believe they would still be OK after ten years but I swapped them out for AGMs when I replaced the engine with its bigger alternator. My gel start battery was just that, a 900CCA start battery and not a house battery.

 

[ukrsindicat]

Thank you, Guys!

 

[Maine Sail]

But I was warned that my 55-amp Hitachi alternator might fry the batteries. If you look at the charge curve for that alternator there is no way it could hurt the gels. Nor would it ever fully charge the gels.

If by charge curve you mean the voltage set point of the regulator then your older Hitachi may not have hurt them at all. Many older regulators are factory set to levels below 14 volts this is good for gels but bad for other technologies as it drastically slows the speed of getting back to 100%. Often times older regulators are set to 13.8 volts. 13.8 will not over charge gels but in order to recharge quickly they should ideally be within charged within +/- .1 volt of max rated charge voltage. The lower the charge voltage, below max for the battery, the longer it will take to get back to 100%.

The OP's regulator is not that old and is likely 14.2-14.4 which would not be a good voltage for many gels.