Dobro dan, Yuriy!

What's your existing set up? Just the cranking battery? The cranking battery + a house bank? If you already have a house bank, what type are they?

The gel's should charge OK with either the alternator or the battery charger. That said, mixing gel, wet cell or AGM's in an integrated system is generally a bad idea. The charge acceptance rates differ, and you won't be able to make full use of the different types of batteries.

I think a more relevant question would be whether or not replacing a dedicated cranking battery with a couple of deep cycle batteries is the best course of action.

A cranking battery is designed to discharge a lot of juice for a very short amount of time. A deep cycle battery is best used to discharge a little juice for extended periods of time.

 

Gel batteries, from what I've been reading of late, actually need to be charged to just under 15 volts, so conventional charging systems start costing you money from the moment you start using a gel. Each recharge falls short of capacity, and this reduces lifespan. Anyway. The guys that make the BatteryTender products have telling info on the subject and a full line of products to properly do the job.

 

Really, 15 volts, which gels are those?

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 without the proper charger or regulator.

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. You can actually create blisters or voids in the electrolyte that lead to the demise of the battery.

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 14.2-14.8 +/-. It is best to check the charge parameters of your specific battery chemistry with the manufacturer as each manufacturer recommends different charge voltages for their products. Some can take higher charge voltages than others and some lower.

Using a car charger on gels can certianly ruin them. That Leece-Neville 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 example 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" charger will put out more than 14.1 volts and usually more like 14.4-14.6 volts and some even higher..

 

I currently have two marine starter batteries that I received with the boat, when I originally purchased her. However those batteries are old(2005) and/or abused. Well, likely rather abused since 5 years is a short life for a batteries. The other day, I went out sailing. I turn the cabin light on for 30 sec. Two hours later I reach to start the engine, and starter went: "Click". Luckly, I had one of my gels that I temporary tied up to the engine(I unhooked it as soon as I get back).

I have 3 gel batteries that I planning on using as the house batteries. I am doing mostly coastal sailing, so 3 gels (57 amh each) should be good to run my VHF, stereo, nav lights and cabin lights. I thought about replacing my current starter batteries with the dual purpose marine batteries. That way I will have more Amh out in sea and will be able to have enough juice to crank the engine.

Thanks, Gents!
Spasibo!

 

Yuriy,

Following up on MaineSail's post, you should take a close look at your entire charging set up. Given the rather sensitive tolerances, you should look at a "smart" regulator to keep that alternator from frying the gels. Likewise, a 110v charger that can be adjusted to output the proper voltage.

Perhaps MaineSail can render a little additional advice?

Vcevo dobrovo!

 

I was thinking of AGMs, not gels.

 

Below is a section of the Xantrex Truecharge II manual showing voltages for the different types of batteries.