Charging Gel Batteries (1 Viewer)

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Dec 10, 2013
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I want to charge 2 new gel batteries before I fit them to our Motorhome, my question is will it safe to use my old CTEK xs 3600 charger. It has 3 modes and the car mode is 14.4V/3.6A.
Sorry if it seems a daft question but I have never charged gel batteries out of situ before and I know that the onboard charger is set for gels so I wondered what the difference was.
 

Lenny HB

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Oct 18, 2007
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It would be OK but it won't get a full charge into them as your CETEK uses the same setting for Wet & Gel batteries, normally with a Gel you charge them until the voltage reaches about 14.2-14.4 volts and then maintain that voltage for 8 hours before reducing to a maintenance charge of 13.6-13.8 volts, the CTEK will probably reduced the voltage to 13.6 after one hour.
 

Don Quixote

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Jul 29, 2012
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Not long enough, but a little common sense helps..........
Even your onboard charger will NOT hold the charge at 14.4 volts after 1 hour no matter what state the batteries are in. The Ctek will do the same as the on board.

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Feb 24, 2013
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Why you want / need to charge them before you fit?

They should be supplied new pretty much fully charged

I would fit them and let the MH charger sort them out after
 

scotjimland

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Jul 25, 2007
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The Gels you have purchased should have been supplied fully charged, so no need to pre charge (unless you know differently) .. just install and let the van charger top up


snap ..lol
 

eddie

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It all goes out of the window of course when you start the engine and put them in parallel with a wet Lead acid engine battery and an alternator chucking out 14.8vdc lol

So it doesn't really matter in the real world, it will all do what it can do.
 
Sep 23, 2013
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I want to charge 2 new gel batteries before I fit them to our Motorhome, my question is will it safe to use my old CTEK xs 3600 charger. It has 3 modes and the car mode is 14.4V/3.6A.
Only the battery manufacturer can tell you the correct charging voltage for their particular battery, but 14.4V seems to be the generally accepted maximum for gel batteries.

It looks as if CTEK have gone for a compromise with this particular charger. They claim the one 'Car' setting is suitable for all common types, including AGM & GEL. They've gone for the upper limit on gel & accepted that it's a bit low for open cell batteries & some AGMs.
 
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daveandsan
Dec 10, 2013
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Thanks for that, will do as Jim and David said and just fit them. Just waiting for the leads now to link them together. (y)

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Sep 23, 2013
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It all goes out of the window of course when you start the engine and put them in parallel with a wet Lead acid engine battery and an alternator chucking out 14.8vdc lol
True enough for a simple split-charge system, although given the minimal cable sizes often used by converters, the voltage drop will probably protect a gel battery positioned well back in the habitation area. :D

Does that still apply where something like a Schaudt Electrobloc is fitted? I know they have a gel setting to limit the charging voltage from the mains charger. Does that apply to the feed from the alternator as well?

I seem to remember reading that some of the Electrobloc units can manage the opposite trick - where the cable voltage drop is so severe that the available voltage fro the alternator is now too low, the Electrobloc regulates it back UP to the level required for the battery type selected.
 

Lenny HB

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Oct 18, 2007
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Even your onboard charger will NOT hold the charge at 14.4 volts after 1 hour no matter what state the batteries are in. The Ctek will do the same as the on board.
Yes it will, the OP has a Hobby so probably fitted with an Elecktroblock, if set to Gel it will charge until voltages reaches 14.3 volts then hold at 14.3 for 8 hours before reducing to 13.8, if set to wet cell it will only hold at 14.3 for one hour.
 

eddie

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The EB still simply parallels the batteries when the engine is rnning +15 is on the yellow wire.

Inside the unit is a normal automotive relay, so callling it a split charge is a misnomer.

In practice though as you say with the skinny cables most converters use and the distance involved you would be lucky to get 14.4 vdc at the leisure batteries irrespective of if they are Gel or Wet

Hence the aftermarket sales of Battery to Battery systems, fromm the like of Sterling Power Products and CTek. In those systems the batteries are seperated and each given the appropiate charge, based on the batteries requirements.
 
Apr 29, 2012
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Holmfirth
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a few years back, I had gel batteries on my scooter, and they were flat, so as I was going into town[while on holiday] I attached them to my vehicle with jump leads. They were in the back, so I didnt see what was happening. Two miles there and back, and the gel batteries had gone from square to nearly round, and spewed gel out on the floor. I found out the hard way that you must have an intelligent charger for them, and never charge at more than 4 amps. Lead acid for me from now on.

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