Gel battery charging 1

[skullforger]

Hi,

I have to charge a 12V gel battery (brand MK, type M40-12SLDG). I have read a lot about charging gel batteries, and some people say you cannot charge them with regular lead acid battery chargers, because they tend to overcharge gel batteries.
However, I've read on the MKbatteries.com homepage that the charging voltage for a gel battery shouldn't exceed 13,8 to 14,1 Volts. But to my knowledge, a regular lead acid battery charger doesn't in fact charge with higher voltages then this... So why is it a bad thing then?
I have a this charger at home: (Robbe Compact Duo Power 6s)

http://www.rcmarket.org/compact-duo-power-6s-eq-pr-20676.html

You cannot set the charging voltage, but it is a 'smart' charger and it can charge Pb batteries, do you think it can charge the gel battery without damaging it?
I also have a car battery charger (a regular 12V 4amp charger), but I don't think this is classified as a 'smart' charger because it's quite old.

Can anyone confirm that I can/cannot use those chargers to charge my gel battery?
Any help would be greatly appreciated.

 

[DanEE]

It would seem to me that the answer is in the statement in the link you provided..

Lead Acid Batteries

Automatic charge cut-off using the CC-CV charge method

If the CC (constant current) and then CV (constant voltage) values match up with the gel battery requirements you would be OK.

The problem with some consumer quality chargers is that the technology they employ to achieve the above has historically been a bit crude and may not play well with a gel battery. But a good microprocessor controlled charger set to the right values should do OK.

Commercial DC plant chargers supporting AGM VRLA batteries essentially do the same thing.. i.e. on major discharge of the batteries, a current limited charge (compatible with the battery manufacturers recommendations) to bring the batteries up and as the voltage rises, then becoming constant voltage at the float level recommended by the battery manufacturer.

You don't want the equalize function with a gel battery.

So the question becomes with the charger you link to, is the above information available (assuming fixed set points in the design) or settable to the values you need?

We use the MK gell batteries as a replacement battery in a number of the smaller UPS systems.

In modern microprocessor controlled commercial chargers, the float voltage is a temperature compensated value with the option to measure temperature at the battery terminal, but I would not expect this function to be in a consumer based charger.

 

[skullforger]

Thank you for the elaborate information! I think I'll try and use my Robbe charger then.
The problem is that you can't set the charging voltage. Once the lead acid type is selected, you can only choose the charging current, the battery voltage (6 or 12V) and the battery capacity (which goes only to 20 Ah, while mine is 40 Ah - would that be a problem?)

I guess I'll keep an eye on the charging voltage then (the charger does display it, but you cannot change it yourself), that is if the 20 Ah selection thing doesn't pose a problem.

 

[itsmoked]

Give it a shot as long as you can measure the terminal voltage frequently. It shall not exceed 14.1V!

If the charger you have isn't a full cut-off charger you do not want that battery held at 14.1V or even more than 13.8V continuously or it will bake dry.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[skullforger]

Ok thanks!
I'll try it out as soon as I can (hopefully this week) and I'll let you know the readings.