battery charging

[iowcamper]

sorry to be a bit thick but i inadvertently left the stereo on in the van last night and now have a flat battery, i have taken it out to charge it up the instructions say i should take the top off the 6 cells which i have done and the water level inside seems lower than the level mark, however the battery says maintenance free on it and is quite new so im assuming this means i dont need to top up with water??
i know this question is stretching the technical thread somewhat but as a newbie who's never had a car where you can even see the battery let alone charge it i dont want to do somehting wrong
any help would be greatly appreciated
iowcamper

[Red Westie]

Maintenance Free normally means that it doesn't have removable tops so yours is unusual. The level indicators in a normal lead acid battery can vary but typically there will be a level platform 20-25 millimetres below the filler hole that should be JUST covered with distilled water (de-mineralized) so the water has no contaminates (water out of a dehumidifier is good) tap water as a last resort.
As for charging....use a household plug in car battery charger, positve (red) to positive (plus sign) terminal of the battery and negative (black) to minus sign on the battery. Red positive post should be slightly larger. Charge for 24 hours with your average 4amp domestic car charger. Although if you just want to get your van started 3-4 hours should be enough to get the engine to fire up.

Martin

[toomanytoys]

Very few batteries are actually maint free... ( my wifes Honda has a "maint free" battery, but the "magic eye" tels you to top up if a certain colour.. I had to slice the big sticker saying maint free off to access the plugs...)

If you have easily managed to remove the cell plugs/caps and can see the fluid level and its low, then yes, top it up with demin water.. place it on charge in a well ventilated area overnight.. no smoking, lit matches etc when returning to the battery the following morning as hydrogen is given off..
Remember that batteries contain acid so be carefull when handling and clearing up any spillages

[iowcamper]

the cell plugs have a cross etched in them that i used to just unscrew them, there is a little bar that drop down inside about 2cm which i assume is what you mean and the water level is quite a bit below this, one of the size cell plugs is clear plastic the other 5 are grey plastic, does that sound normal?

[bigherb]

Maintenance free just means under normal circumstances the battery should not need toping up if the charging voltage is correct. They can have accessible cell tops or be covered with a non removable sticker or fully sealed. As long as the water is covering the plates it's probably ok and will rise as the battery warms during charging. It would be better to be low, than too high and then spilling acid over the bodywork.

[Red Westie]

Good point about overfilling....the level rises quite alot during heavy chargeing periods partly because of heat but mainly because of gassing.
That's why you will always see a good 20mm plus gap between the filler hole and electrolyte level.

Martin

[kevtherev]

taken from our wiki

If the term 'maintenance free', is on a battery, then treat this with caution. There is no such thing as maintenance-free, all batteries are basically the same. A Gel, sealed lead acid and AGM are all only maintenance-free because of the reduced charging performance curves; and not because there is something special about the battery. If you charge a normal lead acid battery to the Gel or AGM curves, then they would not require maintenance either. Remember 'maintenance free' is a handicap to fast charging not an advantage. This feature, which on the surface looks good, is, in most cases the worst feature that you could possibly buy; as this feature dramatically limits the maximum charging characteristics of the battery.

Fast charging costs water, i.e. if you want to charge you batteries fast, don't touch a Sealed/Gel/AGM etc with a barge pole. Fast charging will result in a certain % water loss from the battery. If the battery is sealed the water loss cannot be replaced. REMEMBER FAST CHARGING AND SEALED/MAINTAINCE-FREE ARE A CONTRADICTION OF TERMS.

[VWCamperfan]

Just a quickie here about charging though. You say the instructions told you to remove the caps before charging. I don't know where these instructions came from but you should never remove or loosen the caps before charging. They are there for topping up only and should only be removed for that purpose and for checking electrolyte levels. The reason for this is simple... The caps vent gasses in the closed position so don't need removing. You wouldn't remove them when driving the vehicle but it's charging all the time. The other reason is the acid inside. Apart from it now having a good chance of getting outside the battery and causing a hazzard due to bubbling when charging, you will loose some of the electrolyte whenever you charge the battery. It can be topped up but only with distilled water which means you slowly dilute the strength of the acid in the battery.
The level of the electrolyte should be covering the plates in each cell. About 10-15mm above is about right. Don't let the level drop below the plates, your battery will be damaged and will never fully recover.

[iowcamper]

thanks guys
charged it overnight without topping up and its fine now so will just keep an eye on it and maybe try topping up if it messes me about
rod

[Red Westie]

you will loose some of the electrolyte whenever you charge the battery. It can be topped up but only with distilled water which means you slowly dilute the strength of the acid in the battery.

Not strickly true as the loss in electrolyte level is caused by 'gassing' when the battery is being charged..... technically this is the emission of hydrogen and oxygen from each cell and is caused by the action of water in the electrolyte being broken down by 'electrolysis' (note water not sulphuric acid)

Martin

[VWCamperfan]

you will loose some of the electrolyte whenever you charge the battery. It can be topped up but only with distilled water which means you slowly dilute the strength of the acid in the battery.

Not strickly true as the loss in electrolyte level is caused by 'gassing' when the battery is being charged..... technically this is the emission of hydrogen and oxygen from each cell and is caused by the action of water in the electrolyte being broken down by 'electrolysis' (note water not sulphuric acid)

Martin

Quite true but I was referring to liquid loss due to charging with the caps off and bubbling (known as 'boiling') taking place and spitting out through the filler holes.

[Mr Bean]

Call me negligent if you must but I am an ancient warrior in automotive terms having started life in the days of generator and Voltage regulators. Post regulator I can't remember ever topping up a battery. I mostly run two pre-owned vehicles and expect to get in excess of three years out of a economy level battery and will sonmetimes pay for the three year warranty option if offered. As an insurance I place the reciept in a plastic bag and put it in the tray under the battery. I have never had to claim on a battery warranty. If your alternator is working correctly almost any battery will be maintainance free regardless of what the manufacturer claims.
Regards
Citizen Smith (AKA Battery Slob)