Gel Battery

[tarik]

Morning all,


I have been reading about a Jester entrant who uses a 12v 'Gel Battery.'

I don't usually declare my ignorance to the world but could someone please tell me the difference between a Gel Battery and the usual 12v lead acid battery, which I have on the boat. Are they more reliable?

Many thanks for all replies


David

 

[sarabande]

'wet' lead acid batteries need to be stored as upright as possible to keep the electrolyte covering the plates. Gel/AGM batteries do not use a sloshy liquid but a thick, gloopy, err, gel. This means the battery can be installed at any angle, even with the terminals sideways as frequently seen on motorcycles.


There is a downside that generally a gel battery of the same physical size as a lead-acid battery will contain less AHr and will be more expensive. As far as reliability is concerned in the bumpy, rolly world of sailing, a gel battery will cause less worry than a wet one - assuming the charging regime is under control (gels need a different more intelligent voltage control system in order to get the full charge into the battery, than lead-acid ones).

 

[Sailingsaves]

As Sarabande states.

Are they more reliable? If and as Sarabande said if they are charged properly then yes they are more reliable _ no levels to check, lack of sulphation plus other benefits mentioned.

But if not charged correctly, then they don't last long.

Normal lead acid batteries should be positioned in sailing boats at a correct attitude also for when the boat heels the tops of the plates can become exposed.

 

[Mistroma]

'wet' lead acid batteries need to be stored as upright as possible to keep the electrolyte covering the plates. Gel/AGM batteries do not use a sloshy liquid but a thick, gloopy, err, gel. This means the battery can be installed at any angle, even with the terminals sideways as frequently seen on motorcycles.


There is a downside that generally a gel battery of the same physical size as a lead-acid battery will contain less AHr and will be more expensive. As far as reliability is concerned in the bumpy, rolly world of sailing, a gel battery will cause less worry than a wet one - assuming the charging regime is under control (gels need a different more intelligent voltage control system in order to get the full charge into the battery, than lead-acid ones).

Acid doesn't slosh around in an AGM because it's a starved electrolyte system. Think of something like damp blotting paper to get the idea, it's wet but no excess to leak out.

Gel batteries are entirely different and I don't think they are worth choosing now as AGM are much superior for similar cost (I imagine they might be cheaper now). AGMs have several advantages e.g. you can charge AGMs at a much higher rate to name one.

 

[vyv_cox]

Gel batteries do not accept high charge rates and are therefore not advised for domestic banks. AGMs are now a better choice, although more expensive. Gels do not run out as wet acid would, although not certain they can be used sideways as AGMs can.

 

[Plevier]

Gel batteries do not accept high charge rates and are therefore not advised for domestic banks. AGMs are now a better choice, although more expensive. Gels do not run out as wet acid would, although not certain they can be used sideways as AGMs can.

You can use gel or AGM in any orientation in which the plates are vertical.
You should not stand them so that the plates are horizontal as the weight of the stack may compress the lower end. You can usually work out which way they are from the positioning of the terminals. If they are at opposite ends then the plates are almost certainly across the battery so you should not stand it on end. If the terminals are adjacent at one end the plates are almost certainly along the length so you should not lay it on the face.

Gel batteries arguably have a slight advantage over AGM for slow shallow discharges and slow recharge e.g. constant load remote solar installations where the battery is designed with several days cover in case of cloud. I can't think of any application on a boat where AGM would not be much better than gel because of its higher rate recharge and discharge capability (resulting from better electrolyte mobility and lower internal resistance).

However remember not all AGMs are equal any more than flooded batteries are! Cheap lightweight ones will have very thin plates and a short cycle life, just like wet starter batteries.