Maintaining a 17ah 12v battery booster

[Osem]

Just bought one of these:

http://www.maplin.co.uk/p/portable-p...mpressor-a67hy

As usual, the manual turns out to be a single sheet of paper with what I feel are inadequate/unclear instructions. Anyway, I'm wondering what the best way to maintain this unit is after the initial 38 hr charge which it's currently in the middle of.

The supplied leaflet only states that after the first charge a full charge takes c. 34 hrs but how do I know if a full charge is required? The battery status indicator notes simply state that if the indicator shows a reading of 13-15v it's ready to use. If it shows 12v it should be charged ASAP and if it shows less than 12v it should be charged immediately. I have no idea how accurate the status indicator is however, and I'd have thought the amount of charge time the unit requires would depend on how much it's been used but there's no mention of this and I obviously don't want to damage the unit by overcharging it. For example, is it simply a case of checking the battery status indicator periodically and turning off the unit when the level shows 15v, even if that's taken less than 34 hours?

[Taf]

404

[Osem]

Hmmm... Maplin site seems to be having issues, anyway it's the same as this one:

http://www.ebay.co.uk/itm/12V-5-IN-1...item337e347aa8

and here's another link which seems to be working:

http://www.maplin.co.uk/p/portable-p...mpressor-a67hy

[Taf]

As it's a sealed lead-acid battery, it can quite happily sit on trickle charge forever AFAIK, but won't like being discharged too deeply (just like a car battery) or recharged quickly. They like to be treated gently. 13.7v is a typical charged-state voltage, though the meter will show less than this when it is in actual use. Don't store it too cold either as this will cause problems.

If you have a voltmeter you trust as accurate, you can compare readings on that and the unit's meter to see how accurate it is.

[Osem]

Thanks for the feedback Taff. I was hoping it could just be left on trickle charge but the leaflet states that it shouldn't be charged for more than 48 hours as this can cause damage to the unit so that set me wondering how I'm supposed to know how long to charge it for.

[Taf]

Is there a manufacturer website you can contact?

After the festive period and once the floods abate?

[Osem]

It seems to be a generic product onto which companies like Maplin put their name. I might try to get some feedback from the Maplin site but won't hold my breath.

[Taf]

If the battery is easy to access without voiding any warranty, the manufacturer might have info.

Yuasa is a top brand I trust.