Battery Charging

[Gavin Hatton]

Hey All,

I recently bought a new battery for my 110 and though I'd give it a charge with my mains battery charge in the house before fitting it to ensure it was in a fully charged state.

After having had it on charge for the best part of a day with no sign of the charger saying the battery was full I decided to check the voltage across the terminals (with charger attached) I was shocked to see there was 15.7v!

I then removed the charger and the battery settled at about 13.1v after a few minuets.

My question is does this sound normal, over 15 volt to charge a 12 v battery?

If it helps the battery is a Genuine Land Rover 950CCA seen here

[LandyManLuke]

which charger are you using?

[Gavin Hatton]

I'm using a Challenge Xtreme MCH12A as seen here

[David Sparkes]

Basically, how much charge did the battery have before you started?

Did the vendor say it was fully charged, or half charged, etc?

Was the battery sent 'dry' for you to add the 'acid'?

Have you measured the Specific Gravity at any time? (Either before you started, or now).

When a charger has the control facility to swap from charging to maintenance, as yours does, it is common, even desirable, to charge at a high current and charge the battery faster than you would with any old-fashioned 'constant rate' charger you may have had experience with.

So, your voltage of 15.7 is understandable. Do the charger instructions say anything about what voltages you might expect to see?

Depending on how 'flat' the battery was before you started, it's going to take some time to charge the battery.

More exactly how long was 'best part of the day'? Did you mean 'best part of the daylight hours' or 'best part of the full 24 hours'?

If it lives up to its specifications, the charger seems pretty good to me, but it does say 20 hours to fully charge a 180 Ah battery.

For interest, I've found a spec sheet for the battery, well, one of the alternative part numbers match, so hopefully it applies.

http://www.partnernet.varta-automotive.com/e-newsletter_04_07/en/downloads/Datasheet_Aston_Martin_DBS.pdf

HTH

[Aragorn]

With much over 14.4v you'll start boiling the electrolyte if its continous, and can even result in the battery exploding.

Some chargers (like the optimate) will apply something upto 22v in an attempt to "restore" dead batteries, but it only does this for a short period to get things moving, then drops back to 14.1-14.4v for the bulk charge.

Most will then drop back to around 13.8v for "float" charging.

I have a smaller 6A Challenge Extreme unit: http://cgi.ebay.co.uk/Challenge-Xtreme-Intelligent-Battery-Charger-6-12volt_W0QQitemZ270505485076QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item3efb622314

and i've checked is output in the past, it sits at 14.2v when in bulk mode. I've never checked it in float/trickle mode though i would expect it to be slightly less than the bulk charging rate.

If its sitting at 15.7v all the time, then i wouldnt be using it. I would expect the battery would be getting very hot and no doubt gassing a lot at that voltage, and could quite easily have killed it, or severely shortened its life.

[Gavin Hatton]

Thanks for the replies, I removed the charger from the battery when it reached nearly 16volt and given that the battery was supplied in and 'as-new' state from Equicar having being removed from a Land Rover, so the battery was filled as it should be and the battery then settled at 13.6 I decided although maybe not fully charged it was charged enough to go into the 110.

Having placed a second 110AH leisure battery on charge since the charger only got as high as about 14.5 before going into maintenance mode, so i think the higher voltage must be something to do with the larger capacity of my new starter battery.

All in all I've now got my new battery fitted and the Land Rover now fires into life much quicker and with only one shot of glow plugs, the result I was after.

Thanks again for the useful help/comments,

Gavin