Classic cars forum & vehicle restoration.

petermeachem · Joined: 23 Sep 2013 Posts: 358 Location: Chichester Sussex

Bought a 6v mgb battery today. Problem is my charger is 12v and 6v ones are quite a lot of pennies.
I was wondering if I can use the 12v one.
If I connect it across the terminals it will definitely be 6 volts, or whatever the battery happens to be at that time. It's a Halfords charger which seems to have a bit of electronicals inside. That might get upset if it only finds 6v between its terminals and either switch itself off or over charge. Neither good.
Does anyone know if this might work?

Bitumen Boy · Posted: Tue Nov 12, 2013 5:35 pm Post subject:

I don't think it will do any good, the electronics will stop play. I know I tried to use a Halfrauds electronic charger which I inherited on some electrolysis work, and it wouldn't play - but the Absaar my dad bought in the 80's worked just fine. Of course if you could connect the battery in series with another 6v (shouldn't it have that arrangement on the car anyway?) then the charger won't know the difference Wink

Failing that, look out for a cheap used charger - old ones generally had a switch for 6 or 12 volts as a standard fitting.

petermeachem · Joined: 23 Sep 2013 Posts: 358 Location: Chichester Sussex

That's what I thought. It's for an Austin 7 not an mgb so I just need the one.
I assumed my charger had a 6/12 switch.

This looks the best bet http://www.ebay.co.uk/itm/6V-12V-CAR-VAN-MOTORBIKE-BATTERY-CHARGER-6AMP-6-AMP-6A-NEW-/370669481771
Slightly put off by it having 6 arms on the label but extra points for being on Thornycroft Engines (and pond supplies) site.
I'll ask on Freecycle first, you never know what people will turn up

Bitumen Boy · Posted: Tue Nov 12, 2013 8:16 pm Post subject:

The other option would be to use the 12v charger with a suitable resistance in series - maybe you could cobble something together with an odd bulb or two? Looks like our electrical experts are elsewhere just now...

Greg · Joined: 03 Dec 2007 Posts: 445 Location: Dreamland Margate

I too have a 6v battery on my pop, some years back I bought an 'Optimate' charger which is switchable for either 6v or 12v.

They are no good for a rapid charge but can be left connected to the battery if the vehicle is not used much so there's always a good charge.

They're not very cheap but I've had mine for a long time and it's still going strong Smile

Here's a link to one :

http://pages.ebay.com/link/?nav=item.view&id=301014050709

Hope it's of use,
All the best,
Greg

D4B · Joined: 28 Dec 2010 Posts: 2083 Location: Hampshire UK

Yes I have a 12V Optimate or Accumate can't remember which but they are fantastic little chargers, just make sure to buy one that does 6V and 12V... ie the one above is just the job Cool

petermeachem · Joined: 23 Sep 2013 Posts: 358 Location: Chichester Sussex

It's a bit expensive. I've just twigged, the one I found isn't 6 ARMS it is 6A RMS. Duh

Inglewood · Posted: Tue Nov 12, 2013 9:27 pm Post subject:

If you have an older 6v battery, connect and charge in series with the new one.

petermeachem · Joined: 23 Sep 2013 Posts: 358 Location: Chichester Sussex

I would have done so if I had one.
I'm not sure lightbulbs in series will work, I suspect the charger is reading the battery voltage

Bitumen Boy · Posted: Wed Nov 13, 2013 1:50 am Post subject:

petermeachem · Joined: 23 Sep 2013 Posts: 358 Location: Chichester Sussex

I agree.
I'm not trying to start the engine yet, the wiring loom is in but there are too many loose ends, I'll wait until I connect the lights etc up. I want to make sure the electric bits and bobs work. There aren't many but I'd like the trafficators to work for instance, they never have. They would add sophistication

pigtin · Joined: 23 Nov 2007 Posts: 1879 Location: Herne Bay

I would recommend the lightbulb method, used it several times myself and you can juggle the wattage to adjust the charging rate. If you get it wrong the worst you can do is blow the bulb.
_________________
Due to the onset of my mid eighties I'm no longer sprightly and rarely seen in my Austin special. I have written a book though. https://amzn.eu/d/7rwRRqL

mistericeman · Posted: Wed Nov 13, 2013 5:02 pm Post subject:

The last charger i bought (about 3 weeks ago as it happens from Aldi/Lidl) was an intelligent charger
...capable of re-energising completely flat batteries maintaining charge etc
AND charges at 12v/6v has built in protection for reverse polarity etc

Cost of approx £14 ...

Why bother buggering about with light bulbs etc ???

petermeachem · Joined: 23 Sep 2013 Posts: 358 Location: Chichester Sussex

That's the problem with Lidl, you have to need what they want when they have it in stock.
Which they don't currently.

mistericeman · Posted: Wed Nov 13, 2013 5:36 pm Post subject: