12.4v On Mains (1 Viewer)

[mjltigger]

Hi. I connected my second leisure battery at the weekend and to check all was well I measured voltage on each battery. first thing I noticed was that there is a 0.1v difference between each battery consistently regardless of 'mode' the other thing I noticed was that I only got 12.4v when the Zigg is turned on. Does that seem a little low to anyone else? What might it mean?

 

[DBK]

The voltage difference might be down to how you have connected the second battery. Connected in parallel of course but then, ideally, attach the negative wire from the MH to the negative terminal of one battery but the positive wire should be on the positive terminal of the second battery. If you are just connected to one battery and the second simply slaved to it, so to speak, it will work but the batteries won't share the load as well as they would if the connections are split. A diagram would help if I had one.

As for the voltage, either the charger isn't, or both batteries are duff. An ammeter would tell you what is happening.

 

[andy63]

Just drawn this out to help .It's what DBK is explaining I think..
Sounds like charger isn't working.. voltage should be a lot higher .you could check the charger leads with a volt meter with the leads not connected to battery and see what it's no load voltage is..on charger

Wouldn't expect any voltage difference on battery terminals if they are connected with heavy duty wire and are in good condition..
Ta andy

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[mjltigger]

thanks both. I added a nearly new battery to whatever was in the van when I bought it so every chance the one that was already there is duff.. I will check next time I go out there. I used fairly chunky wires sold as starter leads. The -ve is 30'' and the +ve is 24'' (based on what made up lengths were available) The feed to the electrics comes off the one battery rather than across the two but that's purely down to the fact that the wiring in place was too short to cross connect and as each feed is its own wire that are then bundled into the connector it seemed too much faff to rewire them.

if the old battery is dead or dying will it harm my newer battery to keep as it is for a while until I can afford to replace the pair do you think?

Seems I need to fiddle some more.. Ms Tigger wont be happy lol

 

[andy63]

if the old battery is dead or dying will it harm my newer battery

Hi think the answer to that is yes..It will harm the new 2nd battery..
I'm also thinking it would be worth rewiring the 2 batteries as DBK recommend and I tried to show in the rough drawing.. They will share the load as best they can that way..
I mentioned checking your charger voltage..It should be high 13v to say 14.4v I would have thought..
Hope you get sorted..something sounds wrong with voltages you quoted ..
Ta Andy.

 

[PhilandMena]

You may find these attachments helpful. Also, get a voltmeter so you can measure the voltage from each battery and also establish if your charger is working.
http://caravanchronicles.com/guides/how-to-connect-two-batteries-in-parallel/
http://www.caravanclub.co.uk/media/13871919/ccmnovtechnical.pdf?type=archive
Broken Link Removed

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[SomeoneElse]

With a voltmeter I suggest the divide and conquer principle.
Go back to a one battery situation and measure three voltages.
One with the battery idle, not charging not discharging.
Another reading with it charging on EHU, and finally with a discharge of say a few lights.
In all cases allow at least 10 minutes, better still an hour, for things to stablise before taking the reading.
Then repeat with the other battery as the only battery.
There should be little difference between the reading from the two batteries.

When you know that both batteries are giving similar performance then I would suggest checking all the connections are good (clean and tight).
only at this stage would I consider the configuration of the circuit.

Good luck.