Leisure battery keeps going flat.

[thedogsbollox]

Where do I start.
New leisure battery about 6 months ago.
Just lately, if I leave it about 2weeks without use the Lbattery is dead.
It used to be the split charge relay would click over from one to the other roughly every 2 seconds or so at tickover. Now it is very erratic and sometimes while driving I can hear it going ape, it click egg flacks away for maybe 10 or 15 seconds then stops.
After a long drive I took the positive terminal off the LB and measured the current. 0.12 amps if I remember correctly.
Is this a lot or not?
I pulled the fuses on the Willington kit(one large and 3 small)
Measured current across them. The three small were 0,0, and 0.04 amps which I figured was the stereo.
The large fuse was reading 0.08. This I couldn't figure. Was one battery feeding the other?
I don't know if the problem lies in the split charge relay or the alternator. Where should I start looking?

[ELZE]

Not sure where you are but I have a brand new one that I bought for use on an electric outboard. Used it once and it is still in the garage. Now a year older. Now it may be uselesss by now but its free if you want it? It was a lot of money so its a good one if it still works.

Collection only tho' sorry I am in NE26

[g8dhe]

The 0.08 on the larger fuse might be the current used by the Voltage Sensitive Relay which needs to draw power from one or other source. Its not a lot but yes it will drain the battery eventually. The 0.04 sounds about right for the radio, make sure you don't have anything else plugged in like 12v to USB adaptors they too will draw 10mA (0.01A) without anything plugged in as well!

[Simon Jones]

... it click egg flacks away...

Don't you just love auto correct

It could be the battery has become damaged and will no longer hold a full charge. Can you get it fully charged and then check the voltage with the leads disconnected? If it does not remain stable after a few hours, then the battery could be knackered. You'd still need to identify what was causing it to go flat in the first place otherwise a new battery will go the same way.

What voltage do you get at the battery when the engine is running? Anything less than 13v would suggest split charge is not working.

[Velocette]

Forgive me if I have got this completely wrong but I don't think the split charge relay switches from " one to the other". From what I observe on the battery monitor I fitted recently, the relay switches between separate battery circuits when the alternator output is low or absent and parallel batteries when the alternator is delivering power. The two batteries then share the charging current.

[thedogsbollox]

Forgive me if I have got this completely wrong but I don't think the split charge relay switches from " one to the other". From what I observe on the battery monitor I fitted recently, the relay switches between separate battery circuits when the alternator output is low or absent and parallel batteries when the alternator is delivering power. The two batteries then share the charging current.

Oh right. If that is the case then probably the problem lies in the alternator as it sometimes clicks away when on full chat. It should be charging both batteries then.
What happens when both batteries are fully charged?

[g8dhe]

The alternator puts out a fixed voltage, when the batteries are charged there voltage rises to the point where only a small current is flowing thru them.
Typically the alternator voltage is 14.4Volts max. (any higher and it would cause the batteries to "gas" - emit Oxygen and Hydrogen) at full revs, with a good battery fully charged then the current thru the battery will be in the order of 1-2 Amps at that point, if the battery is flat then the charging current will be up in the 10-20 Amp range after a few minutes charging.

[Dodgey]

Mr g8dhe (what IS your name? ) - is bang on regarding alternator charging current.

As for the Willinton split charging relay kit - this is what it does: Your camping electrics are re-routed to the leisure battery when you plug the little leads into your fusebox - this is so you are now always ONLY using your leisure battery to run your "camping electrics".

The relay element is solely for charging - when the engine is running, and therefore the alternator is running, the main starter battery is being charged. Providing the battery is good , it will almost instantly jump to well over 13.6 volts (more like 14.x). A sensor in the Willington relay sees this increased voltage, which is a clear indicator that a) the engine is running and b) the starter battery is in good health. The moment it "sees" this increased starter battery voltage the relay "clicks" and makes a wired link between the two batteries - which means that, because they are linked, they BOTH charge off the alternator. In normal circumstances, the starter battery will be pretty much full, so the leisure battery will get all the juice (batteries linked in this way (parallel) will take care of themselves when it comes to distributing/sharing charging current).

A side effect of this "link" between the two batteries is that your camping electrics are now running of both batteries - but this doesn't matter as you have the engine running.

When you stop the engine, the starter battery will fairly instantly drop below 13.6 volts (not sure if it's exactly 13.6 - but close) and settle back at something lower. This drop in voltage means the Willinton relay will no longer link the two batteries (another "click"). Now they are separated, you cannot accidentally drain the starter battery with your camping electrics.

[g8dhe]

_________________
Geoff
V6, AFT, full side conversion.
Image Spherical Visions
http://bit.ly/BuyMeABeerOrTwo

See below the line

[Jaws]

All of the above but I suspect the alternator is failing. Buy me a pint if the sediment light comes on soon.....

[thedogsbollox]

Done some measurements.
With the engine off
SB 12.7v. LB 11.7v
At idle
SB 12.24v LB 11.7v
At 2000revs
SB 13.9v. LB 11.7
At 3000 revs
SB 14.05v. LB 11.7

So the LB staying at 11.7 tells me the relay is not switching over. But is this because the starter battery is not charged enough? Do I need to do this test again after a long run?

[corrour]

Looks very much like that relay is not pulling in
Check all its connections and make sure it has a good earth.

[madmile]

It does sound like a failed relay.

Just as an observation, but the .08amp draw sounds like the green light over the ignition switch......it always throws me when checking for a drain on the circuit once i have wired up a conversion. The light draws .09amp when one of the front doors is left open. Just thought i would mention it.

[g8dhe]

Yup would expect the relay to have pulled in by 14.05 volts. But on the other hand you would expect a bit more from the alternator as well at 3000 rpm.

[Jaws]

Sorry to be a bore but I still think the alternator is on it's way out. A good unit should easily produce about 14v at idle if that is what the battery needs. I'm no expert but have experienced a very similar situation. The control circuits in the alternator will compensate up to a point but if the generator is unable to give the necessary power then it will just about keep the SB charged but not be able to charge it quickly enough or fully in order to switch the relay to charge the LB. Typically, if it does connect the LB the resultant power draw drops the voltage and the relay opens again, sometimes giving relay chatter.

Of course it might still be a relay fault but I'm sure the Willinton kit is designed to protect the SB