Split charge system battery drain

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payydg

payydg

Well-Known Member
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Location
Aberdeenshire
Hello,

I installed a national Luna split charge system a couple of months. Recently the batteries have started to slowly drain. Over the last 3 weeks it's sat unused the batteries have gone from fully charged to into the red.

I'm a bit new to the whole split charge thing. Does anyone have any ideas where the drain might be coming from?

Dave
 
Assuming youve wired it up right, sounds like you're gonna have to stick the ammeter on it and start pulling fuses to see what's draining it.

Is it both batteries that's draining? What have you got wired off the second battery?
 
I'm fairly sure i wired it up correctly.

Its strange, both batteries are draining at the same rate. If it was something in the engine would that not drain the starter battery faster?

The only thing wired to the aux at the moment is the stereo...

This is such a stupid question but how do you see whats draining it with an meter... just put it across the battery and pull a fuse and see if the voltage increases? is it that instantaneous?

Dave
 
How old are the batteries?? if ones fooked the other will try to top it up all the time they're connected. Have you got a Manual isolator switch.

I have the live from main to aux wired to a ignition switched 200Amp relay with a manual isolator between main and relay.

I have installed a 2nd fusebox with a feed from Aux to this fuse box anything I wanna run from the aux battery goes thru this fusebox which is supplied via a 60Amp use and a 70smp relay. the relay is triggered manually via a push button switch with a neon lamp in it.
 
No, you need to measure current draw and not voltage.

You have two ways of doing this

1. You need to stick your current meter (aka ammeter) in series with your battery to see how much current is being drawn with everything off. As you are draining your battery, you'd expect to see some current being drawn at rest. Then, start pulling and replacing fuses one by one to see which one causes the current reading to drop significantly. DO NOT start the engine whilst doing this.

2. Leave the battery connected and instead, one by one pull the fuse and stick the two ammeter probes across the two fuse terminals. See which one is drawing significant current.

Testing methods aside, the fact that you're flattening both batteries even though one of them only has a radio wired to it that's switched off, I really would check that you have wired that kit in correctly. I'm not familiar with that make myself, but I'd guess that maybe you have both batteries connected to each other at rest (whereas they should only be connected when the engine is running) and possibly if that kit is relay based, you are powering the relay all the time (again rather than only when the engine is running).
 
My first thought is its wired wrong. If both batteries are draining equally then it sounds like the solenoid is not closing the link between the 2 batteries like it should and you may have an earth leak on one of the circuits.

Basically what mundungus said. :) Follow his instructions to find the fault.

I would start by taking an extra accessories off the battery first though. Then go through the standard electrics.

Good luck.
 
redhand said:
How old are the batteries?? if ones fooked the other will try to top it up all the time they're connected. Have you got a Manual isolator switch.

I have the live from main to aux wired to a ignition switched 200Amp relay with a manual isolator between main and relay.

I have installed a 2nd fusebox with a feed from Aux to this fuse box anything I wanna run from the aux battery goes thru this fusebox which is supplied via a 60Amp use and a 70smp relay. the relay is triggered manually via a push button switch with a neon lamp in it.
Click to expand...

Both are 2 month old oddessey batteries so hopefully they aren't fooked yet.

I have a similar set up. The aux battery outputs to a disco fuse box supplied by a 100 amp fus, this then out puts to the radio. Is it worth installing an isolator switch? What's the advantage of having one on a relay as a posed to an inline switch?
 
BIG_GINGA_BEARD said:
My first thought is its wired wrong. If both batteries are draining equally then it sounds like the solenoid is not closing the link between the 2 batteries like it should and you may have an earth leak on one of the circuits.

Basically what mundungus said. :) Follow his instructions to find the fault.

I would start by taking an extra accessories off the battery first though. Then go through the standard electrics.

Good luck.
Click to expand...

Stupid question I know but what's an earth leak? How does one find and fix such a problem?
 
payydg said:
Both are 2 month old oddessey batteries so hopefully they aren't fooked yet.

I have a similar set up. The aux battery outputs to a disco fuse box supplied by a 100 amp fus, this then out puts to the radio. Is it worth installing an isolator switch? What's the advantage of having one on a relay as a posed to an inline switch?
Click to expand...

yes always worth having a manual isolator smart split charge systems are great but if they fook up there's no way to be 100% sure that the 2 batteries are isolated. the manual switch removes this uncertainty.

having the 2nd fusebox triggered via a relay is just a failsafe for me, to prevent overloading the fusebox or starting an elctrical fire.
 
redhand said:
yes always worth having a manual isolator smart split charge systems are great but if they fook up there's no way to be 100% sure that the 2 batteries are isolated. the manual switch removes this uncertainty.

having the 2nd fusebox triggered via a relay is just a failsafe for me, to prevent overloading the fusebox or starting an elctrical fire.
Click to expand...

So where exactly do you put the isolator switch? Between the aux batt and the fuse box?
 
payydg said:
So where exactly do you put the isolator switch? Between the aux batt and the fuse box?
Click to expand...

no the live feed from the main battery goes to the isolator, Which is mounted on the battery seatbox. Below the passenger seat. from there the live continues to the Aux battery. thro the switch and you are gauranteed that the Aux battery is seperated from the main battery.

having the aux fusebox further protected by a switched relay ensuures that you can completely isolate everything that is connected to the Aux fusebox.
 
wiring diagram I use a switch instead of a solenoid. only differnt is that the solenoid automatically connects the 2 batteries whereas the switch is manual.
Simple-dual-battery-setup-L.jpg
 
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