Split Charge draining battery

[gagvanman]

My bus has a 53AH starter battery and a 105AH leisure battery, and a split charge system.
For some time the bus starter battery goes flat if left for a week without starting.
I initially thought it was a battery problem so replaced with a new one.
However, problem remained.
Recently I had my engine out to do some work on the heads. I disconnected both the starter and leisure batteries. Charged both batteries fully. Checked both batteries every day and no voltage drop.
Engine back in and starter battery connected (Lb left disconnected), no voltage drop over a week.
Connected the Lb backup and within a day the Sb is flat again.
Split charge is done by a 12V 140amp Durite 0-727-33 voltage sensitive/intelligent Split Charge Relay.

Wired as per the diagram:

Any thoughts?

 

[gagvanman]

Seems like nobody on here has suffered this issue with a Durite split charge relay.
Between the showers today, cleaned up the earth connections to both batteries.
Noticed that after running the engine the red light on the relay remained on after engine is shut down.
Did some research and apparently when the red light is on it indicated the relay is in its "engaged state" and that current is free to flow from one battery to the other. I think this means that both batteries are at a voltage level above the relay cutover threshold.
Had a thought about this for a moment, then turned the van headlights on for a minute or 2. Checked the relay and the red light was out.
I don't know if this will resolve the issue, but will leave the van for a few days before checking the starter battery voltage again.

 

[ozziedog]

I don’t have a leisure battery and it does sound like you know a lot more about electrics than me and Gary. Unfortunately most of the Earlybay troops seemed to be out and about over the weekend at various events all over the country. Most have returned now and I’m sure someone with more than a pea sized brain when it comes to electrics will join in with a suggestion or two ( hopefully ) . My only input to this scenario, is to take the earth lead off of each battery and connect a bulb or a tester in between the lead terminal end and the battery post to see if you can see it leaking out. Once you can see it leaking out, which I’m assuming it must do if your battery is flattening, disconnect things that may be connected like the relay or the radio fuse etc etc until you see the drain has buggered off then you may isolate the issue.

Ozziedog,,,,,,,, good luck with the electrical stuff, ,,, work of the devil

 

[Earlybay1]

the durite actually specifies the terminal for each battery. Check that.

 

[creationblue]

The specifications say the relay energizes @ 13.3v meaning current will flow from the alternator to the main battery, through the Durite to the LB then at 12.65V the relay opens thus cutting off the main battery from the LB allowing you to use it without draining the starter battery. So, the alternator will pump out 14.4v when your engine is running and I find both my batteries are over 13volts after switching my engine off. The main battery will settle down to about 12.7v meaning the relay on the Durite will stay energized for a while before opening the circuit.

My conclusion is that the Durite is faulty

 

[warrenstuart]

I’m not familiar with the Durite relays but I agree with creationblue, plus to me that’s a bit hit and miss, my bus just has a conventional automotive relay switched by the alternator charge/sense pin so when the alternator is charging the LB is connected and when it’s not it isn’t which to me is a much more cut and dry way of doing it.
Just thinking outside the box though have you measured the battery terminal voltage while the alternator is charging because if the alternator voltage regulator is faulty and the voltage is way too high the battery terminal voltages will remain high for quite a while when the engine is turned off and your Durite relay will remain open… just a thought

 

[la_bigmac]

Mine is the same as Warren, ignition on it charging else its isolated. I agree with creationblue deduction . I do need to up-rate mine a little as the drain on my LB exceeds the charging capacity. But then I have a stupid amp, capacitors and subs.. What I would say about battery chargers, I switched to a battery conditioner (yuasa) wow what a difference!

 

[Graham L]

We use the Durite VSR relays all the time and never seen this problem before, I'd check it's been installed correctly before going any further.
Are you sure you haven't got a parasitic drain somewhere in the van that's draining the battery on either the leisure battery or the starter battery side?,

 

[gagvanman]

Earlybay1
I installed the system (I was an electronics engineer in a former life) so I am pretty sure it was installed correctly.

Alternator pumps out 14.1v when the engine is running

The lb is 105AH and runs internal lights, pump for water tap, Propex (when on)
radio (which has a removeable facia), and 2 USB sockets. Since installed it has never run to a discharged level.

Durite was installed some years ago so I agree it probably is faulty. I will continue to use the hack of turning on the headlights for a minute once the engine is stopped for now.

Thanks for all your inputs, much appreciated.

 

[T2t25]

I have this issue on my T25 and it knackered both my batteries. I got rid of it and went solar

 

[pgtips]

I had a similar problem with my setup that under certain circumstances the link between the 2 batteries was being held open.
Its a by problem of all the other things you might have installed (it was for me anyway)

I can't recall why I had the issue, I've got my head into lithium battery build and install now but the solution was to install another little relay to make/ break the earth to the durite so it only functions when engine is running. I.e using a live feed from the alternator wire to trigger new relay.

So basically when you turn off engine the durite stops working and breaks all connections. Engine running it does it's job.

I can't take credit for that fix, it was a bloke called pkrboo who gave me the lead and it worked a treat. Simple cheap and quick solution.
Pg

Longer explanation

So new relay gets/needs +ve and -ve feed.
And then the other 2 pins are 87 and 87a. Without power not connected, when relay is energised they join.

Your earth feed to the new relay also bridges across to one (the closed) side of the new relay 87 (double check with your test meter as I'm not in front of a relay right now)
and then run another earth wire from new relay 87a pin into your durite (so that's the durite earth feed).

So engine off no earth connection to durite is an open circuit. Durite off.

Engine running the relay switches and bridges the earth connection , you get earth into your durite which enables it to function.
When durite is functioning your 2 batteries work together and join.

Hope that helps, ask if it's unclear , i remember the whole concept of relays at first was a bit daunting but they're actually quite simple. Pretty cool and useful. In this durite setup your automating the disconnect and connect of your LB.

The lithium battery im building is a completely different beast but actually similar setup. Instead of split charge you use a DC to DC charger. Its the charging time that blows me. Gone are the days of trickle charging overnight at 3 or 4 amps. A 100ah lithium battery could charge from flat in under an hour if your alternator output enough amps. Mad.

 

[creationblue]

I have a Zig with a physical switch between Touring (both LB and SB connected and being charged, or On-Site with the contact between the two open. I still unhook the SB with a quick release clamp to be doubly sure I can start the van when needed lol

 

[matty74]

I had exactly the same set up as OP, relay’s been in for 7yrs. Reading this post made me wonder if I had a similar problem with the Durite. Fitted this cheap VSR version as a test and it works fine. The 12.8v cut out voltage is a bit higher than the 12.65v on the Durite. Ran the engine to see it kick in and then watched the starter battery drop to 12.8v and relay dropped out as it should.
Screw orientation and unit size was a the same as the Durite so it was an easy swap.
Picture is of relay de-energised, starter battery voltage on unit display, Leisure battery in green above that. I normally drop off both -ve’s when it’s in the garage, but I’m gonna leave them connected and see where they’re at tomorrow … and probably solder and sleeve the supply to remove that 6mm through crimp as it’s doing my head in

 

[gagvanman]

Went to run my van yesterday and the starter battery is flat as a pancake. So my hack didn't work for long, looks like my Durite is shagged.
Matty74, where did you get your relay from?

 

[gagvanman]

Recharged battery. I had a relay lying around so have wired it to break the Durite earth cable when the engine is off as per PGtips post. Will see what the starter battery is like tomorrow.

 

[matty74]

Went to run my van yesterday and the starter battery is flat as a pancake. So my hack didn't work for long, looks like my Durite is shagged.
Matty74, where did you get your relay from?

Hey just got it off eBay

https://www.ebay.co.uk/itm/12601512...jyx1vbkQnq&var=&widget_ver=artemis&media=COPY

 

[warrenstuart]

Why don’t you just do it the old fashioned way with a relay switched by the alternator sense/trigger pin… keep it simple

 

[pgtips]

Why don’t you just do it the old fashioned way with a relay switched by the alternator sense/trigger pin… keep it simple

I think the durites are VSR = voltage sensing so after MB is happy then the LB then gets its charge but the voltage is kept stable.

I wouldn't be so quick to junk the durite. If the MB was fully charged then the durite wouldn't 'leak' anything to your MB as its already got full charge. Those amps are leaking into a device somewhere and you have got crossover becuase MB and LB circuits should be totally separate.

But anyway as a test my workaround works fully charge both then just disconnect the durite earth for a few days and measure, if it works (no drain) then go for it but keep an eye on your main battery just in case the leak is draining there.

 

[gagvanman]

Fitted a new VSR (same as matty74) yesterday. Took the van for a spin, will test today to see what the voltages are.