Charging second battery with TJM dual battery system

[Maxhead]

Guys, quick question.

Occasionally I put my smart charger onto the second battery to give it a good top up. What I have noticed is that the dual battery system automatically links the two batteries together and I think is trying to charge both.
My main battery is wet cell and my second battery is a calcium so obviously different charge rates apply.

Is this normal for any dual battery setup? Should it try and charge both?

I have manually disconnected the second battery just to charge.

[Yendor]

That doesn't sound right. What brand of isolator is it?.

Were the batteries already linked when you put the charger on?

[the godfather]

If it has a smart solonoid as most do regardles of brand, it will charge the lowest battery 1st. Rule of thumb is to use the exact same battery in both. They will both only charge to the lowest of the two battery standards. ORE, TMJ, OPPOSIT LOCK and the rest will tell you other wise.

[the evil twin]

That doesn't sound right. What brand of isolator is it?.

Were the batteries already linked when you put the charger on?

Agree with Rodney,

The VSR should only sense one battery and pull in/drop out depending on it's voltage. As mentioned the VSR can stay linked for up to quite a few hours after the engine is shut down depending on the parasitic drain of the cranker if there is no load on the Aux.

If you connect the charger to the Aux while the VSR is still linked that will hold it energised

[fracster]

Guys, quick question.

Occasionally I put my smart charger onto the second battery to give it a good top up. What I have noticed is that the dual battery system automatically links the two batteries together and I think is trying to charge both.
My main battery is wet cell and my second battery is a calcium so obviously different charge rates apply.

Is this normal for any dual battery setup? Should it try and charge both?

I have manually disconnected the second battery just to charge.


My motorhome does this very same thing. Hook up to the engine battery and only that charges, hook it up to the leisure battery and both charge, I have never understood why as they are isolated from each other when the ignition is off.

Be interested to see if anyone knows why this happens.

[the evil twin]

My motorhome does this very same thing. Hook up to the engine battery and only that charges, hook it up to the leisure battery and both charge, I have never understood why as they are isolated from each other when the ignition is off.

Be interested to see if anyone knows why this happens.

What brand and model is the isolation system

[fracster]

No idea mate, it is a factory fit, motorhome is a Hymer, German make.

[WYLD333]

If it has a smart solonoid as most do regardles of brand, it will charge the lowest battery 1st. Rule of thumb is to use the exact same battery in both. They will both only charge to the lowest of the two battery standards. ORE, TMJ, OPPOSIT LOCK and the rest will tell you other wise.

X 2 on this

[threedogs]

I would think its main job was to make sure your start battery is charged first, then switch to the aux,

[the evil twin]

I would think its main job was to make sure your start battery is charged first, then switch to the aux,

There are Battery Management Systems (full on Management Systems not just VSR's or DC/Dc converters) in the RV and Industrial applications that will charge isolated batteries when certain conditions are met. They are very expensive compared to VSR solutions tho.

Fracster may possibly have one in his motorhome. Nisshead won't tho with his TJM unless it is a product of theirs I am unfamiliar with which is a possibility

It is worth noting that no VSR will ensure your Cranker is fully charged.

A VSR (Redarc, TJM, Pirhana et al) will stop a load on the Aux from depleting the Cranker but will in no way ensure a Cranker is given any priority in the recharging when the Alternator is running.

Indeed a VSR may possibly slow the recharge rate of the Cranker if the Aux is down as well and the charge acceptance rate of the batteries exceeds the Alternator max output. In extreme cases a VSR can help you flatten the cranker not because of auxiliary current drain but because it doesn't give the Cranker a chance to recharge

[Yendor]

My RedArc VSR will not activate and link the second battery to the cranking battery if I charge the second battery via a battery charger.

If the VSR was still activated and I connected the battery charger to my second battery this will cause the VSR to remain on, linking both batteries together then the battery charger will be charging both batteries.

It seems strange that Nisshead's isolator is switching on when the voltage across the second battery rises.

[Yendor]

There are Battery Management Systems (full on Management Systems not just VSR's or DC/Dc converters) in the RV and Industrial applications that will charge isolated batteries when certain conditions are met. They are very expensive compared to VSR solutions tho.

Fracster may possibly have one in his motorhome. Nisshead won't tho with his TJM unless it is a product of theirs I am unfamiliar with which is a possibility

It is worth noting that no VSR will ensure your Cranker is fully charged.

A VSR (Redarc, TJM, Pirhana et al) will stop a load on the Aux from depleting the Cranker but will in no way ensure a Cranker is given any priority in the recharging when the Alternator is running.

Indeed a VSR may possibly slow the recharge rate of the Cranker if the Aux is down as well and the charge acceptance rate of the batteries exceeds the Alternator max output. In extreme cases a VSR can help you flatten the cranker not because of auxiliary current drain but because it doesn't give the Cranker a chance to recharge

But.............all the marketing and sales hype tells us it does :rolleyes:

[the evil twin]

But.............all the marketing and sales hype tells us it does :rolleyes:

Hehehehe... once upon a time I used to explain to saleys why VSR's won't do what they claim. Very frustrating for both of us. :furious:

Now I just say "Bullshyte" and walk away. I am happy 'cause i told 'em so, they are happy 'cause i left :xxxx:

[Maxhead]

Guys, thanks for the info. I had to take off after I posted.
I will confirm the two batteries weren't linked when I put the charger on and also get the brand of the isolator.

[Cuppa]

I have a different take to most of what has been written in this thread.

Although I know absolutely zip about the TJM VSR, I can say that there are definitely such things as two way VSR's as I have one in my motorhome (bus). Most folk know of the Redarc SBI12 & the 24v equivalent the SBI24. These are as folks here have described - one way. If the TJM unit is like this & the two batteries are connected when the charger is put on to the aux battery, the only reason I can think of is that the VSR is connected the wrong way round.

However Redarc also produce a two way model which has a 'D' suffix. the one in our bus is the SBI24D. I have solar connected to the aux batteries & the alternator connected to the crank batteries. I fitted this before dc to dc chargers became common, & it allows the alternator to bulk charge both sets of batteries (AGM type) & the solar to 'top them up'. If the voltage of either bank falls below a preset threshold it disconnects the two banks, leaving enough in the crank batteries for starting & ensuring the aux batteries are not over discharged. I can't recall if the disconnect threshold is the same both ways or not.

If the TJM unit works like the Redarc 'D' models you would expect to see both batteries connected when the charger is put onto the auxiliary.

[Maxhead]

OK, Vhecked the batteries were isolated and put the charger(Projecta 15A 7 stage) on to the second battery. 30 minutes after they linked automatically. The charger was still in bulk charge mode.

The dual battery system is tjm IBS(Intelligent Battery System) http://www.tjm.com.au/index.php?nr=no#ln.php?i=IBS

http://www.nissanpatrol.com.au/forums/images/imported/2013/01/32.jpg

The voltage on the second battery is 13.74v and the cranker is 13.56v. I would have thought they should be the same when linked, unless there is some voltage drop in the IBS.

Got me stumped.

[the evil twin]

OK, Vhecked the batteries were isolated and put the charger(Projecta 15A 7 stage) on to the second battery. 30 minutes after they linked automatically. The charger was still in bulk charge mode.

The dual battery system is tjm IBS(Intelligent Battery System) http://www.tjm.com.au/index.php?nr=no#ln.php?i=IBS

http://www.nissanpatrol.com.au/forums/images/imported/2013/01/32.jpg

The voltage on the second battery is 13.74v and the cranker is 13.56v. I would have thought they should be the same when linked, unless there is some voltage drop in the IBS.

Got me stumped.

Hmm TJM website is a tad unhelpful on deep and meaningful spec's and the Voltage drop of 0.18 isn't too bad depending on cable size and length.

You could have a dual sense system but another possibility is that there is enough leakage thru the vehicle electrics or the Isolator itself to bring the Cranker voltage up to 13.5 and trigger the Isolator to link the batteries. That leakage current will be quite small and won't matter normally.

The way to check if that is happening...
1. With engine off turn on the headlights for a minute or so and also put a load on the Aux like a handheld spottie or whatever for a minute or so (more if it is a small load like a frig).
2. Turn the loads off, wait about 5 minutes and measure the resting voltages of the two batteries
3. Connect the Charger to the Aux and immediately check the battery voltages again.
4. The Aux should see the Battery Charger voltage, obviously.
Now, if the cranker is still at or very near the resting voltage in step 2 check it again every 5 minutes or so and if it is very slowly rising then there is a leakage path between the Positive of the Aux and the Positive of the Cranker.

If that voltage rises to 13.5 the Smart relay is dumb enough to pull in the Isolator even tho the Alternator isn't running and now they are linked the Charger voltage will hold the Isolator in.

(see next post)

[the evil twin]

Further to the Above...

If in step 3 the Aux voltage is below 13.5 and slowly rising and the Cranker stays at it's resting voltage... Monitor the Aux and Cranker battery terminals every 5 minutes and if the Isolator relay pulls in when the Aux hits 13.5 ish but theCranker stayed at it's resting voltage up until that point then you have a dual sensing battery management system as Cuppa describes.

I am assuming the unit is set to 13.5 but it may be as low as 13."not much at all" if it is dual sensing

(Edit)... Well picked up cuppa. I must admit that I hadn't thought of the fact that the dual jobbies would find their way into the 4X scene which is why i went off on a tanget. I have only seen them in motorhomes, buses etc and then not very often.

[Cuppa]

If the manual override switch is a switch to earth as on the Redarc's it is possible that you have an inadvertant earthing problem (a short in the manual override wire).

[Maxhead]

Ok, thanks for that boys. I will test this soon.

I did some more investigating and it looks like this is normal if I read correctly. Here's the link with more info then TJM site. http://ibs-tech.ch/en/products/dual-battery-system/ibs-dbs-with-uproc.html

New bi-directional Automatic Battery link

While the engine is running the Main and Aux batteries are linked together for parallel charging from the alternator (green LED linked is on). If the engine is stopped, the two batteries will be disconnected automatically with some delay. Appliances as fridges, lights, compressors, inverters are now safely fed from the Aux battery. With the additional charge by solar equipment, battery charger or generator is sufficient for charging, the starter battery will be charged automatically with Aux battery together (green LED "link" lights).


So looking at this I should have 2 same type batteries !!!

[Yendor]

I just found the same info on IBS website.

It looks like Cuppa is on the money, it's set up like this for Solar panels.

Here is the link

http://ibs-tech.ch/en/document-download/manuals.html

[Sir Roofy]

ok, thanks for that boys. I will test this soon.

I did some more investigating and it looks like this is normal if i read correctly. Here's the link with more info then tjm site. http://ibs-tech.ch/en/products/dual-battery-system/ibs-dbs-with-uproc.html

new bi-directional automatic battery link

while the engine is running the main and aux batteries are linked together for parallel charging from the alternator (green led linked is on). If the engine is stopped, the two batteries will be disconnected automatically with some delay. Appliances as fridges, lights, compressors, inverters are now safely fed from the aux battery. With the additional charge by solar equipment, battery charger or generator is sufficient for charging, the starter battery will be charged automatically with aux battery together (green led "link" lights).


so looking at this i should have 2 same type batteries !!!

then it will equalize,but if one is a bit lower than the other youl
still have your light on till they level

[the evil twin]

Yep, Cuppa wins the Choccy frog :xxxx:

Can't get over how cheap these things are now. Admittedly it was several years ago but last time I was fooling around with that sort of stuff it would cost $400 up to a grand for the gear

[Maxhead]

Ok, cool. I wanted something I could charge my aux with a solar panel and had anderson plugs put in for quick connection but did not realise it would charge the main as well.

Just to clarify though.

Will the aux battery have to be fully charged before the batteries link? Is the system smart enough to sense this?
Today they did not link for around 30 minutes so I'm assuming this would be the case.


Thanks again all. It's good to read and learn about different setups and equipement

[Yendor]

Ok, cool. I wanted something I could charge my aux with a solar panel and had anderson plugs put in for quick connection but did not realise it would charge the main as well.

Just to clarify though.

Will the aux battery have to be fully charged before the batteries link? Is the system smart enough to sense this?
Today they did not link for around 30 minutes so I'm assuming this would be the case.


Thanks again all. It's good to read and learn about different setups and equipement

You will still need to use a regulator with your solar panel.

It looks like it only needs to go above 13.1 volts across the aux battery for the isolator to link the two batteries, so no, your aux battery will not be fully charged before they link.

[Cuppa]

Will the aux battery have to be fully charged before the batteries link?

Whichever battery you connect the charger (or solar) to, will need to reach a certain voltage before the two batteries 'join'. This will be less than 'fully charged' most likely. The documentation for the VSR should give the disconnect & connect voltages.

As for having the same type of batteries - ideally yes - but in practice it will work with different types with no major problem. For 4 years I ran wet crankers & AGM auxillary in my bus system. The only real issues I found were a) the need to keep an eye on the wet crankers & top them up ocasionally, & b) the wet batteries would self discharge quicker than the AGM's & would drag the AGM voltage down to the VSR's cut off point if left. (However when travelling on a daily basis this wasn't an issue. It was however the reason I changed from a one way to a two way VSR & essentially doing so gave me a bit of extra useable battery capacity (from the crank batteries) which was previoiusly wasted. After 4 years & not topping up the crank batteries as often as I should they died a dry death. I replaced them with Optima Yellowtops. Time will tell how they like the setup (they have a quite specific charging regime which differs a bit from the Fullriver aux batteries (not all AGM's are equal)..... but so far so good. Fullrivers are 7 years old & Optima's are almost 2 years old). When not in use I maintain them on a CTEK charger set to 'Supply mode' (13.6v) once fully charged.

[Cuppa]

Just re-read the thread & realised you have a wet & a calcium battery. You may find that the calcium battery has a shortened life due to being undercharged, (they need a higher charging voltage than the wet battery which is what your alternator will be regulated to charge) ,but as you have it you may as well get what life you can out of it. Later, when replacement is needed you can choose something more suitable. (Assuming you don't want to get rid of the VSR & use a dc to dc charger which can provide different charging voltage to the aux battery tha the crank battery.

[Maxhead]

Ok Cool. Not sure if its an advantage or disadvantage...lol

I would rather fully charge my aux as its the one that gets used for everything and the main battery is just for starting. But not a biggie. I can always manually link them to top up the aux from the main if need be.

Thanks guys

[Maxhead]

Just read the manual again and if I just wanted to charge the aux battery with charger or solar I could switch the linking system off if needed, so all good.

Handy little feature

Deactivation of automatic and manual battery dual link function:

Is there a problem with the auxiliary battery (Aux) as short circuit of cells, short circuit or defective battery housing, leading to damage of the generator (alternator). In an emergency situation the battery system can be operated in the vehicle in the basic configuration (alternator, starter battery without additional charge to battery aux). By pressing the link button for 6 seconds (until the sound of the beep), the link is deactivated. In this mode, no manual and automatic battery connection is possible. This feature can after solving the battery problem of the battery Aux by pressing the Auto button for 6 seconds to be reset. Now the system is working again with all the functions.

[Maxhead]

Ok, I have confirmed the system works as it should. The batteries will link when the voltage reaches 13.1V but the deactivation function quickly solves the issue if you want to only charge the aux.

All good thanks gents.