Thread: TD5 Immobiliser - Strange behaviour

Originally Posted by Tombie

The DBS has the aux linked to the main power to the starter. The aux also has it's own earth path.

When isolating power in a DBS both Earth leads need to be removed.

This is not a fault of the Traxide unit.

I didn't say it was a fault with the Traxide unit, just that I don't think it's a good idea to have the system live with the main battery terminals being disconnected.


If it's the same with other DBS systems then I don't like them either.


What I don't like about the SC80 is the constant power share feature - id one battery is crook it will drag the good battery voltage down to its level.


What I would really like is to have the power share facility on demand.

For me it's also difficult to disconnect the terminals on my auxiliary battery because of the fact that its installed in the rear and not accessible.

Well that's dangerous!

As for the Traxide constant share - if one battery is crook the other will be ok as it will cut out and disconnect.

All DBS can experience this.

Consider fitting an isolator switch to your rear battery, if it ever has a short and is that difficult to access you'll end in trouble.. In an accident etc you may really be in trouble.

I'm not sure what you're expecting from an intelligent controller, or vehicle electrics in general... However the guidelines are to isolate all batteries when working on a vehicle, if that means unplugging etc then it should be done.

A zap (like you did create) in the wrong spot can cost a lot in a modern vehicle.

Only thing another brand of isolator may offer is reduced reserve as most delink at a higher voltage... That's pretty much the only thing in your application that will change - it will isolate quicker, leading to less RC for accessories.

Originally Posted by Tombie

Well that's dangerous!

As for the Traxide constant share - if one battery is crook the other will be ok as it will cut out and disconnect.

All DBS can experience this.

Consider fitting an isolator switch to your rear battery, if it ever has a short and is that difficult to access you'll end in trouble.. In an accident etc you may really be in trouble.

I'm not sure what you're expecting from an intelligent controller, or vehicle electrics in general... However the guidelines are to isolate all batteries when working on a vehicle, if that means unplugging etc then it should be done.

A zap (like you did create) in the wrong spot can cost a lot in a modern vehicle.

Only thing another brand of isolator may offer is reduced reserve as most delink at a higher voltage... That's pretty much the only thing in your application that will change - it will isolate quicker, leading to less RC for accessories.

So all isolators allow power sharing through both batteries - I had read that this was one of the features on the SC80 that other isolators don't have?


What concerns me is that if you have a good main and weakening or crook aux battery the main will always be dragged down to the lower voltage level. In other words, if the main has 12.7 volts and is disconnected from the aux which is at 12.4 volts, when you connect the two together the main voltage will be dragged down to the lower voltage because of equalisation. This effectively minimises the power from the main.


I note that the newer USI160 has the manual disconnect feature.


I'm thinking of adding a solar panel and will have to change the isolator and and a DBS that accepts solar input and has a MPPT controller built in. I need to do this because when I leave the car undriven for a week the battery voltrage drops to 12.1 volts (I've never been able to work out why this is.)


One theory is that the AGM in the rear has never been properly charged by the alternator and has been reduced in capacity. The calcium/calcium requires a higher charge rate to an AGM - if you charge an AGM using Calcium/Calcium charge rates it will not go the distance.


Moving the battery to the rear has increased its life though and it has lasted longer than my Exide orbital in the engine bay.

i dunno much about the brands of these dual charge systems but what i know as theory is that if it's not some expensive proffesional system which splits the CHARGE according to each battery's power it will happen what you said that always the weaker battery will stress the stronger one, most of the cheaper systems are actually not dual CHARGE but dual DISCHARGE systems cos they manage the load not the charging...the best practice in this case is to fit two completely identic batteries then the system will be well balanced.

Originally Posted by sierrafery

i dunno much about the brands of these dual charge systems but what i know as theory is that if it's not some expensive proffesional system which splits the CHARGE according to each battery's power it will happen what you said that always the weaker battery will stress the stronger one, most of the cheaper systems are actually not dual CHARGE but dual DISCHARGE systems cos they manage the load not the charging...the best practice in this case is to fit two completely identic batteries then the system will be well balanced.

Yes, in an ideal world I would run two of the same type of battery but, the aux battery being inside the vehicle it has to be a sealed AGM and not a Calcium/Calcium cranking battery. I used to run a deep cycle in the engine bay and kept cooking them - the final straw came when I killed an Exide Orbital in 14 months - that was the catalyst for moving the battery to the rear of the vehicle.


The way to ensure ideal charge rate is to use a DC/DC charger which recognises the battery type being charged but they are expensive. Given that I want to use solar input I may have to start saving the pennies - perhaps in the long term this would be a better option.

Franz, the Traxide unit has a lower cut out utilising more of the main units RC before isolation.

The others just isolate slightly higher.

Any weak battery will pull another down whilst linked and will then drive the isolator to do just that.

Your AGM can charge up to 14.7v although they prefer 14.1-14.2 which is about the limit of a TD5 alternator anyway.

Having the mixed types will not be an issue with your system.

Your voltage drop is it in the main battery?

And a DC/DC charger is not the ideal...

With solar, a small panel won't need a controller and may meet your needs.

Originally Posted by Tombie

Franz, the Traxide unit has a lower cut out utilising more of the main units RC before isolation.

The others just isolate slightly higher.

Any weak battery will pull another down whilst linked and will then drive the isolator to do just that.

Your AGM can charge up to 14.7v although they prefer 14.1-14.2 which is about the limit of a TD5 alternator anyway.

Having the mixed types will not be an issue with your system.

Your voltage drop is it in the main battery?

And a DC/DC charger is not the ideal...

With solar, a small panel won't need a controller and may meet your needs.

Mike,


As you say, I'm not sure that what I want is currently available from any isolator and I was hoping the SC80 would be my saviour - alas not. I think the manual isolating facility on the USI160 might be an improvement but if I have to buy another isolator, I might as well look at a DC/DC charger (whether this will sort all my issues/dislikes is another matter - some further investigation is required).


At the moment, I'm not sure what is causing my voltage to drop down to 12.1 Volts after a few days with nothing switched on and the vehicle not being driven. The main battery is brand new and the aux a few years old now but it tested OK on a load test.


Another issue with the mixed battery system is that you can't charge the batteries together and physically have to isolate the aux every time you want to charge either. With a multi stage charger the rejuvenate stage pumps in over 15 volts which is no good for the AGM. If you use the AGM setting (or the charger automatically recognises the battery being charged) the calcium battery will not be fully charged and this will lead to premature failure.


A small panel "may" not require a controller but I'm thinking of mounting a 100W panel on the roof rack and this will also help with charging the van batteries when solar input is weak and more than one panel is required to keep the charge up to the batteries.