Has my Traxide BMS let me down?

[Tin Lizzy]

Hello. I recently had an unplanned trip away for 14 weeks and returned to find both my main and auxiliary batteries dead flat (D4 down to the bump stops). Both had died and needed to be replaced (very expensive). The aux battery was 5-6 years old, and potentially a bit dodgy, but the main battery was less than two years old an seemed in good nick. I suspect that the auxiliary battery has died and somehow managed to parasite the cranking battery charge until it flattened. I think I left the USI-160 BMS in ignition mode, but can’t be sure. Question…has the isolator not done its job, or would a healthy start battery potentially be killed by lack of use over this period of time (not sure what the cut-out voltage is set at on the BMS)? Any thoughts much appreciated….I’m no brain surgeon.

[John_D4]

Tim from Traxide usually monitors these threads. If he doesn’t reply in a day or so maybe send Traxide an email

[Ferret]

... I think I left the USI-160 BMS in ignition mode, but can’t be sure.

If that is the case I believe it should have isolated your cranking from your aux battery very much earlier than if you had left it in the recommended 'shared' mode.

Your aux battery was probably being propped up by your cranking battery (hence self discharged when isolated for such a long time) and your cranking battery is always running some systems even while parked up for 14 weeks. Result - 2 flat batteries, nothing to do with the BMS I think.

[drivesafe]

Hi Tim and sorry mate, but you can not leave any lead acid battery for 14 weeks without some sort of maintenance charging while you are away.

Even 4 weeks weeks would be the limit and that’s providing the batteries are fully charged in the first place.

If this type of situation occurs again, either fit a low current trickle charger or a small solar panel.

Or a day or so before you leave, fully charge both batteries and then remove the negative lead off both batteries. While this is not ideal, it will leave the batteries in a better state for when you get home.

[Tombie]

Hi Tim and sorry mate but you can not leave any lead acid battery for 14 weeks without some sort of maintenance charging while you are away.

Even 4 weeks weeks would be the limit and that’s providing the batteries are fully charged in the first place.

If this type of situation occurs again, either fit a low current trickle charger or a small solar panel.

Or a day or so before you leave, fully charge both batteries and then remove the negative lead off both batteries. While this is not idea, it will leave the batteries in a better state when you get home.

Only viable if vehicle is in a secure facility.
Otherwise you cannot lock the vehicle.


14 weeks would definitely have the car flatten the main battery - maximum I’ve seen before it won’t start is around 2.5 weeks.

I have a small solar panel on my roof to maintain the vehicle when parked up for this exact reason.

[taffy]

I have Anderson plugs at both front and rear of our l320. With the traxide system it is easy to connect battery charger to either and keep batteries fully charged. I use these to plug into my caravan as well to keep all fully charged when camping with caravan solar and charger.

[BradC]

Only viable if vehicle is in a secure facility.
Otherwise you cannot lock the vehicle.

Before leaving : Bonnet up, lock vehicle, disconnect battery, close bonnet.
On return : Key unlock passenger side door, bonnet up, reconnect battery, close bonnet.

[scarry]

Before leaving : Bonnet up, lock vehicle, disconnect battery, close bonnet.
On return : Key unlock passenger side door, bonnet up, reconnect battery, close bonnet.

Don’t some bridge out bonnet switch,problem fixed for good?

IMHO not really needed anyway.

[BradC]

Don’t some bridge out bonnet switch,problem fixed for good?

IMHO not really needed anyway.

Regardless, it's irrelevant in this scenario. All that happens is when you lock with the bonnet up the horn honks once. It still locks all the doors.
Disconnect the battery and close the bonnet. Job done.

Before you do that it'd be a good idea to check that your passenger side key lock actually works. Most seem to lie unused until they are needed by which time they're frozen solid.

Another option is to power the car up through the white 12S socket and unlock with the remote, but without a battery connected you'll need a solid power supply >= 10A to get the thing to boot. Last time I tried to charge a flat battery with a 5A power supply, the boot up current of all the ECUs was such it kept pulling the voltage down causing a boot loop. Had to disconnect the battery to get a float onto it.

[Tombie]

Before leaving : Bonnet up, lock vehicle, disconnect battery, close bonnet.
On return : Key unlock passenger side door, bonnet up, reconnect battery, close bonnet.

You tried this?

Vehicle wont lock if bonnet sensor isnt bypassed.... I tried....

[BradC]

You tried this?

Vehicle wont lock if bonnet sensor isnt bypassed.... I tried....

Yeah, I do it all the time when I'm doing work that takes more than a day.
Must be a D4 thing, probably something to do with the missing dipstick. On the D3 all locks activate. It just complains with a "beep" that something has been left open.

[John_D4]

My D4 won’t lock with the bonnet/a door open either

[scarry]

You tried this?

Vehicle wont lock if bonnet sensor isnt bypassed.... I tried....

Yes, i thought so,but the D4 isnt here to try,just running off a not real flash memory.[biggrin]

Maybe some models are different spec?

Yes,i think i tried once with dipstick out,didnt make any difference,unfortunately.[tonguewink]

[BMKal]

Don't know if it applies to Land Rovers, but some cars suffer from "short dipstick" syndrome. [bigsad]

My wife's car (a bloody Toyota) occasionally requires a longer dipstick to reach the engine oil. I've been searching the interweb to see if anyone provides a telescopic dipstick. :wasntme:

[Tin Lizzy]

If that is the case I believe it should have isolated your cranking from your aux battery very much earlier than if you had left it in the recommended 'shared' mode.

Your aux battery was probably being propped up by your cranking battery (hence self discharged when isolated for such a long time) and your cranking battery is always running some systems even while parked up for 14 weeks. Result - 2 flat batteries, nothing to do with the BMS I think.

Simple logic…..I think Traxide is in the clear. Death by disuse sadly 😔

[Tin Lizzy]

Hi Tim and sorry mate, but you can not leave any lead acid battery for 14 weeks without some sort of maintenance charging while you are away.

Even 4 weeks weeks would be the limit and that’s providing the batteries are fully charged in the first place.

If this type of situation occurs again, either fit a low current trickle charger or a small solar panel.

Or a day or so before you leave, fully charge both batteries and then remove the negative lead off both batteries. While this is not ideal, it will leave the batteries in a better state for when you get home.

Thanks for the info….not being critical of your system. Tombie has set me straight on that. I know the sleeping battery is frequently wakened by the electronics when it’s trying to sleep. Just wondering what the minimum solar panel size you would pick to maintain the batteries? I only have a 5W panel in my shed and no access to power for charger. Also can I connect the solar to the rear anderson? Oh, one more…. If I disconnect the negative leads, do I have to carry out a hard reset when reconnecting? Thanks in advance 😬

[trout1105]

Have you considered leaving the D4 at home on trickle charge and getting a lift/taxi to the airport next time you have to do an extended stint?

[drivesafe]

Thanks for the info….not being critical of your system. Tombie has set me straight on that. I know the sleeping battery is frequently wakened by the electronics when it’s trying to sleep. Just wondering what the minimum solar panel size you would pick to maintain the batteries? I only have a 5W panel in my shed and no access to power for charger. Also can I connect the solar to the rear anderson? Oh, one more…. If I disconnect the negative leads, do I have to carry out a hard reset when reconnecting? Thanks in advance 😬

Hi again Tin, and last question first.

If you disconnect your batteries and leave them that way for more than say 30 minutes, when you reconnect you will actually be carrying out a Hard Reset.

The reason for a Hard Reset is that modern electric devices fitted with what is known as Volatile Memory, this is memory that is lost when power is removed, but requires a TOTAL loss of power to clear the memory.

All modern electronic devices have massive spike suppressing capacitors fitted and these, by their intended use, can carry a charge for some time after the power to that device is removed.

While these suppression capacitors have some charge, they will keep the data in the Volatile Memory.

With a standard Hard Reset, where you hold the positive ( + ) and negative ( - ) leads together, you are causing a rapid discharge of these capacitors, and that all you are doing.

Because these suppression capacitors are rapidly and totally discharged, any data in the Volatile Memory is cleared.

When you disconnect the battery leads and leave them for some time, the suppression capacitors will self-discharge, again, and once fully discharged, all data in the Volatile memory will be cleared.

So after all that time you batteries have been disconnected, the volatile memory will be well and truely cleared.


Next and while a 5 watt solar panel will work, up to a 20 watt panel would be better.

And when you are leaving your vehicle unused for a period of time, best to set the switch on your In-Cab module towards the LED.

This will mean the isolator will turn off when the sun is not shining and will only turn on once the sun is up and the solar panel is providing a charge.


SPECIAL NOTE. If your USI-160 isolator is more than 10 months old, you will need to connect your solar to the cranking battery or you will only charge the auxiliary battery off the rear Anderson plug.


If the USI-160 is less than 10 months old, ( or is the new UST-175 ) then you can use the Anderson plug at the rear to charge both batteries.

Also note, all DT90 isolators and SC80 isolators with the Green and Red LED can use the rear Anderson plug to charge both batteries.

[Tin Lizzy]

Hi again Tin, and last question first.

If you disconnect your batteries and leave them that way for more than say 30 minutes, when you reconnect you will actually be carrying out a Hard Reset.

The reason for a Hard Reset is that modern electric devices fitted with what is known as Volatile Memory, this is memory that is lost when power is removed, but requires a TOTAL loss of power to clear the memory.

All modern electronic devices have massive spike suppressing capacitors fitted and these, by their intended use, can carry a charge for some time after the power to that device is removed.

While these suppression capacitors have some charge, they will keep the data in the Volatile Memory.

With a standard Hard Reset, where you hold the positive ( + ) and negative ( - ) leads together, you are causing a rapid discharge of these capacitors, and that all you are doing.

Because these suppression capacitors are rapidly and totally discharged, any data in the Volatile Memory is cleared.

When you disconnect the battery leads and leave them for some time, the suppression capacitors will self-discharge, again, and once fully discharged, all data in the Volatile memory will be cleared.

So after all that time you batteries have been disconnected, the volatile memory will be well and truely cleared.


Next and while a 5 watt solar panel will work, up to a 20 watt panel would be better.

And when you are leaving your vehicle unused for a period of time, best to set the switch on your In-Cab module towards the LED.

This will mean the isolator will turn off when the sun is not shining and will only turn on once the sun is up and the solar panel is providing a charge.


SPECIAL NOTE. If your USI-160 isolator is more than 10 months old, you will need to connect your solar to the cranking battery or you will only charge the auxiliary battery off the rear Anderson plug.


If the USI-160 is less than 10 months old, ( or is the new UST-175 ) then you can use the Anderson plug at the rear to charge both batteries.

Also note, all DT90 isolators and SC80 isolators with the Green and Red LED can use the rear Anderson plug to charge both batteries.


Thanks for the comprehensive response Tim. Now I understand fully why the hard reset is needed, and will upgrade my solar for future events. One final thing if I may…..I run two auxiliary batteries - front one is an Optima yellowtop 70amphr and rear is a 120a century AGM. I have seen it suggested that it is bad to mix battery types or capacities together in your system…. I’ve had a few seemingly premature failed batteries over the years but all else seems ok.

[drivesafe]

Thanks for the comprehensive response Tim. Now I understand fully why the hard reset is needed, and will upgrade my solar for future events. One final thing if I may…..I run two auxiliary batteries - front one is an Optima yellowtop 70amphr and rear is a 120a century AGM. I have seen it suggested that it is bad to mix battery types or capacities together in your system…. I’ve had a few seemingly premature failed batteries over the years but all else seems ok.
This is not the case when ( 1 ) charging with an alternator and ( 2 ) when batteries are in parallel.

You can have any mix of battery types and when charged by an alternator, all the batteries will actually charge independently of each other.

If you were charging batteries in a series setup, then yes the batteries MUST BE as close to identical as possible, and this is where the misunderstanding comes when talking about batteries in parallel setups.

For the last 18+ months I have been running a flooded/wet cell cranking battery in parallel with a lithium auxiliary battery and it works perfectly, but this is in a VW Tiguan which has had the SMART alternator function disabled.

In your Land Rover, where the SMART alternator function can not be turned off, you can not add a lithium battery to the setup, but again, you can have any mix of different types and sizes of lead acid batteries ( AGM, Gell or flooded/wet cell ) connected in parallel and all the batteries will charge properly, DEPENDING ON DRIVING HABITS.