Crank battery drain

Submitted: Sunday, Jun 21, 2020 at 09:12
ThreadID: 140170 Views:1428 Replies:10 FollowUps:13
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We have a merc sprinter ex Ambo (smart Alternator) the house battery is charged through redarc bc/dc charger from alternator when driving, combined 320w solar when free camping or ctek when on power. However if we sit still either free camp or on power crank battery drains in approx 3 weeks, battery is 12 mths old, and has been tested by Racq and local batteries as not faulty, have been to 3 auto electricians and our regular euro mechanic but cannon overcome issue, and suggestions welcome
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Reply By: Mick O - Sunday, Jun 21, 2020 at 09:57

Sunday, Jun 21, 2020 at 09:57
It sounds like there is a parasitic drain somewhere. Have you used a multimetre to test what is being drained from the battery when stationary?

The problem with ambulances and emergency vehicles in general is the amount of accessory wiring going to all manner of stuff. You would need to start running down individual connections and identify splices into the wiring looms.

A couple of thoughts. Is the vehicle alarmed and did it have a positioning system fitted in particular. Those use the mobile network so if the phone subscription was discontinued at the time of sale but the unit not removed or disconnected, the unit will still be polling for available networks and causes a big drain.
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Reply By: HKB Electronics - Sunday, Jun 21, 2020 at 09:59

Sunday, Jun 21, 2020 at 09:59
Assuming the cranker is 100Ah that works out to around 200mA draw on the battery over 3 weeks to completely flatten it.

Depending on what is connected to the battery there might not be anything wrong, it is not uncommon with many new vehicles to flatten the battery in that period of time due to standby current drawn by the many electronic devices installed in the vehicle.

Might also be a good idea to look for any un-standed devices that may have been left in the Ambulance like trackers etc.
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Follow Up By: Member - mechpete - Monday, Jun 22, 2020 at 12:11

Monday, Jun 22, 2020 at 12:11
the vehicle tracking system is in the radio system by GPS
not in the vehicle
cheers mechpete
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Follow Up By: HKB Electronics - Monday, Jun 22, 2020 at 14:39

Monday, Jun 22, 2020 at 14:39
It may have a tracker installed in the vehicle somewhere, could possibly have a data modem too,
don't know what they put in Ambulances though.
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Reply By: RMD - Sunday, Jun 21, 2020 at 10:38

Sunday, Jun 21, 2020 at 10:38
18
Exactly what is the definition of FLAT? Is it flat, ie practically nothing or not quite enough to crank AND hold sufficient voltage while doing so to enable the ECU to provide injector pulses?

I have a DC DC unit and it sucks a small standby current from the main battery to stay awake ready for the main to begin increasing and then using charge voltage/current. I presume yours does as well.
The ECU and other standard items draw a small ma current too. Then there is the items Mick suggested may be still there in the background. So after 3 weeks what is the state of the battery in real terms. Most vehicles will be a bit slow or very reluctant after 3 weeks of standing. Many people return home after a few weeks away and find their town car battery has depleted to no crank stage and then gone further into discharge and stuffed the battery. Personally I would NEVER leave a battery on a circuit without some form of maintenance charging system attached if leaving for that period or longer. Do you really have a battery discharge problem? It should not be difficult to provide a small solar reg to assist the crank battery OR when on power a plug pack which dispenses 12v or a bit more and a few milliamps to keep the crank battery in top order.
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Reply By: noggins - Sunday, Jun 21, 2020 at 10:38

Sunday, Jun 21, 2020 at 10:38
Best option for the modern vehicle that can be parked up for weeks at a time is to fit a battery switch.
Looking at my Ranger's workshop book they suggest disconnecting the battery if parked up for 3 weeks or more.
So it's not something new that the vehicle itself is a parasite draw on the battery.
Of course you could fit a small solar that connects independently to the vehicle battery similar to this
that would keep the prime battery charged.
https://www.ebay.com.au/itm/20W-12V-MONO-SOLAR-PANEL-REGULATOR-TRICKLE-BATTERY-CHARGER-RV-AGM-Complete-Kit/351927999144?hash=item51f08b1aa8:g:p8IAAOSw2zNcueW7

Or a 1/ 2 step controller so when the camper battery is charged it would divert the charge to the vehicle battery.
Similar to this
https://www.facebook.com/groups/mandurahbuyandsell/permalink/4034322306579700/?sale_post_id=4034322306579700.

I will admit I'm selling this one.
I had it on my Ranger when I was away camping and not starting the ute for a few weeks at a time.
All power was fed in by 160W solar on the canopy and 2x120Ah batteries just running an Engel and 3 LED lights, so excess power was fed into the Ranger's battery.

Ron
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Follow Up By: Mark C9 - Monday, Jun 22, 2020 at 08:13

Monday, Jun 22, 2020 at 08:13
Had the same with my bt50.
Returned from a few mths OS and it was flat as a tack
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Follow Up By: Pepper - Monday, Jun 22, 2020 at 11:13

Monday, Jun 22, 2020 at 11:13
Ron cannot open your post on mandura buy and sell ,can you provide details or link to the half step controller ?
Thankyou.
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Reply By: Erad - Sunday, Jun 21, 2020 at 11:20

Sunday, Jun 21, 2020 at 11:20
You can try to trace the parasitic drain by measuring the current draw and isolating individual circuits. Start by removing all fuses, then re-inserting them one at a time. Remember that there may be a time delay on some circuits eg cabin lights which may stay in for a few minutes. Once you identify the circuit with the current draw, you then have to assess whether it is a legitimate current draw, or a leakage. That is when the fun begins...
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Reply By: Hoyks - Sunday, Jun 21, 2020 at 12:54

Sunday, Jun 21, 2020 at 12:54
How are the chargers hooked up?

Is the DCDC wired into the ignition circuit, or just links the batteries when the voltage gets above a preset voltage?

You might consider hooking the solar and Ctek up to the starter battery so it keeps it at peak charge and then the DCDC can do it's thing keeping the house batteries charged. If input is cut off for any reason, then the house batteries may get run down, but the starter should still be good.
Of just have an extra Anderson plug hooked up to the starter battery and plug the solar panel or the Ctek in for a couple of hours each week.

I have a newish BT50 and the parasitic drain on that will see me not being able to start it after 2-3 weeks, even with a brand new battery and no one opening doors or anything. Only accessories are a dash cam and a UHF that's turned off. ECU's and the clock always need a tiny bit of power and are enough to drain a battery if left long enough.
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Reply By: Member - McLaren3030 - Sunday, Jun 21, 2020 at 17:15

Sunday, Jun 21, 2020 at 17:15
Hi 18,

You have not said if your “house” lights are connected to your “house batteries”. If they are not, then they will be running off your cranking battery. If you are using your interior lights for any length of time each night, then that may be the cause of your battery drain.

Macca.
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Follow Up By: Gronk - Sunday, Jun 21, 2020 at 17:57

Sunday, Jun 21, 2020 at 17:57
Yep, unless the car has been rewired for this, I'd say you are on the money.

My 200 series will last for approx 5 weeks if I go away overseas, but when camping for longer than 2 days, I'll be very wary of using ANYTHING in the 4wd. Seen so many people camping with just a normal car and they think it's cool to have the music cranking for 3 or 4 hrs. Then they are hunting around next morning for jumper leads!!
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Follow Up By: RMD - Sunday, Jun 21, 2020 at 19:01

Sunday, Jun 21, 2020 at 19:01
Macca
That assumes the rig is permanently connected for the 3 weeks it takes to allegedly flat the crank battery. Do caravan plugs in this day and age really run the lights in the van?
If there is such a connection while running wouldn't it be best to have such power supply switched off while engine is stopped, is normal .
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Follow Up By: Hoyks - Sunday, Jun 21, 2020 at 20:18

Sunday, Jun 21, 2020 at 20:18
Its an ex ambulance RMD.
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Follow Up By: Frank P (NSW) - Sunday, Jun 21, 2020 at 21:31

Sunday, Jun 21, 2020 at 21:31
RMD,
I'm not sure if we're on the same page here, but the ciggy sockets in my 2014 BT50 are live even when key is out and the vehicle locked with the fob.

Cannot think why it's designed that way, but it is.
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Follow Up By: RMD - Sunday, Jun 21, 2020 at 22:22

Sunday, Jun 21, 2020 at 22:22
Maybe I am not quite understanding the OP message , but it seems for the van to run the batteries down as Macca suggested, and it has a DC DC unit charging the van batteries, then the charge is going to the van batteries through a wire and through a heavy wire setup from via a heavy to the DCDC and same aux van batteries.

Frank, I know some vehicle do have live ciggy sockets didn't specifically know BT50 did that. Other Mazda models don't though.

Hoyks
Yes an ex ambulance so anything is possible. Probably doesn't have a complete wiring diagram on the inside of rear door.
For a moment there I didn't realize someone was sitting in a Sprinter for 3 weeks in the one spot without a Caravan, just the vehicle.
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Follow Up By: Member - McLaren3030 - Tuesday, Jun 23, 2020 at 19:54

Tuesday, Jun 23, 2020 at 19:54
RMD,

It is an ex Ambulance, not a caravan. Ambulances do not normally have secondary deep cell batteries, so the internal lights are most likely powered by the cranking battery as any other car/vehicle would be. If the vehicle cranking battery is not connected to the solar panels, then when it is sitting still for a few weeks without the engine recharging the cranking battery, then it is quite likely the internal lights will drain the battery.

If I understand the OP, only the deep cell battery I’d connected to the DC/DC charger, and the solar panels.

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Reply By: Member - DOZER - Sunday, Jun 21, 2020 at 19:41

Sunday, Jun 21, 2020 at 19:41
I have similar and have noticed that the aux battery and main will drop together, today the aux was 12.3 and the main was 12.3, dc-dc was on float, but supposedly isnt charging till it gets voltage from accessories circuit of main system. Lights are always on whilst batteries are connected to the charger. This has never happened previous to my car getting 3 months to a tank of fuel.
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Reply By: Allan B (Sunshine Coast) - Monday, Jun 22, 2020 at 09:41

Monday, Jun 22, 2020 at 09:41
.
Hi 18,

When vehicles such as the Sprinter are converted to ambulances, extra lights are added and for convenience some of these are simply connected to the original wiring loom. Hence they are supplied from the original cranking battery. This is not a problem for an operational ambulance as they do not spend long periods with the engine shut down, however if camped for a number of days and using those lights, the cranking battery will become discharged.

An easy way to check for this is to disconnect the main negative connection from the crank battery then try using lights. Any that now do NOT work must be have been supplied from the crank battery and should not be used with the motor off for lengthy periods. It may only be one or two lights but that would be enough to flatten the battery.

To overcome the problem, any such lights should not be used for camping or should be re-wired to the 'house' battery.
Cheers
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Follow Up By: Member - mechpete - Monday, Jun 22, 2020 at 12:20

Monday, Jun 22, 2020 at 12:20
every thing non MBenz oem
is run off the aux battery under the bonnet
cheers mechpete
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Follow Up By: Allan B (Sunshine Coast) - Monday, Jun 22, 2020 at 13:21

Monday, Jun 22, 2020 at 13:21
.
Mechpete,
In Victoria maybe, but not in my Queensland experience.
I found two internal lights powered from the existing OEM loom in my mate's ex-ambo Sprinter.
I was called upon when a shorted lamp holder took out the fuse.
All other additions were from the aux battery.

Cheers
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Reply By: LIFE MEMBER-snailbait - Thursday, Jul 09, 2020 at 12:02

Thursday, Jul 09, 2020 at 12:02
All Modern Vehicles with ECU will flatten the Starter Bat within 3 weeks so 2 thing can be done put on a slow 2 amp charger or fit a bat switch this also goes for your Caravan or camper trailer bateries
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Follow Up By: Allan B (Sunshine Coast) - Thursday, Jul 09, 2020 at 13:23

Thursday, Jul 09, 2020 at 13:23
.
There is some risk in using a "battery switch" on the crank battery, in that suspending supply to devices such as radios will cause loss of any programming. Not a disaster perhaps, but inconvenient.
Cheers
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