question

andyjturner avatar image

Dc to dc charger draining starter battery ??

Hi all..

Hope someone may be able to shed some light on this one.

So I am using an Victron 12-12-18a isolated DC to DC charger.

This is how I have wired it :

- Positive from starter battery to input positive on Victron
- Negative from earth point under seat to negative input on Victron
- Positive output of Victron to positive of leisure battery
- Negative output of Victron to negative of leisure battery

Then from the leisure battery :

- Positive to the positive of a 12 way 12v distribution board
- Negative from rear earth stud (drivers side rear quarter) to negative of 12 way 12v distribution board

The issue :

- When on a camp site for 2 or 3 days on mains hook up (there is a battery charger under the seat, charging the leisure battery), the starter battery is losing voltage to the point where I can't start the van ??


Is this being caused by the DC to DC wiring / vsr or maybe something else.

Your help would be much appreciated - I am completely lost !

Thanks,

Andy....

dc dc converters
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8 Answers
ddickov avatar image
ddickov answered ·

Hi Andy

I checked the wiring diagram for this and would need to double check you have thick enough cables etc, I would guess the following,

Starter battery needs wired in parallel with the Lesuire battery somewhere along the line as the Lesuire battery is charged from ac in source but the dc to dc I think would isolate charging to this battery only when the alternator is running thus not charging the starter battery anything on board that is wired to the starter battery ignition cigarette lighter etc will drain the starter battery because it is isolated in the system if that makes sense, wiring them in parallel would allow them to constantly charge each other provided they are comparable chemistry and similar voltage as when connection is made will reduce spark risk also, this is just a guess what it maybe is, if the batteries are same chemistry the theory could be proved by connecting two jump leads matching plus and minus for parallel, I would disconnect the inverter and all other systems until it’s done then power it all back up.

They also have two modes power supply mode and charger mode, could I ask what unit you have for shore power hookup is it a victron product as the unit mentioned only charges with the engine running to the starter battery, does your shore power hookup go directly to the Lesuire battery charger? And then that powers the inverter? If so then wiring them in parallel would charge them both from the charger thus eliminating a flat starter battery at the same time


if you have a wiring diagram that would help a lot also, they are available online from victron also


Hope it helps a bit thanks David

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Check the settings of the Orion with VictronConnect.
With the default settings the Orion should only work if the engine is running.

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alanr avatar image
alanr answered ·

I seem to have this problem too,

I have the wire bridge in , and think every now and then the unit is turning on the blue tooth , which draws current from the starter battery,

at the weekend I'm going to change the wiring , and remove the wire bridge , and have the unit turn on by the key ,

I hope this will keep the blue tooth off

I will let you know next week if this worked



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kevgermany avatar image
kevgermany answered ·

Just wondering about smart alternator settings that may keep the Orion running adter switch off. If this is the case check manual for details and add connection to switch with ignition switch.


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alanr avatar image
alanr answered ·

the charging side is off, I can see that on the smart shunt on the house bank,

I will be checking to see how much current the charger is using when in stand by, and when it turns on its blue tooth, this might not be a lot, but over 3 or 4 weeks with the engine not run , will add up,

can I wire the charger to my starter battery switch , so I can turn it off completely, it will mean 4.5 meters of expensive wire,

and will the charge be ok when I turn the start battery switch back on?

the charger will still be connected to the house bank, will it still know they are lithium?

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kevgermany avatar image
kevgermany answered ·

The on/off wiring of the Orion is low current, so no heavy expensive wiring needed.

You should wire into a switched connection in the fuse box. An obvious one is the radio/on off if you cannot find a spare unused one. Another is an aux marked wire/terminal.

When the Orion is off, there should be no current.

For long periods, there are inexpensive battery to battery trickle chargers. Assuming your house battery is permanently charging from AC or solar, this may be an option to maintain the starter battery. The votronic one I fitted trickle charges the starter from the house bank. It requires 'charge' voltage on the house bank before it kicks in, won't flatten the house or starter battery.


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alanr avatar image
alanr answered ·

My setup is on a boat moored in the middle of a river , no shore power.

Ihave solar charging the house bank.

so it looks like I have bought the wrong thing.

should have bought a smarter charger that can charge both ways to over come the current it uses in stand by ,

2 comments
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@alanr Look at the votronic. It's inexpensive, German, seems to be reliable.

There are not many bi-directional dc/dc chargers.
alanr avatar image
alanr answered ·

I found my problem ,

you can,t use the smart shunt to monitor the sarter battery , if you have long ground leads on the 2 battery banks , or an isolated system ,

the smart shunt needs another ground lead for the starter battery, to give a correct reading ,

I have now disconnected the smart shunt starter battery sense wire from the starter battery, as it is of no use .

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