Victron Multipus and start batteries

[sowwaninii]

On our new Leopard 42 we have two start batteries and a house bank. We have a Victron Multiplus which charges the house bank while on shore power, but not the start batteries. I’ve been told the start batteries only charge via the engine alternators. I find it hard to believe that the start batteries can’t be connected to the Victron multiplus to facilitate their charging while on shore power, but have no clue how to wire them. The manual states there’s a trickle charge that can be run to a start battery, but not sure how to do this and whether it can be split to charge both batteries.

[cofc]

Is your house bank the same chemistry as the start batteries? Or do you have lithium for the house and lead acid or agm for the starts?

[sowwaninii]

All agm’s.

[rslifkin]

Personally, I just use a second (smaller and cheaper) multi-bank charger to charge the start batteries on my boat. The multiplus does have a 4a trickle charge output for a start battery, but it's only meant for 1 bank and I don't think it gives an independent charge cycle from the house bank like a separate charger would.

[more]

Originally Posted by sowwaninii

On our new Leopard 42 we have two start batteries and a house bank. We have a Victron Multiplus which charges the house bank while on shore power, but not the start batteries. I’ve been told the start batteries only charge via the engine alternators. I find it hard to believe that the start batteries can’t be connected to the Victron multiplus to facilitate their charging while on shore power, but have no clue how to wire them. The manual states there’s a trickle charge that can be run to a start battery, but not sure how to do this and whether it can be split to charge both batteries.

you don't need charge starter battery under 60-90 days after last time is full charged. simple forget and disconnect in winter

[CharlieJ]

The MultiPlus has a secondary charging port for charging starting batteries that provides 4A and follows the same algorithm as programmed for the house bank.

[BillKny]

Our boat has a separate start battery, charged only by the engine alternator. For twenty five years and two circumnavigations this system has worked perfectly.

If you are not sure how to wire the second battery charger output on the Victron, even after reading the manual, I would strongly suggest you hire someone qualified to do so. Advice here, especially on electrics, can vary from well informed to dangerously ignorant.

[chrisspeth]

Depends which Multiplus you have installed
the 3000 has a seperate small power output for the strzer batteries delivering 4A, which is more then enogh to keep your starter batteries going.
Check the installation manual of your unit
Regards Chris

[Dougtiff]

If ALL your batteries are AGM, put a battery combiner between the house bank and the starting batteries, simple and inexpensive, I've had this setup for year's.

[noelex 77]

Another option is to install one or two of the small chargers for the start batteries. Models are available from Victron, Sterling, Mastervolt, Ctek etc etc.

The advantage is redundancy, but also an independent charge algorithm. While in your case all the batteries are the same chemistry, they will not be at the same SOC and this is not usually taken into account by a single charger even when there are multiple outlets.

Chargers such as the excellent small Victron Blue Smart models are not expensive. These models can be hardwired to the start battery, but if the house battery charger fails they can be easily adapted to charge the house bank.

[wiekeith]

Originally Posted by sowwaninii

I’ve been told the start batteries only charge via the engine alternators.

I’m curious. If the alternators charge your start batteries, and presumably your house bank at the same time, there must be some connectivity between the batteries? Or maybe you have separate charge controllers that split the charge from the alternators between their respective start battery and house bank?

Edit: Unless, of course, your alternators don't actually charge your house bank.

[Dave Isom]

Speak to the organ grinder, not the monkey. ie ring Victron and get their advice.

[smac999]

How does the house bank charge from the engine?

[Stu Jackson]

Originally Posted by sowwaninii

On our new Leopard 42 we have two start batteries and a house bank. We have a Victron Multiplus which charges the house bank while on shore power, but not the start batteries. I’ve been told the start batteries only charge via the engine alternators. I find it hard to believe that the start batteries can’t be connected to the Victron multiplus to facilitate their charging while on shore power, but have no clue how to wire them. The manual states there’s a trickle charge that can be run to a start battery, but not sure how to do this and whether it can be split to charge both batteries.

I'm a bit confused. You used to have a 45 foot monohull and now have a new (to you) catamaran.

"I've been told" makes no sense. Can you not find out by tracing the wiring?

Connections to a charger from either a built in echo charger from the Victron or adding an ACR to the start batteries is a relatively simple task (routing notwithstanding). If a built in charger is available, it can be used to charge both individual batteries. The charger doesn't "Know" what its "end client" is - one or two batteries or where they are physically located.

Perhaps I am confusing what you wrote with my misunderstanding of your knowledge of basic electrical system design and management.

What is it you do not understand? Did a PO do something you don't understand.


Help us to help you in lieu of anyone suggesting that you spend more money on more equipment rather than use what you already have and just buy some wire.

[Dave Isom]

Right....the alternator first charges the start battery which should then be connected via a VSR ( voltage sensitive relay) to the house batteries. Once the start battery reaches 13.7 volts or thereabouts the VSR will allow the house batteries to charge. When the engine is off and you are using house batteries the VSR will isolate the house battery at about 12.8 volts and not allow the house to run the start battery down. A VSR will only work on standard alternators not smart alternators.