Shore power in dual battery setup

[The White Whale]

My current battery setup is a follows
- 3 lead acid battery banks (service, engine, anchor windlass)
- Alternator charges all 3 through battery isolator
- Victron centaur charges all 3 banks with shore power

New setup
- Convert service batter bank to AGM
- Alternator charges ONLY engine and windlass banks (still lead acid) through battery isolator
- Engine bank smart charges (now AGM) service bank through dc-dc victron orion
- Add solar panels that charges service bank through victron mppt

Here is my issue. The victron centaur which currently charges all 3 banks with shore power can only be configured for one type of battery bank, despite having 3 outputs.

One solution is to configure it for AGM and only charge the service bank with it and leave anchor and engine banks to be charged only by alternator. I’m afraid of these banks discharging when we are in port for long periods without running the engine.

A second solution is to configure for lead acid and charge anchor and engine banks and let current from engine battery flow into the service bank (via aforementioned dc-dc victron orion). But is it unhealthy for the engine battery to route all this current? (If not, i could even route the solar power through the engine bank to service bank in similar fashion).

If instead none of the above solutions work it sounds like i have to invest in a second dc-dc charger that can charge engine and anchor bank from service bank. Other options are however welcome.

Thanks!

[Cheyne]

I have ours setup so the Victron charger charges my house bank and a Victron 5 amp trickle charger for the starter batteries when we are on shore power.

Cheyne

[Rumrace]

Honestly Victron make so many products for many solutions. I wouldn’t give up my shore power but I don’t use it much. I have a generator,4 solar panels, shore power and the alternator all plugged into the same charger.
The charger on my power boat uses an ordinary 3 prong extension cord. Only 2 batteries to charge but the boats hydraulics and engine use a lot of juice. Again it gets plugged in to maintain the batteries as it spends lots on time on the trailer. No chance for a solar panel as it’s a wet boat zero clutter including no windscreen to smash your face in. The charger is a trinket I bought on Amazon. It’s junk would take days to actually charge 200amp more just keeps loss to zero.

[Grith]

Another solution is a small inverter connected to your AGM’s and a trickle charger plugged into this and connected to your starter battery which may be cheaper than another dc to dc charger depending on what stuff you already have.
My solar panels charge my lithium power pack with built in 240v inverter so I just occasionally plug in my trickle charger and connect it to my starter battery.

[Tupaia]

Why not replace all your batteries with AGM's they are more than capable of handling the start and windlass. Just set the charger to AGM.

[ranger58sb]

Originally Posted by The White Whale

Here is my issue. The victron centaur which currently charges all 3 banks with shore power can only be configured for one type of battery bank, despite having 3 outputs.

One solution is to configure it for AGM...

A second solution is to configure for lead acid...

Does your charger let you pick or set voltages, versus (or in addition to) battery type?

If so, you might be able to find a happy voltage combo that suits both your AGMs and your wet batteries... assuming you've checked each battery maker to learn their specific voltage recommendations.

Some AGMs are happy with charge/float voltages that are very near voltages recommended for some similarly-sized wet batteries.

And then as @Tupaia suggests, just making all three batteries AGMs could maybe be a lot easier than leaping through all those other hoops. Plus, dual purpose AGMs are pretty good in the engine start and windlass/thruster roles.

FWIW, one our previous boat, as I changed banks gradually, I was able to make one bank AGMs and set that charger for an AGM/wet (charger actually recommended the flooded setting for AGMs). When the wet batteries in other banks eventually wore down, I replaced with AGMs. No discernible ill effects along the way.

-Chris

[The White Whale]

Originally Posted by Tupaia

Why not replace all your batteries with AGM's they are more than capable of handling the start and windlass. Just set the charger to AGM.

Yeah, not a bad idea, I considered this. "Problem" is that to my understanding the alternator is not set up to charge AGMs so I would need to invest in a regulator between alternator and battery.

[The White Whale]

Originally Posted by ranger58sb

Does your charger let you pick or set voltages, versus (or in addition to) battery type?

If so, you might be able to find a happy voltage combo that suits both your AGMs and your wet batteries... assuming you've checked each battery maker to learn their specific voltage recommendations.

Some AGMs are happy with charge/float voltages that are very near voltages recommended for some similarly-sized wet batteries.

And then as @Tupaia suggests, just making all three batteries AGMs could maybe be a lot easier than leaping through all those other hoops. Plus, dual purpose AGMs are pretty good in the engine start and windlass/thruster roles.

FWIW, one our previous boat, as I changed banks gradually, I was able to make one bank AGMs and set that charger for an AGM/wet (charger actually recommended the flooded setting for AGMs). When the wet batteries in other banks eventually wore down, I replaced with AGMs. No discernible ill effects along the way.

-Chris

Unfortunately one can only select predefined charging modes (Lead acid, AGM and GEL I believe).

[The White Whale]

So just to follow up, what's the judgment in routing all current through the engine bank? Is it a no go?

[noelex 77]

Charging a flooded lead acid battery on AGM settings will charge the battery at a slower rate than could be achieved with the correct voltage set points and may slightly undercharge the batteries, but generally it will not do much harm.

The engine and anchor windlass batteries will not be subject to any discharge (apart from self discharge) while connected to shore power. The ideal voltage set points are lower than normal when a lead acid battery is kept in storage mode rather than the normal cyclic use. Therefore the slightly lower voltage set points used for the AGM setting may even be beneficial over the normal flooded settings, especially for chargers that do not automatically recognise and apply a storage algorithm (only a small number of modern chargers will do this). It will also minimise water usage which is helpful when the batteries are unattended.

I would use the AGM settings for your shore charger and charge all three battery banks this way. If you can occasionally (say every few months) apply a high voltage equalisation charge to the flooded lead acid batteries this would be beneficial, but with batteries such as start and anchor winch banks that spend much of their life at 100% SOC, the practical difference in battery life neglecting this step will be small .

[The White Whale]

Originally Posted by noelex 77

Charging a flooded lead acid battery on AGM settings will charge the battery at a slower rate than could be achieved with the correct voltage set points and may slightly undercharge the batteries, but generally it will not do much harm.

The engine and anchor windlass batteries will not be subject to any discharge (apart from self discharge) while connected to shore power. The ideal voltage set points are lower than normal when a lead acid battery is kept in storage mode rather than the normal cyclic use. Therefore the slightly lower voltage set points used for the AGM setting may even be beneficial over the normal flooded settings, especially for chargers that do not automatically recognise and apply a storage algorithm (only a small number of modern chargers will do this). It will also minimise water usage which is helpful when the batteries are unattended.

I would use the AGM settings for your shore charger and charge all three battery banks this way. If you can occasionally (say every few months) apply a high voltage equalisation charge to the flooded lead acid batteries this would be beneficial, but with batteries such as start and anchor winch banks that spend much of their life at 100% SOC, the practical difference in battery life neglecting this step will be small .

This makes a lot of sense. I'll strongly consider this approach, especially given that it works "out the box" with the new setup.

[ranger58sb]

Originally Posted by The White Whale

Yeah, not a bad idea, I considered this. "Problem" is that to my understanding the alternator is not set up to charge AGMs so I would need to invest in a regulator between alternator and battery.

Is that something specific to your particular alternators? I've not heard that before... and as far as our alternators went... they apparently couldn't tell the difference between battery types. If the bank SIZE gets too large, I guess that can be a thing... but for relatively small banks, especially for start batteries and windlass batteries that don't really get drained all that much... it wouldn't seem to be an issue. Unless your specific alternators say so, maybe...

Originally Posted by The White Whale

Unfortunately one can only select predefined charging modes (Lead acid, AGM and GEL I believe).

What Noelex said. Our charger manual -- for the one that only had two settings, FLA and Gel -- actually said to use the FLA setting for AGMs. Worked fine.

-Chris

[smac999]

Charge the windlass and engine. The house will charge via the Orion. From engine or shore.

No current is “routed through the engine battery”. It won’t even know.

A single 30a Orion is Likly too small for your alt and shore. Depends how big the alt is. You can run 2 in Parellel.

[The White Whale]

Originally Posted by smac999

Charge the windlass and engine. The house will charge via the Orion. From engine or shore.

No current is “routed through the engine battery”. It won’t even know.

A single 30a Orion is Likly too small for your alt and shore. Depends how big the alt is. You can run 2 in Parellel.

Max alternator output is 60 amps. Max battery charger (shore power) output is 30 amps. What would be the appropriate max output of the Orion(s). As I have understood, it can damage the alternator to draw too much current from it?

This solution would make easy to monitor power input as everything goes through the Bluetooth enabled Orion charger.

[The White Whale]

Originally Posted by ranger58sb

Is that something specific to your particular alternators? I've not heard that before... and as far as our alternators went... they apparently couldn't tell the difference between battery types. If the bank SIZE gets too large, I guess that can be a thing... but for relatively small banks, especially for start batteries and windlass batteries that don't really get drained all that much... it wouldn't seem to be an issue. Unless your specific alternators say so, maybe...




What Noelex said. Our charger manual -- for the one that only had two settings, FLA and Gel -- actually said to use the FLA setting for AGMs. Worked fine.

-Chris

My Hitachi 60amp alternator outputs 14,4 volts which to my understanding is too little for AGMs. However, as earlier noted in this thread, undercharging the starter and anchor bank might be acceptable as long as at least one source fully charges them at steady intervals.