Charge battery from invertor?

[MONA B]

We have a 1989 GB32 #821 with an alternator “problem” – the Lucas 70A is blowing the 10A fuse from the sense terminal to the house batteries on shutting down. It has been to the shop, rebuilt, works until next shutdown - believe it is the built in voltage regulator that is still failing. There is a diode in sense wire that we believe boosts output voltage to level required by AGM batteries.
We have wanted to upgrade the alternator to something like a Balmar with a separate voltage multi-stage regulator. We get 40A out of Lucas and would hope for a more and a better charge to the crucial HOUSE bank (3 X 4D AGM).
The ENG START (group 31 AGM) and GEN START (group 27 WET to match it’s alternator) are currently charged from Lucas through a Victron Argo Fet isolator.
On shore power (15-50A) a Victron Multiplus Compact supplies 80A multi-stage to HOUSE bank and 4A to ENG START. Includes a Victron Multi Control to work with 15/20A service.
On generator (50A) the Multiplus Compact provides same charging.

We have used a GENIUS 7.2A charger to top up all batteries during winter storage using direct wiring.

Our idea is to:
Replace Lucas with Balmar 70A
Install Balmar ARS-5 regulator to HOUSE bank only.
Install Balmar SG200 Monitor
Install a second Genius 7.2A from ship 110V panel on separate breakers (3 empty).
-one to ENG START GENIUS -one to GEN START GENIUS

When on shore power or generator, each bank would receive a multi-step charge configured to the batterie(s).
When cruising, the critical HOUSE bank would receive all charging. If ENG or GEN start needs a charge, 2000W inverter would provide 7.2A at 132W per Genius.
No extra switches or combiners required and some simple 110v wiring.
Realize that one shouldn't use a battery to charge a battery but this only occurs when Alternator running and if needed.
With thanks for any comments

 

[rslifkin]

You could do it, but I'd personally prefer using a DC battery to battery charger. Less parts involved and a bit more intended for that purpose.

But personally, I also like having the engine alternators go directly to the engine start batteries (unless there's more than 1 alternator per engine). To me, engine start power is safety-critical, while house power is only important. But I also have engines that require power to run, which makes that a slightly bigger concern than with an older mechanical diesel where power is only needed for starting.

On my setup, I used a pair of ACRs to handle charging underway. Each of my 2 engines charges its start battery and has an ACR to tie to the house bank. The ACRs are ignition-interlocked, so they can only engage when that side's engine is running. As soon as you turn the keys off, each engine's start battery is isolated from the house bank and only gets power from the 120v charger (shore power or generator running).

 

[MONA B]

Thanks for reply. We are also considering an ACR or BATTERY SWITCH or DC to DC solution but not sure if one will deliver a multi step charge to the ENGINE and GEN start batteries as far as we can see! When on shore power, we had gotten into the habit of just putting the NOCO GENIUS 7.2A manually onto the two start batteries (1 AGM 1 WET). We had thought of just installing the Balmar side and then see what current actually used by NORCO plugged into inverter.
Right now if we deplete the ENG START we can still parallel the house bank or start the gen.
No hurry on this as launch date on Georgian Bay keeps moving out!
Cheers Edward

 

[rslifkin]

Some of the battery to battery chargers will do a multi stage charge (rather than just following the voltage of the source bank), so that plus a multi stage alternator regulator would give you want you're looking for.

Personally, I haven't worried much about that. My alternators have single stage regulators on them and put out about 13.9 - 14 volts (varies a bit with engine room temperature, so somewhat based on outside temp, voltage goes up as temp drops). So the voltage isn't high enough to cook the batteries while running for a few hours. It's a bit above my normal float voltage, so it still produces a decent charge rate (although not as good as a higher voltage would). It's not necessarily ideal, but I've found it adequate.

 

[tiltrider1]

What you suggest will work fine. It is not efficient but works. ACR’s and removing the chargers from the inverter circuit would be more efficient. Running your alternator to your start battery is not any safer than running it to the house and having ACR’s and a combiner switch.

 

[DavidM]

Well, I have a little different take than my colleague above. I do like having the output of the high performance alternator connected directly to the main load, the house bank.

The only other idea I have is to use a combiner or ACR to connect the output of the alternator to the starting battery when the voltage rises above 13 or so. This automatically takes care of charging the starting battery and avoids the mickey mouse use of an inverter to power the shore charger.

Also go with the 100A Balmar but use the temperature probe to cut back current from the alternator when it gets too hot. 100A is about all you can handle with a 1/2" single belt. Your 3 4D bank probably is more than 400Ahs which keeps the maximum charging current down to 25% of battery capacity.

David

 

[Ventana]

David,
Why do you consider using an AC charger as a Mickey Mouse solution? There are obvious inefficiencies using DC power to make AC power to turn it back to DC power, but many of the boats on this forum have available power to cover it. The use of an ACR has become common, but a separate AC charger for each battery bank will provide a much better controlled charge to each battery.

Well, I have a little different take than my colleague above. I do like having the output of the high performance alternator connected directly to the main load, the house bank.

The only other idea I have is to use a combiner or ACR to connect the output of the alternator to the starting battery when the voltage rises above 13 or so. This automatically takes care of charging the starting battery and avoids the mickey mouse use of an inverter to power the shore charger.

Also go with the 100A Balmar but use the temperature probe to cut back current from the alternator when it gets too hot. 100A is about all you can handle with a 1/2" single belt. Your 3 4D bank probably is more than 400Ahs which keeps the maximum charging current down to 25% of battery capacity.

David

 

[O C Diver]

My boat is setup with a 24 volt bow thruster. To recharge the batteries, I use a 120 VAC multistage battery charger. It works either through the inverter, generator, or shore power. While it's not the most efficient, it works extremely well.

Ted

 

[DavidM]

David,
Why do you consider using an AC charger as a Mickey Mouse solution? There are obvious inefficiencies using DC power to make AC power to turn it back to DC power, but many of the boats on this forum have available power to cover it. The use of an ACR has become common, but a separate AC charger for each battery bank will provide a much better controlled charge to each battery.

As a last resort, well ok use the inverter to convert DC to AC and then through a shore power charger to convert AC to DC to charge the starting battery. But it does sound mickey mouse to me.

A $75 ACR or combiner would do this so much more simply and directly. It is what they are made for.

David

 

[Ventana]

As a last resort, well ok use the inverter to convert DC to AC and then through a shore power charger to convert AC to DC to charge the starting battery. But it does sound mickey mouse to me.

A $75 ACR or combiner would do this so much more simply and directly. It is what they are made for.

David

Not disagreeing, it is a pretty convoluted way to go. That said, I think I am heading down the path of multiple, small AC chargers running off of AC for our boat. The current system (ha) is pretty screwed up, and even though I have several new ACRs sitting in a box I think the AC chargers are a better solution for us.

 

[Insequent]

I am doing a bit of both. I use ACR's for the house bank and start batteries, which are all in the ER. Alternators to house bank first. I do think this is by far the preferred solution.

But my windlass & thruster bank is in the bow. During refit the yard set it up that this bank in the bow connected to a 70A charger, when on shore power. Underway, and at anchor, I had no way to charge the bow bank. So I used a portable car battery charger (10A max) to do it, occasionally. Subsequently I installed a battery monitor and became aware that the windlass & thruster were consuming very little Ah, even when out cruising and moving anchorages quite a bit. So I now very seldom do the 'mickey mouse' thing. But I'm glad to have the option, and can tolerate the inefficiency etc.

 

[O C Diver]

I am doing a bit of both. I use ACR's for the house bank and start batteries, which are all in the ER. Alternators to house bank first. I do think this is by far the preferred solution.

But my windlass & thruster bank is in the bow. During refit the yard set it up that this bank in the bow connected to a 70A charger, when on shore power. Underway, and at anchor, I had no way to charge the bow bank. So I used a portable car battery charger (10A max) to do it, occasionally. Subsequently I installed a battery monitor and became aware that the windlass & thruster were consuming very little Ah, even when out cruising and moving anchorages quite a bit. So I now very seldom do the 'mickey mouse' thing. But I'm glad to have the option, and can tolerate the inefficiency etc.

Yes, I did the math and concluded that the typical usage was typically under 1 AH and never more than 3 AH. As a result, a 6 amp battery charger works extremely well and the inverter hardly notices it running.

Ted

 

[C lectric]

. ********It has been to the shop, rebuilt, works until next shutdown - believe it is the built in voltage regulator that is still failing. *********8

Upon rebuild did they REPLACE the regulator.?

Maybe it is faulty.
There are rebuilds and there are rebuilds. Sometimes that refers to turning the slip rings and smoothing them as they do roughen from wear, replacing brushes, checking the windings that they are not shorted, replacing bearings, and checking the regulator.

Sometimes faults don't show up untill the unit has been run under a decent load for a while. Run in the open air or for a few minutes of testing in the shop may not get it warm enough to stress the regulator.

Maybe that is why the unit checks at the shop but when you use it, it does get hot. Engine heat is trapped in the engine compartment, proximity to a hot engine and the very act of producing power for an hour or a few hours get it over the goofup threshold.

Get them to replace the regulator.

The diode in the sense line should not be a cause of your problem. It will simply drop about 0.7V to the regulator so the regulator jacks up the voltage to the batteries to make up for the diode isolator that must be installed between the batteries and the alternator. VERY common modification to make up for the diode isolators.

Just a suggestion.