ACR or DC to DC charger?

[er9]

Originally Posted by wingssail

Well of course. Almost everyone wants to let the little blackboxes take care of their battery charging and I don't expect to change anyone's view.

I just have to keep putting my opinions about simplicity and self reliance out there, if for no other reason that to let some people know they CAN think outside of the box.

By the way, I know that your wish for automated boat tending, with an App, from around the world, was tongue in cheek, but think about the implication, would you really rather have an automatic boat sailing by itself while you sit on your couch? Why not just give up the boat and watch You tube videos?

I totally agree i am a huge fan of keeping things KISS simple, redundant and bulletproof. i believe that having a boat that is setup in a way that you describe is the preferred method.

that being said the electrical part of boat ownership is something i really enjoy geeking out on. even though im still very much a student and learning as much as i can, i have the fun task of having and being able to redo the entire electrical system aboard to my liking.

as much as ive been able to learn so far from people a lot smarter than me, the way im planning to redo my electrical, i believe is the preferred and most robust way to do it. the 1-2-B switch will still be there but only as an on/off switch or to switch to the backup bank if the house bank has a problem. and on top of all that i will know every single inch of every wire aboard so if there is a problem far offshore i will be in a much, much better position to deal with it.

im glad that these forums exist and people like yourself continue to offer differing points of view. iv'e had more than a few arguments with other members but in the end always learned something i believe. Cruiser forums are a fantastic resource.

and you can absolutely guarantee i will definately NOT be watching some lame you-tubers getting fat on my couch. im gonna have four automated drones following my automated boat so i can watch it from multiple angles on my plasma tv while i eat pop tarts on my Lazy Boy...jeesh...

[er9]

Originally Posted by mvweebles

I recently rewired my boat for long term cruising. Went with LFP for house bank and AGM for engine start, generator start, and bow thruster/windlass. Frankly, did not make financial sense to go LFP for point loads, and LFP is not particularly good for engine start as the BMS is typically programmed to throttle CCA. And then there is the cost differential.

I went with a DC-DC charger between them. I have dual Balmar alternators charging for about 200 amps rating, plus ACRs between the AGM banks to isolate the engine start battery. As A64pilot said, this is for underway - using a multi-bank battery charger has two issues. First, it requires an AC input (shore power or generator). Second, not all muti-bank chargers are created the same. From memory, the good ones are worth the extra money as they truly isolate the batteries. But it is a steep premium.

Peter.

interesting...and to be honest its not something i really need anyways but was a thought. it seems like a better option to just send all charging sources to a single bus that feeds the main bank anyways. and its unlikely im going to have a generator aboard.

[er9]

Originally Posted by a64pilot

I’m nearly certain that my Sterling Pro Charge Ultra has three charge outputs, I’m also nearly certain that they in fact are really just three wires with diodes connected to a single output, the only thing they add to a single output is the diodes.
It will not push more power to a higher discharged bank or any of that, the bank if an LA bank will do that automatically, thats how lead acid banks work, the lower the SOC, the greater current it will accept.

So most chargers with multiple charge points, aren’t really what a lot of people think they are. The diode prevents a discharged bank from discharging a more highly charged bank when the charger is off, other than that it’s just one charger.

so the diodes are basically an electronic check valve? an ACR/VSR works in a similar fashion correct? it will only let current flow in a single direction if i understand them correctly?

[Dockhead]

Originally Posted by er9

I dont like that arrangement. That's what I have now and it's a pain to manage. I'd prefer to automate it and not have to think about. I'm sure it will be way more efficient than me at managing the charging schedule. When I get to the boat all I'll have to do is turn on the power and it's all taken care of. Now if I could just get a phone app to do it all from half way around the world and deliver my boat remotely, fully automated...

I grew up with 1-2-Both-Off switches and I don't like them. No matter how careful you are, one day you will forget and leave it in the wrong position.



And I certainly wouldn't use it to combine batteries of different chemistries. Nor would I use an ACR -- you would fry your start batt putting it through all the same absorption charge cycles the house bank goes through. If you must share a single alternator, I think the B2B is probably the right way to do it, although it's kind of overkill for something so simple as a single start batt. Probably the right architecture is to connect the alternator and all other charge sources to the start batt, leave alternator unregulated. Then B2B from start to house. That way you get your proper 3 stage charging for the house bank.



I don't think you need solar on your start batt, and even a mains battery charger is optional. The main thing is the alternator should be charging the start batt. A separate trickle charger for mains power would be all you need for the start batt, and that only for cases where you spend long periods at the dock between running the engine.



What I have on my boat is an altogether different solution, radically simplified -- total separation of start and house banks with no connection between them at all. All it requires is a second alternator and a second separate battery charger. My house and start banks aren't even the same voltage -- 24v and 12v respectively. This means a fault of whatever type in one system, can't affect the other system, and there are no additional points of failure introduced with interconnection devices like B2B, ACR, etc.

[Cpt Mark]

Originally Posted by a64pilot

I’m nearly certain that my Sterling Pro Charge Ultra has three charge outputs, I’m also nearly certain that they in fact are really just three wires with diodes connected to a single output, the only thing they add to a single output is the diodes.
It will not push more power to a higher discharged bank or any of that, the bank if an LA bank will do that automatically, thats how lead acid banks work, the lower the SOC, the greater current it will accept.

So most chargers with multiple charge points, aren’t really what a lot of people think they are. The diode prevents a discharged bank from discharging a more highly charged bank when the charger is off, other than that it’s just one charger.

I too have the Sterling unit with 3 outputs. Each output can be programmed for the chemistry of the particular batteries and then there is one program that you can define any way you'd like.

[roland stockham]

If you can get an open LA for the start battery that would be good as the higher charge rate may use some water so being able to top up means the batter should last longer. 14.4 will not do it any harm and it will drop to 13.8 one the house bank is charged.

[mitiempo]

Originally Posted by er9

so the diodes are basically an electronic check valve? an ACR/VSR works in a similar fashion correct? it will only let current flow in a single direction if i understand them correctly?

No, ACRs are bi-directional. No diodes are involved, just a solenoid activated by voltage.

[mitiempo]

Originally Posted by Cpt Mark

I too have the Sterling unit with 3 outputs. Each output can be programmed for the chemistry of the particular batteries and then there is one program that you can define any way you'd like.

Not according to Sterling. There is an optional Battery Chemistry Module that is designed for just that though.

https://cdn.shopify.com/s/files/1/06...22295855460459

The Promariner PronauticP is the same charger as the Sterling.

[a64pilot]

Originally Posted by er9

so the diodes are basically an electronic check valve? an ACR/VSR works in a similar fashion correct? it will only let current flow in a single direction if i understand them correctly?

No, an ACR is just a switch, nothing more, it is however an automatic switch.
Personally I think a separate start battery is silly, no need for one, but that wasn’t the question posed, the question posed is charger or ACR.
Charger is “better” but ACR is certainly acceptable and cheaper.

[Maine Sail]

er9,

I would urge you to read this article. It helps demystify the numerous myths (many of which have been brought up in this thread) surrounding ACR/VSR/Combiners and shows you how to do a correct installation for a cruising boat. Also remember that the ACR will work with any and all charging sources not just your alternator.

https://marinehowto.com/automatic-charging-relays/








.

[mitiempo]

Originally Posted by a64pilot

No, an ACR is just a switch, nothing more, it is however an automatic switch.
Personally I think a separate start battery is silly, no need for one, but that wasn’t the question posed, the question posed is charger or ACR.
Charger is “better” but ACR is certainly acceptable and cheaper.

A charger isn't really better.
Remember a charger exposes both batteries to the same voltage. If the house bank is in bulk at 14.4 volts the start battery is as well, often for hours if the house bank is down a lot. No different from an ACR.

[smac999]

Originally Posted by wingssail

Well, just for a simplicity point of view, I'd skip either the ACR or the DC-DC charger.

Just install a Off-1-both-2 battery switch. Hook the house battery to "1" and the engine battery to "2". You just leave that switch on "1" most of the time, and put it on "2" occasionally to make sure that battery is still charged.

Hook your charger (and alternator output, and solar output) to the load side of the switch and you can direct all charging to either batteries or both.

No extra electronics, no extra wiring.

BUT, you have to manage it yourself. No black boxes, no automation.

You can not switch charging circuits like that.

When you turn the switch off when it’s sunny. All your lights / loads stay on directly fed from solar. That means You screwed something up.

If you want to keep the 1-2 switch and control manualy. You still need to put all the chargers direct to battery. Pick one. If you want to charge both then stick it in all. To top them both up.

[Sailnav]

ACR = Automatic Charging Relay

In case anyone, like me, doesn't speak in TLAs (three-letter acronyms).

[Q Xopa]

Originally Posted by Cpt Mark

I too have the Sterling unit with 3 outputs. Each output can be programmed for the chemistry of the particular batteries and then there is one program that you can define any way you'd like.

Hmmm, you must have a different one to me. Mine works as A64 describes his with only one output program for all 3 output connections.

[Q Xopa]

Originally Posted by mitiempo

A charger isn't really better.
Remember a charger exposes both batteries to the same voltage. If the house bank is in bulk at 14.4 volts the start battery is as well, often for hours if the house bank is down a lot. No different from an ACR.

Hmm a 'charger'? There are many different 'chargers'.

If you are referring to a AC Pro charge, agreed.

But for example a B2B Charger, nope, disagree. In fact that is the purpose of B2Bs to charge batts of different chemistries and even in some examples different Voltages.