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Old 25-09-2013, 21:47   #1
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Solar panels with MPPT controller and 2 battery banks

I have 2 solar panels connected to an MPPT controller and they are charging 1 battery bank just great. I want them to charge another battery bank at the same time. What are my options?

1) An A/B switch..not really at the same time, just when the switch is flipped
2) can i get a batter isolater involved and connect it on the output of the MPPT controller?\
3) ????

thanks
Kevins
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Old 25-09-2013, 22:15   #2
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Re: Solar panels with MPPT controller and 2 battery banks

What's the other battery bank for?

The Blue Sea ACR system is designed to bridge between two banks once charging voltage has been reached in one of them (12.7 for over two minutes, I think). Typically all of the charging sources (alternator, panels, wind, etc) go to the house bank, then an ACR sits between the house and the starting battery.
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Old 25-09-2013, 22:18   #3
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Re: Solar panels with MPPT controller and 2 battery banks

The link for the Blue Sea ACR. The reviews suggest it's got some problems, but I found the installation straightforward and it's been completely reliable for a couple (few?) years now.

BLUE SEA SYSTEMS Solenoid at West Marine
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Old 25-09-2013, 22:33   #4
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Re: Solar panels with MPPT controller and 2 battery banks

Another way to address this would be an echo charger, which is similar to the ACR mentioned above.

Basically, you charge Bank 1 to the desired float voltage, and Bank 2 then gets the excess.

You charge Bank 2, therefore, off the alternator when you motor, but reserve the ability to combine the banks if low to achieve an engine crank OR to "switch to 1" if Bank 2 needs service or is otherwise kaput.

I intend to have multiple charging sources and redirects to my house bank: solar, wind, alternator and, if necessary, genset charging. Everything goes to the house bank; if house bank is good within a preset range, juice goes to the start, and when it's at 95-100%, that is echo charged to a second deep cycle forward for the windlass. If my house and start banks fry or are damaged, I have that windlass battery as an "always-ready" backup.

There's combiners and isolators and switches, oh, my, but I'm heading for autonomy from shore power. Your situation may be far more simple.
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Old 26-09-2013, 06:55   #5
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Re: Solar panels with MPPT controller and 2 battery banks

The second bank (bank of 1 battery) is the starting battery. Actually there is a 3rd battery that needs charged as well, the windlass battery up front as S/V Alchemy has. I have not figured out how to charge that one yet other than the battery charger.

I have the setup with wind, solar and generator all charging the house. The start battery and the house are charged by the duo alternator of the engine.

I will look at the blue sea ACR as well as the echo charger.

If anyone knows, I want to charge my house to 14.8v and the secondary source to 14.4v...will either one do that?
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Old 26-09-2013, 07:55   #6
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Re: Solar panels with MPPT controller and 2 battery banks

The ACR won't; it's just a simple voltage based relay that closes a circuit. You could get clever and put a high amperage DC-DC voltage regulator in if you want to get creative but that stuff can add up to costs.

It's not the "best" way to charge what are generally always two different models of batteries (house and starter). My starter battery never needs water, and I think the damage to batteries comes from discharging them deeply rather than being off by 10% on the optimal float voltage (on a barely discharged battery). Just my own observations.

If you do go the ACR route, I suppose you could just have two. One to sit between house and starter, and the other between house and windlass.
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Old 26-09-2013, 08:04   #7
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Re: Solar panels with MPPT controller and 2 battery banks

First a question. How do you split your alternator charge between the three batteries?

The start battery gets very little drain, so the alternator will normally replace the AHs used quite quickly even if you don't motor much.
It's still not a bad idea to get the start battery up to 100% periodically with solar.

To do this I just use manually use the "combine switch" ( this also couples the batteries to start the engine using the house bank if needed).Simple and nothing to go break or fail ( the VSR do occasionally do this). It might not work for the forgetful type, but its a simple option to consider.

The windlass battery has a much heavier draw and I would recomend an automatic system for this.
I would use a VSR for this, other options are:

1.A smart VSR (like the ecocharger)
2.A zero loss splitter like the Sterling (pro split)
3.A battery to battery charger ( Sterling make one of these).
4.Using the solar regulator to throw a relay when certain conditions are met ( such as the hose battery on float)

3. Will charge the windlass battery better than the other options, but is the most expensive. 4. Can be a good option if you have a good solar regulator that will do this.
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Old 26-09-2013, 19:39   #8
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Re: Solar panels with MPPT controller and 2 battery banks

Currently the only way to charge the windlass is via a battery charger..ie shore power.
I am working on a way around that. But I have a design flaw. The wires that run 20ft to the windlass for charging are 8 AWG. so...I want to slow charge them, ie via solar.

I will use the alternator, it's a duo, to charge the house and start. Then the solar to charge the house and the windlass. I think i like the echocharger.

I think the windlass is used rarely when we move from place to place. If we stay somewhere for less than 2 days, then i might have to pull the chain in manually.

what do you think
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Old 27-09-2013, 09:57   #9
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Re: Solar panels with MPPT controller and 2 battery banks

That decision is between you and your lower back.

I will have a main "smart" charger for the house bank the rare time we use shore power. I will pull the current 40 amp charger for use forward with the windlass battery. This will give me the "slow charge" option via relatively small gauge wire runs from an echo charger, or a faster charge regime from either a second shore power cord, a portable genset or even from (noooooo!) the inverter.

Fact is, I have a manual/electric windlass and if I had to bail in that much of a hurry and for some reason had a flat battery (which is highly unlikely given my planned charging regimen), I would tie a float on my rode and dive on it in calmer conditions to retrieve it later. But that would have to be pretty extraordinary a situation. For me, the need to run 40-50 feet round trip of 8 AWG from the engine's alternators/battery banks to power a windlass is overkill. If you are hooked in well during a storm in an anchorage, you would likely keep the engine running to reduce shearing on the rode, not to try to haul chain aboard. You'd probably have a storm anchor out, too, to achieve that.
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Old 17-09-2017, 10:03   #10
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Re: Solar panels with MPPT controller and 2 battery banks

Quote:
Originally Posted by noelex 77 View Post
First a question. How do you split your alternator charge between the three batteries?

The start battery gets very little drain, so the alternator will normally replace the AHs used quite quickly even if you don't motor much.
It's still not a bad idea to get the start battery up to 100% periodically with solar.

To do this I just use manually use the "combine switch" ( this also couples the batteries to start the engine using the house bank if needed).Simple and nothing to go break or fail ( the VSR do occasionally do this). It might not work for the forgetful type, but its a simple option to consider.

The windlass battery has a much heavier draw and I would recomend an automatic system for this.
I would use a VSR for this, other options are:

1.A smart VSR (like the ecocharger)
2.A zero loss splitter like the Sterling (pro split)
3.A battery to battery charger ( Sterling make one of these).
4.Using the solar regulator to throw a relay when certain conditions are met ( such as the hose battery on float)

3. Will charge the windlass battery better than the other options, but is the most expensive. 4. Can be a good option if you have a good solar regulator that will do this.
This was an answer i have been looking for. I have asked in other thread if my three battery banks separated with battery isolation switches can be all charged at the same time with solar via mppt 75/15 which is plus connected on one extreme of three banks and negative to the other extreme. Sorry uf i dont make myself very clear. English not my language. I set my battery switch on 1 when starting engine on one bank, of course that would temporary stop solar charge. Does that cayse harm in any way?
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Old 17-09-2017, 10:23   #11
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Re: Solar panels with MPPT controller and 2 battery banks

To charge the windlass get a Zantrex echo charger. Ort balmar duo charger. Simular thing. Then it will charge from engine and sun. It's crazy not to have engine charging to windlass battery

Sounds like you already have a duo charger between the engine and house???? It might be going in the wrong direction though. (From start to house. Depending if your alt goes to start it house) Connect the alt to the house battery. And run thd duo charge from house to engine. And sure it's always on, not only with key on.
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Old 17-09-2017, 11:33   #12
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Re: Solar panels with MPPT controller and 2 battery banks

Quote:
Originally Posted by kevins View Post
The second bank (bank of 1 battery) is the starting battery. Actually there is a 3rd battery that needs charged as well, the windlass battery up front as S/V Alchemy has. I have not figured out how to charge that one yet other than the battery charger.

I have the setup with wind, solar and generator all charging the house. The start battery and the house are charged by the duo alternator of the engine.

I will look at the blue sea ACR as well as the echo charger.

If anyone knows, I want to charge my house to 14.8v and the secondary source to 14.4v...will either one do that?
Nothing will do that but DC-DC charger, Sterling or ProMariner make good powerful ones.

But most lead chemistries have some leeway, optimize for the big House bank, don't need to coddle Starter.

Windlass batt should be same chemistry as House, or even better combine the two, use a fat wire for distance.
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