Solar controller to first battery

[bensolomon]

I hope everyone is well. I will be adding a single 300 watt solar panel with one mppt controller. I have three batteries that are all wired directly to the battery charger. Can I connect the charger controller to the first battery, and will the charge be distributed to the other two batteries? I also have a xantrex battery bank monitor.

Thank you,
Ben

[smac999]

if the 3 batteries are in the same bank then yes. if they are not connected (ie one is house and one is engine) then it will not charge all.

the neg of the solar controller needs to be on the load side of the battery monitor shunt, not to the battery.

[bensolomon]

Smac,

Thanks for your reply. Two are house, one is engine. How could I get all three to charge? I should place the negative from the charge controller on the load side of the shunt, not the negative side?

Thanks,
Ben

[Chotu]

Ben,

The only way to get it to charge the starting battery is to use an “echo charger”

Battery Chargers | Auxiliary Battery Charger | Xantrex

Otherwise it’ll only charge your house batteries.

Yes, negative from your charge controller must go on the load side of the shunt in your negative wiring so the xantrax monitor can keep count of the power you’re putting back into the batteries through solar.

[goboatingnow]

I connect all my charge sources directly to my biggest and heaviest used bank , my domestics , this includes my alternator , mppt solar and battery charger. No splitters or charge combiners , everything reading the one battery voltage.

I then use a dc to dc battery charger to charge my least used battery , my starter.

[bensolomon]

Thanks Chotu for the echo charger solution. Goboating, thank you for the information. I think for my application, in my simple, little boat, the echo will work best.

Thanks, again, everybody!

[smac999]

How do you cutrently charge both banks from the engine? Do you need to put the switch to both while running?

If not. You may already have an echo charger or acr.

[Boatyarddog]

Originally Posted by bensolomon

I hope everyone is well. I will be adding a single 300 watt solar panel with one mppt controller. I have three batteries that are all wired directly to the battery charger. Can I connect the charger controller to the fist battery, and will the charge be distributed to the other two batteries? I also have a xantrex battery bank monitor.

Thank you,
Ben

We run our 200wt. Panel to our B1, then use the Battery switch to connect the two.
Working fine! I think it's called equalization.
SV Cloud Duster

[stormalong]

Echocharger is a brand name. There are many companies making automatic charge relays (ACRs). As already said, put the solar output to your house bank and hook up an ACR between the house bank and the engine start battery.

An ACR joins the batteries when the voltage rises to the point that indicates charging is happening and disconnects when the charging source goes away. With an ACR you do not need a multiple output battery charger nor is there a need to mess with a off-1-both-2 battery switch. A battery switch requires you to be attentive and remember to select both and then remember to de-select when not charging. If left in the both position the stronger battery will be continuously be discharging into the weaker battery, just wasting power. An ACR is your best choice.

If you have three independent batteries may I suggest that you combine the two house batteries into a single bank (permanently parallel them). Don't do this until you replace the batteries so that the two batteries are the same age and share the same charge/discharge history. By making one bigger bank in place of two the depth of discharge will be lower and the batteries will last longer.

PS. I like Yandina ACRs, mainly because mine is now 20 years old and still working. They also have a lifetime warranty. No connection with them - just a satisfied customer.

[bensolomon]

Smac,

They all go to the battery charger. There is a cross connect panel that isolates the engine battery.

Storm,

I have considered joining the two house batteries. up until now, haven't been brave enough to dive into the DC system because everything works. Has a side note, all my batteries are brand new last year period replaced all three at the same time so the age factor won't be an issue and they're all identical AGM batteries.

[CassidyNZ]

Originally Posted by Boatyarddog

We run our 200wt. Panel to our B1, then use the Battery switch to connect the two.
Working fine! I think it's called equalization.
SV Cloud Duster

That’s what I do too. My solar array is connected directly to the positive and negative buses. When I leave the boat, the 1-2-Both switch is set to Both. That way both banks are charged. When I get to the boat next time, switch to bank 1, leaving bank 2 (emergency bank) fully charged. There will be outcries of “No, Wrong” but it has worked for me for years.

BTW, “equalisation” is a process of charging batteries at a much higher voltage than usual - my Xantrex charger goes up to 18v - for a short time. This apparently blows all evidence of sulphation off the plates? I have no idea why it’s called equalisation - perhaps because it renders all plates in a battery equal? But it’s not about simply connecting two banks together.

[Stu Jackson]

Originally Posted by bensolomon

Smac,

They all go to the battery charger. There is a cross connect panel that isolates the engine battery.

Storm,

I have considered joining the two house batteries. up until now, haven't been brave enough to dive into the DC system because everything works. Has a side note, all my batteries are brand new last year period replaced all three at the same time so the age factor won't be an issue and they're all identical AGM batteries.

You may be interested in these links from this master link:

Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html


********************************
OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4....html#msg30101

1-2-B Considerations (New 2020 - Rodd finally got around to diagramming what I had done in the above link in 2009 )
https://marinehowto.com/1-2-both-bat...onsiderations/

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowner...d.php?t=137615

This is a newer primer for boat system wiring design with a thorough digram: Building a Good Foundation (October 2016)
http://forums.sailboatowners.com/ind.../#post-1332240


What are ACRs, Combiners & Echo Chargers? (by Maine Sail) [scroll to the top]
http://forums.catalina.sailboatowner...d.php?p=742417 and http://c34.org/bbs/index.php/topic,9....html#msg70131

Making Sense of Automatic Charging Relays (2019)
https://marinehowto.com/automatic-charging-relays/

[stormalong]

Here is something that I wrote a few months ago on the topic of the off-1-both-2 battery switch.


https://www.cruisersforum.com/forums...ml#post3131717

[bensolomon]

Stu and Storm,

Thank you very much!!!

[Stu Jackson]

Here's some more thoughts:


IS IT BETTER TO HAVE ONE OR TWO BATTERY BANKS FOR HOUSE USE?
(By Nigel Calder - I DIDN’T write this!!!)

The popular arrangement of having two house banks alternated in use needs scrutiny before I go any further.

LIFE CYCLES: As we have seen, the life expectancy of a battery in cycling service is directly related to the depth to which it is discharged at each cycle - the greater the depth of discharge, the shorter the battery’s life.

This relationship between depth of discharge and battery life is NOT linear. As the depth of discharge increases, a battery’s life expectancy is disproportionately shortened. A given battery may cycle through 10% of its capacity 2,000 times, 50% of its capacity 300 times and 100% of its capacity around 100 times.

Let’s say, for arguments sake, that a boat has two 200-ah battery banks, alternated from day to day, with a daily load of 80 Ah. Each bank will be discharged by 40% (80 Ah of one of the two 200 Ah banks) of its capacity before being recharged. The batteries will fail after 380 cycles, which is 760 days (since each is used every other day). If the two banks had been wired in parallel, to make a single 400 Ah battery bank, this bank would have been discharged by 20% of capacity every day, with a life expectancy of 800 days, a 5% increase in life expectancy using exactly the same batteries!

But now let’s double the capacity of the batteries, so that the boat has either two 400 Ah banks, or a single 800 Ah bank, but with the same 80 Ah daily load. The two separate banks will be cycling through 20% of capacity every other day, resulting in a total life expectancy of 1,600 days. Doubling the size of the battery banks in relation to the load has produced a 210% increase in life expectancy. The single 800 Ah bank will be cycling through 10% of capacity every day, resulting in a life expectancy of 2,000 days - a 25% increase in life expectancy over the two (400 Ah) banks, and a 250% increase in life expectancy over the single 400 Ah battery bank!

There are two immediate conclusions to be drawn from these figures:

1. For a given total battery capacity, wiring the (house) batteries into a single high capacity bank, rather than having them divided into two alternating banks, will result in a longer overall life expectancy for the batteries.

2. All other things being equal, any increase in the overall capacity of a battery bank will produce a disproportionate increase in its life expectancy (through reducing the depth of discharge at each cycle).

FOR BATTERY LONGEVITY, A SINGLE LARGE (HOUSE) BANK, THE LARGER THE BETTER, IS PREFERABLE TO DIVIDED (HOUSE) BANKS.