wiring solar output

[noelex 77]

Originally Posted by Don Lucas

It's one of those "non-diode" Victron isolators that isn't suppose to have any voltage drop across it.
.

If its a MOSFET "diode" isolator they still have a bit of voltage drop. When the battery is flat and the alternator is putting out the maximium amps is also when the there will be the most voltage drop in the alternator wiring. This means the solar regulator will reduce at the battery end when the battery is flattest and the alternator is running. It's not a big deal in the scheme of things but is another reson to wire them directly to the batteries as Maine Sail suggests.

Even with two house banks you will normally be rarely disconecting the input. The input needs to fused and ANL fuses are good for this. You can disconect the input by removing the ANL fuse (or simply sliding it off to side). This means the fuse block will also work as battery switch providing you can mount the fuses close to the batteries and they still accessible and providing it only very rarely needs disconecting.

[sailorboy1]

the isolator seems to be side tracking replies, think of it instead as just a 1/2/off/both switch instead because that is really what the circuit is as far as the house batteries are concerned (all the isolator does is prevent the start battery from supplying the house bank)

[MarkJ]

Don! How do you manage to stuff up something so simple into something so complicated?

The solar panels go into the batteries directly. With a SMALL detour through any controller.

Remember you dont NEED a controller, so consider it an adjunct.


You will never finish the boat and get cruising if you mamby-pamby around with twaddle.
Think of all the rum in the Caribbean and you up there in snow country. Now consider this: the RUM IS RUNNING OUT! If you dont get here soon it will have all been drunk and so will we be.


Mark

[sailorboy1]

Originally Posted by MarkJ

Think of all the rum in the Caribbean and you up there in snow country. Now consider this: the RUM IS RUNNING OUT! If you dont get here soon it will have all been drunk and so will we be.


Mark

The rum better not be running out! Even an Aussie shouldn't be able to drink that much!

[sailorchic34]

In the oh good lord I'm doing something like Don category, I set my boat up with two house banks each about 10' from each other. Mainly as there was not a single spot to put all four batteries near each other.

So I have mine solar panels run via controller / or bypass (in case the controller dies) to a 20 amp DC breaker on the dc panel buss, From there I have #4 for 2' to the battery switch which has 2/0 back to the batteries. I don't have a start battery.

I find that two deep cycle batteries are fine to supply the start current to the dinky diesel. When your on the hook the solar controller is not really needed, unless the panels need MPPT or you have too many panels.

[Gerrycooper56]

So, being a little stupid, how do wire up solar panels to 2 battery banks so that the solar panels charge to the lowest voltage bank?. You've been running all night on bank A, so come sun up you change over to bank B. With conventional wisdom you would attach the solar panel output (from charge controller) to the battery changeover switch output. The charge controller would then only charge the 'live' battery bank, in this case the fully charged one. Could you use a battery combiner so that the charging only goes to the lowest voltage?

[sailorchic34]

Me, I just leave the battery switched for the overnight set and about noon or 1 pm I switch over to the other set. I had thought to keep it simple and add another dpst switch so the output could go to the resting set, but during the day I've not needed to do that. But its an option I guess.

[btrayfors]

I'm not a big fan of having to remember to switch anything. Much better, IMHO, to have a setup which is totally automatic and doesn't require your attention whether morning, noon, night, at anchor, underway, etc.

Here's what you need:

1. ALL onboard charging sources (generator, solar panels, alternator, battery charger, etc.) go directly to the HOUSE BATTERY BANK, with an appropriate high AIC fuse or breaker located very close to the batteries;

2. an automatic voltage follower device (EchoCharge, DuoCharge, etc.) or other ACR connected between the house batteries and the start battery (in order to automatically keep the start battery topped off); and

3. for the solar panel(s), you need:

(a) a controller, wired directly to the house batteries, with a fuse and a simple on/off switch; and

(b) solar panel(s) wired to the controller, with a fuse and a simple on/off switch or breaker.

That's it. Use bigger cables than you think you need to reduce voltage drop way below 3%. Use only quality connectors, crimps, etc. Try to keep the solar panel circuit(s) separate from other circuits.

If you have the possibility of feeding an MPPT controller with more than the usual OC voltage of 17-21VDC -- either with a native high output panel or by wiring multiple panels in series -- then do so, and enjoy the extra power out to the batteries.

Wire your panels up this way and you'll enjoy many, many years of peak performance. Try to skimp on materials, double up on circuitry, etc., and you'll create a bunch of headaches, either now or somewhere down the road.

JMHO,

Bill

[sailorchic34]

Originally Posted by btrayfors

I'm not a big fan of having to remember to switch anything. Much better, IMHO, to have a setup which is totally automatic and doesn't require your attention whether morning, noon, night, at anchor, underway, etc.

Well agree that its easier your way, if you have the money. Being a poor sailor chic who spends most of her time at anchor and without a dedicated start battery, a simple switch works for me.

It also gets me in the habit of checking voltages a few times a day. So if things don't work I catch it sooner too. Also being simple means even I can fix it when it breaks... A big plus for the $500 cruiser... specially the blonde ones.

[Gerrycooper56]

Bill,
As I said, i'm a bit stupid - how does your suggestion work with 2 house banks which you want to keep seperate. My battery charger/inverter was a Xantrex Freedom 25 which could charge 2 banks independently - no problem. I suppose the next thing is to see if there are solar panel charge controllers which have 2 outputs like the Freedom charger

[Gerrycooper56]

ok, so I could install the Duo charge device between the 2 house batteries with the same result?

[btrayfors]

Originally Posted by Gerrycooper56

Bill,
As I said, i'm a bit stupid - how does your suggestion work with 2 house banks which you want to keep seperate. My battery charger/inverter was a Xantrex Freedom 25 which could charge 2 banks independently - no problem. I suppose the next thing is to see if there are solar panel charge controllers which have 2 outputs like the Freedom charger

Gerry,

You're not stupid at all. Lots of folks see these problems from different perspectives and different experience/situational conditions.

I guess my first question would be: why do you want to keep the two house banks separate? From just about any viewpoint, running all house batteries together as a single large bank makes more sense, in terms of simplicity, longevity (of the batteries), economics of charging, and reducing the possibility of user error.

Even if your house battery banks must be physically separated....as mine are....it still makes the most sense to run them in a combined state so as to have a single large house bank. Just leave the 1-2-ALL switch on "ALL" all the time :-)

Bill

[Gerrycooper56]

Bill,
Thanks. I had a situation where one battery bank suffered a cell failure in one of the AGM batteries. IAfter realising what was happening I switched over to the fully charged alternate bank. If the 2 had been connected all the time then I would have had both banks at less than ideal voltage. My charging system (without running diesel) was marginal at best with 3 x 80w panels and an AirX Marine. I suppose in the end, running the 2 banks seperately was a comfort thing - a fully charged backup.

[Dsanduril]

Originally Posted by Gerrycooper56

So, being a little stupid, how do wire up solar panels to 2 battery banks so that the solar panels charge to the lowest voltage bank?. You've been running all night on bank A, so come sun up you change over to bank B. With conventional wisdom you would attach the solar panel output (from charge controller) to the battery changeover switch output. The charge controller would then only charge the 'live' battery bank, in this case the fully charged one. Could you use a battery combiner so that the charging only goes to the lowest voltage?

That's a bad way to manage your batteries, lots of inefficiency.

Me, I just leave the battery switched for the overnight set and about noon or 1 pm I switch over to the other set.

The best way to go.

When you charge and then discharge a LA battery you lose about 15%. Easiest way to think of this, you put the electricity in at ~13.8V (anywhere from 13.x to 14.4) and you take it out at ~12.6 (12.0 to maybe 12.8). Since amps are actually a count of the electrons you move around you can only pull out the same number of amp hours as you put in, but at a lower voltage, which means you lose the 13.8/12.6 (or about 10%, LA batteries average 15% loss).

On the other hand, if you run your equipment at higher voltage (the solar charging voltage) most of it will take fewer amps. Your fridge, most types of lighting, radios, all will take the same amount of power, which means lower amp draw. So, if you can use the solar electricity directly without sending it into the batteries and then back out you will gain a huge amount of power. The only way to do that is to not draw down on one bank while charging the other. You need to be on the same bank as you are using to allow the equipment a chance to get at that electricity before it goes into the battery.

[FlyingCloud1937]

Originally Posted by Gerrycooper56

Bill,
Thanks. I had a situation where one battery bank suffered a cell failure in one of the AGM batteries. IAfter realising what was happening I switched over to the fully charged alternate bank. If the 2 had been connected all the time then I would have had both banks at less than ideal voltage. My charging system (without running diesel) was marginal at best with 3 x 80w panels and an AirX Marine. I suppose in the end, running the 2 banks seperately was a comfort thing - a fully charged backup.

Or maybe if you were running one super bank then you wouldn't have a cell level failure.

If you did, then either by wire or by switch you could have taken the cell level bat that failed off line.

Power Design is about equal amounts of charge/Discharge, or/in other words charge cycle management.

It really isn't difficult.

Lloyd