3 Battery banks and 1 MPPT charge controller?

[hellosailor]

MPPT to the most important battery, presumably the house bank.

Then two echo chargers or West Marine (Yandina) Combiners which can be up to 150A rated, IIRC, to let the charge spill over to the other batteries after the primary battery is up to "full" voltage.

You could put two combiners on the house bank, which would charge both of the other two batteries once the house voltage came up. Or, you could prioritize by putting one combiner on the house bank, letting that cascade to the starter, and then putting the second combiner on the starting battery so the winch battery was the last one to join the party.

Probably will just depend on where your cabling is now.

But putting a 50A solar array on a 40A controller is just a bad idea. You WILL hit a sunny day, and that controller WILL fry, usually at the least convenient time. I'd want to make sure there was No Damn Way that could happen to me.

[MBLittle]

Originally Posted by hellosailor

But putting a 50A solar array on a 40A controller is just a bad idea. You WILL hit a sunny day, and that controller WILL fry, usually at the least convenient time. I'd want to make sure there was No Damn Way that could happen to me.

Why not just put a 40amp fuse between?

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[twinboat]

Just what I read on another site.

Morningstar MPPT controllers, could go over the max watts. You would have no gain, above the limit, but it wouldn`t fry.

Call Tracer to see what they say.

Update- According to Tracer, they have, solar array, over voltage and over current protection built in.

Another point is, the Cyrix i 100 and Yandina combiners are by-directional, where the Echo charger is one way.

If your charging sources are connected to different banks, you want two way combining.

Good luck

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[Ex-Calif]

Originally Posted by twinboat

Just what I read on another site.

Morningstar MPPT controllers, could go over the max watts. You would have no gain, above the limit, but it wouldn`t fry.

Call Tracer to see what they say.

Update- According to Tracer, they have, solar array, over voltage and over current protection built in.

Another point is, the Cyrix i 100 and Yandina combiners are by-directional, where the Echo charger is one way.

If your charging sources are connected to different banks, you want two way combining.

Good luck

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Nice post - thanks!

[sailorboy1]

I pretty much lost interest at the point of starting the project wrong. Are you going to undersize the wiring also?

[hellosailor]

Normally they're not fused at that point. And instead of frying the system, you'd just shut it down, on every sunny day. And then run out of fuses in short order.


Not an effective long-term solution.


Also, a 40A fuse WILL carry 50A for a surprising amount of time. (Varies with the fuse type, but you can look them up.) Probably long enough to allow damage to the other components.

[btrayfors]

Originally Posted by SailorGerry

I've used the Echo Charger but I prefer (and now use exclusively) the less expensive and more versatile Magnum Energy Smart Battery Combiner (ME-SBC). For about $110, you get 25 amps of charge power and the ability to adjust your set points… Smart Battery Combiner (ME-SBC) - Magnum Energy, Inc.

This is indeed a neat little device. It's perfect for some situations BUT, IMHO, is far too complicated for most cruising boats which just want to maintain a second battery -- usually a start battery.

The ME-SBC is a bi-directional battery combiner, while the EchoCharge is a uni-directional voltage-follower device. These are very different both in concept and in application.

The ME-SBC, when it combines, allows current to flow to or from either connected battery. In some situations, this results in very high current flow (in-rush current), as in the case of a fully charged start battery at, say, 12.8VDC being combined with a deeply discharged -- and much larger capacity -- house bank at, say, 12.2VDC. Not a desirable condition and one in which the ME-SBC has to take action to protect itself, either by cutting off completely or otherwise limiting current flow out of the start battery and into the house battery bank.

This cannot happen with the EchoCharge, as flow is in one direction ONLY -- from the house battery bank to the start battery.

There are several settings with the ME-SBC which are critical in getting things right. There are NO adjustable settings with the EchoCharge, which has only three wires to connect and no options.

Both are useful devices. However, I believe that the far simpler EchoCharge design is better for most folks and will do the trick of automatically maintaining and protecting a second battery without need for adjustment.

Bill

[socaldmax]

Originally Posted by hellosailor

But putting a 50A solar array on a 40A controller is just a bad idea. You WILL hit a sunny day, and that controller WILL fry, usually at the least convenient time. I'd want to make sure there was No Damn Way that could happen to me.

I'm going to have to respectfully disagree. First off, that isn't a 50 amp solar array. Rule of thumb, based on experience, is 300 watts = roughly 20 amps at 15v. You don't charge batteries at 12v, you charge them at 14.8-15v, so the correct amperage is about 40 amps.

I currently have a cheap 20 amp MPPT controller that's rated for a max of 300 w of solar, with a 410 watt array on it. It will produce up to 22 amps, then it self regulates. It's been over a year, and it still hasn't fried. I wouldn't normally recommend going 35% over rated amperage, but I wanted to test if for myself.

It produces more power for longer periods of teh day than a similar 300 watt array. Ideally, I think about 10% -15% over would be sufficient to get more power from a given rated controller, a "matched" setup. Rarely does one ever get rated power out of panels - maybe at noon in the summer. Most of the time, you're shaded, or it's cloudy, or the sun is low on the horizon, either because it's winter or close to dawn or dusk.

This only applies in cases where you have a certain size controller (like a 20 amp or 40 amp) and have a choice to go slightly under current or over current with your solar panels. Too high input voltage will kill a controller, but extra solar array current won't kill it, they just self regulate. For example, a guy buys a 20 amp controller and has a choice of buying 2 150 watt panels or 2 165 watt panels, I'd select the 165 watt panels because they won't overload the controller, they'll make more power all day long and produce closer to 20 amps than the 300 watt array all year round, all day long without the added expense of another controller. Often the price jump from a 20 amp controller to a 25 or 30 amp controller is disproportionate yet the price of larger solar panels can sometimes be even cheaper than smaller ones. I just recently bought 10 230 watt panels for $130 ea, brand new.

If he had 800 watts of panels, THEN I'd recommend spending the money for a 2nd controller and splitting up the array. My prediction is with his setup, 95% of the time, he won't even be making 40 amps, and that other 5% he'll be making 40 amps, not a problem.

JMHO, but it's based on experience. Right now, here in Socal, we're getting right at 20-21 amps out of 46 amp solar arrays (700 watts) at best because the sun is so low in the sky. This summer, I expect to see much closer to 46 amps out of them.

[socaldmax]

Originally Posted by Frugal

You may need to take into account that your 40 amp MPPT may suffice on nameplate 50 amps of panels. But on occasions I have had all panels producing maximum output and have nearby cumulus clouds adding reflected radiation. The output has exceeded the nameplate wattage. Suggest you break up your panels into two or three series with MPPT's on each. Safer redundancy and you could direct the outputs to either battery bank or all with heavy duty rotary switches.

All MPPT controller instruction manuals warn against connecting/disconnecting battery power with solar array power applied. You can interrupt solar array power first, then switch to another battery bank, but this will often result in the controller having to reset and auto detect system voltage, possibly having to re-enter some parameters.

It's far easier to charge the main bank then distribute power from there to other banks.

[SailorGerry]

Originally Posted by btrayfors

This is indeed a neat little device. It's perfect for some situations BUT, IMHO, is far too complicated for most cruising boats which just want to maintain a second battery -- usually a start battery.

The ME-SBC, when it combines, allows current to flow to or from either connected battery. In some situations, this results in very high current flow (in-rush current), as in the case of a fully charged start battery at, say, 12.8VDC being combined with a deeply discharged -- and much larger capacity -- house bank at, say, 12.2VDC. Not a desirable condition and one in which the ME-SBC has to take action to protect itself, either by cutting off completely or otherwise limiting current flow out of the start battery and into the house battery bank.

This cannot happen with the EchoCharge, as flow is in one direction ONLY -- from the house battery bank to the start battery.

Bill

Bill - I get your concern and like simple solutions as well. But that particular scenario is not possible with the ME-SBC, as it cannot be set to combine below 12.8 VDC.
Gerry

[ramblinrod]

First, why do you have 3 banks? Connect all your deep cycles into one bank, and they'll last longer.


Second, bad idea to run your charge controller at max. rating. If your panels produce more than rated, or the ambient temp of the controller is high it could fry.


If by 3 banks you mean a starter, windlass, and house bank, stop what you're doing. The starter battery gets charged by the alternator, and the windlass from an echo charger on the alternator. (Your engine is running, if you are using either, so their is no need to connect to solar.)


If you have a small alternator with internal regulator, don't even bother connecting it to your house bank with a diode isolator (it's OK to use a 1/2/ALL switch in ALL for emergencies, should your solar controller fry). If you have a high output alternator with an external regulator, use an Automatic Charging Relay (e.g. Blue Sea ACR) to connect the house bank to the alternator (and start battery) when the engine is running.

[Ex-Calif]

Originally Posted by ramblinrod

<snip>

If by 3 banks you mean a starter, windlass, and house bank, stop what you're doing. The starter battery gets charged by the alternator, and the windlass from an echo charger on the alternator. (Your engine is running, if you are using either, so their is no need to connect to solar.)

<snip>

No offense but I disagree.

If you come into an anchorage and have to drop and raise the hook a couple of times, there may not be sufficient engine run time to charge the windlass battery.

I'd run an echo charger to the windlass from the house side. The advantage over an ACR for this is that you can run smaller wires forward and mount all the windlass equipment up front.

I would run the alternator to the start battery side (no risk of having switches off with engine running) and I would run the house and starter on a 1-2-ALL switch with an ACR for redundancy - i.e. didn't run the engine long enough to charge the start batt. This would also be a good use for the aforementioned combiner as you could charge either way.

[mitiempo]

I would run all charge sources to the house bank. Either an ACR or Echo Charge between house and start battery. An ACR to windlass battery. If you ever have to re-set the anchor 2 or 3 times to get it to hold an Echo Charger will not pass enough current to the windlass battery. The ACR will. It will require larger cables to the windlass battery however.

My first choice would be house bank and start battery only, with appropriate cabling to the windlass. Less batteries to maintain or replace over time and a simpler system. You only buy the cables once but the windlass battery will need periodic replacement.

[MBLittle]

Originally Posted by sailorboy1

I pretty much lost interest at the point of starting the project wrong. Are you going to undersize the wiring also?

Then it looks like your input is no longer needed. Don't let the door hit ya

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[sailorboy1]

I wouldn't and will watch for the follow-up thread.