[chuckg5]

i'm installing a new 150 watt solar panel on a 42' Vagabond. i'm wondering where the voltage goes when the batteries have been fully charged. The control box had a third outlet next to the panel inputs and battery output. it looks tobe a lite bulb. Now, question is, does a load go on this + an - post, like a lite bulb or 'water heater element' or can this be let alone with no load.
i do not want to boil off water in the batteries, killing them.

 

[newhaul]

You don't have to add a load to it. The controlled will stop charging the batteries when they are up however why not add a water heater dump load to use the amps you are making after the batteries are full charged

 

[mbianka]

i'm installing a new 150 watt solar panel on a 42' Vagabond. i'm wondering where the voltage goes when the batteries have been fully charged. The control box had a third outlet next to the panel inputs and battery output. it looks tobe a lite bulb. Now, question is, does a load go on this + an - post, like a lite bulb or 'water heater element' or can this be let alone with no load.
i do not want to boil off water in the batteries, killing them.

The controller will stop automatically charging the batteries when they are fully charged. The load connections are there for you to use or not to power things on board if you want. I use those connections to power my two Engel Refrigerators, Fan, computer and cockpit light. My controller disconnects the load if the battery voltage gets to low and also has protection from short circuits. Saves on the need to run wires back to the breaker panel.
THE BIANKA LOG BLOG: ANOTHER ELECTRICAL PROJECT UPGRADE PART ONE

 

[chuckg5]

thanks, newhaul and mb.
just don't want to destroy battery bank

 

[hellosailor]

Chuck-
Buy a solar charging regulator. It will cut off the charging power to the batteries once they get properly full for the right time. Do this manually, and eventually it won't get done when it should be.

 

[chuckg5]

sailor
thanks, i have a 10watt pmt controller now and am getting 20amp mppt custom shipped from China via amazon prime in about a month of it sailing over the pacific ocean. so i'm good

 

[hellosailor]

Chuck-
Just be careful with that Chinese mppt controller, there have been reports that come of them are in fact not mppt controllers at all. "Trust but verify" and check that it is actually doing that job.

 

[chuckg5]

its going to take a month for that to get to me. How do I verify it is a mppt controller? is there a test

 

[hellosailor]

First I'd open it up to see if there are any ICs or any sign that it is more than just an overvoltage cut-off. But the real test would be with a multimeter while it is under load. Test the input and the output, see if it is really converting excess voltage into extra amperage. (i.e. if the solar panels are putting out 16V @ 2A when charging the battery, is the MPPT controller turning that into a proper 14.4 volts (or less) at a higher amperage?

And I throw that out with totally fictional numbers, not to be used except as a very general guide of concept.

If the MPPT controller isn't boosting charging amperage though, it isn't being "MPPT". Assuming the panels are putting out power and the battery wants to eat more of it. Some controllers will maximize amperage while just "leading" the battery voltage by a small amount, like 1/2 to 1 volt. Others will aim for a target voltage, like 14.4 for the bulk charge regardless of battery voltage, and then add amperage. I'm sure there are even more options and complication.(G)

 

[Skipper Jer]

Its the concern over the MPPT charger that is holding me back from ordering a solar panel charger system. I've been looking at this one Rogue Power Technologies - MPT-2024 20A MPPT Charge Controller . Haven't found any thing bad about it.

 

[kjretlaw]

I have RPT MPT2024 20A MPPT and it works great, cost a few dollars more but built to last and fully programmable. I connected it to the laptop so I could determine if parallel or series was most efficient for my 2 90W panels. Series worked better for me.
Now the bad new Rouge has stopped making the 30A and will soon cancel production of the 20A as well. Why? because no one wants to pay for quality. Made in China is 1/2 the price. It's a shame, they will continue to support all of the controllers sold though.

 

[hellosailor]

Rogue's web site has the "news" that as of Nov.2013 the 20A model is just now available for orders.

Uh...maybe it is just me but when a business is 18 months behind the times on posting news on their web site, and says something that they've just discontinued is available for ordering...I can think of many reasons that company might be problematic.

Business is business. It doesn't matter if your design is the best on earth, if you want to be in business and stay in business, you've got to take care of business.

 

[Skipper Jer]

That is sad news about Rouge. Thanks for the comments.

 

[newhaul]

Chuck I just noticed you are installing a single 150 watt panel it really won't make a difference for your charging weather you use a pwm or mppt controller now when you add more panels and wire them in series it would make a significant difference

 

[newhaul]

Maine sail said it best small array big battery use pwm big array use a mppt controller

 

[chuckg5]

newhaul
thanks for the tip. i'll consider that. reading everything on the subject always states mmtp is more efficent but i usually agree with what MaineSail says, he's always been a good learning tool

 

[newhaul]

Chuck here's the thread that answers so many questions http://www.sailnet.com/forums/electrical-systems/180506-mppt-vs-pwm-solar-charge-controller.html

 

[chuckg5]

Wow, Newhaul
lot of good information. now i know, that i don't know if my two panels ( 50watt) the other 100watt should be in pareall or series. I did learn to cancel my order for the chinees mppt controller and buy a good renolgy 20amp for $115 on amazon. i also know i should spell better than this

 

[newhaul]

Cancel and just spend 300 bucks and call it good Complete Kit 200 Watt 200W Mono Solar Panel 12V 24V RV Boat Off Grid | eBay

 

[IStream]

I have RPT MPT2024 20A MPPT and it works great, cost a few dollars more but built to last and fully programmable. I connected it to the laptop so I could determine if parallel or series was most efficient for my 2 90W panels. Series worked better for me.
Now the bad new Rouge has stopped making the 30A and will soon cancel production of the 20A as well. Why? because no one wants to pay for quality. Made in China is 1/2 the price. It's a shame, they will continue to support all of the controllers sold though.

People will pay for quality in a niche market like boat solar so I wouldn't be so quick to blame cheap Chinese competition. Rogue's also up against Morningstar, Midnite, Outback, and other US-based suppliers of premium-priced quality gear.