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Discussion Starter #1
Hi Folks,

I have four panels on my Spirit 28, installed by the previous owner. Now that the boat is on the hard, it's time to take a look and see what the heck it's all about.

I have four batteries, tied together in two groups. Each group was two batteries, positive to positive, negative to negative.
one set are "car size" marine batteries marked 110ah. The other pair are "double size", with no indication of amp-hours.

The "car size" don't hold a charge, when I pulled them yesterday I discovered they are VERY low on fluid .

Anyway.....
I never looked at the panels much, and wasn't even sure if they were putting anything out. I was busy enjoying my boat when I could, and fixing the big stuff (i.e. engine, sails, etc).

Here is my confusion, the four panels are paired. Each pair is connected to a small control box. Each control box connects in turn to one set of batteries. Those two control boxes are putting out 20v with 6.5-7 amps...... that seems like a lot. And, from what I have read 20v is way more than you want to use to charge a battery.

I would like to replace the control boxes with MPPT units. Do I need an MPPT unit for EACH panel/battery combination? Can I use one MPPT to run all four panels to all four batteries?

thanks
 

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I just bought a phocos pwm 8amp controller since the previous owner of my boat thought it wise to use lithium batteries and a direct link to the panels...the panel puts out around 19volts too...which is common unregulated...I dont know what size my panel is but its looks to be around 100 watts or so max.

mppt controllers are great but much more expensive they also do better with bigger banks and more loads and charge better and dont overcharge as much as shunt and basic pmw controllers...they also have a lower equalizing or floatong charge...which gives better pèak charging and wont fry batteries as much.

having said this I will be doing the same as you and rewiring my panel...

there also seems to be a lot of positive ground panels and chargers these days and I would like to know what most guys do in this situation....

make sure you fuse with at least twice the amperage as the controller allows...my 8 amp charger says it needs a 20amp fuse inline to the battery...

Ill let you know what I end up doing...

good luck!
 

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If you have 4-12V 6 celled batteries, two banks. Connecting them like this is no good. Will not charge evenly or discharge evenly. Unless you have a Battery Combiner. Better to use 6v batts and connect pos to neg.
 

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Discussion Starter #4
If you have 4-12V 6 celled batteries, and you say pos to neg then you have 24V system? Are you sure they are not three celled 6V batts?
Sorry - that's positive to positive, negative to negative. parallel connection.
 

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Discussion Starter #5
From what i'm reading it is possible to run one controller (MPPT) for multiple panels. I am guessing with two sets of batteries (switchable between the two sets, to keep house batteries and starting batteries separate for example), I should have two independent charging units, so that the whole systems are separate from each other?
Or would that matter?
 

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you want to avoid dissimilar sized and amped batteries in general...I would use 2 banks with 2 controllers since you have uneven banks...

unless you go new batteries gel or better you dont "need" the mor expensive mppt chargers but with big banks and stuff youll see 10% or more charge in same conditions...

cheers
 

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Discussion Starter #7
you want to avoid dissimilar sized and amped batteries in general...I would use 2 banks with 2 controllers since you have uneven banks...

unless you go new batteries gel or better you dont "need" the mor expensive mppt chargers but with big banks and stuff youll see 10% or more charge in same conditions...

cheers
thanks. Two might be the way to go.
Is it possible the two panels overcharged my smaller batteries, and dried them out?
 
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thats exactly what happened...The batteries I had were computer batteries backups or something they can be charged at a higher voltage...but the panel was direct...it lasted for a while apparently but not my cup o tee

I once left a brand new battery on those stupid westmarine solar maintainers that are only 5 watts or so for 6 months and sure enough because the voltage is unregulated it fried my battery even with such a minimal power output.

if yo are reusing your old batteries I would not pay extra for the mppt controllers YET...I would first buy a couple of basic pwm chargers at 25% over(amperage) your panels max output...then I would invest in a nice amp controller so you can see what your panels are actually putting out...you can also find parasitic losses this way if you hook it up to various sources.

then if yo want to add panels or battery banks you know exactly what you are dealing with...

I will be doing this next week or so...cables also play an important role...how much bigger than minimum spec, length, how close the charger is to the battery source, etc...all p`lay an important role
 
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Yeah, to second the above, MPPT controllers are for maximizing charge from the solar panels although they do also help the over voltage thing. You definitely need two controllers or there are controllers that connect to separate banks, such as this one

https://rvsolarstore.com/index.php?route=product/product&product_id=73

You might be able to get those two batteries back by refilling with distilled water and running a desulphating charger. I have had really good luck bringing back batteries that would no longer hold a charge with the battery minder chargers. Regular chargers weren't doing the trick. They have them as low as about $50 or so. They also have a solar charger that looks very interesting to me if I had room for bigger panels.

Batteryminders Specials | BatteryMinders.com
 

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Discussion Starter #10

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Hi Folks,

I have four panels on my Spirit 28, installed by the previous owner. Now that the boat is on the hard, it's time to take a look and see what the heck it's all about.

I have four batteries, tied together in two groups. Each group was two batteries, positive to positive, negative to negative.
one set are "car size" marine batteries marked 110ah. The other pair are "double size", with no indication of amp-hours.

The "car size" don't hold a charge, when I pulled them yesterday I discovered they are VERY low on fluid .

Anyway.....
I never looked at the panels much, and wasn't even sure if they were putting anything out. I was busy enjoying my boat when I could, and fixing the big stuff (i.e. engine, sails, etc).

Here is my confusion, the four panels are paired. Each pair is connected to a small control box. Each control box connects in turn to one set of batteries. Those two control boxes are putting out 20v with 6.5-7 amps...... that seems like a lot. And, from what I have read 20v is way more than you want to use to charge a battery.

I would like to replace the control boxes with MPPT units. Do I need an MPPT unit for EACH panel/battery combination? Can I use one MPPT to run all four panels to all four batteries?

thanks
You really need to look at all this as a system and address the issues you have.

#1 Your panels should all be charging one bank through a decent quality PWM or MPPT controller. Stick with KNOWN QUALITY brands such as Morningstar, Genasun, Blue Sky etc.. Stay away from Chinese eBayers.

#2 You need to pick a bank as house and one as start. The start bank needs only one small group 24 battery. There is no sense is carrying around any more "dead lead" than you already have. One large house bank charged by solar and if you want to add an automatic combiner or Echo Charger etc. to top up the start battery than you can do that too. Focus your solar on the bank that needs it most and that will be the house bank.

#3 Your panels will likely better wired in parallel rather than cut in half feeding two banks. Send all solar to the house bank.

#4 You need to know the models and specifications of each panel. If they are all the same than you could opt for MPPT. If they are different brands, voltages etc. then you'll do okay with PWM and the panels in parallel...

#5 If you want good performance the wires will need to be properly sized for the amperage and distance. You will also want a fuse at the house bank within 7" of the positive battery post.

#6 I would have all your batteries tested. Most auto-parts stores will do this for free. If they are toast invest in some new deep cycle batteries. One small group 24 for starting (can be a deep cycle) and 2 or more group group 27 or 31's in parallel (this sizing will depend on your house use). Alternatively, if you have the height, 6V golf cart batteries work extremely well as house batteries. Just wire them in-series for 12V...

If you can give us more information about the system such as batteries, battery switch, engine, solar panel wattage, current, brand, controller brand etc. etc...
 

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The biggest problem with those ebay ones would be reliability, they aren't made to resist rust or anything else. The good units will be essentially weatherproof and will last a lot longer, so yeah it is the basic 'you get what you pay for equation'. They will be better than what you have but would still be a little leary of them. Morningstar makes good products. I used to have a sunsaver that had an extra terminal for a wind turbine which I would hook up with a cheap 12v wall wart to add supplemental 12v ac charging. I would spend a couple extra bucks on a really good charge controller because batteris get really expensive and if it gives you a couple extra years it is very worth it.
 

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The biggest problem with those ebay ones would be reliability, they aren't made to resist rust or anything else. The good units will be essentially weatherproof and will last a lot longer, so yeah it is the basic 'you get what you pay for equation'. They will be better than what you have but would still be a little leary of them. Morningstar makes good products. I used to have a sunsaver that had an extra terminal for a wind turbine which I would hook up with a cheap 12v wall wart to add supplemental 12v ac charging. I would spend a couple extra bucks on a really good charge controller because batteris get really expensive and if it gives you a couple extra years it is very worth it.
The real problem with some of the eBay junk is that it may not even do what the sticker claims it does. I have seen MPPT labeled controllers that are nothing more than cheap PWM's. I even saw one that was an on/off shunting controller labeled as MPPT. If you are lucky enough to get one that actually is an MPPT, the controllers are often very old school designs that are not very efficient nor of a P & O or IC design. The are most often of the old school current sweep design which can tend to perform worse than a PWM on a sailboat that moves..
 

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sorry fo this is a hijack but the controller I just bought has what I beleive tschmiddy is talkng about an extra hookup for devices, is this for adding charging inputs or does it power stuff like for hooking up and anchor light at night(the battery charging type)

thanks
 

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FWIW

The first step should be to get the specifications of the installed system. Take it apart and get model numbers/manufactures specs etc.

Anything you do based on a '6.5amps at 19v' reading is guess work.
 

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Discussion Starter #17
Cristian, the extra hookup is almost certainly for devices to be hooked up (ie load). The charge controller will disconnect the load when the battery voltage gets too low.
What is the benifit of running something right off the controller? Why not just run it off the battery?
My boat sits on a mooring just off the shore from my house. Not a busy place, but I'd like to hook up a small led mooring light, night/daylight activated. A 2w lamp should be ok to just leave on?




Sent from my iPhone using Tapatalk
 
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I don't think this adds up. When you say each bank gets 6.5 amps is this per day or at peak as a charging rate? Even if the latter that would be overcharging unless there is some diversion of the excess current to a load eg a heat producing resistor. I also wonder what the size and type of the panels is because they sound big for the size of the boat unless the power is being used. I think that if you specified the battery voltages and how they are connected with details of the solar system. Then someone with more knowledge than I could assist you. As Maine Sail says you only need one 12v or 2 6 v batteries as a start bank.
 
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