# Can someone tell me what I have bought?



## PrairieBelle22 (Nov 17, 2006)

Hello! I'm not a regular to this forum so please bear with me.

I bought a used solar panel today and don't really know what I can do with what I have bought. The model is an HYM-90 maximum wattage is 90, maximum voltage is 17.9. 

The module is on a frame with wheels and able to me moved and has a black box on the back with a long power cord (about 20' long) coming out of it with a twist plug on the end.

Will this charge a battery or more than one battery? 
What kind of battery should I buy? 
Where can I find out how to hook it all up?

Looking forward to hearing what you have to say. Thank you for your time and input.

Belle


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## JeepHammer (May 12, 2015)

90 Watts,
17.9 volts Max.

This is for a 12 volt battery standby more than likely.

90 Watts Ã· 14 volts (standard 12 volt batteries charge at 14 volts) = 6.4 Amps @ 14 volts.

6 amps is about right for fairly deeply charging one automotive size 12 volt battery,
Or 'Trickle' charging two automotive size 12 volt batteries.

Since you are new to this,

WATTS can be converted into voltage or amperage, depending on demand.
If something wants to draw large Amps, the voltage will drop.

Here is the basic formula to figure out what something is producing in Watts, and what you can do with that power...

Volts x Amps = Watts
Watts Ã· Volts = Amps
Watts Ã· Amps = Volts (Maximum Available)

A 4,500 Watt Generator in household currents,
4,500 Watts Ã· 110 Volts = 40.9 Amps
4,500 Watts Ã· 220 Volts = 20.4 Amps

Some of my solar panels are 250 Watts,
250 Watts Ã· 14 Volts to charge batteries = 17.8 Amps
And it takes between 6 & 10 Amps to properly charge a 'Discharged' battery,
So 14 volts @ 17.8 Amps will charge two 12 volt batteries fairly quickly,

It takes about 3 amps to maintain charge (top off the charge) of each battery,
So this thing would maintain 5 or 6 batteries at full charge fairly easily...

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The average small microwave draws 110 Volts @ 13 or 14 amps.
That's 110 Volts x 13.5 Amps = 1485 Watts.
That's a big draw on a small battery bank, especially for several minutes at a time!

But you get the idea on how to figure Watts into your voltage/amperage...


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## JeepHammer (May 12, 2015)

Batteries,
Standard 12 volt batteries for the application you intend to use them on.
Starting batteries for automotive use, starting the engine, ect.

Deep cycle for fence chargers or something you won't be charging the battery regularly.

CONNECTION.
Positive from the panel to the battery Positive (+),
Same with negative, from panel to battery (-).

If you connect two batteries at once,
The same rules apply, this is called 'Parallel',
The positive from one battery connects to the positive of the second battery,
The negative from one battery connects to the negative of the second battery,
And the solar panel connects positive to positive, negative to negative.

This panel will charge any of the standard 12 volt batteries pretty quickly,
And it will charge two batteries over time, but not nearly as quickly.

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Since this thing has a 'Cart' built onto it, it was probably a back up battery charger at one point, keeping 2 or 4 batteries topped off for emergency use.

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Safety!
COVER THE PANEL WHEN YOU ARE MAKING CONNECTIONS!
A volt meter (around $20) is a VERY good idea,
And a volt meter will tell you what wire is positive and which is negative from the panel,
It will also let you know when the batteries are fully charged.

Pumping current into batteries that are charged only overheats them, warps plates and reduces the life of the battery...
When the batteries show about 13.2/13.6 volts when disconnected from the panel, they are charged...

Since you didn't show pictures of what you have, I can't make specific recommendations on connections, what to keep, what to leave out...
Some back up battery chargers have a built in charge controller, so you won't have to check back on the batteries all the time to see if they are charged...
If your unit has one, you will want to keep it!

If you don't have one, they are about $20 (and up!) and they are a VERY good thing to have so you don't have to babysit the batteries being charged...

Charge controllers kick the charging out when the battery is 'Full', since the panel doesn't know when the battery is charged, and keeps throwing power at it...


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## JeepHammer (May 12, 2015)

If you want specifics/ideas on what you can do with that panel,
Send me a PM, we'll swap email addresses and I can send you diagrams for what you specifically have.

I'm not going to post up diagrams that the SITE can copyright/reproduce even though I already own them and have copyright...


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## PrairieBelle22 (Nov 17, 2006)

Thank you, JeepHammer, for all the information. I have read it over several times and think I'm starting to understand it. 

I do want to hook it up to charge a small battery bank. I have attached three photos to give you more information. I will pm you my email address.

Thanks again

Belle


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## TnAndy (Sep 15, 2005)

You need to understand 90watts is NOT a lot of power. You could keep a small battery bank topped off, but you simply can't draw much from it on a regular basis if that panel is the only source of charging.

You will need a small charge controller between the panel and the battery(s) to prevent overcharging once they are topped off.


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## PrairieBelle22 (Nov 17, 2006)

Could that black box on the back of the panel be a charge controller?


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## TnAndy (Sep 15, 2005)

I suppose it's possible, but most likely it's just a junction box connecting that blue wire to the positive and negative terminals on the panel. Pull the cover off and look.


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## PrairieBelle22 (Nov 17, 2006)

I took the cover off the black box and sure enough it was just the connections from the panel to the cord.

Does it matter which charge controller that I buy? There are a broad range of prices.


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## TnAndy (Sep 15, 2005)

You need one big enough to handle the max amps that panel could produce. 90watts divided by 18v (about) = 5amps. Should be a label on the panel that gives you the max amps it could produce, go by that.

SO, now you're looking for an 8-10amp controller. IF you think you're ever gonna add another panel or two, buy a controller big enough to handle that....otherwise just get a small one.

Looking at the panel (wheels) and that twist lock plug, it was probably part of a so-called "solar generator", and you didn't get the other parts....which were a controller, a battery, and an inverter (to change DC to AC). The OTHER part most likley had a male plug that connected to the panel.

What you would need to do is either come up with a similar deal, or cut the plug off and strip the wire so you could connect it directly to a charge controller on the PV IN terminals. The OUT terminals would connect to a battery, as would an inverter.

Again....remember....this is NOT much power....which is why those "solar generators' are such a joke. The power is in the BATTERY....and if you can't recharge the battery enough ( and a 90w panel will NOT do much), you're simply operating on what power is in the battery, and basically ruining it. Most likely, somebody ruined their battery (and maybe the inverter running it on too low voltage), and threw that part away....which is why you never saw it !


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## PrairieBelle22 (Nov 17, 2006)

So what if I build this to be a small portable system to operate small items like a small radio or plug in a computer or cell phone. JeepHammer told me that it should charge one 12 volt quickly and two 12 volts paralleled more slowly.

I would like to build this small system kind of as a trial run before I go on to a bigger and better system. This will at least help me start to gain a working knowledge.


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## TnAndy (Sep 15, 2005)

"quickly" and "more slowly" are vague terms. Let's use numbers.

90w panel will produce maybe 75-80w in full sun (the 90w figure is under PERFECT conditions in terms of light, angle of the panel, etc). So say you get that for 6 hrs a day (that is probably high, but let's use it). That is 480whrs (80w x 6hrs). Throw in a few for the other hours and call it 600.

Subtract 20% for losses from wiring, charge controller, and any inverter you plug in to change 12v to 120vAC.

Now you have about 400whrs/day to work with.

Look at whatever you want to use, electrically. If it uses 1amp @ 120v, and you use it for one hour, that is 1 x 120 =120w x 1 hour = 120whrs. You could use something like that for a shade over 3 hrs, drawing off your battery, and allowing the panel to put it back in.

Charging a cell phone, using a laptop (desktops are way more power hungry), a small radio....yes, you'd be OK, as long as your panel gets sun regular. Step up to appliances, especially any with any kind of electric heating element, and you'll find you're drawing more out of your battery than you put back, which will kill your battery over time.

Resting voltage (not taking any out, nor putting any in for the last hour) on a 12v battery should read in the 12.8-12.9 range. If you measure 12.6 or less on a regular basis, you're under charging the battery....never fully topping it off. That will lead to early battery failure.

THAT is what I suspect happens to most of those so called "solar generators". They give the illusion that they are more powerful than they are, because a battery will hold far more power than the solar panel produces. Thus, people use, and abuse, the battery, and they fail early. The people that sell them are simply not honest about what can really be done with them. ("You can run your refrigerator in a power outage".....yes, you can....just not for very long  )


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## PrairieBelle22 (Nov 17, 2006)

Very good information, TnAndy. Thank you.

How do you monitor the usage and level of charge on a battery to make sure you do not over deplete it or under charge it?


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## TnAndy (Sep 15, 2005)

Best way is a voltmeter (or a VOM multimeter)... a cheap one is fine, just make sure it reads to at least one decimal place. Batteries need to be measured 'at rest'.....give them an hour after charging or discharging to get accurate readings.

Flooded cell (wet cell...ones you can take the caps off and see the liquid) can also be measured using a hygrometer to measure the specific gravity of the fluid, but a voltmeter works fine too.


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## JeepHammer (May 12, 2015)

Like I said, with specifics,
And NOT trying to over complicate things...

That panel WILL charge the average 12 volt, automotive battery just the way it is.
It will MAINTAIN two batteries, slowly charging them over time.
Like I said to start with,
90 Watts is a start, its by no means a 'Power System'
Charging cell phones, lap top, fence charger for livestock,
Small runs of LED lighting, ect.

Your charge/discharge times will depend a bunch on the battery you choose.
High amperage output batteries usually will NOT live long being deeply discharged.
'Starting' batteries for cars won't take being discharged below 80% capacity very often,
A 'Deep Cycle' battery won't throw a bunch of amps quickly without damaging it, but it will discharge to about 60% and still recover when discharged SLOWLY.

A 'Marine Deep Cycle' isn't either one.
'Marine' batteries are designed to be used as both a 'Starting' battery,
And a 'Deep Cycle' battery.

Its an 'Application' thing here,
If you are going for 'General Purpose' here, then go with a 'Marine Deep Cycle' that will work as a starting and light duty 'Deep Cycle'.

If this is going to be strictly a low amperage 'Power Station',
Then you are better off with true 'Deep Cycle' batteries, like 
'Golf Cart' batteries.
Better charge/discharge rates and since they are the only 'Common' true Deep Cycle batteries available everywhere, they cost less per Amp Hour capability rating.

This will require you to wire TWO batteries in series for 12 volts,
But the longevity will be worth the added work.
They will also intergrate into a larger system as you expand your system.

Right now, you don't have enough panel to do much.
If you don't discharge the battery (and even with two 6 volt batteries) too much,
Your panel should charge fine at 12-14 volts.

I'm not sure what the others are talking about,
But common batteries take a bare minimum of 2.2 volts per cell,
A 12 volt arrangement will have 6 cells,
That's 13.2 volts just to maintain the charge status.
Most 12 volt batteries will draw 14 to 14.5 volts,
90 Watts \ 14 volts = 6.4 Amps
That's a VERY GOOD charge rate for battery longevity of your batteries.

A charge controller will reduce that charge rate as the battery reaches full charge, further increasing longevity.
And, a charge controller will allow you to add more panels without over charging.

About inverters,
Simply put, you don't yet have enough panel or battery for even a small inverter,
Small inverters are horribly inefficient, so it would waste a bunch of your battery,
And until you have enough battery & panel to support a larger, more efficient inverter, its a waste of time and money...

The rule of thumb for a solar array is a bare minimum of total watts produced by the panels,
Equal to the watts you use daily.
Something like a 'Kill A Watt' meter will tell you what anything on a single line is drawing,
Once you know EXACTLY what you are drawing,
Then you get panels to support that draw,
Then, and only then, do you worry about how much battery you need...

Panels charge the batteries,
Batteries feed the inverter,
Inverter large enough to support your entire load combined.

An inverter is a waste of time/money until then...
Trust me, I wasted money right and left on the 'Wrong' batteries, too small and wasteful inverters, panels that didn't produce the rated claims, ect...

Panels, inverters have become more efficient,
The standing rule 15 years ago was 1-1/2 times the square footage of panels as your house,
Now its about 1:1 ratio...

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Now, from someone that has 14 years off grid,
Tracking the sun with your panel makes it MUCH more efficient.
Your 'Peak Sun Hours', highest production from the panel will increase by as much as 40% by tracking the sun.
You will see a 20% bump in production just by moving the panel to face the sun more directly once a day.

Mine adjust every hour, and production is up nearly 40%!
This greatly reduces the number of panels you need, reducing cost along the way...

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Battery care is a HUGE DEAL!
And people rarely, if ever discuss it.
Batteries are expensive, so the longer they last, the less the total cost of your system,
And the quicker your system pays for itself...


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## PrairieBelle22 (Nov 17, 2006)

I appreciate all the information. It is a lot to grasp for a beginner that has no experience in the solar department, but I am looking forward to getting started with the little project.

Belle


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