[dixiedawg]

I know nothing about this charger, it came with my boat. It's old and small and raggedy looking and falling apart at the seams (literally). I didn't expect it to work, and hesitated to hook it up to my battery for fear it might short it out and kill it.

Well. Was I surprised. I hooked it up to a multimeter and got almost 20 volts from it - and today is overcast!

So my question is, is it even safe to use? I'm an electrical dufus. Am I even testing it properly?

 

[kd3pc]

it works, but not in a way that I would count on for my boat....it is not regulated for the use you want.

You can search the web for a DC to DC converter/regulator circuit to augment the panel...

that being said, it would not be on my boat as a battery charger..as is.

 

[Andrew Thompson]

You are testing it with no load apart from the meter, i.e. effectively open circuit. The specs (second photo) indicate it might produce uo top 23,8v in this condition. You're getting just uner 20v on an an overcast day. Seems OK.

In UK these small panels are often used with no regulator, just connected direct to a 12v battery. They work fine. Check this forum if you want to be convinced 5w solar panel

Hope this helps. It has reminded me that my 60W panel and regulator need to be removed from under the bunk and connected up, so thanks for that!

Andrew

 

[Delezynski]

It's working good! Re sew/seal the edges and use it. I have 4 Uni-Solar 32 W panels and love them. Easy to store and use and bullet proof.

The only thing you need to consider is battery bank size. If you have a large(ish) bank, connect it direct. If only one small battery, get a small controller.

I can't remember the panel size to battery equation just now, but I am sure some one will jump in. AND, like was said, do a search.

Greg

 

[bobmcgov]

You are testing it with no load apart from the meter, i.e. effectively open circuit. The specs (second photo) indicate it might produce uo top 23,8v in this condition. You're getting just uner 20v on an an overcast day. Seems OK.

In UK these small panels are often used with no regulator, just connected direct to a 12v battery. They work fine. Check this forum if you want to be convinced 5w solar panel

Hope this helps. It has reminded me that my 60W panel and regulator need to be removed from under the bunk and connected up, so thanks for that!

Andrew

Good reply. Yep, that's open-circuit (unloaded) voltage; the PV panels on our house, nominally 24VDC, run upwards of 39.5V open circuit. Attach them to some thirsty batteries, PV voltage at the charge controller drops to around 32VDC.

5W is near the upper limit I'd want for an unregulated charger; it prolly won't overcharge the battery, but it can cause excessive water loss, which will kill it just as dead.

 

[mitiempo]

I would be very careful connecting any solar panel to a battery or batteries without a controller. This link - first post - by Mainesail explains in detail the damage that is possible.
Do I Need A Solar Charge Controller ?? - SailboatOwners.com

 

[norahs arc]

Notice that on the spec sheet it says "23.8 open circuit voltage" The panel is probably working as designed, your voltage reading is low but it doesn't seem to be in bright sunlight.
This small panel can be connected directly to a battery of 100 amp hours or more but a charge controller would still be desireable.
(Check battery voltage without the panel connected and then with it connected in bright sunlight. The voltage should be higher when connected but with that size on panel it may be so slight as to be hard to detect.)

 

[Jaramaz]

if your solar panel is permanetnly attached to the battery there is a slim risk the battery will boil. Not fun.

Most likely when you attach the panel to the battery, the voltage will go down to something close to the battery voltage (.. as it was before you attached). this is hopefully ~12.5 V. Slowly, as the panel is a small one, voltage will increase.
Maintenance charge voltage is in the range 13.5 - 13.8 V (about, let's not go to deep here). It is OK as long is you are not exceeding this.

Fast charge voltage is ~14.5 V. Above that is certainly not good at all. Here ae are talking boiling.

With your small panel, and a battery of ? 100 Ah? 75 Ah? there should not be any risk to have a semi-permanent attachent, but then I am speaking from experience of a very dark country (but not in the summers ). In any case, I would not leave the panel attached for moths without monitoring now and then.

Using a regulator (which I do, but then I have close to 100 W of panels) consumes some of the energy. Unavoildable. Small and cheap ones are close to worthless; I had one such, wasted $150 ...
So either you get a good one, which is likely to cost, or you live happily with what you have and keep an eye on things.

Another view: PO seems to have used it intensively.

/J

 

[Froggy]

Isn't the meter showing: negative 19 volts?

 

[mitiempo]

Isn't the meter showing: negative 19 volts?

If the leads of a digital meter are the wrong way around the reading is negative. With an analog meter you don't get a reading.

 

[mitiempo]

Small and cheap ones are close to worthless; I had one such, wasted $150 ...
So either you get a good one, which is likely to cost, or you live happily with what you have and keep an eye on things.
/J

You can get a good pwm controller for very little expense. Here is a good Morningstar Sunsaver 6.5 amp controller for $51

SS-6 SunSaver 6A 12 VDC PWM Solar Controller - We Go Solar

If you decide to get a larger panel - up to 80 watts or so - it will handle it.

 

[mitiempo]

if your solar panel is permanently attached to the battery there is a slim risk the battery will boil.
/J

More than a slim risk. If you had read the thread I linked to earlier you would have found that it only takes .2 amps to keep 2 group 27 batteries at 14.4 volts if they are fully charged. 14.4 volts is the point at which batteries begin to gas - boil the electrolyte. Any more than .2 amps and the voltage will rise to a dangerous level, damaging the batteries and eventually destroying them.

Here is the link again: Do I Need A Solar Charge Controller ?? - SailboatOwners.com

Buy a controller.

 

[christian.hess]

cheap ones(panels) can and will fry batteries

I used a cheap 15 watter or whatever crap westmarine sold to keep my battery topped off for 6 months, while I was out of the country...that was the plan

came back and battery was fried...

any panel that shows 19 volts needs to be regulated...or made to put out only 14-15volts by putting in some inline draws which I should of done like a simple fan....or a controller...

in hindsight they say

 

[bobmcgov]

cheap ones(panels) can and will fry batteries

I used a cheap 15 watter or whatever crap westmarine sold to keep my battery topped off for 6 months, while I was out of the country...that was the plan

came back and battery was fried...

any panel that shows 19 volts needs to be regulated...or made to put out only 14-15volts by putting in some inline draws which I should of done like a simple fan....or a controller...

in hindsight they say

What does the price or quality of the panel have to do with anything? A high-quality monocrystalline panel is MORE likely than a cheap amorphous panel to cook a battery -- it produces higher voltage. If you connect a 15W panel to a battery without even a simple $15 shunt controller, you will cook that battery. Don't blame the panel or West Marine -- it's your own damned fault. The OP's 5W nominal amorphous flex panel is at the very upper limit of what you can use without a controller. I'd still fancy (at least) a simple voltage cutoff for it, for reasons discussed above. Prolonged high voltages cause water loss, plate erosion, and internal heating.

 

[mitiempo]

Prolonged high voltages cause water loss, plate erosion, and internal heating.

....and death of the battery.

 

[christian.hess]

What does the price or quality of the panel have to do with anything? A high-quality monocrystalline panel is MORE likely than a cheap amorphous panel to cook a battery -- it produces higher voltage. If you connect a 15W panel to a battery without even a simple $15 shunt controller, you will cook that battery. Don't blame the panel or West Marine -- it's your own damned fault. The OP's 5W nominal amorphous flex panel is at the very upper limit of what you can use without a controller. I'd still fancy (at least) a simple voltage cutoff for it, for reasons discussed above. Prolonged high voltages cause water loss, plate erosion, and internal heating.

sorry it was a bad choice of words

what you need to be cautious about is this

low priced panels that specifically say on the box no need for charge controller

like the ones at westmarines for example

they fool you into beleoving you dont need a controller because of the low output

i.e 15watters etc that are recomended as battery TOP UPS

these will fry your battery if left unattended for long

btw dude chill...I chose my words badly but notice I didnt lay blame on anyone...? in fact you can get from the post that I was jesting about the fact that I cooked my battery from using this method

I simply bought a new battery and kept the panel...westmarine is just one example of places that sell these top up panels or battery keepers and sell them with the no need for controller labeling on them

its part of the reason they are so popular with campers too...

the thing is most people dont leave them unattended for months at a time and THAT is why you dont hear stories about them frying batteries that much

I think its mislabelling and thats the reason I posted my experience

 

[hellosailor]

It's a 5W panel. So in theory, 5W divided by 14.4 v = ~.34A output under load to the battery, and if that's a single Group 24? on a 22' boat, in theory that's enough to slowly cook the battery, slowly boil it off unless there are loads also pulling it down.

Simplest thing to do is hook it up, check battery voltage every day or three for a couple of weeks, and see if it maintains the battery properly. In a week or three it can't cook off enough water to make a big difference unless that's a sealed battery. Given that we don't know how many hours of "pure" light it will get, or the daily output from the panel, or what the batteries are...

Hook it up, check the voltage, see what really happens. If it is too much power, put an automatic anchor light on the boat, that'll drain the battery down enough every night to let it absorb the extra power in the day. (G)

 

[christian.hess]

but its not pumping 14.4 right? unless regukated even if only 5w(@18-19 volts) left unattended damage can happen...as happened with me

not the panels fault but mine for not doing something before leaving the boat for 6 months

ps. I had an automatic bilge pump and a standard stuffing box that dripped, not enough to drain a new 31 class battery at all...

your anchor light or my little fan helps for DIRECT drain..

in the end I would just get a cheap shunt controller or pmw controller or buy a nice morninsgtar and eventually add panels...

peace

 

[HUGOSALT]

Have for the last 5 years a 10 watt Flexible Uni Solar FLX-11
installed on boat without regulator/controller. Have it attached to
2-group 27 lead acid bank (200 amps total) I leave connected after a weekend on boat or similar use for usually a week or so at a time. (would'nt leave connected extended time without checking).
Only draw is from a bilge pump that cycles on for a few seconds every 5-10 minutes.
Have not fried batteries yet using panel in this manner.
Very selden have to add water.
Going into 6th season with batteries.
Still have original box which has specs for OP model also...
OP's panel FLS-5.....rated 5 watts...amp hours/day 2
my panel FLS-11..rated 10 watts...amp hours/day 4
Also stated on box...Charge controller/regulator not required
but recommended.
Panel has held up well and I use it to maintain a smaller
battery as well, which is not connected to ships charging system.
Do not remember output voltage but anything close to 18-19 volts would have stopped me in my tracks. Boat is all covered and batteries off boat now but in 8 weeks will be all ready for launch so I will check and report back.

 

[newhaul]

only draw is from a bilge pump that cycles on for a few seconds every 5-10 minutes..

That's kinda often for bildge pump to run in a newer boat. But does provide the load needed to protect the battery's from overcharge. Personally with a half amp charge I would be more concerned why the pump needs to run that often myself. A monthly check of battery water is or at least should be part of everyone's boat maintance schedule