When I bought my boat (Santana 28) it had one battery, There was room for two batteries in the battery box and
as I had purchased an ST2000 auto pilot I decided to add an extra 'house' battery. The house battery is charged by
a small solar panel (about 7 or 8 watt) and after advice from the dealer I put a regulator in line because it sits in the sun
all day every day. Poking around the boat yesterday I put a voltmeter across the the batteries to check the charge
and the house battery read 15.3 v. The green light on the regulator was on but dim, at that voltage I would have
thought it would not be on at all. Is 15.3v over charged ??. Do I have a problem ?. or is that reading acceptable ?.
If I disconnect the battery from the solar panel the green light flashes. Is all OK ??.

if you measure the voltage with the solar panel working and connected, what you are measuring is the voltage that the panel is providing, not the state of charge of the battery itself. the kind of 12V battery you have is likely to have a terminal voltage a bit over 13V when fully charged.

it's impossible to say for sure what the flashing green light means without knowing which regulator you have, but most commonly it indicates that the regulator thinks that the battery is fully charged...

Thanks fishy, that makes sense. I didn't think to put the multimeter on it with the panel disconnected. I'll
do that next time, The regulator's nothing flash, just a basic protector, but I was advised to put it on even
though the panel is low wattage.

I think fishmonkey is on the money!

MPPT controller like Victron would serve you better for not much more money.

batterys should never reach 15v at the terminal's during normal charging with or with out solar connected.
solar panels produce around 18-22v which the regulator must regulate to 14-14.5v during bulk and absorption stage and 13.5v during float.
at 15v+ your battery's will be overcharging and releasing explosive hydrogen gas.
there is a chance your solar controller might have a auto equalization stage make Shure its switch of and test volts at the battery again,
if not i would be replacing the regulator asap as sirgallivant suggested victron is the go

Select to expand quote

kurt88 said..
batterys should never reach 15v at the terminal's during normal charging with or with out solar connected.
solar panels produce around 18-22v which the regulator must regulate to 14-14.5v during bulk and absorption stage and 13.5v during float.
at 15v+ your battery's will be overcharging and releasing explosive hydrogen gas.
there is a chance your solar controller might have a auto equalization stage make Shure its switch of and test volts at the battery again,
if not i would be replacing the regulator asap as sirgallivant suggested victron is the go

Thanks for that kurt. I had an idea that 15.3 may be too much and as the regulator is fairly new i haven't
suspected that it might be crook. So will replace it with a Victron.

If you do so make sure the one you pick is not working on the top of it's capacity.
Like, if you run a 150w panel which is going to give you approx. 7.5-8amps, your controller is not a 10amp one running on the higher end of its capacity but a 15 or even 20 amp one so it is not working too hard. Another benefit of this decision is, that one can expand the charging capacity by putting an extra panel in and keeping the old controller, later on.

15V+ across 12V battery terminals is not good for extended periods.

some chargers and battery systems are designed for a short term "boost" or "equalisation charge to 14.8V

Are you sure your your multimeter is accurate ?

Another thing to check is the regulator and solar cell earth connections.

When you power up the regulator, connect to the battery first then solar cells second. Some of the 12/24V regulators have an auto voltage detector and get confused if first connected to the solar cells first.

+1 for victron chargers.

A

I checked out Whitworths catalogue for Victron regulators but I couldn't see one listed or for
that matter one with the letters MPPT . So where do I get a Victron ??.

EBay. Shop around.
Wworths is a joke.

www.outbackmarine.com.au/products

Thanks SirG, I'll do that.

Select to expand quote

samsturdy said..
I checked out Whitworths catalogue for Victron regulators but I couldn't see one listed or for
that matter one with the letters MPPT . So where do I get a Victron ??.

You could also try

www.lowenergydevelopments.com.au

They have big following in the trailer sailer community in Melbourne. Buy direct or from Ebay.

A

Another very cheap but effective option is the Tracer MPPT regulator available on eBay. I have had a 10A one fed from a 60W panel running on my boat for about 4 years now and am very happy with it.

Cheers, Graeme

Be careful with Epever controllers.
I had a dodgy one which never turned on. Ever.

Had to jump through hoops, lost big time as item had to be returned to blasted China!? when it was posted from Greenacre NSW.
(company bull**** policy)

Be aware purchasing anything from China or dodgy Chinese companies in Oz. Better paying a bit more to a local company but having the local customer laws protecting you than spending less money but forfeit the protection of local law.

Thanks SirG. I suppose the trick is knowing a Chinese company with an Australian sounding name from an Australian company with an Australian sounding name. I can't tell one from the other, so how do you find out what's dinkum and what isn't ?.

It does sound like the regulator has stuffed up.
im no expert, but I think your wasting your money on a MPPT for a 7 or 8 watt panel. IMO pick up decent quality PWM regulator, Morningstar or Kenco brands come to mind, and see how you go.
it could also be your batteries, if you have connected them together??

Select to expand quote

samsturdy said..
Thanks SirG. I suppose the trick is knowing a Chinese company with an Australian sounding name from an Australian company with an Australian sounding name. I can't tell one from the other, so how do you find out what's dinkum and what isn't ?.

A lot of online stuff is sold through fulfillment companies (Australian Post is one). That way an overseas supplier can sell through an Australian address looking like (on eBay and Amazon for example) an Australian business. It is not illegal (maybe deceitful) and it is one legit way Aussie suppliers are able to sell on Amazon and eBay in the USA.

Anyway I digress.

If you are worried about Chinese made, don't concern yourself so much with the business location, but more where the product is made.

Ps. Nothing wrong with a lot of Chinese made products either. I am sure you are aware of how much is made there. China made comes down to you get what you pay for just like everything else.

Blue Moon. no the batteries are not connected although they can be linked through the rotary switch.
The starter battery is new and is not charged with a solar panel, as I run the boat every week the battery
stays charged because I use the alternator and do enough running around to and from where I sail for it
to stay fully charged. The house battery on the other hand is bigger and older and runs everything, electric
loo, galley water, auto pilot etc. When I'm finished for the day the house battery is depleted but when I arrive
back in a weeks time I've got a reading of 15.3v, so you see why I'm asking is this too much.
The solar panel is small but obviously effective but as you say an MPPT regulator might be overkill, but I
still don't want to wreck my battery.

Sam, when you say 'depleted', how depleted is it? You do not want to be running a deep cycle battery flat. I wouldn't want to run it more than 50-60% flat (regularly). You might need a bigger house bank or more power input solar or wind -if your current set up is not coping

Hi Toph. I've only got a small boat, 28 footer, and with two of us on board day sailing we don't use THAT much power...but we
do use some, and that needs to be replaced before next sailing day, hence small solar panel. So the house battery is not run
flat, which would happen if i didn't charge it. So it's a bit of a balance...but...I would have thought that a small panel and
protection by a regulator would be an ideal set up. Am I wrong ??.

Sam, don't panic and spend money unnecessarily.
MB has had a 40w solar panel since I bought her. It charges the lead acid start battery and two 105amp AGM house batteries (total 210 amps). It has a regulator but charges at 15v or a bit more on very sunny days.
The batteries are always fully charged and I have had no issues of overcharging, gassing or shortened life. A little panel charging at 15 or so volts won't hurt your batteries. The voltage is high but the charging rate is low.
My current batteries have been there for 8 years, have been run down to 50% or so on each Lord Howe trip and are still in excellent shape. The previous batteries lasted over 10 years.

Select to expand quote

samsturdy said..
Am I wrong ??.

I don't know Sam. I'm certainly not the right person to talk to about anything electronic, it took me 2 weeks to figure out why I couldn't run video to a TV
It was just this comment that made me think either your house battery is either not big enough, or is old and not holding a charge

Select to expand quote

samsturdy said..
When I'm finished for the day the house battery is depleted but when I arrive

I do know enough that you do not want this happening

No problem Toph and thanks for your input.

MB. Your response is the one I'm looking for, someone who's experiencing the same thing and can
tell me there's nothing to worry about.
Thank you everybody for your interest and input. It's always comforting to know I can ask and I shall receive.

Thank you all.

That's because you're a decent chap Sam, you make it a pleasure.

Select to expand quote

shaggybaxter said..
That's because you're a decent chap Sam, you make it a pleasure.

+1

I was told you wouldnt need a regulator for anything less than 10W?

Sorry if this is not on topic but I think it is....

I have a 10W panel to keep the battery charged but whats the cheapest way to know how much charge is left in a battery? I am really curious to know how much energy gets consumed on an overnight stay. I often run the engine for a while before dark just to ensure we dont run out during the night but for all I know this could be unnecessary.....

Whitworths sell a digital voltmeter for about $20 and I was thinking of installing one. Would this tell me at a basic level if the battery is charged? i.e. if its below 13v I have to run the motor to boost the battery before dark?

Sorry I am confused by electrics. They are black magic as far as I am concerned.

Select to expand quote

FelixdeCat said..
I was told you wouldnt need a regulator for anything less than 10W?

Sorry if this is not on topic but I think it is....

I have a 10W panel to keep the battery charged but whats the cheapest way to know how much charge is left in a battery? I am really curious to know how much energy gets consumed on an overnight stay. I often run the engine for a while before dark just to ensure we dont run out during the night but for all I know this could be unnecessary.....

Whitworths sell a digital voltmeter for about $20 and I was thinking of installing one. Would this tell me at a basic level if the battery is charged? i.e. if its below 13v I have to run the motor to boost the battery before dark?

Sorry I am confused by electrics. They are black magic as far as I am concerned.

Voltmeters are a handy tool, but volts don't tell the whole story, ideally you need to be able to measure or guesstimate how many amps you use ie. 50 amp hours out of a 100amp hour battery is 50%. And of course it's good to know how many amp hours you put into your battery.
new years eve we used 43amp hours with a car sterio goin till after midnight, several LEDs burning and the fridge being opened on a regular basis

Select to expand quote

FelixdeCat said..
I was told you wouldnt need a regulator for anything less than 10W?

Sorry if this is not on topic but I think it is....

I have a 10W panel to keep the battery charged but whats the cheapest way to know how much charge is left in a battery? I am really curious to know how much energy gets consumed on an overnight stay. I often run the engine for a while before dark just to ensure we dont run out during the night but for all I know this could be unnecessary.....

Whitworths sell a digital voltmeter for about $20 and I was thinking of installing one. Would this tell me at a basic level if the battery is charged? i.e. if its below 13v I have to run the motor to boost the battery before dark?

Sorry I am confused by electrics. They are black magic as far as I am concerned.

Disconnect the leads from the solar panel and let the battery sit for 20 minutes or so. Check the voltage with a cheap meter, don't bother wiring something extra in it's just more to go wrong. Use the chart. Or you could use a light bulb with known values and see how that hold up with the battery discharging. Plenty of info online for checking the amperage draw.

Select to expand quote

FelixdeCat said..
I have a 10W panel to keep the battery charged but whats the cheapest way to know how much charge is left in a battery? I am really curious to know how much energy gets consumed on an overnight stay. I often run the engine for a while before dark just to ensure we dont run out during the night but for all I know this could be unnecessary.....

Whitworths sell a digital voltmeter for about $20 and I was thinking of installing one. Would this tell me at a basic level if the battery is charged? i.e. if its below 13v I have to run the motor to boost the battery before dark?

Sorry I am confused by electrics. They are black magic as far as I am concerned.

if you want to go all out, there are computerised systems that record your total battery capacity, and then actively monitor the power going in and out of your battery. as you can imagine, these are a lot more complicated than a simple voltmeter or ammeter, and cost significantly more, for example, these ones are about $200:

votronic.de/index.php/en/products/measuring-display-systems/battery-computer/boat-version