Solar charge controller - will it fry my battery? (or boil it)

[ghostlymoron]

I've just installed a 20w solar panel to charge my approx 55Ah battery. I bought a charge controller from ebay which I've also installed without problems - the lights light up and the LEDs show the battery 2/3rds full. Having read the spec for the charger I not that 'voltage to stop charging' is 14.4v. Is this too high for my battery? It also says 'parameters may customised by customers' although there are now external adjustment screws. I don't want to delve into the innards. What do you think?

 

[TradewindSailor]

It rather depends on the TYPE of battery you have : wet, maintenance free, gel, or AGM. The instructions for the charge controller should explain the set up for battery type ..... usually with a set of dip switches or combination of keys.

14.4V is fine for the wet lead acids but not for the maintenance free or gel. The AGM might be okay but rather dependant on the quality. You should look at the recommendations of the battery manufacturer too.

As your solar panel is only 20 watt and hence only delivering 1.4 amps at 14.4 V on a good day I doubt if it would do any battery any damage ......

 

[lpdsn]

Having read the spec for the charger I not that 'voltage to stop charging' is 14.4v. Is this too high for my battery?

Just checked the manual for my Sterling battery charger. It's to be set to 14.4V for Gel or Sealed Lead Acid batteries and 14.8V for conventional ventilated Lead Acid.

Sounds like your controller is fine.

 

[TradewindSailor]

The absorption voltage for any battery is temperature dependent: the higher the battery temperature the lower the absorption voltage. The temperature rather depends on where your battery is stored and the charging rate. If the battery is store in a closed engine compartment the temperature can get in excess of 30 deg C ......

Your controller must be very basic if it stops charging at 14.4v. Most controllers nowadays are at least 3-stage. After the absorption charge, the controller usually reduces to say 13.3V for a float charge.

It is worth reading a good explanation of charging batteries. Nigel Calder's book "Boatowner's Mechanical and Electrical Manual' is excellent in my view. Also look at the websites for Trojan Batteries, Lifeline Batteries, Blue Sky Controllers, etc ....

 

[ghostlymoron]

My controller IS very basic. If you read the documentation in my attachments which obviously you haven't, you notice the lack of any reference to multi stage charging. It controls the output from the pv only. For 10 quid you don't get sophistication nor do i want it.

The absorption voltage for any battery is temperature dependent: the higher the battery temperature the lower the absorption voltage. The temperature rather depends on where your battery is stored and the charging rate. If the battery is store in a closed engine compartment the temperature can get in excess of 30 deg C ......

Your controller must be very basic if it stops charging at 14.4v. Most controllers nowadays are at least 3-stage. After the absorption charge, the controller usually reduces to say 13.3V for a float charge.

It is worth reading a good explanation of charging batteries. Nigel Calder's book "Boatowner's Mechanical and Electrical Manual' is excellent in my view. Also look at the websites for Trojan Batteries, Lifeline Batteries, Blue Sky Controllers, etc ....

 

[VicS]

Elsewhere I have found 14.0 and 13.7 volts quoted as the charging cut out voltage for that controller. 13.7 is rather on the low side. The cut in volts , unspecified, will be low also.

Maybe you will have to try it. I doubt if 14.4 will be a problem esp if you have a calcium battery which, as far as I can see, most wet lead acid batteries now are.

13.7 would mean that you never get the battery as well charged as it could be.

If it turns out to be unsatisfactory invest a little more in a PWM controller.

 

[William_H]

The short answer to OP question is No it is very unlikely to Fry or boil your battery. This is because no matter what the controller claims it is always limited by the capacity of the solar panel. If directly connected to a 55AH battery at most it will deliver 1 amp. at a max about 18v. The 1 amp is unlikely to damage the battery especially if the panel is mounted flat so not max sun and unlikely to del;iver that much current for long unless it is high summer in UK.
best bet is to monitor the battery voltage. I doubt it will reach 14.4 volts. If it does I doubt 1 amp will do much harm.
However the question is valid if you change to 100w panel. Idon't know the answer then good luck olewill

 

[VicS]

The short answer to OP question is No it is very unlikely to Fry or boil your battery. This is because no matter what the controller claims it is always limited by the capacity of the solar panel. If directly connected to a 55AH battery at most it will deliver 1 amp. at a max about 18v. The 1 amp is unlikely to damage the battery especially if the panel is mounted flat so not max sun and unlikely to del;iver that much current for long unless it is high summer in UK.
best bet is to monitor the battery voltage. I doubt it will reach 14.4 volts. If it does I doubt 1 amp will do much harm.
However the question is valid if you change to 100w panel. Idon't know the answer then good luck olewill

Without any form of controller the battery will probably need its electrolyte topping up now and then. I found that even with 5 watts uncontrolled into a small leisure battery ( 45Ah ??) No problem with a non-sealed wet cell battery but non-sealed batteries are becoming relatively rare.

With a bigger panel the answer would be a decent PWM regulator.

 

[GHA]

The short answer to OP question is No it is very unlikely to Fry or boil your battery. This is because no matter what the controller claims it is always limited by the capacity of the solar panel. If directly connected to a 55AH battery at most it will deliver 1 amp. at a max about 18v. The 1 amp is unlikely to damage the battery especially if the panel is mounted flat so not max sun and unlikely to del;iver that much current for long unless it is high summer in UK.
best bet is to monitor the battery voltage. I doubt it will reach 14.4 volts. If it does I doubt 1 amp will do much harm.
However the question is valid if you change to 100w panel. Idon't know the answer then good luck olewill

Beware Unregulated

 

[noelex]

This sort of on/off regulator (that this appears to be from the limited information) is not a great choice.

Unlike a PWM regulator as soon as the battery voltage reaches 14.4v it will cut off all power until the battery voltages reaches ??? (This voltage does not seem to be listed in the specs). This can be a very long time with no solar power at all.
It is not just wasting a lot of power that is the concern it is difficult to get the battery to a proper 100% charge which shortens battery life.

To answer your question raising the voltage to 14.4v will not damage the battery, but only holding it at this voltage for a very short time and then turning the solar panel off completely may shorten the life compared to proper charging algorithm that would hold the 14.4v for a couple of hours and then hold a lower float voltage while their is sufficient power available.

 

[ghostlymoron]

Actually I've realised I've misinformed you. The regulator was £5 from ebay. Maybe i should have paid more.

 

[viago]

Actually I've realised I've misinformed you. The regulator was £5 from ebay. Maybe i should have paid more.

probably not. people leave their batteries for years without any controller and the battery stays topped up and fine for their needs. i used a dual controller for years and the batteries were fine. the job of a controller is to stop your battery bursting into flames and keep it topped up. going flat is what you want to avoid.
i'm sure there is some merit in better kit if you have ocd and have money to burn though and those with more knowledge than i will no doubt continue to inform and advise.

 

[ghostlymoron]

The short answer to OP question is No it is very unlikely to Fry or boil your battery. This is because no matter what the controller claims it is always limited by the capacity of the solar panel. If directly connected to a 55AH battery at most it will deliver 1 amp. at a max about 18v. The 1 amp is unlikely to damage the battery especially if the panel is mounted flat so not max sun and unlikely to del;iver that much current for long unless it is high summer in UK.
best bet is to monitor the battery voltage. I doubt it will reach 14.4 volts. If it does I doubt 1 amp will do much harm.
However the question is valid if you change to 100w panel. Idon't know the answer then good luck olewill

No fear of changing to a 100w panel my boat is only 19' long although it's called a 'yacht'.

 

[William_H]

No fear of changing to a 100w panel my boat is only 19' long although it's called a 'yacht'.

Hello Ghostlymoron. Ah a small sail boat man like myself. Mine is 21ft and I have had it for 35 years and still love it.
"it's calloed a Yacht" Ah you have me there because my native language is Australian English. This is a mixture of American English and UK English.
So I have seen small ships called yachts with not a sail in sight and I have seen tiny dinghies with a sail called a yacht. So I always go for "sailboat" which might be more American than UK English but leaves no doubt. good luck olewill