Consistent battery charging - or variable solar output

[Supertramp]

I've always understood batteries like to be charged in specific stages, bulk, absorption float etc. Which works well with a constant mains or engine derived supply.

But how damaging is it to the batteries to get intermittent charges from the solar panels on a 'semi cloudy' day such as now.

 

We might get 30 mins of sun, then nothing for an hour or two, then a bit more, how does either the charger or the batteries keep track? and does it impact on the life of the batteries?

[Paul C]

Its not damaging, it just takes longer.

[Ex- Member]

I've always understood batteries like to be charged in specific stages, bulk, absorption float etc. Which works well with a constant mains or engine derived supply.

But how damaging is it to the batteries to get intermittent charges from the solar panels on a 'semi cloudy' day such as now.

 

We might get 30 mins of sun, then nothing for an hour or two, then a bit more, how does either the charger or the batteries keep track? and does it impact on the life of the batteries?

 

Solar is probably the best and most efficient way of charging batteries on a boat without shorepower. We have 740w of solar. Between March and end Oct solar power supplies all our energy, we don't need additional charging. When we cruise we just do the washing and any high energy stuff like hoovering. Through most the summer we had too much energy, in this instance the solar charge controller steps in and reduces the power to the batteries.

 

The intermittent charge you mention shouldn't and isn't a problem as far as I'm aware. A good charge controller should do exactly that, Control the input.

Edited January 17, 2014 by Julynian

[Supertramp]

Thanks guys, I agree it seems the best / cheapest charging method, just wondered if the intermittent supplies each counted towards the 'charging cycles' that a typical batteries life is measured by

[Ex- Member]

Thanks guys, I agree it seems the best / cheapest charging method, just wondered if the intermittent supplies each counted towards the 'charging cycles' that a typical batteries life is measured by

 

If you think about it most battery charging is intermittent. Like when cruising or generator charging etc and of course solar too. If you're going for to go for it there's some great options at Bimble Solar, ready to install kits or buy the bits individually.

 

http://www.bimblesolar.com/

[peterboat]

I had solar on my old boat I installed a full traction battery bank at the same time. When I sold that boat I moved the batteries onto my new boat they are now over 10 years old and still working well. They still have solar as the main charging system also 3.5 hours of wispergen daily (max 72 amps 12v but varies with SOC of the batteries) and of course 160 amp alternator when cruising, I have an auto washer, dishwasher and all the other household items and use them without thought. The battery bank is 1500 amp hours or so and its maybe the size that has kept it working well?

 

Peter

[junior]

I had solar on my old boat I installed a full traction battery bank at the same time. When I sold that boat I moved the batteries onto my new boat they are now over 10 years old and still working well. They still have solar as the main charging system also 3.5 hours of wispergen daily (max 72 amps 12v but varies with SOC of the batteries) and of course 160 amp alternator when cruising, I have an auto washer, dishwasher and all the other household items and use them without thought. The battery bank is 1500 amp hours or so and its maybe the size that has kept it working well?

 

Peter

Are you on a narrowboat? That's the biggest battery bank I've heard of and come to think of it, the biggest alternator also!

[nb Innisfree]

Are you on a narrowboat? That's the biggest battery bank I've heard of and come to think of it, the biggest alternator also!

We have a 24v 100amp alternator (equivalent to 12v 200amp) some have bigger, also 8x 120ah battery bank. One of the advantages of a large bank is the voltage holds up better under load when they are nearing the end of their life.

 

ETA: Probably stating the obvious but we have a narrowboat.

Edited January 19, 2014 by nb Innisfree

[nb Innisfree]

I've always understood batteries like to be charged in specific stages, bulk, absorption float etc. Which works well with a constant mains or engine derived supply.

But how damaging is it to the batteries to get intermittent charges from the solar panels on a 'semi cloudy' day such as now.

 

We might get 30 mins of sun, then nothing for an hour or two, then a bit more, how does either the charger or the batteries keep track? and does it impact on the life of the batteries?

Ideal absorption charge is at just below gassing voltage, difficult to achieve. Adverc charge controller gets near by charging for 15 mins at above gassing voltage followed by 5 mins below to give batts a rest.

[Staarek]

I think it all depends on your Solar Controller. I wouldn’t expect a lot from cheap Chinese one but I imagine a decent one would do as much as so called smart-chargers (which is Multi stage charging) Bulk charging, Absorption, Equalization, Float. I’ve got Morning Star unit that does that & also allows you to specify exact voltage for each stage which means that you can set it up accordingly to your battery type & manufacturer’s recommendations.