Solar battery maintainer

[salgarfi]

Hello All,

I'm looking for a very simple solution to keeping my batteries maintained when I'm away from my boat (it's a small inland cruiser and its new mooring will have no access to mains electricity). I have two 110ah leisure batteries wired together to operate as one battery. With this being the case, I'm presuming that I can treat the bank of two as one 220ah battery, so would this solar battery maintainer from Halford's do the trick?

http://www.halfords.com/workshop-to...ters/halfords-solar-battery-maintainer-12v-6w

I only need these batteries for 12v lighting and to start the boat's 15hp outboard.

I'm really looking for the simplest of solutions: I'm a bit of a numpty when it comes to things electrical!

 

[VicS]

Hello All,

I'm looking for a very simple solution to keeping my batteries maintained when I'm away from my boat (it's a small inland cruiser and its new mooring will have no access to mains electricity). I have two 110ah leisure batteries wired together to operate as one battery. With this being the case, I'm presuming that I can treat the bank of two as one 220ah battery, so would this solar battery maintainer from Halford's do the trick?

http://www.halfords.com/workshop-to...ters/halfords-solar-battery-maintainer-12v-6w

I only need these batteries for 12v lighting and to start the boat's 15hp outboard.

I'm really looking for the simplest of solutions: I'm a bit of a numpty when it comes to things electrical!

They claim it is suitable for batteries up to 250 Ah but pushing the limit a bit I would think.

It might just about maintain them if the charging from your outboard gets the batteries fully recharged before you leave.

Something between 10 watts and 20 watts with a PWM regulator would be better. That might then have some chance of topping them up if the engine has not fully recharged them.

I wonder if two largish batteries permanently wired together to make an even larger bank is the best arrangement. I assume though that the outboard can be started manually if needs be

220 Ah is a big battery bank for what with LED lighting should be a very small power requirement

 

[ghostlymoron]

5w is tiny and would barely cope with leakage.
A 20w panel would replace some of the power used on lighting and instruments and not cost and more from an online supplier. You'll need a regulator as well.
As Vic says replacing the lights with LEDs would cut your useage tremendously.
Does your motor have any charging capacity?

 

[sarabande]

FWIW I have two 110Ahr batteries (domestic, parallel) on board. They are left to the tender mercies of a 10W solar panel wired (via a fuse ) with the solar panel facing due south at about 10 degrees off vertical. No charge controller.

Typically, when I arrive, the battery monitor shows 12.8 - 13.0v with very nearly 100% charge status.

On starting the engine, the Merlin alternator manager shows 14.5ishV, and a charge rate of c2.0A for about 5 minutes, then dropping to <1A. The Merlin looks after the two domestic batteries as well as the single engine start.

 

[doug748]

I have just got a panel for my boat, see this recent discussion:

http://www.ybw.com/forums/showthread.php?501047-Nasa-solar-panel&highlight=nasa+solar+panel

As an alternative, post 5 gives a better value option for a 10watt panel, which looks fine for your battery bank. For a similar cost you can get framed units from Ebay which come with a regulator thrown in.

I am sure the Halfords job would do the trick - security is a consideration, a loose panel could easily be taken if you are in a bankside position.

 

[salgarfi]

They claim it is suitable for batteries up to 250 Ah but pushing the limit a bit I would think.

It might just about maintain them if the charging from your outboard gets the batteries fully recharged before you leave.

Something between 10 watts and 20 watts with a PWM regulator would be better. That might then have some chance of topping them up if the engine has not fully recharged them.

I wonder if two largish batteries permanently wired together to make an even larger bank is the best arrangement. I assume though that the outboard can be started manually if needs be

220 Ah is a big battery bank for what with LED lighting should be a very small power requirement

This is the battery set-up that came with the boat - it's two leisure batteries and they turn the motor over too. The previous owner had an inverter that would deal with a small TV which he took away with him when the boat went on the market.

 

[jac]

Rule of thumb for southern UK is that a Panel will on average produce ( in Ah) 1/4 of the nominal value of the panel ( in W.) So that 6W panel should on average in Summer produce 1.5 Ah per day.


Bog standard lead acid batteries discharge around 1% a day so maybe 2.2 Ah max from that bank so on average the 6W will not quite keep up on a grey day but bright sunny day and you should be ok.

I would suggest 10W minimum to cover self discharge - If you can physically fit a larger one though, then do give consideration to it. Wiring, controller, effort to install will be virtually the same and by going to say 30W you stand a good chance of replacing a large chunk of what you might use over the weekend.

 

[salgarfi]

I have just got a panel for my boat, see this recent discussion:

http://www.ybw.com/forums/showthread.php?501047-Nasa-solar-panel&highlight=nasa+solar+panel

As an alternative, post 5 gives a better value option for a 10watt panel, which looks fine for your battery bank. For a similar cost you can get framed units from Ebay which come with a regulator thrown in.

I am sure the Halfords job would do the trick - security is a consideration, a loose panel could easily be taken if you are in a bankside position.

Thanks for this link. The item in post No. 5 looks like it could do the business, but it says that a battery more than 70ah wouldn't need a charge regulator. Does anyone know why this might be the case?

Re security issues, I don't think it'll be a problem where I'm going.

 

[VicS]

This is the battery set-up that came with the boat - it's two leisure batteries and they turn the motor over too. The previous owner had an inverter that would deal with a small TV which he took away with him when the boat went on the market.

The smallest of car batteries would be more than adequate to start a 15 hp outboard and a smallish leisure battery enough to power LED lighting. 2 big batteries will cost a lot more when due for replacement and be heavy lumps to lift on/off the boat, also loose more through self discharge, requiring more charging capability to replace what is lost

Different kettle of fish if you want to run loads of power hungry gear of course.

Thanks for this link. The item in post No. 5 looks like it could do the business, but it says that a battery more than 70ah wouldn't need a charge regulator. Does anyone know why this might be the case?

Re security issues, I don't think it'll be a problem where I'm going.

The usual rule of thumb regarding the need for a regulator is that it is not required if the ratio of 10Ah capacity per 1watt of solar power is exceeded, but it is also generally recommended that panels over 10 watts should have a regulator regardless.

 

[salgarfi]

Rule of thumb for southern UK is that a Panel will on average produce ( in Ah) 1/4 of the nominal value of the panel ( in W.) So that 6W panel should on average in Summer produce 1.5 Ah per day.


Bog standard lead acid batteries discharge around 1% a day so maybe 2.2 Ah max from that bank so on average the 6W will not quite keep up on a grey day but bright sunny day and you should be ok.

I would suggest 10W minimum to cover self discharge - If you can physically fit a larger one though, then do give consideration to it. Wiring, controller, effort to install will be virtually the same and by going to say 30W you stand a good chance of replacing a large chunk of what you might use over the weekend.

Thanks for these stats. Actually, the boat will be inland on the Montgomery canal close to Oswestry. I'm moving it from the Trent at Swaley.

 

[salgarfi]

The smallest of car batteries would be more than adequate to start a 15 hp outboard and a smallish leisure battery enough to power LED lighting. 2 big batteries will cost a lot more when due for replacement and be heavy lumps to lift on/off the boat, also loose more through self discharge, requiring more charging capability to replace what is lost

Different kettle of fish if you want to run loads of power hungry gear of course.

I have thought, that when these batteries die, I could simplify things. I am a minimalist, and I don't want anything that's power hungry.., eeek!

 

[ghostlymoron]

To be honest, Vic, regulators can be had for under a tenner on line and give a useful display of status. I've had several such units and found them quite satisfactory. The later ones were pwm.

The smallest of car batteries would be more than adequate to start a 15 hp outboard and a smallish leisure battery enough to power LED lighting. 2 big batteries will cost a lot more when due for replacement and be heavy lumps to lift on/off the boat, also loose more through self discharge, requiring more charging capability to replace what is lost

Different kettle of fish if you want to run loads of power hungry gear of course.



The usual rule of thumb regarding the need for a regulator is that it is not required if the ratio of 10Ah capacity per 1watt of solar power is exceeded, but it is also generally recommended that panels over 10 watts should have a regulator regardless.

 

[salgarfi]

Well.., I'll stay clear of the Halford's option and get something 10 watts and/or upwards. Also, I'll get batteries with less AHs when the present ones need replacing. Thanks everyone!

 

[William_H]

In choosing a solar panel the first and primary question is what is the biggest you can reasonably mount and cope with. The cost should be a lesser consideration given they are not so expensive. Having said that almost any solar charging will be useful but more is generally better. Gives more charge in winter etc. olewill