charging 12v battery with solar panel

[mic]

Morning

im sure theres a way to work it all out but i have no idea.

i use a lesuire battery to power my ittle fishing boat. id like to keep the battery topped up when im anchored but i have no idea how long would be a sufficient charge.... lets say ive drained 50%, there must be a way to work out how long id need to solar charge the 50% back.

85amp calcium battery
4 watt solar panel

so many watts per amp per hour?! or sumfink?

thanks

[ZebraDriver]

In an ideal world it would probably take about 150 hours to recharge your battery. However as this isn't an ideal world, and given that the 4w of charge is very optimistic and given that your battery is slowly discharging itself all of the time the real answer is that it probably won't manage to recharge the battery at all.

4w solar chargers are good for preventing a fully charged battery from discharging itself but not good for much else

ZD

[Marmalade]

4 watt solar panel will maybe keep it fully charge through natural wastage but connect it to a half charged battery and it may be back to full in about 5 years.

You need something at least a lot better like a 60w to charge up a battery in a sensible time.
____________________
Nobby the Bastard: How yo tell the difference between the actual japanese and her just screaming because she's had live fish stuck up her arse? [url=https://www.nicks-shop.co.uk/bcf-goodies-15-c.aspGet BCF stickers and things here[/url] Reflective helmet stickers - Legal requirement in france - Clicky

[Marmalade]

if it is a standard leisure type battery at 110amp a 4w charger at maximum capacity for 8 hours a day would charge it in theory in 37 days if there was no usage or natural wastage.
____________________
Nobby the Bastard: How yo tell the difference between the actual japanese and her just screaming because she's had live fish stuck up her arse? [url=https://www.nicks-shop.co.uk/bcf-goodies-15-c.aspGet BCF stickers and things here[/url] Reflective helmet stickers - Legal requirement in france - Clicky

[uberkron]

That panel will fook your battery. You need about four amps to put power int that battery and a controller to waste what isnt needed.
____________________
i ride a zip 50 2smoke. It overtakes a hundred times a day.

[uberkron]

That panel will fook your battery. You need about four amps to put power int that battery and a controller to waste what isnt needed.
____________________
i ride a zip 50 2smoke. It overtakes a hundred times a day.

[G]

As above, only useful to keep it topped up.

For about £100 you should be able to get a 100w panel and a controller that'll do the job well enough.

But, of course, it might be better just to take the battery home with you and charger.

[mic]

£100 could buy another battery to take with me

I just worry about my range limitations that's all. Rowing is shit, I found out the hard way

[G]

85ah - lets say you need to recharge 40amp hours.
Watts = Volts x Amps.
So 40amp hours * 12 volts = 480watt hours.

So on these very basic figures, you'd need a little under 5 hours charging with a 100w panel.

However, that's presuming it's a Sunny day (at least there won't be trees to give you shade).
Also, a cheap charger won't work as effectively as it could - 'intelligent' chargers will vary the output depending on how charged the battery is.
There will be other losses through inefficiencies and the like.

If two batteries will do it (I misunderstood initially) and you can charge them at home, that's probably going to be your best solution.
You can get a 85AH battery new for £56 delivered on ebay.
Note that in reality there is pretty much no difference between most leisure batteries and car batteries.
So if you can find a decent battery from a scrap yard or similar; may be a decent cost effective solution.
Especially if weight's not an issue, you could probably get a nice little 'battery' of batteries. Bit more hassle to get home and charge, however.

Note that if you can get proper 'traction' batteries (used in fork lifts etc), normally 6v or 2v, then they can handle being discharged to much lower levels.

[unitynotsocri...]

As other posters, you need 3 amp to trickle charge it .

There s some great deals on solar panels because the chinese have been dumping them on the western markets,usually the cheaper amourphos silicon type , as opposed to the expensive ,but more effecient crystaline silicon . another smaller battery might help , depending on your energy needs, and the size of your boat ,you could get another big battery and a 5 amp charger so the batteries never over charge , and allowing you to use a small inverter for microwave/kettle/lighting/playstation etc .

check out CPC and Maplins .
____________________
nearly a normal tax paying tosser.......with ferrileness suzi100,cg125,cb125scb100n,cb175,cd100,cj250t,kh250,c15,125 bantam,super 6,rickman gs750,xt500,250rs,dt175,lifan125,dolomite1850,metro,Morris220ld,morrisfg,leyland princess,range rover,corsa,vw camper .now struggling with legs. MORE ORDER = MORE CHAOS

[RayGregory]

[mic]

[quote="RayGregory"]

[mic]

[quote="RayGregory"]

[mic]

[quote="RayGregory"]

[unitynotsocri...]

4 watt is 333 milliamps , fine for longer term trickle charging on car size upwards but over 60 amp an hour battery rating you should use 1.5 to 3 amps.....3000milliamps an hour @ 12 volt.
____________________
nearly a normal tax paying tosser.......with ferrileness suzi100,cg125,cb125scb100n,cb175,cd100,cj250t,kh250,c15,125 bantam,super 6,rickman gs750,xt500,250rs,dt175,lifan125,dolomite1850,metro,Morris220ld,morrisfg,leyland princess,range rover,corsa,vw camper .now struggling with legs. MORE ORDER = MORE CHAOS

[map]

FWIW came across this bike cover with pocket for solar panel.
https://www.sealey.co.uk/Images/Products/MCBL.png

The solar panel for this is
https://www.sealey.co.uk/Images/Products/SPP01.png

There's an additional waterproof connector that you can leave connected to bike battery and plug panel in as/when required.

I'm taking a wild guess here and will say the solar panel can be used without the cover if required

From Sealey site.
____________________
...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger?

[Rogerborg]

I'll recant an earlier recommendation and assert from experience that a panel of that size is essentially useless and won't even stop a battery discharging, let alone keep it topped up. Doubly so in winter, which is when you actually need it.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[unitynotsocri...]

a panel that size knocks out 125 to 150 milliamp and will charge a honda melody battery in about 30 hours of full summer sunshine with no clouds.....and the slipstream of two thousand CG's pulling all together . However , taking your bike to Ghana or equitorial countries would improve matters greatly as the sun is more intense .

Great for trickle charging Honda mopeds and BSA bantams in storage but effin useless when your motorcycle battery is flat because you kept going on social media all weekend when you should of been camping.
____________________
nearly a normal tax paying tosser.......with ferrileness suzi100,cg125,cb125scb100n,cb175,cd100,cj250t,kh250,c15,125 bantam,super 6,rickman gs750,xt500,250rs,dt175,lifan125,dolomite1850,metro,Morris220ld,morrisfg,leyland princess,range rover,corsa,vw camper .now struggling with legs. MORE ORDER = MORE CHAOS