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Post Info TOPIC: Solar
gypsy2600


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Hi,

 

Just wondering if there is a wrong/right way to charge your caravan batteries whilst the van is under cover.

 

I have been running a power cord from our power point to the van each time the voltage drops to around 12V.

 

Some others charge their batteries by placing their  "mobile" solar panels in the sun or have one on the roof of the carport. 

I think they use the term trickle charge. Those on the roof  or the mobile ones remain connected so they keep trickle charging until the next trip.

Your advice would be appreciated.



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Mike Harding


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Whilst the van is idle the best way to maintain the battery is to connect the van to 240V and turn off everything in the van except the battery management system, this will ensure the battery is kept on "float charge" which is the ideal way to store a lead acid battery. The cost of electricity for this exercise is next to nothing.

 

Edit: Just re-read your post:

Leave the 240V applied to the van permanently; what you have been doing by removing 240V and allowing the battery to self discharge is very bad for it and will reduce its life.



-- Edited by Mike Harding on Wednesday 4th of August 2021 01:34:48 PM

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Craig1


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our permantley connected 240v charger was costing over a $1 per day. queried them, " oh thats what it does". now have a potable panel connected.

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Mike Harding


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Craig1 wrote:

our permantley connected 240v charger was costing over a $1 per day. queried them, " oh thats what it does". now have a potable panel connected.

Something is wrong:

$1 per day = 4kWh - *no way on this planet* would a 12V battery float system use 4kW in one day... unless it were making itself toast and tea every 15 minutes.

I would expect such a system to use about 30W per day maximum.



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"I beseech you in the bowels of Christ think it possible you may be mistaken"

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Whenarewethere


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At a dollar a day, 3 to 4 kWh are going into the battery, I doubt it.

Unplug all the gadgets.

A smart charger will stop charging & will top up when needed, about once a week.

 

I do this our auxiliary batteries.



-- Edited by Whenarewethere on Wednesday 4th of August 2021 02:06:00 PM

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Cupie


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When at home, which is most of the time, I leave the smart charger connected which keeps the van battery on flost.

As I rarely use the Patrol, I have it connected to a solar panel which also keeps its battery on float.

 



-- Edited by Cupie on Wednesday 4th of August 2021 03:32:30 PM

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Peter_n_Margaret


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We have some tinted polycarbonate sheets in the shed roof. They let enough sun in for the solar panels on the OKA to do their thing.
Set and forget.
If they did not, I would use a 5W portable panel.
There is no value in running a 240V charger, for anything.
Cheers,
Peter

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OKA196, 4x4 'C' Class, DIY, self contained motorhome. 960W of solar, 400Ah of AGMs, 310L water, 280L fuel. https://www.oka4wd.com/forum/members-vehicles-public/569-oka196-xt-motorhome
 

 
gypsy2600


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Hi,

 

Would like to thank you all for the advice.

Will leave the 240V connected.

 

Cheers

Bob



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Cupie


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Peter_n_Margaret wrote:

We have some tinted polycarbonate sheets in the shed roof. They let enough sun in for the solar panels on the OKA to do their thing.
Set and forget.
If they did not, I would use a 5W portable panel.
There is no value in running a 240V charger, for anything.
Cheers,
Peter

 Yep you are right.   

My van is under a tarp when home resting so I can't use the solar panels.  Perhaps I'll pick up a cheap aux panel. and a controller that will float the batt.



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Peter_n_Margaret


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Cupie wrote:
 Perhaps I'll pick up a cheap aux panel. and a controller that will float the batt.

 If you use a small enough panel, you don't need a controller. Connect it directly to the batteries.

5W is plenty.

Cheers,

Peter



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OKA196, 4x4 'C' Class, DIY, self contained motorhome. 960W of solar, 400Ah of AGMs, 310L water, 280L fuel. https://www.oka4wd.com/forum/members-vehicles-public/569-oka196-xt-motorhome
 

 
Mike Harding


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Peter_n_Margaret wrote:

 If you use a small enough panel, you don't need a controller. Connect it directly to the batteries.

If you do that then when the battery is fully charged the panel voltage will exceed the maximum specified for the battery.



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Cupie


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Mike Harding wrote:
Peter_n_Margaret wrote:

 If you use a small enough panel, you don't need a controller. Connect it directly to the batteries.

If you do that then when the battery is fully charged the panel voltage will exceed the maximum specified for the battery.

 It was my intention to use the controller to restrain the charge voltage to 13.7/13.8, which is what my smart charger presents on the float stage.



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Peter_n_Margaret


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Mike Harding wrote:
Peter_n_Margaret wrote:

 If you use a small enough panel, you don't need a controller. Connect it directly to the batteries.

If you do that then when the battery is fully charged the panel voltage will exceed the maximum specified for the battery.

 No it won't.

Cheers,

Peter



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OKA196, 4x4 'C' Class, DIY, self contained motorhome. 960W of solar, 400Ah of AGMs, 310L water, 280L fuel. https://www.oka4wd.com/forum/members-vehicles-public/569-oka196-xt-motorhome
 

 
Mike Harding


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Peter_n_Margaret wrote:
Mike Harding wrote:
Peter_n_Margaret wrote:

 If you use a small enough panel, you don't need a controller. Connect it directly to the batteries.

If you do that then when the battery is fully charged the panel voltage will exceed the maximum specified for the battery.

 No it won't.

Will! Will! Will!

My Dad said so!



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"I beseech you in the bowels of Christ think it possible you may be mistaken"

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Peter_n_Margaret


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OK, so when the battery is full, the panel voltage WILL exceed the maximum specified by the battery, but since the current is very low, it will not matter and will not be detrimental to the battery.
Happy now?
And please pick up that dummy.
Cheers,
Peter

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OKA196, 4x4 'C' Class, DIY, self contained motorhome. 960W of solar, 400Ah of AGMs, 310L water, 280L fuel. https://www.oka4wd.com/forum/members-vehicles-public/569-oka196-xt-motorhome
 

 
Craig1


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DSCN6902.JPGHere it is, power bill went up by a lot, around $90 for 88 days, so bought a metering device, plug into each thing. This was the last thing checked, as it " could not" be using all that power. Sure enough it was though. So unplug van and just remember for about 3-4 hours once a month, until recently put panel on instead, with a small Jaycar reg.



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peatop


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I own a Harley and if any of you know Harley thingsdontcomecheep! but the bms $69 I use it for everything lead acid, my camper trailer sits in my driveway as there's no room in my garage and I don't have a cable long enough to reach panels in the back yard

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thomas01


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Craig,

You've got me beat. To use that much power just to keep a battery charged does not make sense. The photo wasn't clear enough to show what the reading on the charger was. Could you please provide further information with regards to voltage and current draw from the charger.

If a small portable solar panel is keeping the same battery fully charged now, there is no way the 240v charger was costing $1 per day to do the same job. If it is correct then I suggest you check the condition of your fire extinguisher, because you may need it soon.

Regards Robert

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Mike Harding


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Peter_n_Margaret wrote:

OK, so when the battery is full, the panel voltage WILL exceed the maximum specified by the battery, but since the current is very low, it will not matter and will not be detrimental to the battery.

Maybe....



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"I beseech you in the bowels of Christ think it possible you may be mistaken"

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Mike Harding


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Craig1:

If a 12V battery was absorbing 4kWh per day there would be a pool of molten lead on the floor - something else is happening.



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Craig1


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Plugged in charger as the breakaway needed a charge and havent been confident about leaving it on "charge "to potentially suck from house battery, 120ah AGM Full River.

It read 14.4v on absorption to start, then later in arvo it was on float, still 14.4v

Breakaway said condition good, but still charging.

Original house battery passed on after 6 years and it had leaked a small amount.

So maybe time to look at alternate 240v replacement as I have proved it uses plenty of 240v and thats what their agent told me when I queried it. Just such a pita to change over this stuff with limited back and tight original install.

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Whenarewethere


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Mike Harding wrote:

Craig1:

If a 12V battery was absorbing 4kWh per day there would be a pool of molten lead on the floor - something else is happening.

4000w/24h/13.85v = 12 amps every hour going into the battery.

 

More likely the neighbours plugged in an extension lead under the caravan!



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Are We Lost


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Maybe it feeds an element in your water heater. Is the water hot?

If the battery is dead it will suck power, but will also be HOT.

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Craig1


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no hot water or lights or rangehood or fridge were on.

The battery could have been slowly on the way out, but if so it took another 10-12 months to die

And no the neighbour did not jump the 6 foot fence to suck some spare juice.

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Whenarewethere


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The Australian standard on the smallest domestic hot water tank 25L is a standby heat loss of 1.18kWh per 24 hours.

I think 4kWh per 24 hours is pushing it. At 167 watts per hour something is warm.

 

 

Maybe the hydroponics lighting setup?



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Procrastination, mankind's greatest labour saving device!

50L custom fuel rack 6x20W 100/20mppt 4x26Ah gel 28L super insulated fridge TPMS 3 ARB compressors heatsink fan cooled 4L tank aftercooler Air/water OCD cleaning 4 stage car acoustic insulation.
Craig1


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actually about 3300 watts at our price then.

No grow lights or pumps or triple air compressors

No heron ac running on gen set either

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kgarnett


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Has the breakaway brake system been accidently activated ?

A tandem brake system would draw somewhere around 14A.
Then 14A x 13V x 24h would equate to 4.368 kWh / day.

Food for thought.


Ken

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Craig1


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Ken,
I will double check that, but dont think so. thanks

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