solar battery maintenance

**Blknight.aus** · 20th November 2016, 01:15 AM

Sure you can.

in that example that with the compressor never cycling off (hence 100% duty cycle)

if you have a roughed out average of your duty cycle divide the estimated life by the decimal percentage of your duty cycel.

IE if you have a predicted time of 10 hours at 100% duty but you know you only average a 70% duty cycle divide by .7

10/.7=14.285(near enough)

IF you're going to play with my field calc stuff remember that they are all based on ignoring perkerts law or having it set up so that it falls in your favor. (which means you get more than your calcs show and is the fudge factor and why I call them field calcs)

theres a bunch of other little things you can do or should be aware of

as the voltage drops the fridge draws more amps, or the duty cycle increases slighty (depending on your fridges setup)

panels and regulators only put out whats needed and the rest evaporates if its not needed. if you plan on charging things its best to do it when the panels are outputting their maximum, perversely, this is also usually the worst time to be charging batteries (heat)

a gang of smaller panels and batteries is better than a single big one for both redundancy and taking care of puekert BUT its more maintenance intensive, costs more and is harder to setup properly.

A single large unit is easier and cheaper but offers no redundancy.

dont oversize the battery capacity, you need just enough to get you from charging to charging and some reserve. higher capacity batteries that are flat need more time to charge and usually higher charging currents.

dont discount how much a small wind turbine will put back into your batteries small wind turbines are now cheaper than some panels and while they dont match up Watt for Watt, the wind turbine can work at night when your loads are lightest.

Fuse the panels at Amax as near to the panel as possible
fuse the regulator at the regulator, the battery and the load output (if it is handling your load switching
Always double fuse leads between batteries (as close to the positive as possible assuming negative earth)
Regulators go near batteries and like to be cool, panels get to be in the sun, like to be kept cool but dont get a whole lot of say about that.

best of luck.

**Ooops** · 20th November 2016, 01:33 AM

Originally Posted by Blknight.aus

not really,,,
theres a rule of thumb for field work that I use but its rough and ready.
.... mathing the RC

sorry to ask but RC?

Originally Posted by Blknight.aus

The best bet for the info is just to look up the battery spec online from its manufacturer.

**Ooops** · 20th November 2016, 02:25 AM

A very useful summary, thanks

Originally Posted by Blknight.aus

...... dont oversize the battery capacity, you need just enough to get you from charging to charging and some reserve.

What % reserve would you recommend?

Originally Posted by Blknight.aus

Regulators go near batteries and like to be cool

So on a permanently mounted roof panel in side the vehicle would be best, but if necessary could it survive in the engine bay?

Appropriately sized cable and within acceptable voltage drop being a given, as its ok to plug solar into the rear Anderson can I take it that a couple of meter cable run between reg and battery is ok?

Originally Posted by Blknight.aus

dont discount ... a small wind turbine
the wind turbine can work at night when your loads are lightest.

Great suggestion, any ideas on sources of info?

**Ooops** · 20th November 2016, 02:30 AM

Originally Posted by DiscoMick

Its not mounted yet, but these are the panel and platform.

Thanks mate

DiscoMick · 20th November 2016, 08:15 AM

My regulator is in the battery box under the front passenger seat.
The comment about wind generators is interesting. I've seen the ones on yachts and thought they would be a good idea for camping as it is often windy at night. What sort of costs are we talking for a compact one? Are they just plug and play?

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**Blknight.aus** · 20th November 2016, 08:23 AM

Originally Posted by Magnet6x6

sorry to ask but RC?

Reserve capacity.

other numbers to watch out for that can be useful are
CCA (cold cranking amps)
Ah (amp Hours)
MCA(Marine cranking amps
CA (cranking amps)
MAX/Min V (maximum and minimum Voltage of the battery, usually an unloaded voltage)
Charge rate (usually for batteries designed to be charged at by fixed current)

Originally Posted by Magnet6x6

A very useful summary, thanks

What % reserve would you recommend?

Something in the positive numbers region. Without knowing all the details its hard to give a direct number and theres a bunch of different ways of achieving reserve. In my case (and my setup is similar to what youre doing, I think.) My reserve is actually my starting battery because I dont have a traxide, However I dont suggest you try that for a few reasons.
1. you dont yet know that I also carry a jump pack that can start my car with no batteries in it. (mainly used for short term power away from the vehicle and it has its on dedicated one way charge lead so its never flat)
2. you might have guessed that as my vehicle is a manual disco1 that I probably know what to do to get it to start without a battery
3. you dont know that when I park up when Im going to use the batteries more than over night I always park up so I have enough room to get a bump start to work (because my answer to the landrover dilemma of do i park on the hill in case the starter fails or on the flat in case the park brake does is to park on the hill and chock the wheels.)

My uneducated answer to any "how much reserve" is almost invariably 30%

Originally Posted by Magnet6x6

So on a permanently mounted roof panel in side the vehicle would be best, but if necessary could it survive in the engine bay?

yes, and yes. But wherever you mount it if it has the option for battery temperature sensing then its a smart idea to fit that up.

Originally Posted by Magnet6x6

Appropriately sized cable and within acceptable voltage drop being a given, as its ok to plug solar into the rear Anderson can I take it that a couple of meter cable run between reg and battery is ok?

Yes, its not utterly ideal but its a good compromise. the setup in my system has the panel up over the front of the roof (in the stepped down section so it doesnt interfere with my roof height) the regulator is mounted in the roof at the rear of the vehicle, the rear power distribution is handled in the right hand rear light cluster area and the battery is up the left front of the vehicle with the power cable run from the right rear lights up through the roof down the drivers A pillar through under the dash to the passangers side, out a gromit in the fire wall and along the left wing to the primary fuse into the battery. While that sounds contrary to the advice Ive given theres an anderson plug at the right rear that is setup to accept a direct connection battery tank when I need to extend my storage capacity or run high current drain gear as well as being able to accept external charging. The cable that runs the length of the vehicle is sufficiently rated that it can be used to run winches.

Originally Posted by Magnet6x6

Great suggestion, any ideas on sources of info?

Google?

normally Id reccoemend jaycar for something off the shelf thats not a budget breaker but your in the wrong part of the planet for them.

**Aaron IIA** · 20th November 2016, 10:02 AM

Originally Posted by Magnet6x6

sorry to ask but RC?

Originally Posted by Blknight.aus

the RC is how many minutes the battery can pump 25A.. convert the RC to hours, mulitply it by 25 and thats how many amp hours are in the battery divide that number by 10 to get the 10 hour rate.

for example battery with an RC of 90 will push 25 amps for 1.5 H

1.5hx25A=37.5Ah

That sould help you. RC is reserve capacity. It is measured in minutes. Your battery should have any of three ratings written on it's top. For deep cycle batteries, xxxAhr, amp hours. For cranking batteries, xxxCCA, cold cranking amps and RC, reserve capacity.

Aaron

DiscoMick · 20th November 2016, 01:07 PM

Originally Posted by Blknight.aus

Reserve capacity.

other numbers to watch out for that can be useful are
CCA (cold cranking amps)
Ah (amp Hours)
MCA(Marine cranking amps
CA (cranking amps)
MAX/Min V (maximum and minimum Voltage of the battery, usually an unloaded voltage)
Charge rate (usually for batteries designed to be charged at by fixed current)

Something in the positive numbers region. Without knowing all the details its hard to give a direct number and theres a bunch of different ways of achieving reserve. In my case (and my setup is similar to what youre doing, I think.) My reserve is actually my starting battery because I dont have a traxide, However I dont suggest you try that for a few reasons.
1. you dont yet know that I also carry a jump pack that can start my car with no batteries in it. (mainly used for short term power away from the vehicle and it has its on dedicated one way charge lead so its never flat)
2. you might have guessed that as my vehicle is a manual disco1 that I probably know what to do to get it to start without a battery
3. you dont know that when I park up when Im going to use the batteries more than over night I always park up so I have enough room to get a bump start to work (because my answer to the landrover dilemma of do i park on the hill in case the starter fails or on the flat in case the park brake does is to park on the hill and chock the wheels.)

My uneducated answer to any "how much reserve" is almost invariably 30%

yes, and yes. But wherever you mount it if it has the option for battery temperature sensing then its a smart idea to fit that up.

Yes, its not utterly ideal but its a good compromise. the setup in my system has the panel up over the front of the roof (in the stepped down section so it doesnt interfere with my roof height) the regulator is mounted in the roof at the rear of the vehicle, the rear power distribution is handled in the right hand rear light cluster area and the battery is up the left front of the vehicle with the power cable run from the right rear lights up through the roof down the drivers A pillar through under the dash to the passangers side, out a gromit in the fire wall and along the left wing to the primary fuse into the battery. While that sounds contrary to the advice Ive given theres an anderson plug at the right rear that is setup to accept a direct connection battery tank when I need to extend my storage capacity or run high current drain gear as well as being able to accept external charging. The cable that runs the length of the vehicle is sufficiently rated that it can be used to run winches.

Google?

normally Id reccoemend jaycar for something off the shelf thats not a budget breaker but your in the wrong part of the planet for them.

Jaycar is online.
https://www.jaycar.com.au/

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**Ooops** · 30th November 2016, 08:14 PM

I've had the set up running without interruption for about a week, here are the readings

14.2w 14.07v 1.08A
1.18Ap 3.33Vm 0.93Kwh
71.1Ah

I've noted during that time

when there's no input from the panel the batteries don't exceed 12.3v ish

the panel seems to max its input at 13.5v and rarely achieves 14v

3.3Vm is a bit weird. I think it can be ignored as I believe it came from a connection I made to a battery on the bench before connecting up to the D3

I've disconnected a spur I had running to the workshop and reduced the cable run between the panel and the crank battery to about 1.5m and there's no change in the 13.5v ish input
I've just checked the panel disconnected and its putting out 20.28v
There's nothing else connected or turned on in the car and AFAIK its been asleep so I can't think what else could be taking power

So why is it limited to 14v or less input and why are the batteries only achieving 12.3v ish?

**Blknight.aus** · 30th November 2016, 09:20 PM

internal discharge in one or more of the batteries.

a diode on one winding of the alternator going leaky but not completely failed yet.

a part of the vehicle not going to sleep properly (security system that stays on listening for the right code because someone has a something transmitting hash on just the right freq)

a corroded joint thats making to earth on something thats permanantly powered.

a relay that drives something thats sticking in the on position even though the relay is de-energised.

something installed aftermarket thats interferering with vehicle operation or is in itself a drain (some cheap USB sockets draw up to 500mA if your using them or not)

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