Thread: solar battery maintenance

Back tracking a little .....

Originally Posted by Blknight.aus

For charging..

Batteries have lots of numbers around them and cover lots of details, the 2 that count most for basic charging are 1. the max charge rate (amps) and 2. the max charge voltage.

some of the batteries have damaged data stickers where bits of info can't be read
In cases where the info isn't to hand is there a convention or a formula or that can be used to calculate the max charge rate (amps) and the max charge voltage?

Originally Posted by DiscoMick

The auto electrician reckoned it was necessary to stop any short as close to the battery as possible.
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Thanks. Using one I understand but I'm still curious as to the benefit of using two. I'm not saying its wrong, I'm just trying to learn some thing.

Originally Posted by DiscoMick

If it helps I'm mounting my 80 watt panel across the front of a Rhino Rack platform

Any chance of a piccy DM?

Hi again Magnet, and 14.3v is fine, so your alternator is working.

If you had doors open and had had them opened for a while, then 12.3v is average.

So again, not any real problem.

As far as charging any lead acid battery goes, if you make sure the charge voltage does not go over 14.4v, you will fully charge any type of lead acid battery and will not risk damaging any type of lead acid battery if you leave the charge source on the battery for any length of time.

NOTE, the 14.4v charge voltage applies to Battery chargers, DC/DC devices and solar regulated charging, and all these types of charging devices should go into FLOAT mode once the batteries are fully charged.

Alternator charging can safely go as high as 14.7v and will not damage batteries because you do not drive long enough to cause a problem.

Originally Posted by drivesafe

14.3v is fine, so your alternator is working.

If you had doors open and had had them opened for a while, then 12.3v is average.

Thanks for the peace of mind

What were your thoughts on connecting the solar panel to the crank battery? Should the negative go an earthing point on the body or is it ok to clamp directly to the battery?

Originally Posted by Magnet6x6

Thanks. Using one I understand but I'm still curious as to the benefit of using two. I'm not saying its wrong, I'm just trying to learn some thing.

If you are joining in a second battery, you need a fuse at both ends of the joining wire. If it rubs through and shorts out, you need it to isolate at both ends, as you have a power supply at both ends.

Aaron

Originally Posted by Aaron IIA

If you are joining in a second battery, you need a fuse at both ends of the joining wire. If it rubs through and shorts out, you need it to isolate at both ends, as you have a power supply at both ends.

Aaron

Thank you Aaron

Originally Posted by Magnet6x6

Back tracking a little .....



some of the batteries have damaged data stickers where bits of info can't be read
In cases where the info isn't to hand is there a convention or a formula or that can be used to calculate the max charge rate (amps) and the max charge voltage?

not really,,,

theres a rule of thumb for field work that I use but its rough and ready.

max voltage for any kind of lead acid battery is 14.5v (field rule) on a low charge rate

optimal charge rate is the 10 hour rate (which is how many amps it takes to flatten the battery in 10 hours and is worked out by mathing the AH value or mathing the RC into an AH rate and then working that AH rate

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

37.5Ah/10h=3.75A. (which is nearly exactly what it takes to drive an engle so an engel with a 100% duty will eat that battery in 10 hours (it wont it lasts longer because peurkets law)

so 3.75 Amps or near enough 4 amps is the optimal rate of charge for that battery

max charge rate I normally recommend is roughly double that BUT remember most chargers will self regulate on the voltage level so the battery looks after itself.

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


Winding back a little to your comment about genuine panels.

most panels make what they say, to start with. the Quality of a panel is how long it keeps its output within 10% or so of its max power.

panels degrade a little bit quite quickly, then enjoy a fairly good life span before slowly (and then exponentially) beginning to drop their out put.

Originally Posted by Magnet6x6

Thanks. Using one I understand but I'm still curious as to the benefit of using two. I'm not saying its wrong, I'm just trying to learn some thing.


Any chance of a piccy DM?

Its not mounted yet, but these are the panel and platform.
I thought about mounting it directly to the bars, but I already had the platform and bars so its easy to use it and cover more roof. Just need some angle brackets and clamps.
I've already wired up the Defender so its ready to plug in.
Incidentally, I don't know about the smart alternator in D3/4s which vary their output depending on load, but my Defender just churns out a steady 14 volts, which is perfect for charging batteries.
I recommend before heading away you use a good battery charger overnight so everything is 100% charged, as driving may only take your batteries to 80-90%. The last 10-20% needs a slow charge from a multi-stage charger.


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