Leaving on the hard: Batteries OK?

[Paul Elliott]

Originally Posted by lowey49er

Your friend is on the right track ,cover two of your three solar panels with a cover and make sure the starter battery is connected to your bank ,( use small jumper leads ,if not), for the number of sunny days you will get during the winter the one solar panel will do just fine and not cause any battery grief,
I do this with my mobile home , where I have four 200watt solar panels and ten 55amp/hour gels in the bank, the batteries are always showing 13/14 volts and I leave the inverter and the fridge/freezer running while I,m away.I also use a 60amp. controller.

If you already have a properly set-up controller, there's no need to cover any panels.

With a no-controller, direct panel-battery connection then you might be able to limit the charge to a safe level by shading panels, but this requires measuring the current and adjusting the shade appropriately. I wouldn't recommend this at all.

Also, I don't think the OP should directly connect his start battery to his house bank. In his case the house bank uses flooded lead-acid batteries, and the starter battery is AGM, which wants a lower float voltage than the FLA bank. Perhaps it would be OK if he dialed down the controller so it didn't overcharge the AGM. Then the house bank would at least be kept from going flat.

Remember, we are talking about a seven-month layover, so what might be OK for a day or two could lead to fried batteries in the long run.

I also think the AGM starter battery will be fine for seven months with no charging at all. AGMs have a very low self-discharge rate.

[hellosailor]

If the solar panels are connected via a decent charge controller...Why on earth would you need to cover or disconnect any of them? The controller should be limiting the charge to the batteries, regardless of what is being fed into it by the panels.

[doublewide]

They will lose water while trickle charging. The caretaker will have to add distilled water periodically.

[blackswan555]

Presuming you do have good float settings available the water should be ok, ( temp compensated around 13v, "Should" ,,,, But I would check sg & levels every few months if possible)
I look after a few off grid solar systems using FLA's, As the Island I live on is seasonal & a lot of the properties are empty for 6 months in winter I have a similar problems, Some have float capability (panels) some do not,
My " best winter practice" is similar to a float battery (big UPS, telecoms backup, etc), In a float battery it would be every 6 months (EQ approx every 100 cycles in off grid), In our case end of season,

Charge batteries fully until SG's stop rising at normal voltage, EQ batteries untill SG's stop rising, (top up water half hour before end to correct levels, half hour before gives it time to mix) check and spray grease all connections, If you have float, turn it on, If not disconnect all connections to them, Keep in mind that batteries will freeze if you store them in cold climates (lower charged, more easily) If you can, Check them every few months, SG's & water,
Start of season, remove, clean, grease all connections & reassemble,check water, Do not top right up now, it will expand during charge and make a mess, If you have had decent float, The SOC/SG's should still be high, If no float, recharge at normal voltage to full,
Next bit, difficult to give numbers but the idea is to drain the batteries down to %50 SOC with a C/5 load, (make them work hard) The purpose being to combat sulphation which occurs when batteries stand idle or are under used, Crystals block pores, Good hard discharge / recharge clears them, Deep cycle batteries,,, well the clue is in the name, They NEED to be deep cycled occasionally, Drain batteries to around 50% / 1.200sg, (I use electric heaters) allow to rest depending on temp, Recharge at normal voltage & EQ, The final EQ as well as combating Sulphation sorts out the stratification that has happened in storage (heavy "acid" sinks to bottom)

Tim