Thread: storage battery discharge

Just checked my cheapie battery protector it cuts out at 11.5 engel have either 10.5 or 11.5 depending on what you select

regards battery life do you leave your solar set up charging when you are at home the regulator should go to trickle charge when they are fully charged so they should in theory last longer that way.

as far as I know,,,

it charges when the suns up,,

no sickies for solar panels

10.5 is the lowest voltage that gives a decent compromise between overall battery life AND the amount of power you draw from them.. HOWEVER...

setting it slightly higher (say 10.8 or so) gives you a bit of margin to deal with the error factor within the units.

solars pretty much set and forget unless you count the occasionally re aiming of the panels to net a few more amphours out of them.

Depends on the battery type.

Supercharge recommend no lower than 11.56v ( 20% SoC ) for their Allrounders, but some AGMs, like an Optima will tolerate 0% SoC, 10.5v but I would keep it a bit higher and stick to not going below 11.56v for any battery.

Originally Posted by Pedro_The_Swift

At some stage this year I will be replacing my solar reg with a better quality unit. The one I'm looking at has a low voltage disconnect which I can adjust.

What one are you looking at?

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Morningstar Corporation » ProStar

Originally Posted by Pedro_The_Swift

Morningstar Corporation » ProStar

Me too

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Originally Posted by Pedro_The_Swift

.................................The question is,, what volts can I run the bats down to?
or,
what is the Engal low voltage threshold?........................

How low should the batts be taken to is perhaps more important. The lower the battery voltage is taken the more time and effort to re-charge properly. Generally speaking dead flattening a battery and then 'fast' recharging is a good way to kill off a battery, especially a non-deep cycle type.
Blknight and drivesafe are both correct. You can take your battery down to below 11 volts but it's not a very good idea to take it below around 11.5 volts.
The other side of the coin is the recharge cycle. It's easier and quicker to re-charge a battery from 11.5 volts than from say 10.8 volts, and your chances of having a good battery at the end of the charge cycle is greater.
My Engel MF35 compressor runs at below 11 volts but not very efficiently. I reckon its duty cycle at this voltage would be around the 90% mark compared to say 40% for full voltage under the same conditions.
I run an Engel MF35 with a 'cool zone' top off an Optima 66AH deep cycle battery and an Engel MF17 off 120AH of AGM battery. Under 'normal' conditions (Central Australia in June/July say 25-35 degrees C) the MF35 fridge which is set at +2 degrees C is opened probably 20 times per day and the battery lasts approx 36 hours without recharging. The beauty of the Optima battery here is that it fully charges from the alternator in about 1 hour or so. The MF17 is used as a freezer and is set at -5 degrees C and is opened only once per day. After 36 hours its battery voltage is still above 12 volts.
Don't know if any of this helps Pedro but having a system that allows a residual voltage of 11.5 volts or greater under your 'worst case scenario' would be a good if possible. I've found that the Optimas quick charge characteristic is not to be underated and more than compensates for its comparative lack of capacity (N70 equivelent Optima deep cycle is 66 AH compared to 'standard' N70 of around 90-100 AH).
It is not uncommon to see portable solar panels set up with the regulator at the panel feeding 20 metres or so of comparatively light cable to a vehicle/battery. ie. the regulator at the wrong end of the cable. Another pitfall to be wary of. Not saying this is you Pedro but a general observation.
A question here, any reason why you've chosen a non MPPT type regulator ? I understand these are more efficient than conventional regulators.
I used to maintain small rural/remote solar powered systems using Morningstar regulators and found them to be very reliable. Only had one failure and that was due to a lightning strike.

Deano