Battery supply voltage - What's best??

[Periphery]

Hi All, I've done some searching but I'm not finding the information I'm looking for.

(Edited: I've found a few posts suggesting 24v and upwards is recommended, but is 48v better than 24v??)

I've used the WS-8-150-DC and WS-12-250-DC units with a 24v supply direct from batteries before but now have the opportunity to increase (or decrease) the supply voltage to the switches I will be installing in future. What is the optimal voltage for best performance / power consumption with the batteries being recharged via solar (from 12v to 72v)?

Thanks in advance for any feedback.

[sirhc]

24V to 48V battery banks are better than 12V yes.

Q: Is 48V better than 24V?
A: It allows you to further drain the batteries in an emergency but to recovery dead batteries you need 10A per battery to recover dead batteries.

Keep in mind these SMART units are best when connected directly to battery bank with an inline fuse with charging unit connected to battery bank as well. A smart multi stage charger is best.

Charging unit should be rated larger than switch power supply rating.

[Periphery]

Thank you sirhc, I appreciate the confirmation. I did wonder if 48v would be more efficient (losses due to step-up transformers?) but perhaps I am being too finicky. 24v solar controllers tend to be cheaper, supplementary small 24v wind turbines are easier to come by and adding battery capacity is a little more flexible.

[Julian]

power supply efficiency does vary slightly based on load current and input voltage. The 12-250 and 8-150's DC supplies operate most efficiently at 24v, and slightly lower at 48, since the supply operates more often in the 'buck' region.

[lligetfa]

power supply efficiency does vary slightly based on load current and input voltage. The 12-250 and 8-150's DC supplies operate most efficiently at 24v, and slightly lower at 48, since the supply operates more often in the 'buck' region.

???
AFAIK the power supply only outputs 50V. It is the switch that then down-converts that to 24V and 3V.

[sirhc]

power supply efficiency does vary slightly based on load current and input voltage. The 12-250 and 8-150's DC supplies operate most efficiently at 24v, and slightly lower at 48, since the supply operates more often in the 'buck' region.

???
AFAIK the power supply only outputs 50V. It is the switch that then down-converts that to 24V and 3V.

The SMART DC power supply will accept 9V-72V

So if it is being fed > 50V it has to down convert 50V to feed the switch board which then yes down converts to 24V and chip voltages like 3V, 1V, and so on.

If there is a 48V battery bank the SMART DC converter will switch between up and down converting as when a 48V battery bank is charging the voltage often goes up above 50V.

The simple answer is 24V and up is best.

If 48V bank then in an emergency you can opt to fully discharge the batteries to keep a tower up.

With a 48V bank and 9V is the lowest it can draw down the bank then if your using 4 x 12V batteries in series each battery can be drawn down to 2.25V or basically dead.

With a 24V bank and 9V is the lowest it can draw down the bank then if your using 2 x 12V batteries in series each battery can be drawn down to 4.5V or also basically dead.


Keep in mind that if you draw a 12V battery down below 9V to 10V you often need 10A per battery to recover the battery, reference your battery specs.

The SMART DC power supply efficiency is very similar anywhere from 24V and up.

[Periphery]

Great detail. Just what I was looking for. I think I'll run with 24v as adding capacity is cheaper and easier.

[Accel Wireless]

I would not drain batteries below 50% just for the fact that going that low you run the risk of damaging the battery or it might reverse polarity on it.

[sirhc]

I would not drain batteries below 50% just for the fact that going that low you run the risk of damaging the battery or it might reverse polarity on it.

Depends on what type of battery and charger your using.

If "good" AGM or deep cycle batteries the risk is low of damaging battery fully draining it, I prefer AGM as no off gassing.

Also when you drain a battery fully dead or below a certain level (battery dependent) you may need 10A per battery to recover.

At my AC sites I use a MinnKota smart charger that charges each battery separately up to 10A each so when AC power recovers it can recover a dead battery.