Need a reliable solar/battery solution for network repeater station

[RonJohn]

Our plant has a network repeater station located in a field with two ProSoft RLX2-IHG network radios for connecting our plant network to a well water pumphouse. We have two 12VDC marine duty batteries connected in series powering the radios with a 100W solar panel w/ charge controller to recharge the batteries.

The issue is that several times each winter, the batteries voltage drops due to long periods of heavy clouds & cold temperatures. The radios go through an unnatural shutdown when voltage drops down around 10V and won't power up even after batteries are recharged unless a hard reboot (disconnect/reconnect power plug) is performed.

I'd like input on what devices are out there to prevent the need the need for a hard reboot. Maybe it's something to shut down power to the radios in a more orderly fashion, or better yet a way to keep the batteries from dying out so quickly, either by maintaining charge or preventing voltage drain in cold temps. I'm sure this isn't a novel situation, but it's a new one to me. Thanks in advance for your help!

 

[Robb B]

generator with a low voltage detection? put the batteries voltage on the detection circuit, with a reasonable threshold, maybe 11.5V, the generator can recharge the bank. Many solar charge controllers come with an auxiliary power source connection.

 

[the_msp]

PULS DIN Rail UPS, their battery is 12V and the controller steps up to 24V

PULS 22.5 → 30V dc Input DIN Rail Uninterruptible Power Supply (240W)PULS 22.5 → 30V dc Input DIN Rail Uninterruptible Power Supply (240W)


PULS Rechargeable Battery Module, for use with UBPULS Rechargeable Battery Module, for use with UB

Note if the UPS (battery) ever goes completely flat, you need 24V, not 12V, to 'shock' it back to life

 

[the_msp]

Mfr. Part No.:
UB10.241

Mfr. Part No.:
UZK12.071

 

[BryanG]

Don't supply the ProSoft RLX2-IHG direct from the battery/solar, use a DC/DC converter. This will give you a few advantages, it gives you a reliable smooth stable dc supply, it will shut off the output if the batteries go below a voltage level, it won't switch on the output until the battery volts go above a hysteresis threshold, it stops the batteries from a deep discharge, and depending on the input voltage range for the Prosoft device it might allow things to work for longer. The name isn't good but I have used ones from Meanwell:
https://www.meanwell.co.uk/power-supplies/dc-dc-power-supplies/ddr-120-series

 

[Peter Nachtwey]

I am in my camper as I write this. My camper now has Lithium-ION batteries, but it came with lead acid batteries ( interstate SRM-31 marine deep cycle ). Lead acid batteries have a voltage drop as power is used. THe charge slowly and weigh a lot. They also shouldn't be drained below 12.1 volts unless it is an emergency because that drains them down below 50% and that starts to degrade the batteries faster.

Lithium-ION batteries will maintain a voltage over 13 volts even when 80% of their capacity is used. LI-ION batteries will also provide more charge and discharge cycles as well as charge faster.

The problem with LI-Ion batteries is that it is hard for the charge controller to tell how much energy is left since the voltage doesn't decrease much if at all as energy is used. The good part is that the voltage is maintained at a constant level so there is no problem moving the slide out in even if the battery is down at 20%. Also, LI-ion batteries weigh half as much.

https://www.power-sonic.com/blog/lithium-vs-lead-acid-batteries/

I much prefer my LI-Ion batteries for camping.

BTW, it is 15-16 degrees F here.

 

[OkiePC]

For AC powered installations with battery backup, I used a bunch of the PULS UB10.241 but found that their battery okay relay is not reliable and have started using this battery controller instead:
https://www.automationdirect.com/ad..._power_supplies/specialty_modules/psh-bcm360s

Note that it uses a 12VDC battery and produces 24VDC output. RHINO has other models that accept a 24V battery input and those are even less expensive. I think they're rebranded TRACO units.

For solar, you may want to look at these:
https://www.morningstarcorp.com/products/sunsaver-mppt/

But in any case, your charge controller needs to have a low voltage disconnect where it will shut down the output completely when the battery voltage drops below an acceptable level. With the Morningstar stuff, that is usually about 10% below rating and has some limited adjustability.

 

[RonJohn]

Folks, thanks to all of you for the replies.

BryanG - I looked at the MeanWell supplies. Based on the specs, I'd probably have to go with the 24V input model as the under voltage lockout for the 12V model is too low (8.5V). It's 16.5V for the 24V model, so we'd end up dropping out sooner than now but be able to restart automatically, hopefully.

Peter, I agree that Lithium-ION is the way to fly. Boss balked at the price last year, but if this keeps happening, I wonder if we could get away with one LI-ion instead of two deep well marine batteries, given the characteristics. I do know that our current charge controller would need replaced for LI-ion storage.

OkiePC, thanks for the feedback on the Puls & Rhino units. A-D says Rhino is on backorder. I will definitely look into the Morningstar product, especially if we end up going with a LI-ion battery upgrade.

 

[diat150]

None of these answers actually answer the question. Increase batteries and solar panel capacity. Thats the only answer to increasing the runtime on the radio system. If you have power at the water well I would look at installing a battery charger which would eliminate the need to increase the capacity of the solar and battery bank, assuming you dont lose power at the water well for long periods of time.

 

[RonJohn]

None of these answers actually answer the question. Increase batteries and solar panel capacity. Thats the only answer to increasing the runtime on the radio system. If you have power at the water well I would look at installing a battery charger which would eliminate the need to increase the capacity of the solar and battery bank, assuming you dont lose power at the water well for long periods of time.

Agreed that preventing the voltage drop outs is the long term answer, however taking steps to automatically restart the radios when voltage does drop out is a big help in the interim.

We have power at the well pump but it's about 1/4 mile to the relay station from there. Running AC from the pump house to the relay station is an option they're exploring come springtime.