Emergency Solar Power Source

[AdmiralCochrane]

Exactly.  I have seen some that had current limiting ability, that is what I would buy and I would not expect them to be inexpensive. 

[Lscott]

4 hours ago, Sshannon said:

 

He specifically asked about a good charge controller. 

There is a wide spectrum of charge controllers. What he needs is very dependent on the particular equipment, batteries and panel array.

If the panel array/size is large compared to the battery bank then try to find a charge controller that can be "programmed" to limit charge current, voltage points etc.

I have several "good" charge controllers from this company.

https://sunforgellc.com/product/gv-5/

My solar panels range in size from as small as 5 watts up to 100 watts. I pick the panel size to match the charge controller and battery pack I want to charge, I have several LiFePO4 types from 3.3AH to 40AH.

However the charge controllers I have are not "programmable". So, what is a "good" charge controller in one system design may not be so good in another.

[WRKC935]

The issue with a non-current regulated PWM charge controller is the state of discharge when the sun comes up or the winds begins to blow in the case of a wind system.  What happens is the cheap charge controller will apply the float charge voltage value to the battery.  Depending on it's state of discharge, that can be a current below or ABOVE the maximum rate of charge for the battery that's connected. 

Couple ways around this, but it WILL effect the charge rate if you overdo it. If a single 7Ah battery needs 2.5 amps maximum of current being dumped into it, if you put 4 of them in parallel and charge them with a 10 amp source, then they are only getting 2.5 amps PER battery.  But that maxes out the source current, and leaves NOTHING for doing anything else like charging phones or other tasks.  So you really NEED a good charger to do it right.

 

But there is another issue with charging batteries.  And that's just trickle charging them when they are depleted or significantly discharged.  Batteries also need a minimum amount of charge current to charge them.  Not providing enough current is almost as bad as too much current.  And of course, they will not typically recharge completely in the window of time you have the secondary charge source working IE wind or sun.  And NEVER leave a battery open circuit for an extended period without charging it.  THat will destroy a battery.  I have a string of very large and heavy  two volt lead acid batteries that this was done to.   I am going to TRY to dump current into them and see if I can get them to charge, but I am not hopeful that will happen.

 

[WRFP399]

Here is good information on charging lead acid batteires.

 

https://batteryuniversity.com/article/bu-403-charging-lead-acid

 

[WRWR489]

I use a 200 watt panel and 3 group 27 marine deep cycle batteries and after a week of cloudy days I am still at 13.7 volts. I have a 10k gen for the house, but the batteries are just for radio stuff.

[AdmiralCochrane]

On 4/8/2023 at 4:15 PM, WRWR489 said:

I use a 200 watt panel and 3 group 27 marine deep cycle batteries and after a week of cloudy days I am still at 13.7 volts. I have a 10k gen for the house, but the batteries are just for radio stuff.

I've been considering the same set up.  What panel and charge controller are you using? 

[WRWR489]

I will have to look it up. The setup has been in use for 1.5 years. It all came from Amazon, but I upgraded the charge controller from the one that came with the package deal.

[WRWR489]

This one, but upgraded to the wanderer controller.

https://www.amazon.com/Renogy-200-Watts-Volts-Monocrystallin/dp/B015DEY2TM/ref=sr_1_3?crid=JQ2BBMBVYVTD&keywords=200%2Bwatt%2Bsolar%2Bpanel%2Bwith%2Bcharge%2Bcontroller&qid=1681165702&sprefix=200%2Bwatt%2Bsolar%2Bpanel%2Bcharge%2Caps%2C124&sr=8-3&ufe=app_do%3Aamzn1.fos.c3015c4a-46bb-44b9-81a4-dc28e6d374b3&th=1

[WRKC935]

Since this was last discussed I have moved forward on getting equipment moved over to the battery plant.  I am now running 3 repeaters and 5 base stations (repeaters programmed for base station operation) on the battery plant.  The plant is 48 volt and has 4 strings of 75 AH batteries connected to it.  I need to get out the welder and build another battery tray and increase the string count to 6 or 8, but that's a different discussion. 

The system is grid tie only at this point.  No solar or wind equipment has been setup for it.  A project for a later date.  Looking at running 4 wind generators based on the plastic 55 gallon drum design.  Will be building one and seeing how that works before building the other three.

System as it sets is a commercial rectifier (charger / power supply) that is a modular setup with 8 40 amp switch mode supplies.  These feed into the attached power distribution panel that has connections for both battery strings and loads.  There are five 48 volt to 24 volt switch mode buck converters with a current capacity of 40 amps per unit connected to the plant that are paralleled output.  These feed a separate power distribution panel to feed the 24 volt loads.  One feed is running over to a 'sub panel' that is rated 70 amp in and has 5 15 amp breakers that are feeding the base radios and repeaters.  This is their only power source and have been running in this configuration for about a month now.  I am working on getting some additional cable tray in place and will then be running additional feeds to other equipment. 

Another project is to convert the 12 volt plant that is separate from the 48 volt plant over to that plant.  This will be 48 volt to 12 volt conversion.  most likely will be two 60 amp buck converters in parallel feeding another distribution panel for the 12 volt loads. 

I am researching the fact that Cisco had a backup power setup for some of their switches that i already have.  I may be able to directly feed these switches with 12 and 48 volt power and take them off 110 all together.   They are running on UPS currently but if I can move stuff over to the battery plant, then I will have less equipment to maintenance.