[Fourlanders] Questions about portable power and solar

[Tom McElroy]

Great topic guys.  We were thinking about running off of batteries,
charged by the sun.
But we don't want to run QRP, we want to blast out  100 watts or so.
Do we get any bonus points in that mode?

73
Tom

On Tue, Jun 23, 2020 at 5:30 PM Ryan Kovacs <tukosei at gmail.com> wrote:
>
> I will tell you my experience and setup. I have 2 - 100 watt  (12volt) panels on the roof that feed into a Bioenno solar charge controller (SC-4830JUD). The controller is only for LiFePO batteries. The system is completely independent of grid power. The controller feeds into a 40ah Bioenno battery. This powers all my radios except one. Sometimes I am running 3 radios, 12 hours for 3 or 4 days and never have an issue with power.
> I used to have a different type of controller for lead acid before I changed to LiFePO and never had an issue with that either.
>
> Ryan
>
> On Tue, Jun 23, 2020 at 4:57 PM Ted Wood <ted at k4k.pw> wrote:
>>
>> Fourlanders,
>>
>> Field Day has me thinking about batteries and solar. I've wanted to
>> retrofit my shack out with solar power for a long time and I was
>> thinking a good starting point would be powering just the radio "stuff"
>> first, upgrading until eventually everything is running off of it. I
>> have started off very small scale with a PWM charge controller for the
>> battery with the thinking that I could run the controller off of my
>> shack DC power supply until I was ready to make the switch to a single
>> PV panel. In this way, I had hoped I could run off battery easily and
>> have a fairly robust and seamless charging experience and battery backup
>> solution for the shack. Unfortunately, it would seem I did not do enough
>> homework. DC power supplies are not appropriate power sources for a PWM
>> charge controller. According to many online forums, due to the
>> controller expecting a current limited source such as a PV cell, (and
>> the DC supply is expecting the inverse) you have a situation where
>> there's no current limiting and the controller will draw whatever it
>> can, potentially damaging either the controller or the power supply.
>>
>> Bearing this in mind, here's my goal. I'd like to have something that
>> can take advantage of solar power, when it is available, to charge a
>> bank of batteries but that can switch to charging via commercial power,
>> by way of a DC supply like the one running my radio gear, either until I
>> have panels installed or, once panels are installed, on a cloudy day. I
>> know I can charge the gel cell battery just fine off a standard 12v
>> supply but I'd like to use something that can float the battery instead
>> of overcharging it and shortening it's lifespan (so something that can
>> cut off the charging current when the battery reaches a voltage threshold).
>>
>> Ideally the setup would look something like this fully time, the battery
>> acting almost like a giant uninterruptible power supply.
>>
>> Solar/Power Supply -> Battery bank -> Radio
>>
>> What sort of device am I looking for? Do you have any resources that
>> might help me understand these topics more? How do you do it?
>>
>> --
>> 73
>> Ted
>> K4KPW
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