[TenTec] Help with gel cell battery and solar charging system....

Dr. Gerald N. Johnson geraldj at storm.weather.net
Sun Jun 7 19:27:29 PDT 2009

On Sun, 2009-06-07 at 12:14 -1000, Ken Brown wrote:
> Hi John,
>      I recommend Home Power Magazine. If you can find someone who 
> subscribes, who would let you borrow a bunch of issues, or a library 
> that has it, you can learn plenty about these kinds of systems. Even 
> without subscribing you can get a lot of information on their web site. 
> You can also get a package deal including past issues on CD if you 
> subscribe. There is lots and lots of information there.
>      If you intend to run your radio directly from the batteries, not 
> using an inverter and 120 VAC, then you probably want a 12 VDC battery 
> system. You would probably use 12 V photovoltaic panels. A MPPT ( 
> maximum power point tracking) charge controller between the photovoltaic 
> panels and the battery will possibly be a source of RF noise, since they 
> are switched mode voltage converters that can get some charge current 
> into your batteries, even when the voltage coming out of the PV panels 
> is lower than the battery voltage. Since these charge controllers are 
> voltage conversion devices, your PV panels may not have to be a 12 volt 
> system to use a 12 volt battery. You can also use DC to DC voltage 
> conversion from the battery to the radio, another possible noise source, 
> but also another possible way to have higher current at the load with a 
> higher voltage lower current capacity battery.
>       By using a 12 volt battery system, you could operate the radio 
> directly off the battery, with no switched mode voltage conversions 
> running at night when the sun is down. A nominal 12 volt battery system 
> will drop below 12.6 volts output when there is still a lot of available 
> energy left in it.  Low voltage cutouts to protect the battery from 
> excessive discharge are typically a bit under 12 volts for a nominally 
> 12 volt battery system. But will the Orion II still be working at that 
> voltage? You need to find out what DC voltage the Orion II really needs 
> to work properly. A six cell battery system may not actually provide 
> that voltage for very long. You may need a DC to DC converter between 
> the battery and the load anyway, in which case you may want to consider 
> a higher voltage battery. 24 volt and 48 volt systems are pretty common 
> these days. 12 volt systems getting less and less common anymore when 
> inverting to 120 VAC. By using higher voltage PV arrays and batteries, 
> you can use smaller wire. Twelve volt systems these days seem to be only 
> use for very small systems with only one or two PV panels in the array.
>      The simplest system for you would probably be one or more 12 Volt 
> PV panels, a charge controller and a 12 volt battery of the necessary 
> Ampere Hour capacity, which depends on your usage. You may also want 
> another way to charge the batteries when you get a lot of cloudy weather.
>      QST had an article about 12 VDC to 120 VAC inverters recently, 
> which was the best description of the difference between 'True sine 
> wave" inverters and modified square wave inverters (which the inverter 
> manufacturers marketing departments call "modified sine wave") I have 
> seen. The renewable energy folks at Home Power Magazine and other 
> information sources often only discuss that difference in terms of what 
> devices you can power, and not so much discussion about the generation 
> of RF noise.
>      If you have a safe place to keep your battery, which includes 
> venting and a way to contain any possible electrolyte spillage, then I 
> would go with a liquid electrolyte lead acid battery. Plain liquid 
> electrolyte batteries are a bit more tolerant to accidental abuse than 
> gel cells, and for the same capacity they are usually cheaper. If you 
> overcharge or charge at too high a rate you may evaporate some 
> electrolyte. With a liquid cell you can replace it by adding some 
> distilled water. With a sealed gel cell battery, if you vent any water 
> vapor from the gel electrolyte, it is gone forever, and the battery will 
> never be the same.
> Ken N6KB
There is a ham made product for getting 13.8 volts out of a 12 volt lead
acid battery, surely its not noisy. Whether it would handle an Orion II
at full transmit, I don't know.

Fully wet cells are the most tolerant. Auto batteries are not very
tolerant of deep loading without rapid charging. Deep cycle or marine
batteries are more tolerant of long discharge times. When you pick out
one in the big box store, learn the date coding and pick the one that
has been on the shelf the shortest time. It will give you the best

You need a charge regulator and one that makes up for low solar panel
voltage gets considerably more energy per day.

Energy from solar panels is horrendously expensive compared to paying
the power company even 14 cents a KWH unless you have to pay several
thousand bucks a mile for the power line.

73, Jerry, K0CQ

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