I have a small backup battery (7Ah SLA for now, but probably a 130Ah flooded cell outside later) for my two in-house transceivers and two things that could potentially charge this battery: a 30A 13.8V linear power supply and a small 0.5A Battery Tender trickle charger. Right now, I have my HF radio plugged into the 30A PSU and my VHF radio plugged into the Battery Tender and the battery with a simple Y cable I made. This seems to work, but it has the downside that any use of the radio (7-15A draw) drains the battery fairly quickly as the draw is an order of magnitude higher than the charge rate.
I'd like to wire all of these devices into a common circuit.
Three and a half related questions:
- Recognizing that the Battery Tender is likely to see the power supply's output as a fully charged battery and shut off whenever the power supply is running, is there any obvious problem with having two sources of approximately the same voltage on the same circuit?
- Since this would be in parallel, the battery would still end up providing some (half?) of the current to drive the radios when they're used, right?
- As far as I know, car batteries are charged by simply throwing 13.8V at them from the alternator with no attempt made to reduce available current once the battery is charged. Can I just charge the battery with the power supply by simply having them in the same circuit? If the power supply is on but not powered, is it possible that it might accidentally provide 120V back into my wall socket?