Kenwood System Key Generator

[Mirtha Hinrichs]

SoI got to thinking... I've got a gas generator but in an emergency, I'm not going to want it running 24/7. What are you guys doing for battery backup to power your base station (I'm guessing repeater backups are much more complicated)?

APC UPS? Something else? I'm not so concerned that the radio stays on if the power goes down as much as a means of running the radio for a time, perhaps recharging the batteries with the generator or hooking it up to a solar panel.

Personally I would go the route of batteries as the primary backup. Then, because I have them, I would use them also as the primary power source. I would keep them topped off at all times using a high-quality smart charger; one the floats when full and recharges fast.

If I were planning for extended power outages, I would then look to either a propane generator or solar panels. If generator, I would use propane because I have 400 gallons almost always available onsite and fuel does not go bad.

In the event of extended power outage, and assuming I was using a generator to recharge the battery, I would likely use a high-capacity smart charger to allow bringing the batteries up to full capacity with least amount of generator runtime, thus making the most efficient use of the generator when it was on.

I would use small UPS units only for short term specialty needs like a computer because most are not designed for long-term use and because they have generally very limited storage capacity. UPS in general are not incredibly efficient. They use power to convert voltage from DC to AC. They will also draw your batteries down when turned on, even when you are not drawing any load from them yourself.

From a repeater standpoint, I have a built in back up battery which can run the repeater for about 24 hours. This was tested this year after a hurricane came through and knocked out power for a while. Luckily damage was limited to downed trees and some shingles blown off the roof.

Many repeaters come with a battery revert/charger system just for this. Most times batteries are only meant to hold over the system until the genset is up and running (about 5 minutes.) I put two RV deep cycle batteries in, and for a system that runs low power it can run for quite some time.

Motorola makes a separate module for some of their older repeater systems (GR1225 for example) which could work for any radio. -hln9455a.html This is the unit I have in my own repeater build. There is no downtime at all and it even runs the fan to keep the repeater cool.

Checking amazon they also have revert kits selling for about $65. -BBM-1225-Converts-External-interrupted/dp/B0073HTV76 They do the same thing the HLN9455A does. Do make sure you purchase a good power supply that is rated for the load draw and charger draw at the same time. And like any other battery set up, be sure to fuse at the battery, and at the power supply for safety and circuit protection.

I have a pair of 6-Volt Trojan golf cart batteries sitting in a large plastic tote just outside of the house. The batteries are hooked in series with a 100 Amp Maxi Fuse for short-circuit protection. I have #2 copper welding cables running inside the house to a ground bar, and a 12 Volt distribution block with 12 ATO type fuses. (look for 'marine fuse block') Everything in my ham shack, including my GMRS repeater, runs from that. I have a regulated power supply hooked up to it to float-charge the batteries.

The power rarely goes out here, but if it ever did, I have a portable 5KW Generac Niagara mounted to a steel wagon siting in my garage, ready to wheel out and plug into the changeover panel on the back of the house.

Thinking along these lines, any idea how a 100 watt solar panel hooked to a solar distribution controller to a 12 volt deep cycle battery (similar to your Trojan setup) would do? I'm in So Cal so the one good thing we do have is sun.

I have several LFP, Lithium Iron Phosphate, batteries. Gave up on any type of Lead Acid since they tend to get wrecked if you don't keep them on a battery tender at all times to trickle charge. The LFP's can be charged up and sit around for months or longer, great for emergency use, and they don't discharge hardly at all. In fact for long term storage it's recommended NOT to fully charge them. Try that with a Lead Acid type and you will kill it.

The LFP batteries have a higher terminal voltage, around 13.3 VDC to 13.4 VDC when charged making them a better match to mobile equipment that expects a nominal 13.8 VDC. When the battery is nearly discharged, 90 plus percent, the terminal voltage is still around 12.8 VDC more or less. A Lead Acid battery is around 12 VDC when its at 50 percent capacity. Most mobile equipment spec's 13.8 VDC at +/- 15 percent so the low voltage cut off is at 11.5 VDC. You won't get most of the capacity out of a Lead Acid battery before the electronics starts to shut down or misbehave.

The link below is for a company that is friendly to two-way radio users for batteries and chargers. I have one of the 6 amp-hour packs for portable handheld radios and one of the 40 amp-hour ones for fixed location use.

LiFePo is probably a better route than LiPo... and yes, the extra cost, IMO, clearly outweighs not having a working base/repeater if the whole power grid goes down for a few weeks, or... when you or others might need it the most... which can happen... tell that to some people in Puerto Rico.

I used to have a solar array hooked up to my system, but I took it off line due to the fact the solar regulator was cheap, and inferior. It tended to over-charge the batteries, and boil them out on very sunny days.

If I had the money to spend, I would switch to a different type of charge controller, and go with LiFePo batteries, but for now, my setup is working just fine for me, and has been for several years now. It is great for temporary power outages - but if I lived in California, or someplace with rolling blackouts, I don't think it would last long. In my case, the power was out for about an hour and a half last spring during a thunderstorm, and it worked fine through that, allowing me to keep checking into the weather net on the local 440 repeater. My power is very reliable. I flickers or browns out on a semi-regular basis, but it has only been totally off for about an hour or two at a time, 4 times in the last 15 years. Major props to South Central Public Power District of Nelson Nebraska! Great job guys.

Ya'll got me thinking.. I have 400w solar, 4 6v RV batteries and a 2000w pure sine wave inverter in my 5th wheel camp trailer parked near the house. I've left the batteries in going on 5 winters and just let the quality charge controller handle the maintenance. I do check water twice per year but so far have been able to leave them through the winter with no issues.

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