Battery Backup for the Ham Shack

Here's how I'm now providing battery backup for my ham shack: the Chunzehui Electronics-Salon CZH-LABS Model F-1006 Low Loss PWRpath Battery Backup Module.

Before I get to this $39 device, let's talk about how I got here.

You've probably seen this item.  It's the Super PWRgate PG40S from West Mountain Radio.  It's a $140 box that electronically switches between mains and battery power - and charges your backup battery.  Cool unit, but a little pricey for me.

So I have used an elegantly simple battery backup solution in my ham shack.  It's merely a SPDT 12V relay that has Anderson PowerPole connectors attached to it and allows automatic switching from a 13.8VDC mains power supply to a 12VDC sealed lead-acid battery.  I've had it running a couple of years and found it on eBay while looking to build my own.  At $25, it's a reasonable enough price to buy rather than build.

It works well, but it does not offer automatic charging of the battery and the radios briefly switch off as they transition to battery power - though most of my rigs will power back on automatically.  That appears to be a feature of newer rigs, as my oldest HF rig (an Alinco DX-70T) does not power back on following the switchover.  When mains power is restored, the switchover back to mains is seamless.

I've never tried a switchover during transmit - and won't.  No reason to risk ruining a rig over curiosity.  If all my rigs are running receive, the station draw is in the 3A neighborhood, so it's a good test.

I have 2 50AH SLA batteries that I rotate on charge; that is, I keep one on the charger while the other is running the station as backup battery.

Recently I noticed a new item that looks to do what I want at a far cheaper price than the PWRgate: $39 from Amazon. It's the Chunzehui Electronics-Salon CZH-LABS Model F-1006 Low Loss PWRpath Battery Backup Module.

This unit uses MOSFETs to switch, rather than Schottky diodes and apparently has less voltage drop and heat generation.  I took it apart to inspect it before attaching any serious load to it.  Looks good.  The FETs seem to be 2 each in parallel - probably to handle the 30A load.

The charger in it is simpler than the West Mountain one - this one delivers up to about 1A versus up to 10A in the PWRgate.  There's a big resistor that is not attached to a heat sink.  So that limits the charging it will do.  Best to use it only as a maintenance charger.

I assume the multi-turn pot is to adjust the charging cut-off, but there's no documentation to that effect.

Docs are straightforward.

Here's what was included:

The case is really heavy duty! Thick metal.

Hooked it up last night and it works very well! Power switched seamlessly and the auto-charge function appears to work.  I tested it with perhaps a 20A load (transmit) and a 3A load during switchovers from mains to battery and back.  I let it run overnight, though unhooked it when I left this morning.  I don't like leaving (high) power supplies running while away.

This is a remarkable product for less than $40.

I would recommend spending another $20 and getting a higher current charger (e.g. 5A) for the times you really run-down the battery.  I have a 50AH station battery and if that were completely exhausted, the PWRpath could take 2-3 days to fully charge it - and it would be quite hot doing so through that resistor.  For keeping the battery topped-off, the PWRpath is ideal.

On the load side, I run the output into an 8-port fused PowerPole strip, very similar to this one.

It may be this one, but I could swear I paid more like $40 for it, a couple of years ago. $58 is not bad for all you get.

Yeah, that has to be what I have. I remember being impressed with the packaging. Very well thought-out!

I have 2 of these: one for home and one for the "go kit".

Back to the PWRpath.  Here are my suggestions to improve the product and / or to work around what I perceive as flaws:

  1. Fuse the battery. Unsure if there's a risk the circuit could create a direct short if the battery circuit failed.
  2. Make sure your load is fused - either with the rig's power cord or with a distribution strip like the one above.
  3. Fuse the power supply input similarly.
  4. Use an external charger for deep charges of a large battery.


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