Advice on debugging a ResMed Power Station II?

Hey all, I have a ResMed Power Station II that I used last year during a week long camping trip (with access to power during the day to charge), to power my S9 Adapt SV, it worked great. Yesterday I was going on a one day trip, I charged it, the lights indicated charging and full, but it wouldn't power the cpap machine. When I connected them via the DC cable and turned on the battery; the cpap did not power on, and the battery shows a blinking green light which indicates "on but not discharging" (it should be solid). The voltage is correct (24V, though I tried both); the battery is charged; the cpap works fine on wall current; and it doesn't seem to matter if the humidifier is connected or not.

It seems like the most likely explanation is the DC cable is bad - that would cause exactly this result - so I ordered a new one one, but I'm just wondering if there is anything else I could be missing or should try. The manual had very little in the way of troubleshooting suggestions. The temperature is well below the 95 degree max. I leave in a week for a week long camping trip and I have to get this working. It only has a 6-month warranty and it's quite pricey, I really don't want to have to buy another one.

Ideas welcome,
thanks.

If you have access to a volt-ohm meter, you could check for continuity in the cord in question. If is bad (one of the connections is broken), then that lead will show no conductivity and establish the cord is the problem.

Thanks for the reply. I ordered a replacement cord overnight, but got the same result today when it arrived. The blinking light is blue, BTW, not green - it's the DC status/discharge light.

I always used to have a multimeter when I was younger but I don't think I have one anymore, let's see....nope. Anyway, seems it is not the cord that is problem. I sent a message to ResMed support and will try calling them tomorrow.

Since the problem is not solved via cord replacement, perhaps a new multimeter would allow you to check output voltages on the power supply. They are fairly inexpensive these days at places like Harbor Freight.

FYI, the issue was the battery being dead because of not recharging it every month. Expensive mistake.

You might want to check on the feasibility of replacing the cells inside the battery.
Before that, check if the battery can be "renewed".

The real problem is Resmed, using proprietary design just to make even more money selling accessories. I'd buy a 12 volt powered unit if I was going off the grid, in fact I'd buy one because its the standard for most D/C products.

I'd pick a 12 volt one just for off grid, and a real battery to power it. Jim

patrissimo wrote:FYI, the issue was the battery being dead because of not recharging it every month. Expensive mistake.

"Dead" as in "throw it in the trash?" That is a big problem with lithium batteries. Not recharging them every month makes it worse, but it can happen even if you do everything right.

Lithium ion batteries have a very low rate of self discharge. About 1% per month. That means that the battery would go dead in around 8 years.

It appears the problem is with the design of the circuit. If the circuit continues to draw off the battery even when off, you have problems and need to recharge often. Circuits can be designed to eliminate this parasitic draw.

HoseCrusher wrote:Lithium ion batteries have a very low rate of self discharge. About 1% per month. That means that the battery would go dead in around 8 years.

It appears the problem is with the design of the circuit. If the circuit continues to draw off the battery even when off, you have problems and need to recharge often. Circuits can be designed to eliminate this parasitic draw.

It's more complicated than that in the real world. They often don't live up to expectations.

One of the problems is that almost all lithium ion battery packs have a safety circuit that will "blow a fuse" when it detects certain things like deep discharge or overcharge. They have to do this because lithium batteries tend to catch fire if they are abused in various ways.

I still maintain that a properly designed circuit that uses lithium ion batteries doesn't have to be charged every week...

I have a spare pack for my computer. 6 months ago I discharged it to 50% for storage. I just put it in and it is still at 50%. It wasn't charged every week and didn't go dead.