Just bought two new Gill batteries

[donv]

I talked about this with my mechanic, who grew up around Commanders.

Basically, when the master switch is off, the batteries are isolated and not connected to each other. When the master switch is turned on, relays activate to connect the batteries in parallel.

While it would be possible to charge both batteries with a single charger (per the spec sheet), functionally it would end up being more complicated than just having a single charger on each battery.

[ghancock]

That is interesting.  I've not seen that setup so if that is the case then he would be correct.  I figured the batteries were hard wired together all of the time.  If that is the case though then it would also be possible to wire in the 2 chargers with quick disconnects and not have to take the batteries apart to do the charging.  At least I would think so.

Glenn

[donv]

2 chargers with quick disconnects is exactly the plan.

[donv]

So, it turns out that when the batteries are shut off, they are connected in parallel. So one charger will do it after all...

[Adam Frisch]

Question - if I buy one of those Li-Ion portabe GPU units (StartPac is one manufacturer) and plug it in when I arrive and do my preflight, go to the toilet, finish my coffee etc - will it "top" up the batteries?

Reason I'm asking is I'd ideally like to use it for the engine start of course, but if I'm alone somewhere it just feels a little unsafe to do so, leave cabin and unplug it whilst the right engine is spinning.

[donv]

As always, I don't know about the 680V. However, in 690 and later, the AFM warns against trying to charge the batteries using external power. So I would say that's not a great idea.

If I were you, I would get a battery tender, and then not worry about it.

Whatever you do, don't try to use external power for a start without someone else there to pull the plug! That's a really dangerous thing to do.

[Adam Frisch]

Thea reality is my plane lives outside and I will most likely not have access to GPU starts except for when I refuel. That means I can't battery mind and I have to rely on battery starts for at least 50% of the starts. What are my options?

[donv]

That's how most Commanders are operated. I was discussing GPU starts during my recurrent. I do my recurrent at a large 135 operator who operate something like 10 690s, and the chief pilot said they never do GPU starts. Never.

He's actually interested in my battery tender experience, as they have some 690s in Alaska that they think might benefit from that.

What it means in the end is that you'll need to replace the batteries more often. I just got two years out of mine, and I probably could have pushed them to go longer, but I wasn't comfortable with that. At recurrent, they thought two years was pretty good.

The good news about Turbo Commanders is that there is nothing powered from the battery when it's parked. Even the clocks are wind-up and not electronic, so there is very little to no drain, and it can sit for a month or more and still start right up.

[donv]

Here is my newly installed battery tender setup. Just pull the plug out and put the cover on when you're ready to go.

[ghancock]

Awesome, pretty much like I did in my 310 and plan to do in my 680FP if (when) it ever gets to my hanger.

Adam, I believe they may make some solar tender units but not sure if they go to 24volts and not sure how long it would be on your plane after you left the airport :-)

Here is one such deal: http://www.batterystuff.com/solar-chargers/

I'd do more research on it but would seem it would be entirely possible and if you put it up top the center of the wings somewhere it would be hard to spot. 


Glenn

[Badger]

Glenn,

Question from this old thread:  What trickle charger do you use?  And, do you keep it connected whenever the aircraft is in the hangar?  Thanks!

[donv]

You can see mine in the picture above. I always leave it plugged in when in the hangar.

[Badger]

Thanks!

[Steve binnette]

Here is my newly installed battery tender setup. Just pull the plug out and put the cover on when you're ready to go.

I have the same setup in my 980. Hoping to get a year or two more from my batteries.

Time will tell.  I rarely use a GPU.

[ghancock]

Here is mine:



Glenn