Celestron PowerTank Lithium Pro switching off while slewing using SynScan handset and Skywatcher Explorer 200P EQ5 Pro GOTO Telescope

[Chris Jones]

I recently bought a Skywatcher Explorer 200P EQ5 Pro GOTO Telescope, featuring the SynScan Computerised GOTO Equatorial Mount and to power it I bought the PowerTank Lithium Pro.

I am having a problem and wondered if you have any ideas about how to solve it. 

When I use the SynScan handset to align the telescope to the stars it goes through the automatic procedure first. then I have to fine tune it using the up/down/left/right buttons on the handset. When I slew it on the lowest rate it works as it should but when I slew at the highest rates (8 or 9) the PowerTank shuts off and the handset goes dead. The shop replaced the PowerTank Lithium Pro but still the problem persists. I’ve never seen a battery shut off before, it’s instant. I’m contacting the shop and am hoping to ask the same questions of the SynScan people but I thought I’d ask if any of you might know if the PowerTank had some kind of shut off mechanism? Say when it encounters too much load from the telescope or a back emf from the motor drive? Maybe this is something that’s built in or that any of you have encountered before?

This is my first bit of serious kit and having it switch off part way through alignment is spoiling the experience somewhat.

Many thanks

 

Edited March 30, 2021 by Chris Jones

[michael8554]

The Celestron spec says it will supply 5 Amps, which is what the EQ5 spec says is required.

All I can suggest is a slightly loose and so high resistance connection, fine for low current but bottling out on higher demand.

Or long cables made of thin conductors.

Michael

[lenscap]

52 minutes ago, michael8554 said:

The Celestron spec says it will supply 5 Amps, which is what the EQ5 spec says is required.

Actually the EQ5 Pro spec says it requires 2A, so a 5A supply will be plenty.

I found this statement in the Power Tank Lithium Pro spec;

"Battery shuts off automatically when insufficient current flow is detected to prevent you from inadvertently draining your battery"

Perhaps the low current shut-off on the power tank is faulty. Could you try a known-good supply such as a 12v car battery to see if the fault is in the power tank or the mount?

Edited March 30, 2021 by lenscap
typo

[Cosmic Geoff]

I have a Celestron LiFePo battery, and found that it shuts off if the charge level is too low.  That could be consistent with it shutting off under heavy load.

[michael8554]

21 hours ago, lenscap said:

Actually the EQ5 Pro spec says it requires 2A, so a 5A supply will be plenty.

Most of the recommended power supplies are 5A, I agree that's not the same as the mount spec.

Michael

[Chris Jones]

On 30/03/2021 at 11:28, michael8554 said:

The Celestron spec says it will supply 5 Amps, which is what the EQ5 spec says is required.

All I can suggest is a slightly loose and so high resistance connection, fine for low current but bottling out on higher demand.

Or long cables made of thin conductors.

Michael

Hi Michael

The only cable I have is the one that comes with the Powertank. It's brand new so I am assuming it's ok. The slewing works with no problem when the mount has no telescope nor counterweights on it. Would that fit with your argument?

[Chris Jones]

On 30/03/2021 at 14:58, Cosmic Geoff said:

I have a Celestron LiFePo battery, and found that it shuts off if the charge level is too low.  That could be consistent with it shutting off under heavy load.

I had the tank on charge for 8 hours and the problem happened. It was the same with the previous PowerTank. the mount slews ok with no telescope nor counterweights on it, it happens when I ass ten scope and weights. I measured the current with a multimeter and the highest current I got was 3.1 A, at which point the device shut down.

[lenscap]

Since the shutdown has happened with two different power tanks the cause is likely to be with the handset or the mount rather than the battery. Can you try a different power supply such as a 12v car battery. If the behavior persists you will know that the handset or mount is faulty.

33 minutes ago, Chris Jones said:

I measured the current with a multimeter and the highest current I got was 3.1 A, at which point the device shut down.

This current seems high.  My 200p/EQ5 draws just under 1A with both axes slewing at Goto speeds. (It is Onstep, not Synscan but the motors are similar).

This suggests a mechanical or electrical fault in the mount/handset which is causing the mount controller to draw too much current & shut down.

BTW is the mount under warranty or second hand?

[Chris Jones]

29 minutes ago, lenscap said:

Since the shutdown has happened with two different power tanks the cause is likely to be with the handset or the mount rather than the battery. Can you try a different power supply such as a 12v car battery. If the behavior persists you will know that the handset or mount is faulty.

This current seems high.  My 200p/EQ5 draws just under 1A with both axes slewing at Goto speeds. (It is Onstep, not Synscan but the motors are similar).

This suggests a mechanical or electrical fault in the mount/handset which is causing the mount controller to draw too much current & shut down.

BTW is the mount under warranty or second hand?

Dear Lenscap,

It's new and under warranty and I may go back to the shop with it when lockdown eases a little (it's some distance away). they were helpful and provided  anew battery but were flummoxed as to the casue of the problem, so in the meantime I have contacted the UK agent for skywatcher and also celestron to see if it's something they've encountered before. It may be such and easily put right. I'll see if I can get a car battery as a control test, thanks.