12v supply to SW HEQ5 pro mount

[julian489289]

I have begun to use my home made power box as previously posted on this site "Portable 12v Power Box".  Now that it is getting use, I have noticed a slight flaw, I think. 

Despite using an 85 ah 12v deep cycle leisure battery to power the box I have noticed that the red LED light on the HEQ5 sometimes blinks slowly when in use.  I think this means that the mount is getting less than 12v??  I note the output voltmeter on the power box is around 12v-12.5v when this happens.  If I just supply the mount with no other accessories I get a steady red LED on the mount.

The other equipment that I use connected to the Power box are;

8" dew strip plus telrad dew heater (constant draw), electric focusser (only draws power when in use), 12v USB power hub & power to my Canon DSLR 650D.

I have read somewhere but cannot recall where, that the sweet voltage for the HEQ5 pro is 13.8v??  Have I dreamt this as I cannot find this info now?  I am now thinking of a 12v buck/step up converter to add to the power pack to boost the 12v supply to 13.8v.  However, I see these convertors vary from 2amp to 10amp DC output and was wondering what ampage to go for, 5amp and what to boost the voltage to??

I would love to hear your thoughts/suggestions in this matter please.

Looking on ebay I have seen examples below and would welcome comments ;

  http://www.ebay.co.uk/itm/38V-DC-DC-Converter-Digital-Boost-Buck-Step-Up-Down-Module-Solar-Charging-Y5R7/112509948792?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

http://www.ebay.co.uk/itm/DC-DC-Automatic-Step-Up-Down-Boost-Buck-Converter-Module-5-32V-To-1-25-20V-5A-UK/371988371346?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

http://www.ebay.co.uk/itm/5A-8A-10A-150W-200W-DC-DC-Boost-Converter-Charger-Step-up-Step-Down-Power-Module/272509451478?ssPageName=STRK%3AMEBIDX%3AIT&var=571577447312&_trksid=p2055119.m1438.l2649

Hope you guys can help, thanks for looking

Kind Rgeards

Julian

 

[LightBucket]

I have just had similar issues with my EQ6 and himebuilt hub, see here, there is some good advice, the mount will run fine from around 12v to 15v...I use a 13.9v bench power supply.

 

[julian489289]

Thanks for the reply.  I was also wondering what max output ampage to go for 5a or more?

[LightBucket]

Also if your leisure battery is only putting out just over 12v then either it needs a charge, or it’s on its way out, as they should put out at least 13.5v we had one for years on our caravan, and as soon as the voltage dropped below 12.5 when charged, it never lasted more than a few weeks then we had to get a new one, also they like to be used and not just once in a while....

[julian489289]

The battery does put out 13.5v when not loaded, however, when I connect all accessories the voltmeter display drops to around 12v and this is when the LED on the mount starts to flash. 

[cjdawson]

Sounds like you are putting too much strain on the battery.  That's why the voltage is dropping, that's normal.  However, it could be an indication that the battery is on the way out.

[LightBucket]

On 25/09/2017 at 09:12, julian489289 said:

The battery does put out 13.5v when not loaded, however, when I connect all accessories the voltmeter display drops to around 12v and this is when the LED on the mount starts to flash. 

I have this problem recently, mine turned out to be one of the main wires supplying the power hub, not up to the job...when slewing mount the light was flickering all the time as the voltage was dropping, the culprit was a cigar plug and socket extension lead which was rated at 5 amps, got rid of that and 13.5v all the time and solid red light on the mount...

[Merlin66]

I've been successfully using a voltage convertor 12v to 15 v , 120 watt on both my HEQ5 and NEQ6 for the past six years or so, certainly stops this type of problem and works 100%

 

[julian489289]

Thanks guys.

To further clarify your queries, the battery was new in March this year, 12v 85ah so I would have thought that it should be fine. 

I am running my HEQ5 mount from the battery power box (not mains fed) and I also connect my dew heaters for the scope & telrad.   It also provides power to my electronic focusser which does not constantly draw power and power my DSLR through Simon FLETCHER's DSLR 12v to 7.4v power box.  Also connected to my power box is my 12v 7 port USB hub so that each accessory can be connected to my laptop.   Do you think this is too much for my power box??

At the start of the night, I get 13.5v output from the battery even with all accessories connected.  It is as the night progresses and when this output drops to around 12v this is when the led on the mount begins to flash.  Hence the thought of using a step up boost converter.  I assume that the power lead connecting the mount to the power box must be OK and of sufficient quality as when output is above 12v the mount led does not flash??  

My understanding was that as the battery voltage starts to fall the boost convertor would ensure that my power box always outputs sufficient voltage for the mount.  Is this correct?

Then I have the questions, would a 12v to 15v be too much for the mount and my other accessories or to get a variable converter and set this output to 13.5v.  Also what wattage to go for, I note 100w gives max current of 8a.  Then, would I need a converter which is heat sinked as I understand that these run very hot which may affect their performance??   Merlin66 where did you get your converter from and could you suggest a link to one please as there seem to be so many different converters??  Is your converter heat sinked and does it run hot?

Sorry for the many questions but I just want to make sure that I buy right and just once rather than a number of converters to find the right solution.

Thank you 

 

[LightBucket]

It really does sound as though the battery is starting to fail....as the voltage is dropping so quickly..that is what happens

The thing is with leisure batteries, is they like to be used all the time and not left unused, I know you say it was new in March, but how long had it been standing before you bought it...!

Having a 12v to 15v converter, wont really help if the voltage is dropping, you need a constant 13.5 volts for a good few hours, as it is an 85ah battery and lets say you are drawing a fairly average 5 amps, (obviously that will be up and down) then it should put out 13.5v for around 15 hours, if it isn’t, then it’s starting to fail..

[pete_l]

2 hours ago, julian489289 said:

At the start of the night, I get 13.5v output from the battery even with all accessories connected.  It is as the night progresses and when this output drops to around 12v

Unless your 3 dew heaters are very powerful, a battery of this size should easily last several nights.

One thing, is the battery being recharged to its full capacity? I'd check the terminal voltage when your charger indicated "full"

[parallaxerr]

Something that hasn't been mentioned yet is the power cable. I use a home made power box with a 12V regulator running off a 4S Lithium Polymer battery, so my HEQ5 only ever sees 12V.

When I first tried it with a coiled cable I had previously made up, the LED would flash, I suspected the supply too. However, I then changed the cigarette lighter plug on the supplied power cable for a DC jack so it was compatible with my supply and no more flashing light @12V. That's with dew heaters running off the same supply and both axes slewing at max rate.

[julian489289]

51 minutes ago, pete_l said:

Unless your 3 dew heaters are very powerful, a battery of this size should easily last several nights.

One thing, is the battery being recharged to its full capacity? I'd check the terminal voltage when your charger indicated "full"

Thanks Pete

I have a voltage meter connected in the power pack.  After a full charge it shows 13.5v sometimes 13.8v.  But this during the night, perhaps over 2-3 hours with everything connected begins to drop towards 12v??

[julian489289]

42 minutes ago, parallaxerr said:

Something that hasn't been mentioned yet is the power cable. I use a home made power box with a 12V regulator running off a 4S Lithium Polymer battery, so my HEQ5 only ever sees 12V.

When I first tried it with a coiled cable I had previously made up, the LED would flash, I suspected the supply too. However, I then changed the cigarette lighter plug on the supplied power cable for a DC jack so it was compatible with my supply and no more flashing light @12V. That's with dew heaters running off the same supply and both axes slewing at max rate.

I will check the power lead but I do not get the flashing LED when my voltmeter shows 13.5v in the power box but only when it gets to around 12v does the LED begin to flash??

[parallaxerr]

You could still have a drop across the lead that isn't an issue with 13.5v but it may be supplying the mount with less than 12V when your power box reads 12V.

I'd be tempted to measure the resistance in the lead, I can check mine as a reference if you like?

[LightBucket]

21 minutes ago, julian489289 said:

I will check the power lead but I do not get the flashing LED when my voltmeter shows 13.5v in the power box but only when it gets to around 12v does the LED begin to flash??

That’s normal..

[parallaxerr]

My bad lead has a resistance of 7 ohms which means less than 2 amps at 12V, light flashes.

Good lead = 2 ohms, thus capable of carrying 6 amps at 12V, no flashing.

As I said, my supply is 12V 5A regulated so voltage is constant.

Some reports state the HEQ5 draws in excess of 2A when slewing so it's worth checking

[julian489289]

17 minutes ago, parallaxerr said:

 

 

11 minutes ago, LightBucket said:

That’s normal..

That's what I was thinking, does that not mean the lead is OK??

[julian489289]

8 minutes ago, parallaxerr said:

My bad lead has a resistance of 7 ohms which means less than 2 amps at 12V, light flashes.

Good lead = 2 ohms, thus capable of carrying 6 amps at 12V, no flashing.

As I said, my supply is 12V 5A regulated so voltage is constant.

Some reports state the HEQ5 draws in excess of 2A when slewing so it's worth checking

Thanks Jon.  I will have to borrow a multimeter to check mine.  By the time, the red Led begins to flash is when I am doing the astro photography subs so the mount is just tracking not slewing at this time.  Does that mean the mount would be drawing much less than 2A?

[LightBucket]

7 minutes ago, julian489289 said:

 

That's what I was thinking, does that not mean the lead is OK??

Yes, if it works fine with battery fully charged giving out 13.5v then lead is ok..

[parallaxerr]

Just now, julian489289 said:

Does that mean the mount would be drawing much less than 2A?

Yes, it should be drawing milliamps then. That suprises me given how mine behaves, I actually measured my regulator output at 11.9V and still no issues.

 

[parallaxerr]

3 minutes ago, LightBucket said:

Yes, if it works fine with battery fully charged giving out 13.5v then lead is ok..

It means it's OK at 13.5V, nothing else. But, given the info in the last post, I too would be looking at trying a different battery.

[LightBucket]

2 minutes ago, parallaxerr said:

Yes, it should be drawing milliamps then. That suprises me given how mine behaves, I actually measured my regulator output at 11.9V and still no issues.

 

My EQ6 will work fine slewing on both motors on full speed with 11.5v but absolutely no less, and nothing else drawing power, and during this it draws just under 2 amps unloaded, and around 4 amps fully loaded

[parallaxerr]

1 minute ago, LightBucket said:

My EQ6 will work fine slewing on both motors on full speed with 11.5v but absolutely no less, and nothing else drawing power, and during this it draws just under 2 amps unloaded, and around 4 amps fully loaded

Exactly, however it transpires the OP's problem occurs when tracking, not slewing, at which time the mount draws significantly less.

[Merlin66]

The convertor I use I think came from Maplin. No heat sink etc. 

It's marked 120W Laptop car power supply, L40BB

Input 12-16V DC 11.3A max

Output 15/16/18/19/20V DC 6A, 22/24V DC 5A, 120W max

I use it on the 15V setting. No issues, no drama.