Power pack for AVX?

[jason32]

Hi guys,

I just bought a car jump starter pack from Tesco http://www.tesco.com/direct/4-in-1-power-pack-jump-start-portable-power-usb-power-supply-and-led-torch/141-1002.prd?pageLevel=&skuId=141-1002

It looks like made of extremely cheap materials, just want to know if it would be safe to use it for powering the AVX mount? The manual has many typos and I dont trust anything it says. Specs are not clear but it does say its 17ah.

I paid £52

[ronin]

Does appear to be a fairly robust item and the 12v outputs should do the job on the AVX.

They say to recharge at regular intervals, so that will mean a lead acid battery inside.

The problem with that is the user.

We tend to go out, power things up and carry on until the power starts to run out and the mount goes a bit nuts.

At that stage you/we have drained the battery and also damaged the battery, and it just does not work as well afterwards. It is unfortunately a case that if you expect the battery to last say 4 hours then after 2 hours you stop, pack up and go home. And if all is going well the chances of you even reading your watch is remote.

If you power more then the scope then add that in to the consumption.

As the unit will likely not have taken it into account, make sure that any power output sockets are the right polarity, usually center positive.

[michael.h.f.wilkinson]

The 17 Ah rating is similar to many 17Ah packs for astronomy so it probably is reasonably accurate. However, I would never use anywhere near the full capacity, as that ruins sealed lead acid (SLA) batteries. The astronomy ones often sport extra outputs (like 3V, 6V, and 9V) which are needed by some mounts (like mine). I have had a Skywatcher one for quite a few years, and it worked well until I stored it for too long without a recharge in a garage that was too cold. I replaced the dead 17Ah by a 22Ah deep cycle SLA battery, which is a lot cheaper than replacing the entire power pack. I make a point of monthly recharges and storing it inside. Yours should last if you don't let it discharge too far, and store it in a warm enough place.

[jason32]

Does appear to be a fairly robust item and the 12v outputs should do the job on the AVX.

They say to recharge at regular intervals, so that will mean a lead acid battery inside.

The problem with that is the user.

We tend to go out, power things up and carry on until the power starts to run out and the mount goes a bit nuts.

At that stage you/we have drained the battery and also damaged the battery, and it just does not work as well afterwards. It is unfortunately a case that if you expect the battery to last say 4 hours then after 2 hours you stop, pack up and go home. And if all is going well the chances of you even reading your watch is remote.

If you power more then the scope then add that in to the consumption.

As the unit will likely not have taken it into account, make sure that any power output sockets are the right polarity, usually center positive.

The manual doesnt mention anything about polarity of the 12v sockets, so the standard is center positve? so maybe they are using that too?

[souls33k3r]

Bought a tracer 22Ah. It's a beast and lasts forever with me running my EQ6 mount and 1 dew heater strap. Never looked back

[GeoffB]

For £39 Halfords have a 17ah pack with 2x cigarette plugs and a usb port. It is a lot cheaper than a tracer granted ti has a SLA batteryso is heavierand lime any sla battery pack comes with a frequently recharge notice, but is just over half the price of the celestron 7ah pack, and definately well below the cost of their 17ah equivalent ok you might need to put a bit of red cellophane over the included white led lights but if you use a laptop camera and motorised mount this could aid your power needs possibly by adding an inverter.

[GeoffB]

To check polarity buy your self a cheap electrical tester from one of the DiY chains they are only about £20 and a lot cheaper than stepper motors. However I think there must be an international standard otherwise celestron and meade would not be able to determine the polarity and their leads would not be fit for purpose.