Cheap li-ion batteries- any good?

[MarkInSpace (Mark)]

Any experience with the cheap li-ion battery packs available on eBay?
I’m wanting to power my HEQ5.
https://www.ebay.com.au/itm/174259683785

[glend (Glen)]

Pretty much all li-ion batteries are made in China these days. Battery packs are usually just an assembled block of AA cells, if you remove the covering to examine them. My electric bike battery pack is an assembled block of AA cells. I was speaking to a guy at Jaycar about the big Li-ion batteries they sell, and he admitted thry were just a bunch of AA cells bridged together inside a nice outside packaging.
There are numerous Utube videos that show how to build large Li-ion batteries out of AA cells. There was one I saw where a guy had built a complete Solar Battery system on the wall of his garage, from hundreds of cheap Chinese AA cells with little link components.
So yeah, why not, a Li-ion pack can power an HEQ5, if you have enough AMP capacity to support the motors.

[billdan (Bill)]

A lot of people on CN use Car jump start batteries which will last all night before a re-charge. As long as they are Lithium based and not Lead-Acid.

So checkout Supercheap Auto or Bunnings that sell them, you will have to cut off the car battery crocodile clips and solder a plug suitable for our use..

https://www.cloudynights.com/topic/7...lescope-mount/

[MarkInSpace (Mark)]

So Li-ion is better than Sealed lead acid?

[MarkInSpace (Mark)]

I found this: doco says it can deliver 12V and it looks well built...
https://www.jaycar.com.au/20-000mah-...ports/p/MB3797
any thoughts?

[glend (Glen)]

Originally Posted by MarkInSpace

I found this: doco says it can deliver 12V and it looks well built...
https://www.jaycar.com.au/20-000mah-...ports/p/MB3797
any thoughts?

That 20,000mah is equivalent to total 20amps, at USB voltage and amps. I doubt you could rig it to power an HEQ5, which requires 12Vs. Skywatcher says the HEQ5 needs, 11 to 15 V DC 2Amp (Tip positive).

The car starter booster battery packs are probably ok, but keep in mind they are designed to provide alot of amps for a very short period, to start a car, and typically they contain about a 17amph battery.

If you need 12V 2amph for say four hours, you need 8amps of supply. Since recommendations are to never discharge below 60% capacity that 17ah battery might not do the job for a long period of time. A 20Amph 12V battery would be a better choice. Also have a look at 12V alarm batteries, they are designed for home alarm back up, are small, and you can buy various AH capacities. Doesn't matter if they are sealed lead acid. Sealed lead acid batteries are always cheaper. Have a look at this one:

https://www.batteriesdirect.com.au/s...yABEgJgnfD_BwE

[MarkInSpace (Mark)]

I found this at repco, I’ll give it a try...
https://www.repco.com.au/en/globes-b...200/p/A5483555

[MarkInSpace (Mark)]

FYI, I purchased the 8Ah version at Repco - its on sale for $99 - so that seemed a good deal.
Upon opening the box at home, I really like the device - about 3/4 the size of a brick, plus there's a handle on top.
I've tested it at home by re-purposing the cable from an old charger and clamping the wires. Everything seems to run fine, controller seems good, and I can slew both axis at the same time. I'll let it run for a few hours and watch the results.
Repco sell spare connectors for the unit, so i bought a pack and will properly solder them up tonight.

[mswhin63 (Malcolm)]

Originally Posted by MarkInSpace

I found this: doco says it can deliver 12V and it looks well built...
https://www.jaycar.com.au/20-000mah-...ports/p/MB3797
any thoughts?

Not really, I have an HEQ5 and the specs state peak current of 2A yet the max output current is 1.5A. The battery may appear good on the outside and may well power the HEQ5 but I always like to add at least 10% above the maximum spec to be on the safe side.

There are two USB output, but paralleling the output may be risky if they have additional circuitry for phone recognition. This usually restricts the power output based on what is connected.

[mswhin63 (Malcolm)]

Originally Posted by MarkInSpace

I found this at repco, I’ll give it a try...
https://www.repco.com.au/en/globes-b...200/p/A5483555

I can't find an amp hour rating, it may well work but I would need to know what is the Amp-hour or Watt-hour capacity before buying it.

There are 3 types of car starters, ones are lead-acid and possible to deliver high current and offer longevity. The most popular now is the supercapacitor version that holds massive stored energy and can release it but does not offer longevity. Lion batteries could be a good alternative if they have progressed any further for car starters.

[MarkInSpace (Mark)]

Hi mswhin63 -
These are AGM batteries - the one i bought is 8 Ah - turns out that is too little - it powered the scope for about 3 hours or so, then started beeping (beeps at 60%). When i bought it, the store guy said i could return it for a different model - which i will do.
They have a 12ooA and a 1700 A version. I’ll look at them and make up my mind.
I’ll post the results.

[Camelopardalis (Dunk)]

That Jaycar unit looks like a winner BUT most mounts when they start a slew want more than what can be stepped-up from a USB connector.

I found this out by trial and error...I have a 15mAh unit from JB and it works perfectly besides the initial current required to start moving...so a bit of a gotcha

[MarkInSpace (Mark)]

No problem - this unit has a 12V output port!

[mswhin63 (Malcolm)]

Originally Posted by MarkInSpace

Hi mswhin63 -
These are AGM batteries - the one i bought is 8 Ah - turns out that is too little - it powered the scope for about 3 hours or so, then started beeping (beeps at 60%). When i bought it, the store guy said i could return it for a different model - which i will do.
They have a 12ooA and a 1700 A version. I’ll look at them and make up my mind.
I’ll post the results.

As mentioned, you need to get Ah rating. The total current is not a measure of capacity on how much current is can push. 1200A may be able to blow a hole in a 3/16th spanner, 1700A may melt it in half. But if the Ah rating is on 8Ah then it won't be enough.

As you have already tested the 8Ah battery it is easy to determine how much you need. Simply multiply by the time you actually need to use it for and add extra 10% on top as a comfort zone.

For 12 hours - Ah required = (12 x 8)/3 = 32Ah plus 10% = 34.3Ah.

Anything above 34.5 Ah should give you approx 12 hours with leftover. AGM can go to 60% reasonably well although still better to go to 80%.

[MarkInSpace (Mark)]

I ended up with the biggest version of the unit they had - 22Ah. I was out tonight for 4 hours, lots of slewing, and had no problem. It’s a nice compact unit, but much heavier than the 8Ah version - 6kg. Still, it’s compact and the spare connector availability is a big bonus for me.