Do powerpack/jump starters have the power they claim ?

[Justin Smith]

I posed this question on A N other forum but, somewhat surprisingly got no reply. Maybe the members of this forum have some thoughts ?

I needed a portable power pack partly because I now have an automatic car (they cannot be bump started) a d partly because we needed a power pack for camping. I bought a Gooloo GE2000 with supposedly 10,000mAh capacity, though rather inconsistently it says on the box it has 66.6WH battery capacity (10,000mAH at 12V would actually be 120Wh, not 66.6 ? ).

I tried it with my NiMh battery charger linked to the power pack's 12V output but was shocked how quickly it discharged.

So I took it to work and tested it.
I set up a 17 Ohm load from the unit's 12V output and monitored how long it took to discharge the GE2000.
I calculate a 17 Ohm load at 12V should absorb about 8.5 Watts, though in actual fact the average voltage over the test was about 11.2. But even 11.2V into 17 Ohms should be 7.4 watts.

So, if the GE2000 really does have 66.6 Watt hour capacity it should take 9 hours to discharge ?
It didn't, it was flat in about 2.5 hours, by which time its output was down to only 10.4V (would that actually power a battery charger requiring 12V ? ).
2.5 hours at 7.4 watts is about 19 watt hours, less than a third of its claimed capacity of "66.6 watt hours"...... 

Also, when recharging it with its 15V x 1.0 amp charger (= 15W), it should take about 4.5 hours the charge (66.6 divided by 15).
It didn't, it reported it was 99% full after only 90 minutes. It never moved from 99% for a good hour after that, but switching the unit off and on at that point brought up 100% so I am assuming that was just a software issue (it may not register 100% whilst charging till it's rebooted ?).

Am I right, the unit is way down on power ?
Are the others any better ?

[alexp999]

10,000mAh is just them adding up the max rating of all the cells, which are at 3.7V. It’s not based on the output voltage of the unit (though it should be) 

A lot of these things especially cheap Chinese eBay ones also just straight out lie and put weights in to make it feel like it’s full of cells. (Not saying that’s the case with this one)

[TomsFocus]

I don't think this would be much use for charging a car battery.  Need to have 13v or more ideally.  Plus I have a 400Wh powerbank that I can run flat within a few hours on a 230v 4A mains charger.

It should, however, be able to jump start a car easily.

[alanfp]

I haven't checked your readings / methods / maths, but my experience is that yes, they work... if your battery is discharged but otherwise relatively healthy.

As Tom says, it's not designed for charging a battery.

it's designed to start the car (say 600 A for 3 seconds which is about 500 mAh, I think). Then you can get on your way and your alternator will charge your battery.

[alanfp]

6 hours ago, Justin Smith said:

it was flat in about 2.5 hours, by which time its output was down to only 10.4V

10.4 volts isn't completely 'flat'. Flat = zero volts, I would say. But anyway, the manufacturer's figures are probably approximate theoretical figures under optimal lab conditions. So they may not have the power they claim, but they will start your car (several times over). 

[Justin Smith]

14 hours ago, TomsFocus said:

I don't think this would be much use for charging a car battery.  Need to have 13v or more ideally.  Plus I have a 400Wh powerbank that I can run flat within a few hours on a 230v 4A mains charger.

It should, however, be able to jump start a car easily.

Breakdown in communication here !

When I said "recharge my batteries" I meant the batteries we use for our camping lights etc !
The battery charger we use has a 12V PSU and I just plugged it into powerpack's 12V output. 

>>I have a 400Wh powerbank that I can run flat within a few hours on a 230v 4A mains charger.<<

230v at 4A is 920W, so I am surprised it powers it for more than about 25 minutes !

[Justin Smith]

14 hours ago, alexp999 said:

10,000mAh is just them adding up the max rating of all the cells, which are at 3.7V. It’s not based on the output voltage of the unit (though it should be) 
A lot of these things especially cheap Chinese eBay ones also just straight out lie and put weights in to make it feel like it’s full of cells. (Not saying that’s the case with this one)

>>10,000mAh is just them adding up the max rating of all the cells, which are at 3.7V. It’s not based on the output voltage of the unit (though it should be)<<

I  agree, it's bordering on mis-selling.

>>A lot of these things especially cheap Chinese eBay ones also just straight out lie and put weights in to make it feel like it’s full of cells. (Not saying that’s the case with this one)<<

I get that they quote the best figures, but a claimed 66.6W hours is a massive difference from the 19W hours I got. It's so far out I am questioning my methodology, hence the thread !

[alexp999]

1 minute ago, Justin Smith said:

>>10,000mAh is just them adding up the max rating of all the cells, which are at 3.7V. It’s not based on the output voltage of the unit (though it should be)<<

I  agree, it's bordering on mis-selling.

>>A lot of these things especially cheap Chinese eBay ones also just straight out lie and put weights in to make it feel like it’s full of cells. (Not saying that’s the case with this one)<<

I get that they quote the best figures, but a claimed 66.6W hours is a massive difference from the 19W hours I got. It's so far out I am questioning my methodology, hence the thread !

I don't see 66Wh mentioned on the lisiting, only 10,000 mAh. Is it on the product packaging?

10,000 mAh at 3.7V is 37Wh. Which is when they are in perfect conditions, 100% to 0%. So your 19Wh sounds much more reasonable based on it being 10,000 mAh advertised.

[TomsFocus]

9 minutes ago, Justin Smith said:

Breakdown in communication here !

When I said "recharge my batteries" I meant the batteries we use for our camping lights etc !
The battery charger we use has a 12V PSU and I just plugged it into powerpack's 12V output. 

>>I have a 400Wh powerbank that I can run flat within a few hours on a 230v 4A mains charger.<<

230v at 4A is 920W, so I am surprised it powers it for more than about 25 minutes !

Fair enough, I don't have experience with camping equipment. 

The car battery charger doesn't run at 4a constantly.  Starts with 1a and then tests the voltage every 20 minutes to see how far it's increased.  If it isn't increasing quickly enough, it then moves up to 2a and repeats that process until it's fully charged and drops down again just to maintain. 

[Justin Smith]

34 minutes ago, alexp999 said:

I don't see 66Wh mentioned on the lisiting, only 10,000 mAh. Is it on the product packaging?

10,000 mAh at 3.7V is 37Wh. Which is when they are in perfect conditions, 100% to 0%. So your 19Wh sounds much more reasonable based on it being 10,000 mAh advertised.

The 66 Watt hours is on the packaging and in the instructions. It is odd it isn't in that amazon advert.

You are right that 10,000mAh at 3.7V is 37watt hours, but I only got about half that, so even that is wildly inaccurate.

[alexp999]

9 minutes ago, Justin Smith said:

The 66 Watt hours is on the packaging and in the instructions. It is odd it isn't in that Amazon advert.

You are right that 10,000mAh at 3.7V is 37watt hours, but I only got about half that, so even that is wildly inaccurate.

The 66Wh seems totally made up, or literature from a different product.

There will be some loss in the conversion from 3.7V to 12V. And as I say, they are just listing the theoretical maximum capacity of all the cells added up. Add in some discharge and over charge protection circuity, transformer losses, temperature/environmental losses, etc. You will never get the full theoretical 37Wh.

A product branded GooLoo, sold by a Chinese company with a 10 word name is one of those typical cheap chinese products I was talking about, where they nearly always lie and mis-lead.

It's quite possible it has fewer cells than it should and just has some weights in the casing. I watch a lot of bigclivedotcom on youtube and see this a lot.

[Justin Smith]

11 minutes ago, alexp999 said:

The 66Wh seems totally made up, or literature from a different product.

There will be some loss in the conversion from 3.7V to 12V. And as I say, they are just listing the theoretical maximum capacity of all the cells added up. Add in some discharge and over charge protection circuity, transformer losses, temperature/environmental losses, etc. You will never get the full theoretical 37Wh.

A product branded GooLoo, sold by a Chinese company with a 10 word name is one of those typical cheap chinese products I was talking about, where they nearly always lie and mis-lead.

It's quite possible it has fewer cells than it should and just has some weights in the casing. I watch a lot of bigclivedotcom on youtube and see this a lot.

Have you, or anyone else, got a recommendation for a powerpack / starter which can not only start a car (with supplied croc clips) but also has a 12V output socket and a 5V USB, but with more more capacity ?

[alexp999]

6 minutes ago, Justin Smith said:

Have you, or anyone else, got a recommendation for a powerpack / starter which can not only start a car (with supplied croc clips) but also has a 12V output socket and a 5V USB, but with more more capacity ?

Noco are usually the recommended brand on here.

I've got Halford's 3L Lithium jump starter, I only keep it for that though, I don't know how well it works for other things, but I've used it to jump mine sucessfully.

[alexp999]

Its probably worth mentioning that the decent lithium jump starters use a different cell type to those in normal power banks. Power banks typically use "laptop" 18650 cylindrical cells, but jump starters normally contain what looks like a giant modern phone battery, purpose built, layered and designed to provide high current. It may mean that good jump starters don't always make for the highest capacity as a 12V or 5V powerbank, as they've been engineered more for high current than high capacity.

[Justin Smith]

50 minutes ago, alexp999 said:

Noco are usually the recommended brand on here.

I've got Halford's 3L Lithium jump starter, I only keep it for that though, I don't know how well it works for other things, but I've used it to jump mine sucessfully.

I did look at a Halfords power pack, this one, but it does not quote its watt hour capacity, I even phoned them to ask but they didn't know either. Also it's a bit bigger than the others !

[alexp999]

6 minutes ago, Justin Smith said:

I did look at a Halfords power pack, this one, but it does not quote its watt hour capacity, I even phoned them to ask but they didn't know either. Also it's a bit bigger than the others !

That's a lead acid one, it's just got a small car battery in it.

I had something like that before the lithium ones were common and it was a pain to keep charged and then died because I kept forgetting. Lead acid doesn't like sitting around discharging. Lithium is much better at maintaining its charge.

I'll try and remember to look at my lithium one at lunch time to see if it says anything on the bottom about capacity.

[Justin Smith]

34 minutes ago, alexp999 said:

That's a lead acid one, it's just got a small car battery in it.

I had something like that before the lithium ones were common and it was a pain to keep charged and then died because I kept forgetting. Lead acid doesn't like sitting around discharging. Lithium is much better at maintaining its charge.

I'll try and remember to look at my lithium one at lunch time to see if it says anything on the bottom about capacity.

Very useful post.

I defn shan't buy one of them !

[unofix]

On 6/18/2023 at 5:01 PM, iantt said:

This one is around 5 years old.( Who would have thought a lithium battery would last that long)  Still works like new. Handy size to fit in glovebox.

Was using the gb70 to start dead flat transits / cars etc probably 4+  times a day 5 days a week for a few years. Now I keep it in my car just incase I have flat battery The gb40 is a good size to have for normal every day cars

 

[iantt]

Noco good for jump starting but if used as a powerbank  it's not so good. Only used it as a power bank a few times to charge up a few smartphones while sat in the back of a transit van for 48 hrs with no usb ports. Managed 3 phones before it was flat. 

[iantt]

Oh, and had to run a laptop via an inverter in the middle of nowhere for an hour or so until the inverter couldn't cope with the voltage drop from the jump pack. 

[Justin Smith]

2 hours ago, iantt said:

Oh, and had to run a laptop via an inverter in the middle of nowhere for an hour or so until the inverter couldn't cope with the voltage drop from the jump pack. 

I don't suppose you know what the watt hour rating of that power pack was ?

[iantt]

[Justin Smith]

10 hours ago, iantt said:

That quotes 56 watt hours.

I don't know what the power of your laptop is but my old one I am using at the moment quotes 19.5v at 2 amps, which is nearly 40W. So a 56 watt hour powerbank losing efficiency through an inverter maybe isn't that bad as regards its quoted capacity ?
But, bearing in mind a laptop's on board battery should power it for "hours" it also implies the powerpack really isn't that high capacity !

I was just checking up on car battery ratings, and the higher power replacement battery from Halfords for my car quotes 65 amp hours, which at 12.5V would be 812 watt hours, That puts into context how puny those "power packs" are, even if they were at full capacity (which mine was not anyway).....

 

[alexp999]

1 hour ago, Justin Smith said:

That quotes 56 watt hours.

I don't know what the power of your laptop is but my old one I am using at the moment quotes 19.5v at 2 amps, which is nearly 40W. So a 56 watt hour powerbank losing efficiency through an inverter maybe isn't that bad as regards its quoted capacity ?
But, bearing in mind a laptop's on board battery should power it for "hours" it also implies the powerpack really isn't that high capacity !

I was just checking up on car battery ratings, and the higher power replacement battery from Halfords for my car quotes 65 amp hours, which at 12.5V would be 812 watt hours, That puts into context how puny those "power packs" are, even if they were at full capacity (which mine was not anyway).....

 

It won’t be anywhere near 12.5V for most of those Ah though. You have to factor in the voltage drop as it discharges. 

[iantt]

That's why they are primarily a jump starter pack and do that job excellently. That little pack of mine will start multiple dead flat transits in a day before needing a charge overnight via usb charger plug.