Car jump starter for fridge

Submitted: Wednesday, Sep 14, 2016 at 16:57
ThreadID: 133440 Views:7699 Replies:9 FollowUps:8
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There are mini jump starters on ebay, claiming 68800 Milliamphours of output. Is it viable to use one of there to power a Waeco in the back of a car overnight, then recharge via the vehicle alternator. They cost around $70 to $100.
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Reply By: Sand Man (SA) - Wednesday, Sep 14, 2016 at 18:14

Wednesday, Sep 14, 2016 at 18:14
Not suitable Mikee5.

These mini jump starters provide a high amount of current for a short period.
You require something that provides a sustained amount of current (under 10 amps) but for a prolonged period of time.

You need an auxiliary battery to power the fridge, separated from the starting battery by an isolator and capable of being charged by the vehicle alternator while the engine is running. (Dual battery system)
Bill


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AnswerID: 604377

Follow Up By: V8 Troopie - Wednesday, Sep 14, 2016 at 19:00

Wednesday, Sep 14, 2016 at 19:00
I second that. There most likely is a super capacitor in these things. I played around with supercaps and the big ones certainly can start a car.

It would power a small light for quite some time but a fridge, maybe a few cycles.
They do have the advantage of very rapid charging if your charger is up to that.

As Bill says, stick to an auxiliary battery for that application.
V8Troopie
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Reply By: Life Member - Duncan W (WA) - Wednesday, Sep 14, 2016 at 20:42

Wednesday, Sep 14, 2016 at 20:42
Mikee5, I used to use one prior to getting a duel battery system in my old 4wd. I could run my Waeco for 3 nights before needing to recharge the power pack. Mine was the 900amp one from Super Thief and was an excellent buy at the time. I upgraded to the 1100amp one when they came out.
A good cheap alternative.
Cheers
Dunc
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Follow Up By: garrycol - Wednesday, Sep 14, 2016 at 22:19

Wednesday, Sep 14, 2016 at 22:19
Completely different piece of kit.
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Reply By: Member - Mike P4 - Wednesday, Sep 14, 2016 at 21:37

Wednesday, Sep 14, 2016 at 21:37
The lithium ion battery in these small chargers is great to start your car and charge your phones but will not run a fridge for long. They discharge power very quickly hence the ability to start large motors from a small unit. But lack reserve capacity.
AnswerID: 604390

Reply By: Jackolux - Wednesday, Sep 14, 2016 at 22:07

Wednesday, Sep 14, 2016 at 22:07
I have run a CPAP machine from one for 2 and bit nights .
AnswerID: 604391

Reply By: Batt's - Wednesday, Sep 14, 2016 at 23:45

Wednesday, Sep 14, 2016 at 23:45
I would agree with the above comments designed for high output etc. If you don't want to set up a dual battery system then you can get a dual purpose battery to replace your starting battery. Before I set up a dual battery system this year I ran my fridge off my starter battery which is a 105ah supercharge allrounder done that for around 7yrs in 2 different 4WD's without any problems. You just need to figure out what power draw your fridge has and get a battery to suit the bigger the better. My fridge/freezer is power hungry so I would get 2 days out of it and was still able to start my 4.2ltr diesel just throwing the idea out there..
AnswerID: 604393

Follow Up By: Genny - Thursday, Sep 15, 2016 at 08:19

Thursday, Sep 15, 2016 at 08:19
Not a great advocate of introducing/increasing the risk of NOT starting after being parked up in an isolated spot. My natural trend to caution would steer me towards a power source other than my starting battery.
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Follow Up By: Batt's - Thursday, Sep 15, 2016 at 11:52

Thursday, Sep 15, 2016 at 11:52
It works fine if you first try experimenting at home how long your fridge and other accessories will run for and it's a good idea to do the same experiment if you have fitted a dual battery system. Keep a voltmeter handy to check battery level and having a battery charger handy if or when you run the battery to low. You can determine approx what your limit is and stay well within that but when you're on the road don't forget to take weather conditions and distances driven into account to give yourself a good safety margin. You can also fit a digital voltmeter gauge to your car to keep an eye on the battery if you need though I never fitted one. It all may sound like to much work or effort to go too for some but it's better to have some knowledge of your products limits from playing around at home than to just plug it in and expect to never have any trouble when out in the bush which quite often happens to those who are not interested in learning about their gear and it's limits. In saying that yes we all have things we're interested in and things we are not that's how it is.
When I was working at TJM yrs ago I had a customer with a new Pajero that didn't want a dual batt system so I recommended trying this which he did and he was quite happy with the simplicity of the idea and was not aware these batteries were available. He returned a few months later and was very happy because he didn't have to lug his fridge into motel rooms for overnight stays but he still carried the 240v adaptor for the fridge which I use to do if I thought I was pushing the batteries limits.
Sorry about the big story you may not have expected this kind of reply but while some may think it's still too risky others take measures to reduce the risks and get good results and as I previously mentioned I done this for around 7yrs and never had a flat battery.
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FollowupID: 874160

Follow Up By: Genny - Thursday, Sep 15, 2016 at 12:24

Thursday, Sep 15, 2016 at 12:24
Love the long story. Shows you are a chap who does his sums!
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FollowupID: 874163

Reply By: Genny - Thursday, Sep 15, 2016 at 08:28

Thursday, Sep 15, 2016 at 08:28
Some folks seem to be confusing two technologies here.

The OP is asking about this style of gadget:-

jump starter/powerbank

This will (probably) jumpstart your car, it will NOT run fridges/cpap machines etc for long, if at all.

VS

This much larger gadget will do all of the above, within reason.

Jumpstarter
AnswerID: 604404

Follow Up By: Jackolux - Thursday, Sep 15, 2016 at 12:37

Thursday, Sep 15, 2016 at 12:37
I have run my CPAP machine for 2+ night on a 13800ma Lithium Jumpstart .
I only did it at home to see if it would .
I agree a fridge would probably be expecting a bit much .
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FollowupID: 874165

Reply By: Alloy c/t - Thursday, Sep 15, 2016 at 09:41

Thursday, Sep 15, 2016 at 09:41
The short answer is NO , it will not run your fridge .
AnswerID: 604414

Reply By: Allan B (Member, SunCoast) - Thursday, Sep 15, 2016 at 11:45

Thursday, Sep 15, 2016 at 11:45
.
Mike,

Until recently, most of these Lithium-ion jump starters claimed a 20,000 mAh battery (20 Ampere hours). Now some are being advertised as 68,000 mAh although they appear to be little physically larger. I would believe that these ratings are rather inflated for advertising reasons and actual rating would be more in the region of 12Ah (12,000mAh) with probably only about 8-10Ah actually useable.

The energy used to crank an engine is only in the order of 1.0Ah, yes one ampere hour, as the current of around 600 to 800 Amps only flows for no more than 2 or 3 seconds. So these little jump starters have adequate stored energy available to start an engine.
However if used to power a small fridge which typically uses maybe 2.0Ah then it would consume the available 10Ah in 5 hours or even less time if a larger fridge or freezer. Allowing for a claimed 68Ah which would probably deliver about 36Ah it would power the small fridge for 18 hours at best.

So yes, I believe that it could work, but only adequate for a small fridge for a limited time.
It would be interesting to hear from anyone who has actually tried it.

Bear in mind that it would need to be recharged which would possibly take a few hours from the car alternator.
Cheers
Allan

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AnswerID: 604418

Follow Up By: Member - Boobook - Sunday, Sep 18, 2016 at 11:29

Sunday, Sep 18, 2016 at 11:29
Eggg Zackery Allan.

And good to see someone on this forum understands the difference between power and energy too.
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FollowupID: 874245

Reply By: The Bantam - Friday, Sep 16, 2016 at 00:11

Friday, Sep 16, 2016 at 00:11
The other thing you may find is that the unladen terminal voltage of some of these LiPo jump starters is quite high.

One unit I looked at had an unladen terminal voltage of 22 volts, when hooked up to start a car that terminal voltage drops consideably by the time it gets to the battery and the starter.
They have some sort of inverter and charge management that may take some time to charge the unit.

These units also may indeed start a car, under some circumstances , but have no hope in others

Consider this.
I have a Milwalkie battery drill ... many will have similar ....... there are various packs for those but 18 volt 4 Ah is common ..... and that is a realistic rating ........ compare these LiPo jumps starts for size and weight with a modern respectable power tool battery and you will get some idea of the truth.

If you want a cheap ( not that cheap) compact option for your fridge ...... look at a 20Ah 12 Volt, sealed lead acid ( this is what is in some of the other sort of jump starts) .
You should get one for around $100 retail ....... if ya fridge is down to temp and it is not too hot ... it might run your fridge over night. ...... it will certainly run ya fridge for 4 to 6 hours.

Waeco used to sell a fridge with one built in.

The best bang for bucks is a sealed maintenance free N70 marine battery in a marine battery box .... that will give you about 80 AH and will run ya fridge for about 3 days all going well ....... or a full 24 hour day if the fridge is working hard.

cheers
AnswerID: 604432

Follow Up By: banksy 69 - Sunday, Sep 18, 2016 at 06:41

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