Thumper Pack

Submitted: Tuesday, Jan 10, 2017 at 20:56
ThreadID: 134090 Views:1743 Replies:11 FollowUps:17
Hello, looking to purchase a thumper pack to run our Waeco 50Litre Fridge/Freezer, any recommendations as there are so many on the market. Heading away shortly and will be off grid for at least five days consecutively. Have 2 x 80watt portable solar panels for recharging. Any thoughts or help would be great. Thanks
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Reply By: The Bantam - Tuesday, Jan 10, 2017 at 23:17

Tuesday, Jan 10, 2017 at 23:17
buy a quality battery and put it in an off the shelf marine battery box. ....... AND remember to restrain and ventilate this battery properly.

cheers
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Reply By: RMD - Tuesday, Jan 10, 2017 at 23:29

Tuesday, Jan 10, 2017 at 23:29
What size battery are you aiming for?
A 50litre fridge will use a reasonable amount of current ie, amp hours per day AND night if hot weather. More if used as a freezer.
The solar has to be able to run the duty cycle AND recharge all AH from the night use too OR the battery will go flat.
Warm weather and overcast may see insufficient charge to the battery, so some alternative may be required to keep the fridge /battery charged enough so battery damage doesn't occur. I presume you have a solar regulator for the panels.
A small battery AH capacity may not be sufficient, so rather than a thumper size you may require a THUMPER ie, bigger AH rating. Min 105AH.

That, with good sun and the panels would allow for continual use without battery damage or fridge stopping as a result of low voltage.

The panels will have to be aimed for maximum solar return.
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Reply By: Iza B - Wednesday, Jan 11, 2017 at 07:32

Wednesday, Jan 11, 2017 at 07:32
Last time I checked, the Waco draws about 3.5 Amps when running. Multiply by about a 40% duty cycle and you are looking at draining 17 AH over night, very rough figures. That drain will increase during the warmer temps and increased use during the day.

I think the advice on a high quality marine or deep cycle around 100 AH is good advice. I'd be comfortable with the idea that 160 watts out there during the Peak Sun Hours will keep the drinks cold.

Iza

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Reply By: Sand Man (SA) - Wednesday, Jan 11, 2017 at 08:20

Wednesday, Jan 11, 2017 at 08:20
Hi Goldlink,

You know the old saying, "you get what you pay for"!
Sure, a cheap option is to buy a deep cycle battery and stuff it in a marine battery box. But, in reality you won't save all that much. Considerations on isolating this auxiliary battery from the starting battery with an isolator and a means of charging it when traveling need to be taken into consideration.

I can suggest two better alternatives for you to consider.
A Sidewinder Flyer "smart" battery box to which you add a battery of your choice.
The Flyer comes with it's own built-in isolator (optional model) and both Merit and Cigarette sockets to plug your devices into. It includes the correct size wiring cable to connect it to the starter battery. A suitable battery is an AGM style which is the safest to have in the rear of your vehicle.
ABR - Sidewinder Flyer

Another option is the genuine Thumper from the Home of 12 Volt.
These are very practical and again come with a complete charging kit
An 80Ah Thumper is a good size for a 50l fridge and is still portable enough to remove from your vehicle to place closer to your campsite, or use as a jump starter, or portable 12v supply for many other 12v devices. It is a fully sealed, robust solution in one "box".
Home of 12 Volt Thumper

Anything larger than an 80Ah solution, whether in one "packed" box such as the "Thumper", or a separate AGM battery and box such as the "Flyer", will render it virtually non-portable due to excessive weight.

I have a Flyer in the tub of my vehicle with a 100Ah AGM battery in it and it isn't portable. It stays where it is in the front corner, securely fastened down.
I also have my trusty 75Ah+ Thumper which I take on longer trips because it is portable and I use it for a multitude of uses.

Both these options work out about the same price and you would be looking in the order of $700-$900, (depending on size) when all features are taken into account, but you will have a sound auxiliary power source as a result.

Bill


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Follow Up By: Member - Bruce and Di T (SA) - Wednesday, Jan 11, 2017 at 10:19

Wednesday, Jan 11, 2017 at 10:19
I'd endorse the genuine Thumper from the Home of 12 Volt. We've had one in our Prado and it has been excellent. We leave it permanently in the rear of the vehicle and so every time we drive off in it the Thumper is charging. We've run an Engel off it as well as a Waeco as a freezer. We also have Blue Apple solar panels from the same place. No affiliation.

Di
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Reply By: Les - PK Ranger - Wednesday, Jan 11, 2017 at 08:53

Wednesday, Jan 11, 2017 at 08:53
Come good deals on what you need here . . .
Home of 12 V sale

Something like this would be perfect, and reasonable price . . .
120 amp/hr package

No association, was just clicking around to get a visual on the Thumper when I found this.
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Reply By: Baz - The Landy - Wednesday, Jan 11, 2017 at 09:30

Wednesday, Jan 11, 2017 at 09:30
Hi Goldlink

I’ll preface my comment by saying this isn’t an exact science and requires assumptions to be made.

You have indicated that you might be “off-grid” for up to 5-days at a time, so in principal based on “back of the envelope” calculations perhaps something as small as a 50A battery will suffice. But you might want to give some margin and look at 80A.

Power Use

Fridge: 3.5A cycling for a total of 10 hours each 24-hour period in summer (Total 35Ah)

Power Input

2x80W Panels generating 3A each operating at 70% efficiency with a peak solar period of 7 hours in summer (Total 30Ah)

Let’s assume you use a 50A battery to run the fridge and it has a maximum discharge of 50%, giving circa 25A available.

Assume a full SOC at the beginning of a 5-day period.

Battery available: +25A
Solar input: +30A
Power draw: -35A

All things being equal you will have an approximate draw of 5Ah per day and if you have a 50A battery, this should give you up to 5 days “off-grid” before the battery requires an additional source of charging (eg: vehicle alternator or a generator).

Whilst there are a number of other factors that could influence the outcomes, hopefully this gives some guidance.

Cheers, Baz – The Landy

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you get the test first, the lesson
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Follow Up By: Allan B (Member, SunCoast) - Wednesday, Jan 11, 2017 at 11:38

Wednesday, Jan 11, 2017 at 11:38
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Hey Baz, I asked my friend Albert about this and he said.... well, I'll let him say it.......


Albert then went on to say that "The relative size of thumbs vary somewhat and if you use a 'thumb' method for this determination to arrive at say a 50Ah battery and it turns out to be too small then the thumb may have been relatively undersize and you will now need to purchase a larger battery so you will now have two batteries of relatively differing sizes which will cost more relatively than if you had used a relatively larger thumb in the first place thus putting you in a relatively better status as a conclusion".

Does that make sense to you? .... Me? I'm relatively confused!
Cheers
Allan

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Follow Up By: Baz - The Landy - Wednesday, Jan 11, 2017 at 12:45

Wednesday, Jan 11, 2017 at 12:45
“If I had an hour to solve a problem I'd spend 55 minutes thinking about the problem and 5 minutes thinking about solutions.”
Albert Einstein

In the 5-minutes (less actually) I had to think about a solution I concluded, like a few others, that an 80A battery would probably suffice and best be accommodated by a “thumper” of that size – but hey, how long is that piece of string?

The question had me doing a bit of thinking and research – and I’m the better for it, isn’t that one of the great things about this forum, a question posed is a potential learning opportunity…! I wonder if Albert had anything to say about that?

Baz – The Landy
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Follow Up By: Allan B (Member, SunCoast) - Wednesday, Jan 11, 2017 at 13:05

Wednesday, Jan 11, 2017 at 13:05
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Baz, I found the following reference to the length of a stationary string. It seems to depend upon which direction you measure it from ........

Cheers
Allan

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Follow Up By: Baz - The Landy - Wednesday, Jan 11, 2017 at 18:00

Wednesday, Jan 11, 2017 at 18:00
Alan

The last time I turned my mind to the perplexing question of “how long is a piece of string” it seemed not to matter from which direction you measured it nor was a ruler required.

And a cursory glance of the string pictured confirms the logic still stands.

"It is twice as long as it is from one end to the middle…"

Does that make sense to you?

But, we are digressing and hijacking the OPs question, so I’ll bid you a good evening on that note and leave you to test the hypothesis offered for measuring the length of a piece of string...

Baz – The Landy
“Experience is a hard teacher,
you get the test first, the lesson
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Follow Up By: goldlink - Wednesday, Jan 11, 2017 at 20:09

Wednesday, Jan 11, 2017 at 20:09
Thanks for all your hard work and explanation, much appreciated !
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Follow Up By: RMD - Wednesday, Jan 11, 2017 at 20:41

Wednesday, Jan 11, 2017 at 20:41
I have a WAFFLE Maker if that is any help!
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Follow Up By: Baz - The Landy - Thursday, Jan 12, 2017 at 13:05

Thursday, Jan 12, 2017 at 13:05
Hi RMD

I don't normally respond to ambiguous responses that aren't directed specifically to me...

But in this instance if your comment is directed at my original response, happy to hear any critique of it, I’m here to share my experience where I can, but above all else to learn from the experience and knowledge of others, especially if there is a differing of opinion or view.

Cheers, Baz – The Landy
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you get the test first, the lesson
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Follow Up By: Allan B (Member, SunCoast) - Thursday, Jan 12, 2017 at 13:36

Thursday, Jan 12, 2017 at 13:36
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Baz, likely RMD was aiming at me and the bit of frivolity that I started.
Cheers
Allan

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Reply By: Les - PK Ranger - Wednesday, Jan 11, 2017 at 10:12

Wednesday, Jan 11, 2017 at 10:12
Yes Baz, so many variables.
The panels the OP has might not have output as stated, many ebay / cheaper ones don't.
My 100w folding blanket type puts out 6 amps in full sun, my 150w 9 amps, pretty much a tiny bit over specs they print.

I wouldn't depend on any sort of calculations, all it takes is some cloud and your solar input is halved, my 100w blanket output in heavy dark grey cloud is 2.5 amps, enough to keep up with my Technii fridge no worries, but then would drain overnight a fair bit.
If base camping, you must have over supply of daytime amps in from solar, or greater capacity to hold charge for a number of days use.
Then, the alternator can recharge it when on the move again, hence the link to a suited package as in my above link.

Personally I feel most people would not base camp totally for 5 days and not drive ANYWHERE for that time, even short explores of local tracks etc each day, or duck into town for some supplies, would be enough to greatly reduce the need for either more solar input, or larger battery capacity.

How much all these things relate to the OPs needs is like that proverbial piece of string.

Personally, I wouldn't like to go less than say a 100 amp/hr AGM battery with 160w solar, even if you could cope with half that capacity over say 5 sunny days.

Me, I don't think I've ever camped that long !!
More daily touring moving along to a new place daily.
I never need solar in this situ, but have hooked it up if staying somewhere for a day or three, about my max attention span without going somewhere :)
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Follow Up By: Baz - The Landy - Wednesday, Jan 11, 2017 at 12:54

Wednesday, Jan 11, 2017 at 12:54
Putting some thought into the power use/power generation, will give a basis for forming a view as to what might be needed to cover power supply...

Exact science - not by a long shot, but a good starting point hopefully.

Cheers, Baz



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you get the test first, the lesson
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Reply By: swampy - Wednesday, Jan 11, 2017 at 13:03

Wednesday, Jan 11, 2017 at 13:03
hi
Reality needs to be adhered to here .
PSH is Peak Sun Hours ,anything else bonus .
Average Australia is 5.5hrs per day of 100 % production of solar
160watt = max output = 9ahr
5.5 hrs x solar production 9ahr
=49.5ahr minus electrical losses etc
49.5 - 20% = 39.6 ahr

losses can be cable size to small ,controller type ,litte cloud etc etc etc

50lt fridge can draw upto 50ahr in a 24hr period
[very hot and opened frequently ups the on time cycle]

In very moderate weather 30ahr /24hr period

At least 160 watt solar
At least 100ahr battery
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Follow Up By: goldlink - Wednesday, Jan 11, 2017 at 20:10

Wednesday, Jan 11, 2017 at 20:10
Thanks Swampy for all the help !
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Reply By: Member - Roachie - Wednesday, Jan 11, 2017 at 19:02

Wednesday, Jan 11, 2017 at 19:02
Goldlink,

Interesting that you haven't commented/thanked any of the respondents, who have gone to some considerable lengths to try and give you advice.

Hoping this was not a troll question.
Roachie....Don't follow me....I'm lost!

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Follow Up By: goldlink - Wednesday, Jan 11, 2017 at 19:57

Wednesday, Jan 11, 2017 at 19:57
I am really sorry i havent replied, I have just got home from work, starting at 7.00am this morning and first time I have logged onto the forum.
I really appreciate all the help and advice that everyone has given me and has given me some things to consider. Thanks to everyone one again, now for me to do my homework !
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Reply By: goldlink - Wednesday, Jan 11, 2017 at 20:00

Wednesday, Jan 11, 2017 at 20:00
Thank you to everyone that has assisted with my question, sorry I havent acknowledged the great research and info that has been given, just got home from work. Now to do my homework, looking forward to my impending camping trip hopefully with a cold fridge !
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Follow Up By: Baz - The Landy - Wednesday, Jan 11, 2017 at 20:36

Wednesday, Jan 11, 2017 at 20:36
Good luck with it all...and the question had me giving some thought to power expenditure and generation!

Cheers, Baz - The Landy
“Experience is a hard teacher,
you get the test first, the lesson
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Reply By: Member - abqaiq - Thursday, Jan 12, 2017 at 07:36

Thursday, Jan 12, 2017 at 07:36
Alternative Thinking
Swampy had some good points and he noted those are average figures for solar, could be less sun = less power. I note that the Thumper systems use traditional lead batteries so get heavy fast. Running batteries down to low voltage significantly reduces their life. Remember lead batteries have to have oversize ratings as the discharge "curve" is basically a straight line from full to minimum voltage, so the rating of 12 v is some where along the middle of that slope.
Perhaps you should look at LiFePO4 batteries as they produce relatively constant voltage from full to minimum charge (most good systems have high/low V protection, same concept as Thumper), just like your portable power tools. They are dry type, chargeable from the truck and weight 1/3 or less of a comparable lead chemistry battery, and a smaller lithium battery equals a lead battery in rating.
Probably kick up a lot of dust with this post!
Hauling unnecessary weight is a no, no - IMHO.
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Follow Up By: Les - PK Ranger - Thursday, Jan 12, 2017 at 08:19

Thursday, Jan 12, 2017 at 08:19
If you've got the $$$ for sure !!
My next AGM replacement will likely be lithium, prices are dropping on them and there will be ever decreasing pricing on these, to a level that will justify the extra cost.
Beside being smaller, lighter, they have much more usable power, a huge advantage too.
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Follow Up By: Allan B (Member, SunCoast) - Thursday, Jan 12, 2017 at 08:31

Thursday, Jan 12, 2017 at 08:31
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Yes, I also endorse LiFePO4 batteries, especially where you may be considering Thumper type storage. More expensive initially but better value overall as they are long-lived.
For the same Ah storage they are smaller, lighter and provide more consistent output voltage.
They also accept a higher charge current so will recharge from the alternator faster although this is no advantage if charging from a typical-sized solar system.
Certainly, when my current AGM's require replacement it will be with a LiFePO4 battery
Cheers
Allan

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Follow Up By: Member - Blue M - Friday, Jan 13, 2017 at 02:26

Friday, Jan 13, 2017 at 02:26
Yes, I am starting to rethink which way I should go next time I have to replace my Full River AGM's.

I have 5 x 120ah, 2 in the car and 3 in the van, and without any discount there are around $495.00 each. :-(
May be a little more if freight comes into it.

With a bit of luck that should not be for a couple of years yet.

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Follow Up By: Les - PK Ranger - Friday, Jan 13, 2017 at 10:41

Friday, Jan 13, 2017 at 10:41
Blue M, considering you only get around 50% usable battery power from the AGMs, lithium you get to use around 80%, so you might only need 4 lithium, plus they are much smaller / lighter, and charge faster, as their other main benefits.
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