Author Topic: Fuse placement and terminal/bus bar questions for 12v powerbank  (Read 1903 times)

Offline Greekman

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Fuse placement and terminal/bus bar questions for 12v powerbank
« on: December 20, 2017, 01:07:01 AM »
so, I have started building a "small appliances powerbank" (12V & 5V USB outputs). So i have some practical matters to solve.

1. Where do I place the fuses?
logic says that there should be at least one, right at the battery + pole. (or even better a second one at the -pole)
but I will be making 2 circuits connected to the battery.
- One for solar charge controller input/output and
- One direct in/out to the battery (for grid charger and direct out for hanheld radios) (I have read that it is better to have direct out to power radios to avoid noise coming from the solar charger etc)
So i need you advice if I am to place more fuses and where.

2. I need a tidy way to connect a bunch of wires to the battery connectors. I do not want to bridge terminal buses like in this
https://www.youtube.com/watch?v=531t9mB_NN8
So far i have found these terminal blocks, but they cannot be screwed on the powerbank plate, and i wonder if the clips will loosen as time passes. https://www.youtube.com/watch?v=_KhBoxgyXgI
I am open to ideas but I must avoid marine grade/marine price material.

notes:
- batteries will be two 7Ah SLAs, amperage not more than 5 at the moment
I know about the laptop charger trick to fuel the solar charger/controller, but I already have the grid charger and no laptop yet.

Offline Fixit

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #1 on: December 20, 2017, 04:22:48 AM »
I often use these for speed and safety .

https://www.amazon.com/Holder-LinkStyle-Automotive-Warning-Marine/dp/B075WTTMBJ/ref=sr_1_7?ie=UTF8&qid=1513768588&sr=8-7&keywords=12v+fuse+panelWhen wanting to make a lot of wire runs.
They do have them in different amps and number of fused taps.

Online Carl

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #2 on: December 20, 2017, 04:53:57 AM »
I suggest a fuse from POS to POS of the batteries ,if in parallel,as catastrophic protection and a fuse between batt bank POS and the POS buss that all in or out devices connect and finally a fuse in line to each and every device that you want to PROTECT.

The FIXIT linked fuse buss is a good way to protect devices that don't already have fuses in their power leads.

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #3 on: December 20, 2017, 05:07:05 AM »
nice advice the fuse between batteries.....
to be honest I found out the fuse holder suggested, but i will need 4 of them and they will end up costing more that the two SLAs

BTW...are these stackable?
https://www.ebay.com/itm/5x-Circuit-Fuse-Tap-Adapter-15A-Mini-ATM-Blade-Fuses-Holder-Car-Auto-32V-/172833500514?_trksid=p5731.m3795

Online Carl

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #4 on: December 20, 2017, 05:14:30 AM »
nice advice the fuse between batteries.....
to be honest I found out the fuse holder suggested, but i will need 4 of them and they will end up costing more that the two SLAs

BTW...are these stackable?
https://www.ebay.com/itm/5x-Circuit-Fuse-Tap-Adapter-15A-Mini-ATM-Blade-Fuses-Holder-Car-Auto-32V-/172833500514?_trksid=p5731.m3795

I don't think so as they allow you to tap the POS wire while the fuse only protects the original circuit.
But if you plan to connect and run over 10 devices at once,you probably do not have enough power available.

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #5 on: December 20, 2017, 06:21:49 AM »
hmm.... I think I can make it work. I am not 100% sure, cos it is better to verify the concept with pen & paper, and a DMM upon receipt, but...

I will first connect one of these piggybacks on this, as piggybacks terminate on a hot lead.
https://www.ebay.com/itm/5X-In-Line-Standard-Blade-Fuse-Holder-Splash-Proof-for-12V-30A-Fuses-Car-Bike-cw/282735698639?hash=item41d45c62cf:g:xJ4AAOSwol5YxlPW
Its wire will be cut in half and one end will connect to the battery main fuse, powering the whole assembly.
The other half will go to an output (no1). Adding a piggyback will fuse output 1.
Then more piggybacks/outputs will be added (2-3 per instance). The last in line (unfuzed) will be used for a 12V cigarette socket as the jacks themselves are fused.


« Last Edit: December 20, 2017, 06:27:07 AM by Greekman »

Offline machinisttx

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #6 on: December 29, 2017, 11:00:10 AM »
I'm not quite sure I understand exactly what you're doing but have you considered repurposing salvaged items? As an example, the interior fuse panel or main power distribution panel from the engine compartment of a scrapped car/truck. I have no idea about how things are there, but I suspect that the places I deal with would probably give me one for free or a couple of bucks at most if I asked....and it would probably still have all the fuses in it. Using something like this would give you a single(fused) connection to your batteries, and also includes fused power distribution.

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #7 on: December 29, 2017, 11:05:09 AM »
  I still wonder why he wants a small battery to have output wiring and fuses for something like 40 devices? It can't provide that level of power for long and it is far more easy to wire common connectors to the devices and just plug in the device in use...I do this with Anderson Powerpole connectors and even build various adapters to make the items capable of multi source power.

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #8 on: December 30, 2017, 12:15:36 AM »
...As an example, the interior fuse panel or main power distribution panel from the engine compartment of a scrapped car/truck. I have no idea about how things are there, but I suspect that the places I deal with would probably give me one for free or a couple of bucks at most if I asked....

That is an option I am still considering. If by scrap yard you mean what we see in the movies, piles of old car you can cannibalize, No, we do not have such things. There are dealers of used spare parts that totally strip the car and shelve the parts and sell at 40-60% of the dealership prices. I will have to know exactly what i want, almost by model, and i am sure the local dealer will not let me rummage through.

I already had a look at 220V panel buses, but they are larger than needed, require a far larger wire and are totally uninsuluted.

  I still wonder why he wants a small battery to have output wiring and fuses for something like 40 devices?

well actually, not more than 5, and not simultaneously. At the moment I am thinking 2x cigarette lighter sockets, 2x APP and a banana female socket.
When i spoke of small devices I meant the wifi router, 2 usb lights and some usb charging, and maybe a HT radio (charging/operation).

I have found a neat way to get two wires from a ring/spade terminal and thick ones for that matter.
Also a neater way to bridge barrier strips than this https://www.youtube.com/watch?v=531t9mB_NN8

Now may i piggyback a new question?
how would a PWM solar charger like 12V (exactly), 1A from a "AC-DC stabilizer" supply I already have?

Online Carl

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #9 on: December 30, 2017, 05:04:38 AM »

Also a neater way to bridge barrier strips than this https://www.youtube.com/watch?v=531t9mB_NN8

Now may i piggyback a new question?
how would a PWM solar charger like 12V (exactly), 1A from a "AC-DC stabilizer" supply I already have?

Some PWN solar controllers work at less than 12 volts,but not all,and those that do work will boost the voltage to a level that will float charge a battery though they do produce some RF noise as they contain inverters.You may find that a small battery maintainer can be found to do this job for less cost and already packaged for the purpose.

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #10 on: December 31, 2017, 09:43:14 AM »
Thing is I already have several of them and a dump charger (float and maybe trickle). I hoped I could do periodical battery maintenance with what I already have, by feeding the solar controller.
RF noise is no worry, since nothing will be operated at the same time

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #11 on: December 31, 2017, 10:17:40 AM »
Thing is I already have several of them and a dump charger (float and maybe trickle). I hoped I could do periodical battery maintenance with what I already have, by feeding the solar controller.
RF noise is no worry, since nothing will be operated at the same time

I have done the same with a 12 volt 'aircraft' adapter for a laptop that needed 19 volts and a charge controller...using what you have should work and is reason to try it out before needed.

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #12 on: December 31, 2017, 10:55:49 AM »
I did not know that these existed....
Or i could wire a DC-DC LM-series step up converter.doh!

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #13 on: December 31, 2017, 01:28:44 PM »
I did not know that these existed....
Or i could wire a DC-DC LM-series step up converter.doh!

A company named DROK sells many power modules on Amazon,many with BUCK/Boost capable 8 to 60 volts in and (adjustable) 12 to 120n volts out at 15 amps DC.With digital voltage readout at under $12 US..You may want to look for DROK where you shop on the internet.

https://www.amazon.com/gp/product/B01GFVI6R6/ref=oh_aui_search_detailpage?ie=UTF8&th=1

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #14 on: December 31, 2017, 07:12:29 PM »
Yes, I remember it....But buying this or something similar always got pushed back by other more "time sensitive" purchases.
It seems now its time has come.
And of course, This thing is a must to have around by anyone that messes with DC power.

Offline kid_couteau

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #15 on: December 31, 2017, 07:44:07 PM »
https://www.amazon.com/gp/product/B0129HYAW0/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

I have this one
Plan on making a converter so I can charge my laptop.

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #16 on: January 01, 2018, 10:48:22 AM »
happy new year everybody!

so...I searched a bit more for fuse blocks and I got these two

https://i.ebayimg.com/images/g/TQIAAOSw2olZcaQS/s-l1600.jpg
this is a 2x3 fuse +2 lead in wires block which is what I want, except for the lead in wires that seem to be 1mm thick (close to 18ga).
This is just adequate for 15A and 8inch length of wire, so I am -in theory- covered as is. (had a look at several online sources and calculators)
I wonder if the contacts can be removed to solder a thicker wire.

https://i.ebayimg.com/images/g/0hUAAOSwTQtZ~CAN/s-l1600.jpg
In this case i can mod it by enlarging the holes on one side, passing through a thick monocore wire and soldering it.
Then an isolator can be made over the "bar"

have you any expereince with them?

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #17 on: January 01, 2018, 02:20:17 PM »
I would use the first block and maybe a single fuse to protect the batteries from catastrophic failure ...I think the two feed wires are plenty heavy because the two 7 amp hour batteries are actually designed to produce under an apm for about 10 hours EACH and if you want them to last I wouldn't demand much more energy from them for any length of time even if they can produce 200 amps or so EACH ,for a few seconds.

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #18 on: January 02, 2018, 01:12:36 AM »
really? I thought their rating is 2C, so I planned for a possible 12V cigarette socket inverter (130W?) for charging a laptop in the future  :-\

Offline Greekman

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #19 on: January 02, 2018, 02:14:38 AM »
edit:
Seems like 2C is achievable but at a huge capacity loss (a tech manual shows it to be 2.8Ah for a 7Ah battery) that would give me 66Wh hours at most..
Now i will have to redo the calcs for a 65w laptop charger + inverter.

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Re: Fuse placement and terminal/bus bar questions for 12v powerbank
« Reply #20 on: January 02, 2018, 05:35:54 AM »
  Most lead acid cells are rated (Amp hours) at a 20 hour rate ...I use the 10 hour rate as the math is faster and not so different than actual use.
I attempt to charge or discharge a battery at no more than 1/10 of the Amp Hour rating and to 50% of capacity in NORMAL USE.

 For TWO of the 7 Amp Hour batteries I would try to use no more than 1.5 Amps current over a 5 to 6 hour period of time to preserve battery life.
I will run a 12 Amp Hour on my Ham radio as it is easier to carry and does work for 3 to 5 hours with this, much higher than designed ,load of 7 Amps average ...20 Amps or so PEAK with voice peaks in SSB (voice) on HF.

  You CAN use more than the design of a wet cell battery ,but it costs the time you can use the energy...I would use matches for fire and not the auto lighters...though the few seconds of power might be OK for your needs and the laptop charger would also work,but with 90% efficiency of small inverters and 80 - 90% efficiency of the laptop charger ...you will not be capable of charging the laptop more than 2 or 3 times before your two 7 Amp Hour batteries will need to be charged...Your idea will work,though not as long a duration as you appear to think it will.

  I am not saying it will not work,just that you can not get the amp hour rating out of the batteries without harming the lifetime of the battery...UPS will put out 150 watts and often more with 2 of the 7 amp hour batteries...but only for 1/4 to 1/2 hour.

This is just my thoughts on the project,don't stop just for me.