Electrical

 
 
 
 
 
 
RockAlong
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Electrical

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Posted: 10.01.2020  ·  #1
I am in the process of converting my camper and started doing some electrical work. Need something simple, only for Led lights, usb and water pump. Fridge will come way down the line.

First thing I did was to buy a step up converter from 5v to 12v so I could attach my e-bike battery to the system.

It worked fine with the Led lights but as soon as a plugged something else, bang, no workie. Current was too low (obviously you would say but I wanted to try to keep the system as simple as possible)

Managed to get a used car battery which is doing the job.

Questions:
1. Do all of ye ground your negatives to the chassis? I'm a bit perplexed by doing this since I might install an inverter down the line which will need grounding as well.
2. Can I charge the battery from the mains with the system connected somehow? what I am doing now is to disconnect the system to charge but I would rather something less hacky if possible.
3. I will use 16mm cables from batter to battery in the future and 5mm cable from battery to the switch panel, concerns here?


Thanks!


baguette
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Re: Electrical

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Posted: 10.01.2020  ·  #2
At this stage of the conversion I would put in all the wiring necessary to cover future requirements. 230v mains sockets and lights, and a fridge, back to a consumer unit (ELCB & MCB's). A 12v supply for low voltage stuff like water pump, lights, fridge, etc. etc.
It's far easier and only a small cost to do it now instead of trying to run additional wiring later when the build is finished.

Be very careful about the e-bike charging, the batteries fitted to e-bikes often require a very specific charging regime otherwise they can be terminally damaged. FWIW I would use the original mains (230v) charger supplied run off a pure sine wave inverter.

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The Rambler
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Re: Electrical

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Posted: 13.01.2020  ·  #3
I am frightened to ask what was the 5 Volt source you were stepping up to 12 V to charge your eBike. I hope not a USB chargepoint. Anyway, as Baguette points out, you’ll have to use the original mains charger for the ebike charging. And you will have to run off a 12 Volt battery for low voltage stuff. The car battery you picked up should get you going. Ideally you would want to run a deep-cycle ‘leisure’ battery, which is more suited to running your habitation systems than a starter battery over time.

There are three common ways to keep your leisure battery charged.

1. From the alternator when the engine is running - via a split charge relay
2. From a solar panel/ charger
3. From mains charging.

You don’t need to have all three, they merely complement each other and the first 2 are usually not sufficient to fully charge a depleted battery in an acceptable amount of time. That is unless you are driving for a very long time or you have a good solar setup in the middle of summer. Mains charging is where you would expect to get your battery fully charged overnight when plugged in to EHU. There are many chargers out there suited to charging while allowing loads to run. Brands such as CTEK accomplish this. If you’re looking to run an inverter from your battery to charge an ebike, be sure to do the math. Charging an ebike could be drawing 20 or 30 amp-hours from your battery. If you have only 100 amp-hours in your battery, that would be a significant draw. You don’t want to discharge your leisure battery below 50%. Good luck.

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RockAlong
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Re: Electrical

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Posted: 13.01.2020  ·  #4
Thanks for the input guys, really appreciate taking the time for this.

As I wrote on my post I am no longer using the Bike battery, the current was too low for anything other than led lights. (I may use it for the lights as a backup)

I see plenty of CTEK chargers but the ones I saw you need to disconnect the battery from your system in order to use it, I would like something less fiddly. I'm sure there is something out there.


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Re: Electrical

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Posted: 13.01.2020  ·  #5
My understanding is that the CTEK can be charging while your battery is also in use. Did you read somewhere that this is not so? All your 12 volt loads should be wired back to the battery terminals, via fuses and switches. The mains charger will also connect to the battery. If the charger is a proper intelligent charger that is load aware, you should be able to run loads whilst the mains charger is operating. To be honest, I don't know how the manufacturers really achieve this like they claim. But don't worry too much about the little dance that takes place between the charger, the battery and the loads. Once you know that you have a charger that can charge while you are running appliances, just assume that the charger is charging the battery and also acting like a voltage supply to your appliances.

If your LED lighting or any other sources require a DC voltage other than 12 Volts (between 11 and 14 volts in practice), be sure to step up or step down as appropriate. But then why are you using appliances that are not 12 volt? Be sure to use 12 V LED lighting. You can run 12 Volts to cigarette lighter sockets you install, and which you can plug in USB charge points. If you plan on running a TV, be sure to get one that runs on 12 Volts from a mains adapter, then just bypass the adapter etc. My TV is actually 14 Volts but runs fine on 12 V.

I'm not really sure what your concerns are about chassis grounding your leisure battery/ or loads, assuming you are running with a negatively grounded battery wiring. The chassis should also be earth bonded as well for any EHU connections. 16 mm battery to battery cable should be ok. Will you be using a split charge relay for this? What you run to the individual loads really depends on what the expected current draw is on each branch. LED lighting is generally very low these days (under 2 amps).

Disclaimer: I contacted the manufacturer of my inexpensive mains charger (Maypole multistage charger), who told me not to use the battery whilst under charge. I then installed a relay that would disconnect the loads from the battery when EHU was connected and the charger running, and diverted the loads to run off a reasonably hefty (up to 30 Amp) 12 Volt power supply instead. But that's just me. you can avoid this with the right charger.

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