Advice on my electrical system

zhono

New Member
Feb 2, 2012
13
0
1
MA
As part of my new build, I have an LED headlight, and 2 LED strips(one back and one front) that act as running lights, break lights, and turn signals. I might also add a horn in the future. I plan to power that stuff with a 12v 7ah SLA battery(maybe 2 in parallel), and keep a small charger handy for when I'm near an outlet.

But obviously, like many, I would like to charge the battery while riding. My current idea is to get a cheap 12v 6w dynamo on ebay, and a rectifier/regulator combo that takes in a range of 12v-18v AC, and outputs 12v DC. So my basic system would be dynamo into the rectifier, out of the rectifier into the battery to charge, and out from the battery to power the lights.

Anyone have any experience with this? Would this work out? The only thing I don't know how to do(if it's even necessary), is to isolate the charging circuit from the load. i.e. I only want the dynamo to be supplying power for charging the battery and not the lights, and I want my lights to only draw power from the battery and not the dynamo. So ideally the whole system should be self-sustaining, without me having to disconnect the battery for separate charging at a wall socket.

I would also note that the vast majority of my riding will happen in daylight hours, and so neither the headlight nor the running lights will be powered most of the time. Just brake lights and turn signals for probably 90% of my riding time.

And extra thought: would it be possible/feasible to double-up, and use two dynamos, each with their own rectifier, and combine that for better charging?

Various links to the specific parts in question:

My headlight
https://www.amazon.com/gp/product/B00XVAEP8E

My running/brake/turn lights
https://www.amazon.com/gp/product/B01ITBTSHC

Load resistors(to make the turn lights actually blink)
https://www.amazon.com/gp/product/B00L4V9ECY

My battery(I have 4 of these from a fairly successful e-bike build that I changed my mind about)
https://www.amazon.com/dp/B003S1RQ2S

The dynamo I'm looking at
http://www.ebay.com/itm/BICYCLE-BEACH-CRUISER-GENERATOR-UNIT-12V-6W-DYNAMO-CYCLING-BIKES/262688555528?ssPageName=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

The rectifier
http://www.ebay.com/itm/AC-DC-Power-Supply-Module-To-DC-5V-9V-12V-15V-Rectifier-Filter-Voltage-Converter/322598417570?ssPageName=STRK:MEBIDX:IT&var=511587289401&_trksid=p2055119.m1438.l2649
 

Tony01

Well-Known Member
Nov 28, 2012
1,386
819
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sf bay area
Get your build running first and run a lithium 12v system till then. I'm working on a system using a sturmey Archer dynohub (hds20). Those bottle degerators will blow up quick.
 

zhono

New Member
Feb 2, 2012
13
0
1
MA
Get your build running first and run a lithium 12v system till then. I'm working on a system using a sturmey Archer dynohub (hds20). Those bottle degerators will blow up quick.
I was actually looking at dynohubs already, but all the ones I could fine were pretty expensive(for me). I can't even afford a small lithium battery right now, so I'm stuck with my SLA's. Still trying to sell my e-bike conversion kit, but the money from that was going to be used to buy either a 26 inch frame with the integrated gas tank from BikeBerry, or a set of 26 inch heavy steel rims with 11 or 12 gauge spokes.