Can I just link a bunch of these together in parallel?  - Page 1
Forum section: electronics / projects

author: skydeaner
author_rank: Contributor
timestamp: May 19, 2013, 02:40:24 am
content: I have a motorcycle generating 7v-24v depending on rpm after being sent through a bridge rectifier. I'm having trouble finding a buck/boost circuit that will suit my amperage needs. Roughly 8-10a.Can I just link a few of these in parallel?http://www.prodctodc.com/auto-dc-335-to-1230v-boost-buck-converter-12v-24v-solar-voltage-regulator-charger-circuit-p-327.html#.UZg6kbUQZjQOr would that not work at all LOL.Thanks in advance. Or if you have any other suggestings I am open eared. Of course I need the output voltage to be 13.8v.

author: ivan747
author_rank: Super Contributor
timestamp: May 19, 2013, 03:04:29 am
content: Unless you modify the circuits, it's going to be hard to parallel these without losing a bit of power. The problem is their voltage will not be 100% the same, so if one is 13.80V and the other is 13.81V, the later one will be taking much more of the amperage that the load is sinking.A way to overcome this is to place a very low value resistor in series with the outputs of all the DC-DC converters. When one of them is significantly above, the extra current though the resistor will generate a drop in voltage, which means the output voltage of that module will eventually match the rest.And try not to run these at 2A. They seem quite small in my opinion and although they claim they can handle 2A, I guess they will be happier when ran at 1.5A, specially in a demanding environment like a motorcycle, with the heat and vibration.

author: AlfBaz
author_rank: Super Contributor
timestamp: May 19, 2013, 03:25:10 am
content: In the final use of this is the output varying from 7-24V or can you have it fixed at the high end (24V)?

author: skydeaner
author_rank: Contributor
timestamp: May 19, 2013, 04:21:54 am
content: Final output is varying. I cannot lock it at higher voltage

author: Psi
author_rank: Super Contributor
timestamp: May 19, 2013, 04:26:07 am
content: These would probably work.(You didn't say it had to be cheap)http://www.powerstream.com/dc-buck-boost.htmhttp://store.mp3car.com/DSX12VD_140W_DC_DC_Regulator_p/pwr-025.htmThis one would need some tweaking over serial to disable some of the cutoff/timer limits intended for PC operation and i'm prettysure you can change the output voltage to 13.8V)

author: skydeaner
author_rank: Contributor
timestamp: May 19, 2013, 10:50:26 pm
content: Those are way too expensive, it isn't worth all that lol.. Me and my kids just ride around on the scooter for fun.Right now I have just a 10a buck regulator. So when the voltage goes above 15 or whatever, it kicks in and starts charging the battery and supplying voltage, but a lot of times I have the kids on there and I'm not going fast enough to even get to that point.I custom wrapped this stator in the generator, maybe I should just rewrap it with smaller diameter wire, but I really need all the amperage I can get. All of the lights on the scoot pull quite a bit of power.

author: mikes
author_rank: Regular Contributor
timestamp: May 19, 2013, 11:12:31 pm
content: Do you really need regulated 13.8 V, or just "automotive 12 V?" You've already got a rectifier on the output, just hook up a 12V battery, and maybe a simple series pass regulator to keep it from overcharging, depending on average charge/load.

author: skydeaner
author_rank: Contributor
timestamp: May 20, 2013, 12:25:51 am
content: Yeah the shitty little lead acid keeps boiling/bubbling dry from getting too high of voltage or something

author: C
author_rank: Super Contributor
timestamp: May 20, 2013, 12:37:22 am
content: My first thoughts was to switch in a transformer to boost your voltage before the rectifier. As the frequency probably changes with engine speed, this would mean using a wide frequency band transformer like an audio transformer.But, You state you want max power, so if you want to pull max power from an alternator, you need a good load for an alternator not the short high current pulse once each half cycle you currently have. In my thinking what you really need is the alternator driving a power factor correction (PFC) circuit that then feeds your buck regulator.C

author: mikes
author_rank: Regular Contributor
timestamp: May 20, 2013, 01:24:06 am
content: Quote from: skydeaner on May 20, 2013, 12:25:51 amThe easy way is to Google "12V solid state motorcycle generator regulator".You'll need to figure out what you have - likely a permanent magnet/stator generator (dynamo), but sometimes a field/armature one, or even an alternator.Somethinglike thismay work (looks like a series regulator) orthis(a shunt regulator) if you have a PM/stator generator. I have no experience with either, just trying to point to the sort of thing that may work for you. Figure out what you have, and search around. This should be enough to get you started.

author: Paul Price
author_rank: Super Contributor
timestamp: May 20, 2013, 09:27:45 pm
content: How many wires are on your generator...just one output lead? Does the generator/alternator have a field and armature connection? What are you trying to connect the generator to? What voltage and current do want to end up with? Is this just generator for charging your battery on the vehicle?