kelabar
Senior Member
Posts: 399
Likes: 469
|
Post by kelabar on Jul 18, 2020 18:26:31 GMT 10
I want to mess around with alternators for battery charging. As well as other mechanical systems like pumps, motors and agitators.
I'm looking for suggestions about small engine sources. I don't really want to use lawnmower engines because they have a vertical driveshaft. Something with a horizontal driveshaft would be easier for messing around with. Not too big as portability is nice. Preferably 4-stroke but this isn't critical.
Possibly petrol powered water pump engines. Or some of the two-stroke garden tool or chainsaw engines. Anyone got any other ideas?
|
|
bushdoc2
Senior Member
Posts: 370
Likes: 464
|
Post by bushdoc2 on Jul 18, 2020 19:32:00 GMT 10
Model aeroplane engines? These tend to high revs, but a pulley system fixes that soon enough.
Sounds like if only running an alternator, you don't need a full lawnmower-sized engine...or the fuel consumption it requires. Biggest drama will be regulating revs/current for proper charging. Alternators vs generators: important difference.
|
|
|
Post by Joey on Jul 19, 2020 20:20:35 GMT 10
Watch your RPM's as well on the alternator. As alternators have a ideal power band for RPM for them to produce optimal charge output, most new alternators come with a bench test certificate in the box that shows it's performance at different tested RPM's. As for voltage output, you will be looking at around the 13.9-14.4V output of the alternator to charge a 12v battery. Less then that and you will drop cells in the battery and be out to buy new ones.
|
|
norseman
VIP Member
Practical is Tactical!
Posts: 2,145
Likes: 1,853
Member is Online
|
Post by norseman on Jul 20, 2020 9:05:07 GMT 10
Bought one of these for under $200 20 years ago, was very sceptical but starts every time and runs like a champ! Two stroke though!
|
|
kelabar
Senior Member
Posts: 399
Likes: 469
|
Post by kelabar on Jul 25, 2020 20:50:53 GMT 10
Thanks, everyone. Great ideas. I hadn't thought of rc aircraft engines. Good one. Dirt cheap too. I had a quick look at model boat engines as well. There are even steam engines for use on model boats. Impractical but cool! For info, if you take your alternator out of your car and spin it it won't produce any power. Alternators need to be energised by electricity before they will charge a battery. The alternator warning light or voltmeter in your dash normally does this in your car when you turn the key on. Generators (not petrol 240V generators) are similar to alternators but they produce power whenever spun. So a generator can charge a totally flat battery. An alternator would need some electricity from somewhere else to do this. Massey still sell a couple of generators too, if anyone is looking for one. I added some gear to a vehicle a couple of years ago. I calculated the max Amps it would ever need then asked a mechanic for recommendations on alternator sizing. I pointed out that the vehicle rarely ever did over 2250 rpm so maybe the Amps needed to be uprated a bit. He said not to worry because alternators these days are set up to produce a lot of power at low revs. So I checked the charts and sure enough they do. I had assumed a more or less linear relationship between revs and output. Great, lower revs for the same power. Nice. I will eventually set up a welder run off a couple of alternators and see if it works. Been wanting to try that for decades! Thanks norseman (anyone else still think of members by their usernames from other forums?). I had no idea they made little 2-stroke pumps like that. Probably walked past them hundreds of times though! It looks like a brushcutter engine and they can take a lot of work and still keep going. Plus I would have a small pump. Double bonus. They have a throttle too which will help. The 4-stroke pumps are OK but a pain to move around. I'll check out the 2-stroke ones. Cheers.
|
|
kelabar
Senior Member
Posts: 399
Likes: 469
|
Post by kelabar on Aug 5, 2020 20:40:05 GMT 10
There are a couple of small 4-stroke engine pumps around too, only a couple of hp. One uses a small Honda 4-stroke brushcutter engine and that engine is available separately.
|
|