ARRL

Forum Home - Rules - Help - Login - Forgot Password
Members can access, post and reply to the forums below. Before you do, please first read the RULES.

Battery Charging

May 27th 2012, 17:12

dksac2

Joined: May 24th 2012, 23:18
Total Topics: 0
Total Posts: 0
I'm playing with a low cost idea to charge a couple deep cycle batteries quickly for stationary field mobile use.

It would involve using a 3.5 HP horizontal Lawn Mower engine to turn a 63 Watt GM internal regulated alternator by belt and pully's and the output of the alternator hooked to the batteries. This set up with the proper pully size can have the lawnmower engine just over idle and save a lot of fuel compared to just using a jumper from a vehicle for charging.

My question is, will the batteries help stablize the power and produce a clean enough voltage to use with a 45 watt amplifier without putting whine on the audio. I could use one of the Capacitor type noise reducers on the output to cut down on the noise, they are made to handle upto 40 watts.

I'd like to be able to transmit while charging the batteries, it would give a higher voltage (13.8v) or as close as possible if I needed as much range as possible with the set up I have.

Mostly I'd just use the battery without the charger, but want to know of possible problems using the amp and 2M/70cm handheld transceiver with the generator hooked up to the batteries and charging, I like the idea of a quick charge on the batteries and extra voltage at the same time.

If this will not work, I'll just use one battery at a time hooked to the equipment while the other is charging and switch between the two batteries.

I have limited funds, otherwise I'd get a good inverter generator. I plan on doing so someday, but can make the homemade generator from parts I have laying around for the most part at very little cost to me.
I have solar panels and a charge controller for those times I would be doing less transmitting. I am looking for different ways to charge the batteries, I like having more than one method to charge a a low cost to me as well as when the grid is down or not available.

Your thoughts and ideas...Thanks

John KF7VXA
May 28th 2012, 07:42

KB0HAE

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
You might check the QST archives. I seem to remember an artical about using a vertical lawn mower engine and automotive alternator for what you want to do. Electrically there shouldn't be any difference.
Jun 6th 2012, 21:58

KH2G

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Actually the setup described works quite well. If the batteries are really low, you might have a bit of whine but a bypass cap on the charge line should take care of it. In the "Mother Earth News" I've seen a number of similar setup used by those who prefer to stay off the grid.
Enjoy
Dick KH2G
Jul 24th 2012, 21:36

dksac2

Joined: May 24th 2012, 23:18
Total Topics: 0
Total Posts: 0
Thanks, I think that answers my question about noise.

It really is a neat set up. A 3.5 HP Vert engine uses little gas and an alternator with a built in charge controller works well (I've seen them used, working on my own, just never seen them used for radio use). It is not going to be the best way to charge batteries on a regular basis, a good dedicated charger such as the "Battery Minder +" is what I usually use once the batteries are brought up to about 75% charge with a higher amp charger. The Battery Minder uses a pulse to knock the sulphate off of the plates. I have used it to bring back some dead batteries with excellent results as long as they are not shorted. The darn thing really works well, $40.00 at one of the farm supply places.

My Best, John
Oct 23rd 2012, 19:20

K7EVI

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Only one comment, and not being critical, but for 40 amp alternator, I need 6 hp, so for 63 Amp I would recommend at least a 7.5 to 10 HP engine. Any smaller and the engine will stall when the batteries are below about 50 to 60%. Also realize the speed of the engine and the speed of the alternator also determine the output and the required pulley size on the engine. Changing pulley size on the alternator is not very practical. Backwoodssolar.com is a good source for current information - although they no longer sell the full generator kits.
7 years off grid.. Doug

Back to Top