Proper Charger/Controller for engine to alternator setup

5 Posts
Mar 29, 2007 10:44 am
Proper Charger/Controller for engine to alternator setup

Hello,

I have a 6HP lister diesel engine which I would like to use to charge a battery bank.  My original plan was to purchase a generator head where I would plug in a charge controller to charge the batteries, but I figured I could get by more cheaply and more efficiently if I had a large alternator hitched up to a charge controller.

At this point, I want to just see if I can get this thing to charge a battery bank and then, when I feel comfortable with the setup, I would like to expand it to include solar and perhaps enlarge the battery bank.

My alternator is a 14V 175Amp Leece Neville (4830LC) and I would like to purchase four 420AH Trojan batteries.  I plan on charging to 80% with a 50% discharge rate and equalize on the weekend. 

Can anyone out there recommend a really good charger/controller that can charge this pack (840 AH)in a reasonable amount of time given this configuration?

Many thanks in advance,

Phil
 
351 Posts
Mar 29, 2007 02:00 pm
Re: Proper Charger/Controller for engine to alternator setup

Phil:

I am not sure that there are any advantages to using a charge controller with your alternator. I would be tempted to hook the alternator to the batteries and see how it works without a controller.

The output is going to be governed first by the rpm that the diesel is running at. (Have you thought of throttle control ?) It will produce 60 amps at an alternator rpm of about 1200-1300 rpm. Secondly the alernator will regulate the amperage based on the charge state of the batteries.

4-5 hours of run time should accomplish the charge you are after. 

The setup you are trying will work, but isn't real effecient. You are running the 6hp engine to do about 1 hp worth of work.

Ken
 
5 Posts
Mar 29, 2007 03:55 pm
Re: Proper Charger/Controller for engine to alternator setup


[snip...]

The output is going to be governed first by the rpm that the diesel is running at. (Have you thought of throttle control ?) It will produce 60 amps at an alternator rpm of about 1200-1300 rpm. Secondly the alternator will regulate the amperage based on the charge state of the batteries.

4-5 hours of run time should accomplish the charge you are after. 

Thanks Ken.  I appreciate your reply.  Since that test won't cost me any (more) money I can give it a try.

The alternator outputs 175Amps at 6000RPM's.  The engine running RPM is 650RPM with a 24" flywheel.

When you mention that the alternator can charge 840AH in 4-5 hours do you mean when the alternator is at full output or do you mean when it's outputting at 60Amps?

If the latter, then wouldn't it take about 14 hours to charge at an alternator output of 60 Amps (840AH/60A)?

Also, would I have to constantly fiddle with the throttle to adjust the amount of charge going into the batteries?

My rationale for the controller/charger is that if the controller is intelligent enough than it can be programmed and give the batteries what they need when they need it (including equalization) without me fouling things up.

Also, it would be able to give me visual indication of what the state of charge the batteries are at. 

Anyway, I'd like to try it your way to see what happens, but ultimately I would like the comfort of a charger/controller.  So if any one has suggestions for one, I would be delighted to hear them.

On another note, I tried spell checking my post using the spell check button and I found that the spell check feature is...well..how you say "less than stellar".

Phil


 
351 Posts
Mar 30, 2007 04:42 am
Re: Proper Charger/Controller for engine to alternator setup

Phil:

What is the alternator pulley ratio ? If it is 2:1, that will give you 1300rpm on the alternator at the 650 engine rpm. A 3:1 ratio would be 1950 rpm.

You said you planned charging from 50 percent to 80 percent on a daily basis. That would be about 252AH daily, or 4.2 hours at a 60amp rate.

You should not have to fiddle with the throttle constantly. I would set the engine at a good rpm (to deliver the bulk amperage I wanted) and let it run until the amps start dropping off, then you can lower the engine rpm.

If I were going to hook up a charge controller, I would want to disable or remove the electronic regulator on the alternator. I would probably use a rheostat to let me control the alternator output. Many electronic regulators do not see a charge controller as a load, so they back the amps way down, leaving the controller very little (if any) amperage to charge with.

Ken
 
5 Posts
Mar 30, 2007 09:06 am
Re: Proper Charger/Controller for engine to alternator setup


What is the alternator pulley ratio ? If it is 2:1, that will give you 1300rpm on the alternator at the 650 engine rpm. A 3:1 ratio would be 1950 rpm.

I haven't received my alternator yet (it looks like it's going to be delivered today but DHL is handling it so even though it's at the facility 10 miles away from my house, I should proably get it by mid April sometime) and it doesn't come with a pulley.

I was trying to figure out what size pully to put on it.

Using the equation:  generator pully size = (engine pully size * engine RPM)/generator RPM   

I can change the pully size by determining what RPM the engine and the alternator should run at. 

Originally, my uneducated instincts told me to max the RPM of the alternator to its highest comfortable RPM (6000 RPM) to output the 175 Amps.  I wanted the largest pulley I could put on it (to avoid slippage) so using the engine stats of RPM = 650 (that's highest comfortable engine RPM) and Flywheel = 24" and alternator RPM of 6000, my pulley size is 2.6 inches (pretty small don't you think?).

Quote

You said you planned charging from 50 percent to 80 percent on a daily basis. That would be about 252AH daily, or 4.2 hours at a 60amp rate.


I can see where you got the 4.2 hours (252/60) but I'm not sure where you got the 252AH. I plan on using 4 Trojan 420AH batteries which is a total of 1680AH.  I discharge to 50% (when the batteries reach 840AH). I need to bring the batteries up to 80% of their capacity (1344AH).  To do so means that I need to charge 1344 - 840 AH = 504AH.  504/60 is 8.4 hours.

Please let me know if I'm way off the mark here or if I've misunderstood where you are coming from.

Acutally this is all very encouraging because this means I can significantly increase my pulley size along with my comfort level.  If I drop the alternator RPM's down to 2000 (which, according to the specs, generates 140 Amps), I can put about an 8" pulley on the alternator (and have the engine run at 650RPM). 

This also means that I can charge 540AH in slightly less than 4 hours. Or, up the alternator RPMS to 3000, put a 5.2" pulley on it and generate 160 Amps which would charge the 540AH in around 3 hours.  I'm getting the alternater RPM's and Amp output from the Leece Neville spec chart for that alternator.

Quote
I would set the engine at a good rpm (to deliver the bulk amperage I wanted) and let it run until the amps start dropping off, then you can lower the engine rpm.

OK. Now here is where I hit a roadblock -- what instrument would I use to monitor the the amperage going into the battery pack?  Also, what instrument would I use to monitor the battery usage (an e-meter?)?

Quote
If I were going to hook up a charge controller, I would want to disable or remove the electronic regulator on the alternator. I would probably use a rheostat to let me control the alternator output.

Now this is kind of beyond my knowlege and abilities. I'd like to learn how to do something like this, but it looks like I'd need to spend more time learning electronics. 

So let's say I go the route of alternator direct to the battery pack.  How would I equalize the battery pack and bring it up to 100%?  Would that simply be running the engine alternator for a longer period of time until the pack came up to 100%?

Thanks so much for spending time answering my questions.  I really appreciate it.

Phil
 
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