OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines Honda GXV160 power increase ?

Hi Gambler,

also been watching, with a bit of awe.

Here's my 5c worth of pure untested hot air...

I note what you said about switching the alternator electrically. Note switching the alternator out of the charging circuit is a no-no, it's like disconnecting the alternator from the battery in a car and will lead to damage. Not to mention you're switching large current loads (Well, I've tested this part, on my car!).

However switching the alternator's exciter circuit is much less current and will de-energise the alternator without causing any charging-circuit breakage. This is what the regulator does anyway when no current is required. You can do this with a remote-controlled relay for testing to begin with, perhaps an auxiallary switch on your remote control. If it works, simply configure some small circuit that de-loads the alternator when the motor current exceeds x Amps.

This, of course, does not take away the base mechanical friction load, only the charging load.

Hi Patrick,
I appreciate your concern regarding the switching of the load circuit of the alternator.
I don't operate an exciter circuit on this alternator.
Much to my surprise it wasn't needed when I first hooked it up being armed with a bit of wire and an alternator warning lamp. If you spin this thing fast enough it makes power on its own.
The regulator is built into the alternator and not readily accessible so disconnection of any control circuit will be difficult.
What damage do you think could occur if I was to open the charging circuit?
My plan was to open it whilst the mower was stationary to minimize the arcing of the switched dc current.




NormK
I am not planning to go into production with this as I have lost already too much sleep during this build.......lol

Hi Gamber,

Oops, remembering my "older-school' alternator, with semi-external regulator/brushes! Your alternator simply has everything inside the alternator casing. So no easy exciter switching.

Now the battery provides a constant large 'load' for the regulator to work against and helps smooth any AC ripple. Without the battery the alternator becomes an ineffectively controlled and underloaded AC (and DC) generator.

What usually happens when you disconnect the alternator from the battery (in a car) is the considerable electromagnetic energy stored in the alternator has to be dumped somewhere, usually into (either) the delicate car electronics and/or the alternator's diode pack. Either way, something gets damaged. With no car connected, it'll be internal alternator damage.

Oh, by the way, newest cars may actually be controlling the alternator, through the ECU now...so the newest alternators may have that input (and several other input/output wires) again.

One more thing: how about a smaller alternator? 20A or so should do. Motorcycle, maybe even a quad or similar?

Sounds like the alternator is able to keep up the current so that not the drive problem. The problem sounds more you simply don't have enough hp to operate the alternator and blades at the same time. The theory that it is only using about 1 hp is gong to be off as it is not a lossless system. You may be needing as much twice that or more depending how efficient the the conversion is.

As the electrical load increase so does magnetic loading from the alternator rotor that must be overcome and a GCV160 is already taxed by the grass cutting even on a regular walk behind mower sometimes. You probably will find something in the order a 240cc or larger is going to be needed; although, you could try a 190cc and see what the results are.

I know you said you don't put on a larger engine but sometime it is necessary. That what research and development is all about. It finding out what will work and what won't.

These are just my opinions so just take into consideration only as you would need to use your best judgement on what will work.

Hi Gambler, I have spent some time discussing this with my son in NZ he is a sparky and we believe the problem is the alternator is wired incorrectly, it can't work the way it is. We need a close up pic of the alternator terminals, as it appears it is trying to push power in 2 directions and it can't work. For starters you must run a switched exciter wire. The output wire from the alternator must go directly to the battery positive. The drive motors must be wired from the battery, not from the alternator. If you wire it this way you should see a charge rate at the battery of about 14 volts. Check this and lets know how you get on

Just to go over this again, what I believe is happening is you are trying to push power into the battery in one direction in the same wire that you are using to drive the motors which wants to run power in the opposite direction in the same wire. Might work with A/C but I don't think it will work with D/C. I probably would have used this wiring idea because it reduces the number of wires you have to run, but this proves it is very easy to come unstuck

Hi AVB,
as per my original post (and I believe you agree) it is becoming more and more apparent that this engine is undersized for the application. For the moment it will have to do as the yearly budget for this little project is depleted.
However I will keep an eye out on gumtree and fleabay , who knows I may pick up a bargain somewhere.

cheers

Hi Norm,
regarding the alternator and its connections let me assure you that it does make 13.8 volts of dc power without the need of an exciter circuit.

I have drawn up the circuit arrangement and included what I believe to be the current flow directions or lack of over 2 scenarios.

Scenario 1( sketch 2)would cover running the unit after it has been sitting for a while with tne battery voltage below 13.8 volts.

Scenario 2 ( sketch 1 )would cover the unit been running for a while and the battery voltage caught up with 13.8 volts.

I can not see how changing the connections would alter the operation.
Maybe your son is a better leckie than myself or I am ready for retirement.....lol

anyhow here are the circuits



cheers

Gambler, I still can't see how you are charging the battery, you are bypassing it and hoping a bit of power will stick in them. Of course you will get 13.8 volts, you can pick that reading up anywhere on any positive wire but it is not going into the battery.You have to put power into the battery and then draw the needed power from the battery, make the battery do the work, as it is at the moment the battery is having a holiday. As it is wired of course you don't need an exciter wire because you already have it wired into the circuit.You are combining your charge wire with the exciter wire. You have to go back to the basics as per a car it was fitted in. Alternator charge goes to the battery, the exciter wire brings the alternator into circuit, the alternator charges the battery and everything is then fed from the battery. This is not the way you have it wired.My son looked at the early pic of it with the 2 batteries in place and his immediate reaction was it won't work. If you would like I have a mate who lives 5 mins away and he is an autoelec and I can flick him the drawing and get his opinion and go and discuss it with him. I'm not saying you should retire, but often it is the simple things that can trip us up.

Hi Norm,

if you don't mind and its no trouble please get your mate to have a look at the circuit.
Please note only the main output terminals of the alternator are connected.

looking forward to his findings, no rush

cheers

From looking at the diagram draw I personally see no problem in how it wired other than that the two battery should be independently fused in case one shorts it will cause to other to discharge at an extreme high rate with a risk of explosion or fire. You even indicated that the alternator is a 3 phrase unit.

Many ride-on mowers use a similar setup except they only have one battery. Yes of there little to no drain when alternator output voltage is above the batteries voltage. Then as the alternator output voltage drops below the batteries voltage then they supply the addition power until drained to below the alternator output.

Sorry Norm K but I think you have it all apex over base re current flows and connection points. As it is wired is perfectly fine, current will flow into the batteries if their voltage is lower than the alternator output no matter where the connection is made. 50 years as an electronics technician working on everything from fighter jets to stand alone solar power systems tells me it is so.
One thing though, the wire being used is way too small for 50 amp draw. AVB is right that the batteries need to be isolated from each other. Apart from fuses which would hae to be quite high current anyway given the charge current, a diode in each charge input wire will stop them from feeding back to the other battery if one gets a short.

Could be right Trev, all gets complicated, I'll wait to see what my mate comes up with, if anybody can solve it he can

Trev there is another simple way to prove I'm wrong (I have no problem with that) is to run a wire from the alternator output to the battery, a switched wire to the exciter terminal and a heavy battery wire to the motor control box. Should be all it needs

Probably the only thing that will make a difference there Norm is the heavy wire, which I would run everywhere, not just to the motor control. At least 10mm wire, something like ride on mower starter cable. Without knowing the exact alternator, it could well be a self exciting variety that doesn't need the extra wire other than to light the Alt light on the dashboard. Believe me, there is no difference in where the wires connect in this machine, current will flow where it is needed, just think of electric current the same as water in a pipe.

Wow,
thanks for all the input fellows.
Now to put the fires out.
The alternator is of the self exiting type from a mitsubishi motor vehicle.
Charging current to the two batteries combined is only around 2 amps unless I have flattened them by driving around without the engine running in wich case the charging current is around 4.5 amp.

The electric motors came out of a wheelchair and full load current is 22 amp at 24 Vdc as per nameplate.
This equates to 11 amp per motor at 12 volts totalling 22 amp under full load.
The circuit wiring is 4mm2 in size and good for around 28 amp.
There is a 25 amp circuit breaker within the speed controller enclosure to protect the wiring from a short should the speed controller decide to kark it.
I agree that there could be further protection between the batteries but have yet to see one of these UPS batteries fail and short.
As mentioned earlier I think I will suffice with the current setup until I can afford a larger capacity engine preferably with electric start in wich case I will have to upgrade the wiring.

Again, thanks for all the input, it sure makes for good conversation

Gambler, Mark has had a look and the problem is 24 volt motors are running on only 12 volts. They will not have the torque that the motors should provide, less than half, but double the current consumption.
Marks solution is IF the speed controllers are 24 volt rated then you need a 24 volt alternator and your current batteries wired as series. Batteries may be low on capacity but the voltage will allow the motors to run at the correct efficiency.
If the speed controllers are 12 volt you will need 12 volt motors
On a side note the motors will generally consume 20/25 amps at full load which means the existing batteries will have a short full load run time.
Mark is happy to help with any further info should you require it and he feels the 6hp motor is more that adequate
Hope this helps

Now that makes more sense now that we now know what the motors actually are and would explain the lack of torque too. As with 24 running at 12v they just stalling out under the load. Right now it like running a V8 on 4 cylinders it will run, just no power.

As NormK posts Gambler will need to change the motors or change over to a full 24v system.

Hi all,
I dont have a problem with a lack of torque. The motors are very capable of climbing hills on 12 volt until the engine revs drop due to additional load. Travel speed is not affected but its no good mowing at low engine speed for obvious reasons.
I deliberately chose a 12 volt system because 12 volt alternators are easy to come by at very reasonable costs. I could have designed the system for 24 volt as the (single) speed controller is also capable of being supplied with 24 volts.
I have run the mower on 24 volts battery power just for shits and giggles and turned into a speed machine looking for a 1/4 mile tarmac to vent its anger.
I agree with the statement of half the voltage double of current consumption when you apply ohm's law to a fixed load (the hill in this case) .
Has anyone got suggestions on how to come by a cheap 24 volt alternator as I am curious and like to try this out. Would be awesome if it worked.

How about an old truck or 4X4. I have one from a 1980-1988 Nissan Patrol. You could have it if you were closer.

The other thing is you will burn the motors and speed controller out if you keep running it on 12 volts. Millions of trucks use 24 volt alternators so should be fairly easy to come by.

Here is one
http://www.ebay.com.au/itm/Deutz-Bosch-Alternator-24v-55-amp-/322097465818?hash=item4afe8149da:g:wNYAAOSwKtlWlC~X
I also have a new alternator in the shed been there for years,I was told it was off a Volvo. It is a fairly big alternator so it could be a 24 volt one, not sure how to tell, might have to get Mark to look at it. You are welcome to that one if it is suitable

Sorry Gambler, the Volvo alternator I have has a sticker on it with 14v on it

No worries Norm,

just purchased the Bosch from Fleabay

Should arrive before next weekend so

watch this space

Hi Gambler, you may have put a bit of time and money into it but I think you might be in front of the $5000 he wants for this one



http://www.gumtree.com.au/s-ad/the-patch/garden-tools/remote-control-lawnmower-4x4-/1109160347

Nice one,
Parts of our block are even steeper than where he is standing and are constantly wet in winter due to septic irrigation being on acreage.
Can't see any sign of of an alternator and judging by the size of those batteries makes me think that ones he runs out of battery power he takes it back to the shed for charging.

Makes me wonder how much mine would be worth once its properly sorted.

Gambler,
It is always the first one that is hard, after all the wrinkles are sorted the second one will be much easier and I'm sure you would get a tidy sum for the prototype. Must be thousands of properties that need this sort of machine

Hi Gambler,
A mate and I have decided to build one of these cracking machines. He has a few acres in Pakenham that is fairly steep and he can't use his current ride on on it. We are planning on a 36 inch cut based on the R36 Deutscher, fairly simple design with a 13 hp motor fitted. Any advice or tips you can offer regarding tracks,remotes and drive motors. Anything you would do differently the second time around?

Hi Gambler.
Another problem we have thought of with yours is possible oil starvation on the severe slops, which may be one of the reasons the Gumtree 4wd one was using a 2 stroke motor. Something to keep in mind

Hi Norm,
good on you for building one yourself and may I welcome you to the dark side..........

A 13hp engine is a great start to eliminate the problems I am experiencing. As for the motors I would try to get some wheelchair motors as they are built for heavy duty going and more importantly continues load. Your local disability scooter hire place is the way to go for these or you could try your luck on ebay like me.
I had considered using wiper motors but looking at the shaft sizes and lengths decided against it.
If you want a tank style control then a Dimension Sabertooth 25 x25 is a must as it is operated via one joystick only and childsplay to use .
The remote I use is a Fly Sky 6 channel model plane controller which comes complete with receiver and is directly compatible with the Dimension motor controller.
The biggest hurdle I had to overcome was the tracks which I am pleased to say was only solved 3 weeks ago.
These are front motocross tyres with the sides cut out using a sharp carpet knife.Motorbike shops give these away for free as it costs them money to dispose of them.
I manufactured little guide blocks (pyramids) out of harwood which are glued to the inside of the tyre with sikaflex and held in by a screw whilst they set.These hold the track in place under lateral load when crossing hills side to side and the sikaflex expands when the tracks are tightened.
The wheels are made from formply and turned to fit the little pyramids in a wood lathe. They are working at the moment but i am on the lookout for some plastic material that will be longer lasting.

As I will be working on it this weekend I will take some close ups of the tracks and other bits and bobs to help you out. The 24 volt alternator arrived today and is ready to be trialled on Saturday.