Leece Neville 555. surge protection ?

[ukboater]

Hi

I am making a 12v charging set for my barge using a yanmar L40 power unit (3.8PS) with a belt driven Leece Neville 110-555 alternator. 12v

I find that the alternator prevents the engine from running up to speed because my 2 Rolls 4000 batteries demand full power immediately if they are discharged. I am driving it at 2000rpm which is around 90/100a on the power curve.  I have seen 100a momentarily on the clamp meter but the engine couldn't handle it and grunted a lot. If I put an isolator on the positive to the battery so I can turn the alt on and off is this going to blow the rectifier? Its a self excited unit with just + & - wires..

There seems to be conflicting information about this subject.

Any help will be appreciated. This is for testing and fine tuning. Obviously I don't want to damage that superb alternator but it does seem to be built like a tank so maybe its OK? I will be fitting a sterling or similar digital regulator to the final build.

Anyone know for sure if it has surge protection on this unit? Presto lite 8LHA2070VB WITH 8RG2112 regulator.

Thanks

[mobile_bob]

one of the most useful functions of a marine controller such as one made by companies like
balmar, ample power, sterling is their ability to control the output of the alternator so as to make use of the available power from a small engine.

most have some sort of ramp up or soft start too which is useful in keeping down dusting of the belt drive in larger engine applications and again is useful for small engine applications.

that is what i would suggest

fwiw
the oem regulator provides really no surge protection in that if your battery needs 100 plus amps at startup, the regulator will allow the alternator to deliver it, provided you have enough engine to drive it.

bob g

[ukboater]

Thanks for that.

OK I will confess. During initial testing I used a crocodile clip to attach to the battery and disconnected it when under load then I reconnected it, otherwise the engine would not rev up at all.. Max was about 30a on disconnection. I'm now worried that I may have damaged the diodes.

I imagine they are OK but I probably shouldn't do that is that right,?

I'm also interested in using a 100w 50ohm rheostat as the generator is specifically for bulk charging with PV to take care of the lower amp absorb charge.

[mike90045]

as the generator is specifically for bulk charging with PV to take care of the lower amp absorb charge.

Huh ?  I think that's pretty odd.

But anyway, what you want to do, if possible, is to get into the regulator portion of the alternator, and fiddle with the Field winding, to control the output.  Maybe it's all sealed up, and then your other option is to get a couple (2 to 5) high amp rated diodes, wire them in series with your battery, and that will reduce the voltage seen by the batteries, and thus, the amps. Then a switch(s) is added (high amp also) across diode(s) so you can switch all or some out (shorting the DIODES) and allow more juice to the batteries.  This is all manual control, and should not affect the alternator, which will still see a decent load, and not flail it's output voltage into diode killing range.  But don't forget to eventually give the batteries a full charge.

[BruceM]

+1 for Bob's suggestion.  Get a proper regulator for the job. Anything else will be a kludge, especially when you can't even start up without disconnecting.  If you got 30 amps of charging with the alternator disconnected, perhaps you disconnected only the negative lead and there was an alternate ground path via metal frame.  Many alternators have the negative output bonded to the frame. 

If I had not choice but to make a temporary kludge, I'd be thinking more of a 0.02 ohm, 200 watt resistor to provide a voltage drop that was 2 volts at 100 amps (scale the value accordingly if you need to reduce current more- 0.04 ohms would result in 4 volts drop at 100 amps).  As the charge current began to decline, it would allow the battery voltage to increase.  Given the low resistance, I'd also think about using some steel sheet in the negative path as the resistor.  It must be big enough to dissipate the 200 watts plus without getting dangerously hot.   If I'm right about your existing ground path through the frame resulting in 30 amps,  you can see that steel can be an effective power resistor.  Steel fence wire also comes to mind.

[ukboater]

I disconnected the positive. The 30a was the Max on the clamp meter just before disconnection because the engine did start and run but not at its rated speed (3000) more like about 1500. This is when I took the positive off, engine raced to 3000 then I reconnected the positive and it slowed to about 1500. Governor adjustment did not help, it was simply overloaded.

There are no external loads its just clipped to a battery no earth strap or anything. I think the 555 is insulated return anyway.

Reason for bulk charge only is I believe in saving diesel (GBP1.00 per litre for generator use in small quantities) and using the savings to buy batteries more regularly so the system is 'fresh' less engine time etc.

Not sure if the maths add up but its my theory anyway.

Small consumer on residential barge about 80ah a day at 12v.

[mobile_bob]

on the back of the alternator, you will find the little covered unit which is the regulator

it is held on with two small screws, iirc they are 5/16" hex head

you will have to remove the two leads that go into the regulator from the positive post
and the negative post

once you remove the cover/regulator unit, you will also see a pair of wires leading to the brush holder, you will need to remove those two wires too.

you will then have the regulator in your hand, and an alternator with the brush holder available to connect whatever you like for field control.

as Bruce stated, trying to use a reostat is going to be a kludge requiring you to be a babysitter
while the unit is charging, you will have to dial in what you want to start off with and continually fiddle with the reostat to control the charging while you are running the setup.

nothing particularly wrong with the approach if you are left in such a position to have to closely monitor the charging because you have no other approach and have a lot of extra time on your hands.

as for alternate current paths, the 110-555jho series are both negative and positive isolated from the case, so that the unit could be used in either a negative ground or positive ground application.

revisiting the purpose built regulator,  we have a member here that is/has developed a regulator that would work for your purposes. however failing that option i would strongly suggest one made by "sterling" available on ebay for about 100 bucks or so.  the balmar units are quite pricey, however they really do what they claim so that might be something to also look into.

i have on hand units made by balmar, xantrex(balmar) , ample power, hehr, heart interface, and a couple others, however i have never worked with the units made by sterling.

a good purpose built regulator ought to provide a soft start/ramp up function (programmable) to allow for engine startup, warmup and a reasonable stepped or ramp up to a programmable output level.  then it ought to provide for a three step charge regime (programmable) and again programmable for any of the current battery technologies.

most all good controllers also provide a means of equalization as well.

they really are very good at what they do, and i highly recommend using one, if for no other reason than you will not have to babysit the unit every time you want to use it to charge your batteries.

as for disconnecting the output of the alternator while it is running, that is never a good idea, however you likely haven't hurt anything yet.

a genuine 110-555jho uses a set of avalanche diodes which will clamp the output voltage to about 30vdc in a load dump situation.

bob g

[Tom Reed]

Another option if using a belted application is to change to a smaller pulley on the engine. If you want to get the most out of the alternator you're going to need to do this anyway.

[ukboater]

Thanks again mobile Bob.

Yes I am putting a smaller pulley on the engine next week as I suspect a better target output for this engine is 75a because there seems to be a consensus that you get around 20a 12vdc per engine HP and I am using dual spz bee belts which must use a bit of power.

I thought I was going to get 30a per HP but the L40 is not a big unit with large flywheel.

I notice the Australian 'Roto DC Gen set' uses a similar (Chinese?) power unit but they only rate it at 70a 12vdc.They are direct drive and use a water cooled exhaust which is what I am going to do as I am surrounded by fresh water..

Hopefully I can extract sone hot water by fitting an EGR cooler in the exhaust pipe

[ukboater]

Another thought I had was to fix a car brake drum (new Toyota ones are only about ten pounds here) to the end of the output shaft . This would act as a flywheel and a flat pulley to run a high speed low load bilge/deckwash pump with an air con clutch pulley on it. Apparently serpentine belts can run OK on s flat pulley above a certain ratio (3:1)?

It would be nice to have a pump option on the engine specially on a clutch with remote switching

Question is would the fairly heavy brake drum damage the engine or its bearings. It's a half speed camshaft output version with 20mm keyed shaft.

[Tom Reed]

A brake drum may not be the best choice to use as a drive surface for a belt. The centers are rather thin steel and not designed to take a side load. Now if you could find an old truck with a transmission mounted band brake for a flywheel that might work better and give you a flat surface to drive a belt from. Now the flywheel will not give you any additional continuous power into the alternator, but it will assist with high momentary loads.

[ukboater]

Hi

The brake drum is actually a single cast iron piece and pretty heavy duty. I will need to machine a hub with a keyway to mount it.

I know it won't give more power but possibly smoother output?

[ukboater]

Its a brake drum for a Toyota corolla.

[XYZER]

After talking to Bob about allowing the engine to warm up before applying a alternator load he suggested putting a switch on one of the brush leads. This allows me to intervene or apply a charging load at my whim. Works good Bob....Thanks!

[BruceM]

Good thought, xyzer.  For the current limiting kludge, putting a rheostat or adjustable power resistor in the series with one of the brushes would be a way better solution than what I previously suggested; it would limit the maximum current output, but would not affect the regulated finishing voltage at all.  I'll WAG it at 10 ohms but measuring max brush current with an amp meter first would be best.  A time delay relay in series with the resistor could be used to provide a bit of warm up delay, also.  A whole lot less work to just buy a proper regulator, per Bob's suggestion.