regulator size

jonnyr48 · Post by **jonnyr48** » Sun Oct 27, 2013 11:52 am

yo dudes, im running the lombardini 25LD 425-2 (md190) with the revs turned up, i know the alternator is kicking out 13 volts at a fast tickover, but i think the old md150 ruggerini regulator that i have now is packing up. ive been told this engine has a 20 amp regulator or a 30 amp, which would you guys recommend i get?
cheers, jonny.

tappy · Post by **tappy** » Sun Oct 27, 2013 5:25 pm

Ummm, bit puzzled why you need a new anything? 13V at tickover is good if that's what you're seeing at the battery...

Which alternator are you using - the one that goes inside the flywheel, or one that looks more like a car alternator and is belt driven?

jonnyr48 · Post by **jonnyr48** » Tue Oct 29, 2013 7:26 pm

hi tappy, no its not what im seeing at the battery, thats why i think i need a new regulator! its the internal (flywheel) alternator.

tappy · Post by **tappy** » Wed Oct 30, 2013 12:29 am

OK, so where are you measuring the 13V? If it's not "at the battery", then by definition it's also "not the regulator output" so it's probably not the regulator that's the problem? If you're measuring the 13V on the alternator output at a fast idle then it's possible the alternator itself is goosed...
Sooo, at various rpms, what voltage do you get at the battery, what do you get at the regulator output, and what do you get at the alternator output (with regulator disconnected)?

jonnyr48 · Post by **jonnyr48** » Sun Nov 03, 2013 11:18 am

hi tappy, no idea, im crap at electrics! an aa bloke measured it when i had a problem starting. looks like i´ll have to get some help on this one, i dont even have a meter or anything. thanks for your help anyway
cheers, jonny

gilburton · Post by **gilburton** » Sun Nov 03, 2013 2:47 pm

Start from basics and get your battery checked. Before starting and after to see if the voltage rises when running. How old is your battery? Have you been using more lights etc now that the darker nights are here?

jonnyr48 · Post by **jonnyr48** » Mon Nov 04, 2013 12:26 pm

the battery is brand new, a huge monster of a job.i`ll give it a try, ta

tappy · Post by **tappy** » Wed Nov 06, 2013 11:10 pm

No worries boss - we're all on here to help & be helped. Pop into Maplin or somewhere similar and pick up a Multimeter for £5.
Then come back and we'll talk you through some tests. Spend a fiver, avoid spending £100 on replacing the wrong components...

jonnyr48 · Post by **jonnyr48** » Sat Nov 23, 2013 11:12 am

sooooooooo... dont laugh,it looks like i have a 24 volt alternator! and a new 12 volt humungus battery that i dont want to replace...so do i get a 24 volt regulator, and just lose half the alternator output and not worry about it, or is this going to wreck the battery? all suggestions appreciated
cheers jonny

gilburton · Post by **gilburton** » Sat Nov 23, 2013 12:00 pm

Seems unusual but how do you know it's 24v? Is anything stamped on your starter?
Have your bulbs/battery etc been suffering problems?
Might be possible to get the alternator rewired for 12v?? but is your starter 24V as well??
I presume your old 12v regulator is broken??
Pity you've already bought a battery as you could have got 2 smaller ones and wired them in series to get 24v.
Of course you would need a 24v regulator and change your bulbs/flasher unit to 24v.
To me if it is 24v changing it all to 12v inc your starter would be costly and not worth it so get a 24v regulator and sell your battery and fit 2 in series to get 24v??
No doubt someone who knows will be on here soon to advise

jonnyr48 · Post by **jonnyr48** » Sun Nov 24, 2013 12:45 pm

at the mo i have a new 12v battery, 12v starter thats working, buggered regulator and 24v alternator. its an ex-military engine, i thought the original 24v starter was unusual, now i understand the military run 24v as norm, since it turned out the bloody heater plugs were 24v too im certain this is also a 24v alternator! if i can run a 24v regulator without damaging anything else, this would actually be my simplest/cheapest option but i have no idea if this is so ..........? anybody any idea?

gilburton · Post by **gilburton** » Mon Nov 25, 2013 12:36 pm

Well I'm no expert but it would seem to me you need to match the alternator/regulator in voltage.
Is it a separate car type alternator or is it built in to the flywheel??
If it's a car type anything suitable will do. They can even run backwards if drive take off is a problem.
I ran a 2cv alternator backwards.The 2cv required a separate alternator but I believe most car ones have it built in??

coachgeo · Post by **coachgeo** » Mon Nov 25, 2013 2:39 pm

jonnyr48 wrote:at the mo i have a new 12v battery, 12v starter thats working, buggered regulator and 24v alternator. its an ex-military engine, i thought the original 24v starter was unusual, now i understand the military run 24v as norm, since it turned out the bloody heater plugs were 24v too im certain this is also a 24v alternator! if i can run a 24v regulator without damaging anything else, this would actually be my simplest/cheapest option but i have no idea if this is so ..........? anybody any idea?

Heater plugs? Is this what we call Glow Plugs here in the states? If they are 24v and you've kept them at that......... I suspect it then highly recommended you stay with 24v. Pushing half the juice thru your glow plugs to start the engine (half as warm if not even less) cant be good in the long run.

Cut your losses and get a two small 12v batteries and group them to 24v.

What I wonder is can you also wire thru two voltage regulators to take care of 24v? Other wise though if this was a military unit check with some military vehicle bulletin boards. A military collector type fellow is bound to have an answer for you on the 24v regulator.

tappy · Post by **tappy** » Tue Nov 26, 2013 3:36 pm

Running a 24V regulator with ballast to bring it down to 12V will be incredibly waseful, unreliable, and won't give reliable 12V anyway.
Running 2 x 12V regulators in series and taking a tapping from between them almost certainly won't work either - I think you'll end up with an unstable system and fried regulators.
You *could* try using 2x 12V batteries in series most of the time, and in parallel during starting, but this would require a large changeover relay to cope with the current and in practise it's not very good for batteries - one of them always ends up doing a bit more work.
I have an old 24V starter motor off a Hatz 2G40 that *might* fit if you wanted to revert to 24V. 24V will make life generally a bit more difficult as you won't often be able to use common vehicle electrical parts - bulbs, relays, flasher units, some switches etc.

Sounds like you need to make a list of prices of 12V and 24V replacements and see what's gonna cost less.
I'd inspect the alternator windings carefully first tho' - when a regulator fails it can take the alternator out with it. It probably hasn't, but it's worth checking before you start pricing up...

jonnyr48 · Post by **jonnyr48** » Tue Nov 26, 2013 6:42 pm

thanks guys, looks like changing the alternator is going to be the best??!? option. bloody pricey tho!

mark_in_manchester · Post by **mark_in_manchester** » Wed Nov 27, 2013 6:27 pm

I think you might be able to place a small 12v battery in series with your main one, in the charging circuit - and use a new 24v regulator which I guess will be cheaper than a 12v alternator. The charging current will be the same for both batteries in series - so you'll have to keep an eye on the electrolyte level in the small one, which will boil much faster than the large one. Then take all your electrical supply for the bike, including starter motor, from across just one battery - your large one.

Or - to be more clever and substitute something else for second 12v battery - find out expected charging current for standard 24v battery. Typ this is about 1/10 of the rated capacity of the battery - so 50Amp-hour battery will charge at 5 amp-ish. Regulator spec may tell you what current you will expect to supply.

You then need to drop the 'spare' 12v across an extra load in series with your big 12v battery. Say (for example) regulator wants to supply 5A at 24v. (Power = v * A, so this total power would be about 120W). To drop 12v across a load drawing 5A, Ohm's law says v = A * R - so resistor would be v/A = 12/5 = 2.5 ohms. This would get hot - power = v*A = 60W. So a 12v 60W headlight bulb would do very nicely! You could even wire in the 'dipped' filament of your headlight permanently, in series with the battery in the charging circuit. If the bulb blew, you'd stop charging - only downer.

Does that make any sense? This way you only need some thought, rewiring and a new 24v regulator.

Edit to add - this only makes sense if you now have 12v everything - incl heater plugs - but would like to retain 24v alternator.

cheers

Mark

coachgeo · Post by **coachgeo** » Thu Nov 28, 2013 5:32 am

????? Unless I miss read it........ thimks ya got it backward. Appears all his engine components are 24v EXCEPT the battery and replacement alternator he already purchased which are both 12v. He needs a new regulator though either way he goes.

mark_in_manchester wrote:I think you might be able to place a small 12v battery in series with your main one, in the charging circuit - and use a new 24v regulator which I guess will be cheaper than a 12v alternator. The charging current will be the same for both batteries in series - so you'll have to keep an eye on the electrolyte level in the small one, which will boil much faster than the large one. Then take all your electrical supply for the bike, including starter motor, from across just one battery - your large one.

Or - to be more clever and substitute something else for second 12v battery - find out expected charging current for standard 24v battery. Typ this is about 1/10 of the rated capacity of the battery - so 50Amp-hour battery will charge at 5 amp-ish. Regulator spec may tell you what current you will expect to supply.

You then need to drop the 'spare' 12v across an extra load in series with your big 12v battery. Say (for example) regulator wants to supply 5A at 24v. (Power = v * A, so this total power would be about 120W). To drop 12v across a load drawing 5A, Ohm's law says v = A * R - so resistor would be v/A = 12/5 = 2.5 ohms. This would get hot - power = v*A = 60W. So a 12v 60W headlight bulb would do very nicely! You could even wire in the 'dipped' filament of your headlight permanently, in series with the battery in the charging circuit. If the bulb blew, you'd stop charging - only downer.

Does that make any sense? This way you only need some thought, rewiring and a new 24v regulator.

Edit to add - this only makes sense if you now have 12v everything - incl heater plugs - but would like to retain 24v alternator.

cheers

Mark

mark_in_manchester · Post by **mark_in_manchester** » Thu Nov 28, 2013 9:54 am

[quote]at the mo i have a new 12v battery, 12v starter thats working, buggered regulator and 24v alternator[/quote]

Johnny - can you clarify? Reading this I'm speculating that you put a new 12v battery on, it was sluggish to turn over so you obtained a 12v starter, then when it started the 24v alternator cooked the regulator since battery was 12v. My post will get you going if you have 24v alternator, still. If you have 24v heater plugs too, then ignore my lightbulb idea and use the second 12v battery in series - use both for both charging circuit and heater plug supply, but use only one for starter motor and all the bulbs / fairy lights / blue neon pimp-tubes under your heavily-tassled western saddle...

coachgeo · Post by **coachgeo** » Thu Nov 28, 2013 5:14 pm

(with foot in mouth) yeah I weed ea woung

translated- yep I read/remembered it wrong.

Add to the list 24v glow/heat plugs

jonnyr48 · Post by **jonnyr48** » Thu Nov 28, 2013 7:03 pm

pheeew! thats a lot of science to digest! - yes i have 12v starter plugs (now!), 12v battery, 12v starter, and 24v alternator.according to a helpful lombardini parts agent, this alternator should kick out about 80 to 100 amps ?(!) but i like your idea mark if it can work....?

mark_in_manchester · Post by **mark_in_manchester** » Thu Nov 28, 2013 8:59 pm

Good, so you can use bulb idea. Decide what you want your charging current to be, and use the right bulb in series with the battery in the charging circuit. 21W (indicator) bulb = just less than 2A. 60W headlight bulb = 5A, as we discussed. If it were me, I'd put the headlight bulb on all the time, in series with battery - but try it in a lash-up with a spare bulb first, just to make sure you're happy it's working.

Downside with this is that alternator will only be trickling the battery - nothing else. All loads will pull current from the battery, and alternator will be limited to this 5A whatever the load. Since the largest load will be the headlight, it makes sense to use this in the charging circuit.

cheers
Mark

Nanko · Post by **Nanko** » Fri Nov 29, 2013 9:40 am

Or find a DC to DC converter , they can convert input voltages up to 80 V to an adjustable 14 V output.

jonnyr48 · Post by **jonnyr48** » Sun Dec 01, 2013 10:23 am

ta nanko, its the amperage thats the problem, if i understand it right, the voltage is about 13v which is fine. thanks mark, i guess it would make sense to make sure what the 24v regulator will supply, i´ll ask tyrone at engine parts and filters. how do i wire the dipped bulb in in series? and what happens when i switch the bulb to main beam?

tappy · Post by **tappy** » Tue Dec 03, 2013 12:34 am

Mark, Coach, Jonny:

The regulator will not output a fixed current, it will output a fixed voltage. If the various loads in the system can swallow more current at the regulated voltage, then it will supply it (until the alternator can't cope). If they can't swallow the current then the regulator won't supply it. They regulate voltage, not current.

Neither the "12V" battery or the "12V bulb" have any way of regulating the voltage lost across each of them.

The bulb resistance is fixed, so when the current flow reduces, the voltage lost across it reduces, and the battery then sees a higher voltage.
SO, as the battery becomes fully charged, so the current through it needs to reduce, it will actually see a higher voltage and start to overcharge.

To an extent this might be self limiting but as I said, I think you'll just end up with an unstable, unknown voltage between the two.
If you then start tapping other loads from the mid-point between the two that is your nominal 12V, then the current through the bulb will change again, and the "12V system" & battery voltage with it.

Tungsten halogen bulbs are very sensitive to supplied power - too little and they blow just as fast as too much. Dropping the voltage across one to 11.5V can blow it in minutes if you're unlucky. So you'd need to use very basic, poor light output bulbs.

If we know what all the other loads in the system are going to be then we can do some sums and try to work out what might happen, otherwise I think you might end up eating bulbs or batteries.

coachgeo · Post by **coachgeo** » Tue Dec 03, 2013 7:12 pm

Still think your best bet is to talk with Military folk who have experience with gensets with 24v systems. Here is a start that might help you I pulled from a UK military vehicle site. Maybe they will have some info for you. Granted these guys may deal not with "gensets" but with 24v "generators" that attach by belt to a vehicle engine.... but still they might can point you in the right direction. Also it is possible that any commerical Lombardini place would also be able too. Suspect the 24v regulator has a lombardini part number.

milweb.net wrote:FV Spares
FV Spares
2 x NOS FV760740 No 10 Mk 3 24volt Generators £150 each, 2 x used take off ones £50 each, 1 x NOS 24v Control Box no 9 Mk3 £75, 1 used one £35. All plus carriage or collect from Northallerton, N Yorks.
07836 622860

mark_in_manchester · Post by **mark_in_manchester** » Wed Dec 04, 2013 9:49 am

[quote] The bulb resistance is fixed, so when the current flow reduces, the voltage lost across it reduces, and the battery then sees a higher voltage.
SO, as the battery becomes fully charged, so the current through it needs to reduce, it will actually see a higher voltage and start to overcharge. [/quote]

I don't think the bulb reistance is fixed - it rises as the bulb gets hotter. This should mean that the bulb is a good current limiter for a very discharged battery, but you're right - as the battery approaches full charge the voltage at its terminals depends on the relative impedance of the (cool) bulb, and that across its own terminals. It would want a bit of monitoring, to be able to have confidence in it, and I should have thought of this before opening my mouth!

tappy · Post by **tappy** » Wed Dec 04, 2013 9:10 pm

Yep - you're absolutely correct, the filament's resistance is not fixed but I'd expect that to be a second order effect, in the same way that ballast resistors were used with 6V coils on cars with 12V batteries...

I had a look for suitably sized DC-DC converters last night and can't see anything big enough for less than the price of another alternator anyway.
Plus it's just another source of expensive failure.

gilburton · Post by **gilburton** » Wed Dec 04, 2013 9:38 pm

Sorry not in to electrickery but could the alternator be modified to 12v by rewinding or bypassing some windings??

Nanko · Post by **Nanko** » Thu Dec 05, 2013 12:13 pm

All for around 12$ and as far as I can see suitable for 12 V and 24 V alternators.
24 V alternators need some kind of voltage limiting,(transistor and zenerdiode)

http://www.ebay.com/itm/DC-DC-Step-down ... 58a6a0e27e

http://www.ebay.com/itm/12A-100W-Adjust ... 3cd6f28876

http://www.ebay.com/itm/DC-DC-15A-Conve ... 35cee0c275

tappy · Post by **tappy** » Fri Dec 06, 2013 6:58 pm

gilburton wrote:Sorry not in to electrickery but could the alternator be modified to 12v by rewinding or bypassing some windings??

Depends on how it's wound in the first place. These lombardini, ruggerini & hatz alternators seem to be generally single phase which means your best bet is to just re-wind them.

DieselBike.net

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