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Author Topic: Lister SL2 Startomatic Battery Charging  (Read 463 times)

jonnymcc

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Lister SL2 Startomatic Battery Charging
« on: December 17, 2018, 09:06:11 AM »
Hi All,

I have an SL2 which I have running and all connected up. I usually just hand crank it, but recently I connected some batteries and the starting function is working. (apart from not operating the fuelling solenoid, but I'm not panicking about that)

Doesnt seem to be any battery charging though. I're read about a burned out rheostat, though nothing in my control box looked burned.

Are the charging electrics located in the generator top box or the wall box? I take it the ammeter on the wall box is for battery charging?

How is battery charging carried out? By the mention of a rheostat I assume there is a rectifier diode and the voltage reduced by resistance?

Any help/advice greatly appreciated.

Cheers,

Jonny

oldgoat

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Re: Lister SL2 Startomatic Battery Charging
« Reply #1 on: December 17, 2018, 10:42:07 AM »
Normally there is a switch on the top box to set the charge rate to Hi or Lo follow that wiring to the resistor. The taps on it may be just dirty and a cleanup will fix it.

jonnymcc

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Re: Lister SL2 Startomatic Battery Charging
« Reply #2 on: December 17, 2018, 12:12:52 PM »
Hi, thanks for the response. Noticed that switch but the lettering was worn off so i didnt know what it did. Suspected it may be high/low. Doesnt make any difference at present.

Thanks for your advice; I'll get the lid off and have a look at the terminals as suggested.

Cheers,

Jonny

oldgoat

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Re: Lister SL2 Startomatic Battery Charging
« Reply #3 on: December 18, 2018, 11:18:15 AM »
The switch is CR5 and the resistor is CR in the diagram I sent you. Note that it goes through contact LC2 which is on the main contactor relay this must be operated to get an ammeter reading. CR is the top resistor in the top box on my setup.

jonnymcc

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Re: Lister SL2 Startomatic Battery Charging
« Reply #4 on: December 18, 2018, 12:31:25 PM »
Thanks, I'll get a look at the diagram this evening. Hmm, I know that the switch is connected to the lower resistor in my box. I had forgotten I've already remade all the connections in there so all ok. Was wrecking my head last night trying to work out the wiring. Difficult to test when you don't understand what is going on. I think there is a rheostat in that top box connected by fuse to the positive battery supply, which is also bolted to the box casing; I cant see how its insulated from the casing, but it is!

My main worry was that it looks like my set has 240v outputs connected to the fuel rack solenoid - would have thought these would be 24v.....

Cheers,

Jonny

jonnymcc

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Re: Lister SL2 Startomatic Battery Charging
« Reply #5 on: December 18, 2018, 09:19:31 PM »
So, i managed to miss the damage to the charging resistor. Any idea for a replacement??

oldgoat

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Re: Lister SL2 Startomatic Battery Charging
« Reply #6 on: December 19, 2018, 08:20:58 AM »
The fuel solenoid is connected to 24v via the contact on the start relay. I rewound my resistor with stainless mig welding wire from memory 6 ohms should do the job.

jonnymccni

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Re: Lister SL2 Startomatic Battery Charging
« Reply #7 on: December 19, 2018, 07:55:33 PM »
Thanks for that, I was thinking about a rewind, though I'm a bit lazy......

Taking the current at around 4 amps and a charge voltage of 28.8v gives power of 115w ish. What about a modern 150w 6.8 ohm resistor?

Like this:

https://www.ebay.co.uk/itm/Resistor-Aluminium-6-8-ohm-150-W-2-5-kV-5-HS-Series-Wirewound/272683756229?hash=item3f7d37eac5:g:LrQAAOSwK6RZJF-4:rk:1:pf:0

What do you think?

Cheers,

Jonny

ajaffa1

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Re: Lister SL2 Startomatic Battery Charging
« Reply #8 on: December 19, 2018, 10:53:51 PM »
Hi Jonny, looking at your photos I notice that your top box contains two wire resistors. I am guessing that the high/low charging switch is between them  so you would use one for high charging and both for low charging.

I therefore believe that your maths might be a bit out on the ebay resistor.

My later model ST2 has only one wire resistor with adjustable taps (see photo) I am guessing that this would have the same resistance as yours, I will try to put a meter across it over the weekend and post the results.

Bob

jonnymcc

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Re: Lister SL2 Startomatic Battery Charging
« Reply #9 on: December 20, 2018, 06:34:33 AM »
That would be great, thanks Bob. It doesn't "look" like the switch world on both resistors, looks like it just switches to the other tap point on the lower one. Though I'll see if i can trace the wiring this evening.

On another note, found out why the fuel solenoid doesn't work, the pot is empty and smells like it was once on fire.....


ajaffa1

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Re: Lister SL2 Startomatic Battery Charging
« Reply #10 on: December 20, 2018, 08:42:24 AM »
Hi Jonny, sad to hear your fuel control solenoid is toast, it should contain two solenoid coils, can`t remember if they are on one bobbin or two. These can be rewound if the bobbin/s are intact. If not it is possible to turn a replacement bobbin/s from nylon or paxolin. I will try to measure the correct resistance across these coils this weekend.

I had to rewind a couple of coils in my control panel, it`s very hard to find good information on what size wire to use and what the correct resistance should be. One coil I rewound three times, with different wire, before I got something that worked.

Looks like you might be right about it having been wired to the 240 volt side of things, that would certainly explain the fire. One trick I learned when I was rebuilding mine was that a burned solenoid coil usually still contains approximately the same amount of copper, thus, if you weigh it you will get a pretty good idea of how much wire to wind onto the replacement.

Failing all else there are perfectly good modern fuel control solenoids available, shame to not keep it original but unless you want to take it to shows who cares.

Bob


ajaffa1

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Re: Lister SL2 Startomatic Battery Charging
« Reply #11 on: December 25, 2018, 04:22:45 AM »
Hi Jonny, sorry it has taken me so long to get back to you. We had a bit of a weather event here last weak with more than 300 mm of rain in a day. Been a bit busy trying to clear up the mess.

So, on the charging resistor we have 17.5 ohms on low charge and 7 ohms on high charge. If it helps, the center ceramic bobbin has a diameter of 1.125 inches and there are forty turns of resistance wire to the linear inch.The overall length of the winding is 4.5 inches. This would equate to the resistance wire being around 0.025 inch which would be 23 SWG or 22 AWG, however I have no idea as to how thick the insulating coating would have been so the wire diameter is probably one or two gauges smaller. A quick calculation suggests that this equates to around 53 feet of resistance wire in total. So you need a resistance wire with a resistance of around 1/3 ohm per foot.

On the fuel control solenoid there are two coils on a single bobbin with a small relay switch on the top. To open the fuel rack both coils are used in parallel and they have a joint resistance of 3.6 ohms. Once the rack is open the relay switch cuts out one of the coils and holds the rack open with just the one coil, the resistance of that coil is 7.1 ohms.

I`ve attached a couple of photos which I hope will make my ramblings a bit clearer, have a Merry Christmas.

Bob

jonnymcc

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Re: Lister SL2 Startomatic Battery Charging
« Reply #12 on: December 27, 2018, 08:33:18 AM »
No Problem Bob, thanks very much for the info!

Unfortunately, my FCS has been stripped out after the burning and there is nothing in there apart from the upper switch contacts. I'm pretty sure from the wiring that someone has fed it 240v, I need to tidy the wiring up as they have just taped it up inside there. This is not something I feel a great need for; I don't use the automatic function, though I may like to repair it sometime in the future, I would assume that the best way forward is going to be if I can fit some sort of modern replacement inside the original housing.....

Anyway, back to the charging, thanks for those measurements. I was trying to get a resistance on the remainder of mine and got approx. 5 ohms, so I reckon that 7 ohm should be about spot on. I actually bought a new replacement resistor for a slightly more modern start o matic which I spotted on ebay recently thinking the values should be similar; now I can check it out and see :) The dimensions are different but layout is the same....

Any idea what causes the resistor to fail? A short somewhere? I had a feeling maybe it was to do with someone running it without a battery connected and the +ve contacting the -ve or the frame?

Any idea what the second resistor in mine does? Looks identical to the charge resistor, but the wires too/from it go into the generator housing; could it be acting as a shunt resistor?

Thanks for your help; hope you had a great Christmas, and have a happy new year.

Cheers,

Jonny

oldgoat

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Re: Lister SL2 Startomatic Battery Charging
« Reply #13 on: December 27, 2018, 12:13:47 PM »
That is the shunt field resistor if you get around 240 out of the alternator leave it alone. The big resistor in the top of the gen. housing is also called a shunt field resistor used to set the current of the cross field and controls the voltage gain or droop under load.

jonnymcc

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Re: Lister SL2 Startomatic Battery Charging
« Reply #14 on: December 29, 2018, 11:20:20 AM »
Ok, back to the drawing board!

I took some measurements and made a rough circuit diagram of my charge resistor today. Thing is, i eventually worked out that the damaged part of the resistor isn't in use anyway! It's bridged by a black wire.... I found 12 ohm marked on it but only around 6 ohm is used. Anyway I'm getting continuity across the resistor and up to the control box. Some of the wires on the charge circuit in the control box have been very warm at some point in the past...

Also i can't understand how the resistor burned out where it did, unless someone has already in the past repaired it by swapping it round..... Anything likely to over heat that circuit?

What's my next point to check the charging circuit?

Cheers,

Jonny