steve.sharratt Posted September 7, 2022 Report Share Posted September 7, 2022 Hi, I have what I think is a 24v alternator but I can’t find any indelicate on markings. Is there a way to bench test to find out voltage and, ideally amps? Link to comment Share on other sites More sharing options...
Tony Brooks Posted September 7, 2022 Report Share Posted September 7, 2022 A test bench would have a resistive load so it can be run up without a battery but I doubt you have one so I would suggest you find your local alternator and starter specialist and pay them to test it. If you post your nearest town hopefully someone can recommend. Link to comment Share on other sites More sharing options...
BEngo Posted September 7, 2022 Report Share Posted September 7, 2022 If you know someone with a lathe that could be used to spin the thing up and then a multi meter will give you its voltage. For current you will need an ammeter or a shunt and some sort of variable load. A lot of headlamp bulbs in parallel would do but you need to know the voltage. Start with one lamp and keep adding till the output voltage starts to drop. Measure current. Some prerequisites: Enough speed and power from the lathe. You want about 3000 rpm at the alternator and possibly a couple of kW The alternator must have a voltage regulator-either built in or its external one wired up fully. A battery to excite the alternator will probably be needed. Warnings: It will probably have to be a mechanical lash up. These are inherently dangerous If the alternator output goes open circuit whilst on load you will almost certainly have an EX alternator. Alternators can generate high voltages in the wrong circumstances. Keep your fingers away from the connections. Much better to post a pic on here. Someone will be able to identify it. Or take/send it to you local auto electrical folks and get them to test it. If stuck Lancashire Rotating Electrics are good and do a swift turn round. Link to comment Share on other sites More sharing options...
ditchcrawler Posted September 7, 2022 Report Share Posted September 7, 2022 (edited) I took my 100amp one to our local guy in Lowestoft for repair. I gave it to him and he looked it over, saw the 100amp stamping and said "well they are optimistic" That was just on physical size. I have never seen it above 50 Amps output. Edited September 7, 2022 by ditchcrawler Spilling 1 Link to comment Share on other sites More sharing options...
steve.sharratt Posted September 7, 2022 Author Report Share Posted September 7, 2022 3 hours ago, Tony Brooks said: A test bench would have a resistive load so it can be run up without a battery but I doubt you have one so I would suggest you find your local alternator and starter specialist and pay them to test it. If you post your nearest town hopefully someone can recommend. I have looked but didn’t find anyone. I am in Staines TW184TS if anyone can recommend. 3 hours ago, BEngo said: If you know someone with a lathe that could be used to spin the thing up and then a multi meter will give you its voltage. For current you will need an ammeter or a shunt and some sort of variable load. A lot of headlamp bulbs in parallel would do but you need to know the voltage. Start with one lamp and keep adding till the output voltage starts to drop. Measure current. Some prerequisites: Enough speed and power from the lathe. You want about 3000 rpm at the alternator and possibly a couple of kW The alternator must have a voltage regulator-either built in or its external one wired up fully. A battery to excite the alternator will probably be needed. Warnings: It will probably have to be a mechanical lash up. These are inherently dangerous If the alternator output goes open circuit whilst on load you will almost certainly have an EX alternator. Alternators can generate high voltages in the wrong circumstances. Keep your fingers away from the connections. Much better to post a pic on here. Someone will be able to identify it. Or take/send it to you local auto electrical folks and get them to test it. If stuck Lancashire Rotating Electrics are good and do a swift turn round. I get your point. Find an expert! Good idea about a photo though. I will get one on soonest. Link to comment Share on other sites More sharing options...
Tony Brooks Posted September 7, 2022 Report Share Posted September 7, 2022 Not a recommendation but try https://www.bdolanautoelectrics.co.uk/car-electrics Listed as Egham. Link to comment Share on other sites More sharing options...
cheesegas Posted September 7, 2022 Report Share Posted September 7, 2022 (edited) Unistart in Hackney are very good and will be able to test it. Due to the location they get a lot of boater trade and really know their stuff. Edited September 7, 2022 by cheesegas Link to comment Share on other sites More sharing options...
GUMPY Posted September 7, 2022 Report Share Posted September 7, 2022 https://www.sahibs.co.uk/ Have checked several for me and replaced/repaired some. On the Nth Circular just past Hanger Lane gyratory😎 Link to comment Share on other sites More sharing options...
alan_fincher Posted September 8, 2022 Report Share Posted September 8, 2022 Not particularly close to you, but an old fashioned style place that have done useful things for me with an elderly alternator, (also starter motors) L R Gawley Link to comment Share on other sites More sharing options...
Tony Brooks Posted September 8, 2022 Report Share Posted September 8, 2022 I would add Burghfield starters and Alternators. In fact if you boated to Reading for the week after next I would be happy to run you and the alternator to them. Link to comment Share on other sites More sharing options...
Tonka Posted September 8, 2022 Report Share Posted September 8, 2022 What about Cox Auto Electrics at Atherstone. They would do it. Link to comment Share on other sites More sharing options...
ditchcrawler Posted September 8, 2022 Report Share Posted September 8, 2022 The one in Daventry as well, cant remember the name but will look it up if you need it Link to comment Share on other sites More sharing options...
steve.sharratt Posted September 12, 2022 Author Report Share Posted September 12, 2022 On 08/09/2022 at 11:41, Tony Brooks said: I would add Burghfield starters and Alternators. In fact if you boated to Reading for the week after next I would be happy to run you and the alternator to them. That’s a kind offer, thanks Tony. I have called Kev? and he has been very helpful but unfortunately specialises in 12v systems. He is still able to test, to at least ensure it is functioning. I have sent him some pictures (which I will add to this post). Cheers Link to comment Share on other sites More sharing options...
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