Ian Vincent Posted March 4, 2011 Report Share Posted March 4, 2011 I am now at the stage of rewiring my TR3a. I am using a Dan Masters Powerblock solution which for the benefit of those not familiar with it, assumes that you convert to negative earth (and an alternator) with the core component being a board with 7 relays on it to control the main output areas and a single power terminal which connects to the battery connection on the starter solenoid. The ammeter sits across this connection between the power terminal and the starter solenoid. The kit assumes that you are using a stock GM 2 wire alternator with the main output terminal connected to the battery side of the starter solenoid and the smaller terminal connected to the ignition light. I am using a Lucas 3 wire unit so under normal circumstances I would also be connecting the sensing terminal to the battery terminal on the starter solenoid. This would mean that I will have two heavy duty wires running in parallel from the two big positive terminals on the alternator, to the same point on the starter solenoid and it's starting to get a bit cluttered with large capacity wiring (having already got a 300 amp wire from the battery attached to it along with the main power connection to the Power Block board). So my question is, will it be OK for me to join together the + and the B+ terminals at the Alternator rather than attach separate wires and run them back to the same terminal on the starter solenoid. To help with understanding my ramblings, I have attached the Powerblock wiring diagram. Rgds & Thks Ian Quote Link to post Share on other sites
Phil Tucker Posted March 4, 2011 Report Share Posted March 4, 2011 Hi Ian I have used the three wire type alternators in the past and as you suggest just linked the two positives at the unit. I notice that you have sketched your ammeter in the feed to the powerblock. In this configuration it will indicate the load drawn by the car and not the charge rate/ balance. I have in the past modified several early TRs fitting small 36A alternators and retaining the 30-0-30 ammeter. OK the ammeter could be overloaded by 6A or so but most of the time is only bounces around the zero. From experience the only time it got close to full scale deflection is when the car was jump stated because it had a flat battery and then only when the engine was revved hard. I have attached my ideas on the connection to teh powerblock. I hope this helps. Best regards Phil Tucker. Alt wiring.pdf Alt wiring.pdf Quote Link to post Share on other sites
Ian Vincent Posted March 5, 2011 Author Report Share Posted March 5, 2011 Hi Ian I have used the three wire type alternators in the past and as you suggest just linked the two positives at the unit. I notice that you have sketched your ammeter in the feed to the powerblock. In this configuration it will indicate the load drawn by the car and not the charge rate/ balance. I have in the past modified several early TRs fitting small 36A alternators and retaining the 30-0-30 ammeter. OK the ammeter could be overloaded by 6A or so but most of the time is only bounces around the zero. From experience the only time it got close to full scale deflection is when the car was jump stated because it had a flat battery and then only when the engine was revved hard. I have attached my ideas on the connection to teh powerblock. I hope this helps. Best regards Phil Tucker. Very many thanks Phil, particularly for the correction with the ammeter. Rgds Ian Quote Link to post Share on other sites
Menno van Rij Posted March 5, 2011 Report Share Posted March 5, 2011 I'm sure you're not too concerned about the fully original TR3A; the Power Block isn't an original feature after all. So, why bother with the Am meter? My car has the same power block configuration and I ditched the Am meter in favour of a period correct Volt meter. First, the Am meter isn't usseful with a modern style alternator and I was very concerned having loads of elektric power running closely behind the metal dash! (Volt meter nearly... visible on the last pic. Menno Quote Link to post Share on other sites
ianc Posted March 5, 2011 Report Share Posted March 5, 2011 My article in Section J4 of the Technicalities CD covers both 2-wire and 3-wire alternators, and in the current TR Action there is a further article by Jim Christie and me about 2-wire units. Ian Cornish Quote Link to post Share on other sites
Ian Vincent Posted March 8, 2011 Author Report Share Posted March 8, 2011 I'm sure you're not too concerned about the fully original TR3A; the Power Block isn't an original feature after all. So, why bother with the Am meter? My car has the same power block configuration and I ditched the Am meter in favour of a period correct Volt meter. First, the Am meter isn't usseful with a modern style alternator and I was very concerned having loads of elektric power running closely behind the metal dash! (Volt meter nearly... visible on the last pic. Menno Many thanks for the suggestion Menno but I want to keep the inside of the vehicle looking as original as possible even if the some of the engineering isn't. To be honest, in the past I have had vehicles with ammeters and voltmeters and beyond checking that they are charging, I have rarely used them. Let's face it, the majority of modern vehicles don't bother with either. On a slightly different but related topic, there is a world of difference between the gauge of the wire supplied with the Powerblock and the wiring of the original loom. You could probably stick a 200 amp alternator on the vehicle and a battery of lights and other gadgets without overloading anything (apart from the ammeter if you don't bridge it!). Rgds Ian Rgds Ian Quote Link to post Share on other sites
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