jonnyswamp Posted December 12, 2022 Share Posted December 12, 2022 One for the big forheaded people on here I will be fitting one of these DC 12V 500A 4 Pin SPST Starter Relay Contactor Double Batteries Isolator Control | eBay To link up 2 batteries just for starting purposes (especially in this cold weather) Can the relay switch be closed using the crank position on the ignition, would make more sense than fitting an odd switch on the dash panel and would always start on 2 batteries Sounds good in theory to me ? Quote Link to comment Share on other sites More sharing options...
Andy135 Posted December 12, 2022 Share Posted December 12, 2022 Wouldn't you usually want to keep the two batteries separate, and only use the House for cranking when absolutely necessary? Otherwise you'll be using them both for cranking every time, which means they'll both need to be charged from the charging system equally, rather than giving the Start battery preference. I'd have thought there could also be a risk of the relay sticking, thus causing both batteries to discharge rather than just the House. I guess what I'm saying is that if it was a good idea, why don't boats designed with 2+ batteries have relay switches already fitted as standard? Quote Link to comment Share on other sites More sharing options...
JonC Posted December 12, 2022 Share Posted December 12, 2022 A big diesel engine probably is best started using to batteries, especially when cold. I run on ‘both’ most of the time and haven’t had any issues. Quote Link to comment Share on other sites More sharing options...
Gordmac Posted December 13, 2022 Share Posted December 13, 2022 I would ask if you are trying to treat the symptoms rather than the problem. If your engine isn't starting ok on one battery perhaps finding out why and sorting that is a better approach? Andy135 and JonC 1 1 Quote Link to comment Share on other sites More sharing options...
captin slows old outlaw Posted December 13, 2022 Share Posted December 13, 2022 i have a second battery with an isolation switch, if the starting battery is low i can always yous the 2 battery's together,then once the engine has started i can isolate the spear battery. Quote Link to comment Share on other sites More sharing options...
Saintly Fish Posted December 13, 2022 Share Posted December 13, 2022 Just now, captin slows old outlaw said: i have a second battery with an isolation switch, if the starting battery is low i can always yous the 2 battery's together,then once the engine has started i can isolate the spear battery. Best get the boat in the water first though Pete !! Quote Link to comment Share on other sites More sharing options...
captin slows old outlaw Posted December 13, 2022 Share Posted December 13, 2022 20 hours ago, jonnyswamp said: One for the big forheaded people on here I will be fitting one of these DC 12V 500A 4 Pin SPST Starter Relay Contactor Double Batteries Isolator Control | eBay To link up 2 batteries just for starting purposes (especially in this cold weather) Can the relay switch be closed using the crank position on the ignition, would make more sense than fitting an odd switch on the dash panel and would always start on 2 batteries Sounds good in theory to me ? try suzuke on that he seams to be up together on that sub-get Quote Link to comment Share on other sites More sharing options...
captin slows old outlaw Posted December 13, 2022 Share Posted December 13, 2022 1 minute ago, Saintly Fish said: Best get the boat in the water first though Pete !! 😜 Quote Link to comment Share on other sites More sharing options...
jonnyswamp Posted December 13, 2022 Author Share Posted December 13, 2022 (edited) 7 hours ago, Gordmac said: I would ask if you are trying to treat the symptoms rather than the problem. If your engine isn't starting ok on one battery perhaps finding out why and sorting that is a better approach? I see what you're saying The starter motor is 14/15 months old and there's new cable from battery to starter, clean connections etc I just think the engine is too tight when freezing cold, spun over fine on 2 batteries, struggled on the usual one Always been fine until now which I put down to the very low temps There's a few other 250's in my marina with the same engine, I'll see what their set ups are like Edited December 13, 2022 by jonnyswamp Bit more info Quote Link to comment Share on other sites More sharing options...
JonC Posted December 13, 2022 Share Posted December 13, 2022 What engine do you have? Quote Link to comment Share on other sites More sharing options...
jonnyswamp Posted December 13, 2022 Author Share Posted December 13, 2022 (edited) 54 minutes ago, JonC said: What engine do you have? The "black engine" 4.2l inline six 230hp Edited December 13, 2022 by jonnyswamp Quote Link to comment Share on other sites More sharing options...
JonC Posted December 13, 2022 Share Posted December 13, 2022 7 hours ago, jonnyswamp said: The "black engine" 4.2l inline six 230hp 4.2 is a big lump, I think my daf Lf is about 5 lt and it has too fuck off big batteries. jonnyswamp 1 Quote Link to comment Share on other sites More sharing options...
Odyssey Posted December 13, 2022 Share Posted December 13, 2022 What CCA do you have in your battery? And what’s the capacity in AH? fir reference, I’ve got 2x 800CCA, 140AH batteries in parallel per engine (3.6l v6 petrol). I can start on one battery but it’s slow when cold, that’s with new cables and terminals. A lead acid battery will lose charge in the cold, the coupled with a diesel it’s worth checking west size you got to just be sure it’s got sufficient juice to start. I would also go for a 1-2-combine tyoe switch instead of mucking about with contactors…. The cheap ones got a habit of sticking open or welding shut… jonnyswamp 1 Quote Link to comment Share on other sites More sharing options...
GPSguru Posted December 13, 2022 Share Posted December 13, 2022 2 hours ago, jonnyswamp said: The "black engine" 4.2l inline six 230hp So I guess that will be the Merc ......... nice motor Yes, the cold weather will play havoc with starting, as that motor will need a lot of current to get it going. Not only will you have thicker engine oil to turn, but you will also have an additional 50 amp of glow plug current. So the battery must be able to supply the additional starter current, the glow plug current, and whilst supplying all that current, also maintain quite a high (IIRC 11.5V) voltage to the ECU in order to fire the injectors. Given that the temperatures we have recently experienced are a rarity, I would be inclined to just keep a couple of purpose made jump leads in the boat for when you need to parallel the batteries for the extra current. Automatic marine battery systems are marmite, some swear by them, others swear at them, and there is a lot that can go wrong. When I had my boat built in 2019, I specified twin batteries, but also specified a simple (but quality) OFF - 1 - BOTH - 2 switch, and not the blusea automatic system that they wanted to fit. Generally I run on both, but when at anchor or drifting, I switch to one battery and save the other for starting (if needed). Quote Link to comment Share on other sites More sharing options...
suzook12 Posted December 13, 2022 Share Posted December 13, 2022 On 12/12/2022 at 4:53 PM, jonnyswamp said: One for the big forheaded people on here I will be fitting one of these DC 12V 500A 4 Pin SPST Starter Relay Contactor Double Batteries Isolator Control | eBay To link up 2 batteries just for starting purposes (especially in this cold weather) Can the relay switch be closed using the crank position on the ignition, would make more sense than fitting an odd switch on the dash panel and would always start on 2 batteries Sounds good in theory to me ? Yes it can. You would need to take a wire either straight from switch or starter solenoid. You could even use a second starter solenoid, same thing. jonnyswamp 1 Quote Link to comment Share on other sites More sharing options...
jonnyswamp Posted December 14, 2022 Author Share Posted December 14, 2022 (edited) 8 hours ago, GPSguru said: So I guess that will be the Merc ......... nice motor Yes, the cold weather will play havoc with starting, as that motor will need a lot of current to get it going. Not only will you have thicker engine oil to turn, but you will also have an additional 50 amp of glow plug current. So the battery must be able to supply the additional starter current, the glow plug current, and whilst supplying all that current, also maintain quite a high (IIRC 11.5V) voltage to the ECU in order to fire the injectors. Given that the temperatures we have recently experienced are a rarity, I would be inclined to just keep a couple of purpose made jump leads in the boat for when you need to parallel the batteries for the extra current. Automatic marine battery systems are marmite, some swear by them, others swear at them, and there is a lot that can go wrong. When I had my boat built in 2019, I specified twin batteries, but also specified a simple (but quality) OFF - 1 - BOTH - 2 switch, and not the blusea automatic system that they wanted to fit. Generally I run on both, but when at anchor or drifting, I switch to one battery and save the other for starting (if needed). This engine doesn't have an ecu or glow plugs, but I get your point Edited December 14, 2022 by jonnyswamp Quote Link to comment Share on other sites More sharing options...
jonnyswamp Posted December 14, 2022 Author Share Posted December 14, 2022 8 hours ago, suzook12 said: Yes it can. You would need to take a wire either straight from switch or starter solenoid. You could even use a second starter solenoid, same thing. Starter solenoid sounds better, thanks Quote Link to comment Share on other sites More sharing options...
GPSguru Posted December 14, 2022 Share Posted December 14, 2022 4 hours ago, jonnyswamp said: This engine doesn't have an ecu or glow plugs, but I get your point Is it a carbed petrol ? Quote Link to comment Share on other sites More sharing options...
jonnyswamp Posted December 14, 2022 Author Share Posted December 14, 2022 5 hours ago, GPSguru said: Is it a carbed petrol ? No, old school diesel, 4.2l 230hp mercruiser, no ecu, mechanical fuel pump etc Quote Link to comment Share on other sites More sharing options...
GPSguru Posted December 15, 2022 Share Posted December 15, 2022 6 hours ago, jonnyswamp said: No, old school diesel, 4.2l 230hp mercruiser, no ecu, mechanical fuel pump etc Yes, it has an old school glow plug system. No glow plug light, the plugs are energized through a timed relay that is connected to the ignition live. The plugs 'glow' for 8 secs. Each plug draws 10 amps. I haven't looked, but I assume the relay is old school with a mechanical bi-metallic timer, and it is probably bolted to the engine. Without the plugs, it would never start in temps of 5c or lower (unless you pump ether into the intake 😉) This system was used by old school yota, BMC, commer, Bedford, and Vauxhall engines. Modern engines (that fail to start more often), are vastly overcomplicated with algorithms to determine how long the plugs should glow given the air and fuel temp, and some have a diesel heater in the secondary fuel filter bowl to shorten the glow time, blah,blah, etc, blah ........ Geoff and jonnyswamp 2 Quote Link to comment Share on other sites More sharing options...
jonnyswamp Posted December 15, 2022 Author Share Posted December 15, 2022 (edited) 19 hours ago, GPSguru said: Yes, it has an old school glow plug system. No glow plug light, the plugs are energized through a timed relay that is connected to the ignition live. The plugs 'glow' for 8 secs. Each plug draws 10 amps. I haven't looked, but I assume the relay is old school with a mechanical bi-metallic timer, and it is probably bolted to the engine. Without the plugs, it would never start in temps of 5c or lower (unless you pump ether into the intake 😉) This system was used by old school yota, BMC, commer, Bedford, and Vauxhall engines. Modern engines (that fail to start more often), are vastly overcomplicated with algorithms to determine how long the plugs should glow given the air and fuel temp, and some have a diesel heater in the secondary fuel filter bowl to shorten the glow time, blah,blah, etc, blah ........ Interesting, I was told that these engines didn't have any glow plugs and simply rely on fuel pressure to start, even in the cold weather EDIT They certainly aint very visable either Edited December 15, 2022 by jonnyswamp daio web 1 Quote Link to comment Share on other sites More sharing options...
GPSguru Posted December 16, 2022 Share Posted December 16, 2022 5 hours ago, jonnyswamp said: Interesting, I was told that these engines didn't have any glow plugs and simply rely on fuel pressure to start, even in the cold weather EDIT They certainly aint very visable either I am happy to be proved wrong Nick, but TBH, I dont know of any oil burners that do not have plugs for cold temperature use, and when plugs fail, most engines are non starters in temps below 5c. I guess your engine is 2004 ? . Mercrusier used Isuzu, VM, GM, and yota (Land Crusier, loverly engine) as the base for their diesels, which is yours ? Yes, they will be difficult to spot, on my 2.8L VM Jeep, the plugs are tucked up under the inlet manifold, the only way to see them is with a mirror (when you know where they are) or looking up from underneath. On my last volvo D4, the plugs were on the rear of the engine, tucked up under the exhaust manifold. On my MY19 Discovery Sport, the feckers are buried under tons of shite in the engine bay, somewhere under the twin turbos and EGR valve. I know that apparently LR charge near on £1K to change them, but their hourly rate is £150 /hour to support their glass fronted palace 🙄 daio web 1 Quote Link to comment Share on other sites More sharing options...
Gordmac Posted December 16, 2022 Share Posted December 16, 2022 The old 6cyl Fords in my last boat didn't have plugs, there was a button on the Simms pump which fed more fuel I believe. Some other engines had one heater in the inlet to heat the incoming air. Quote Link to comment Share on other sites More sharing options...
GPSguru Posted December 16, 2022 Share Posted December 16, 2022 (edited) 55 minutes ago, Gordmac said: The old 6cyl Fords in my last boat didn't have plugs, there was a button on the Simms pump which fed more fuel I believe. Some other engines had one heater in the inlet to heat the incoming air. I am guessing that was the old ford dorset engine ( 2700 ? mid 60’s to mid 80’s ). IIRC it had a specially designed combustion chamber to promote heat generation during compression, however, they were still a bast’id to start on a really cold day. The cold start lever on the pump was just like the choke on a petrol, to add more fuel relevant to the ambient temperature. As a point of interest, the big cummins 5.9L, and 6.7L had a heated grid in the air intake, which has the same effect as glow plugs. Edited December 16, 2022 by GPSguru Quote Link to comment Share on other sites More sharing options...
suzook12 Posted December 16, 2022 Share Posted December 16, 2022 The old transit DI engines had a cable to the pump from a temperature stick thing, that caused the pump to overfuel. Can't say it was hard to start Quote Link to comment Share on other sites More sharing options...
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