Crazyhorse 47 Posted January 10, 2019 Share Posted January 10, 2019 Hours spent on the net trying to find an answer to this, silly thing is, even the manufacturers don't seem to know? How hot is too hot? (Yes, I know, when there's smoke...it's too hot!) There must be a "duty cycle" temperature? Quote Link to post Share on other sites
Island Time 1,230 Posted January 10, 2019 Share Posted January 10, 2019 Over 120 deg c is too hot for long life. Most decent external regs with alt temp monitoring will reduce output too keep it below about 120 c .... Quote Link to post Share on other sites
Crazyhorse 47 Posted January 10, 2019 Author Share Posted January 10, 2019 The plot thickens! One "90" the other is 130!! (neat photo? not mine!). Enertec said 90c is not going to work as most engines get to that temp so it will just be shuttin off all the time, the use 130deg c thermal switches! Water boils at 100. I can put my hand on our 2GM20 after a few hours running no problem so thinking, split the difference? 120? Bought some 90c cutoffs from Jaycar will give them ago but what do I cut off? The regulators N connection to the excites (it controls the earth side of the field) or the D+ which is the P side of the excites? The idea is to have the thermal switch cut the power even though the engine is running to allow it to cool then the switch turns if back on again, no cooked or blown diodes! Quote Link to post Share on other sites
idlerboat 116 Posted January 11, 2019 Share Posted January 11, 2019 If it is getting "to hot" in the first place then something else is wrong.... Rather than allowing it to get to that point and then shut it down, wouldnt it be better to throttle back the load on the alternator ? It should work fine in the engine bays ambient temperature (just like in a fully sound enclosed genset). The diodes should outlast the bearings . Quote Link to post Share on other sites
Crazyhorse 47 Posted January 11, 2019 Author Share Posted January 11, 2019 If it is getting "to hot" in the first place then something else is wrong.... Rather than allowing it to get to that point and then shut it down, wouldnt it be better to throttle back the load on the alternator ? It should work fine in the engine bays ambient temperature (just like in a fully sound enclosed genset). The diodes should outlast the bearings . Sounds good but no. 120 amp alternator N type with negative field to eath regulated charging 300 amps SLA. Starting floating voltage 12.2 to 12.7v then 1000w windlass, 8 amps fridge freezer...not to mention the tablet watching movies! It's a case of too much for to little yet with 300 ah batteries at 50% charge and a 120 amp alternator, there should be loads of grunt when using the windlass (or watching terminator on the tablet). This would not cook a 120a alternator as the internal regulator would wind back the field current. Mines external because waiting half a day to charge the batteries using a litre of diesel an hour is rediculous ( and upsets the greenies). What I see (after a hooch or two) is to have a temperature switch that simply cuts power to the field until the thing cools down. It will disconect Mr Polleys regulator totally and it now looks like it has to be in the field wire, not the D+ as he suggested. The D+ wint achieve anything as its bypassed by running the B+ to the D+ to supply a voltage to the excites constantly, regardless of turning off the key. (This is doing my head in...but..I have a still on board!) Quote Link to post Share on other sites
Crazyhorse 47 Posted January 11, 2019 Author Share Posted January 11, 2019 Yep I would switch the field wire for quick temp decrease. Which mean zero charge until the temp switches back closed. What happens when you drop potentiometer back to 13.6V? That should decrease heating affect by decreasing load on the Alt. But, the problem of insufficient cooling at high Amps is still there. Which you need to speed up absorbtion phase. Which is the problem I had. My 120A delco would overheat within 3mins. My fix. (464Ahrs fla's) Bosch 115A x2......$200NZ (1x Drop in spare) Bosch brush set x2......$70NZ(1 set for spare) Mark Grasser Smartcharge ext reg with bat & alt temp regulation.....$250NZ Generic 4A 12V fan for forced air $100NZ. (Never needed to install) Disclaimer: As I dont have a data logger so I can't confirm no tampering by the ext regulator on heat control just never shows on the Ammeter. Then I'm not glued to it. Alt is noticeably cooler than engine in all stages. And, no high draw devices like windlass (yet), just 3A fridge , 3A autopilot. So not exactly apples and apples. I need to do a capacity test, then run the alt, then maybe it would heat. Thanks Lats. My thinking too. No point in cutting the D+ with the thermal switch if there is a link to it from the B+! A blower I think is manditory when charging more than one battery bank and running: VHF, ICOM HF, AIS, SCANNER, FRIDGE FREEZER, FRIDGE, USB CHARGER, SIMRAD MFD, TILLER PILOT..did I mention the "turdinator"? (You crap it, it's zaps it..) uses more power than old sparky in San Quinton!.."roll on two". The thermal switch is a 90deg c one from Jaycar, just peace of mind really when topside fighting 2 foot waves in a 5kt sou'wester and the missus takes a dump! Quote Link to post Share on other sites
idlerboat 116 Posted January 11, 2019 Share Posted January 11, 2019 I have over 500 amps of AGms, plus a SLA for the engine. The engine bat to house has an isolator combiner between them. I run a small frame 35 amp alternator !! No problems... I live aboard and have TV fridge stereo computer and much more... Plus 2 solar panels (200 watts) . Never had a problem with lack of power or over heating... Quote Link to post Share on other sites
Island Time 1,230 Posted January 11, 2019 Share Posted January 11, 2019 Seems to me you are trying to re-invent the wheel. You may end up with a solution, but it almost certainly wont be as polished or effective as a properly engineered and thoroughly tested system. If you get enjoyment from this, it my be worthwhile. I ran a Balmar small frame alt 70 amp iirc, with a next step NS2 external reg, (bat temp sense but not Alt) 400 a/h vrsla batts , lots of instruments, PC, AP, SSB, microwave, 1500w inverter, 200w solar and 400w wind gen for about 14 years. No issues at all with power, never overheated the batts or the alt. The simple fix is a decent regulator and a hot rated alternator. IMO Big systems can be complex. The Belt management, alt temp sensor, batt temp sensor regulators that balmar and others do are not for entertainment! Quote Link to post Share on other sites
Crazyhorse 47 Posted January 11, 2019 Author Share Posted January 11, 2019 Can't fit a large frame alt to a yanmar 2GM? Got a GENUINE Bosch coming, see how that goes? Quote Link to post Share on other sites
Island Time 1,230 Posted January 11, 2019 Share Posted January 11, 2019 Which model? Whats the spec? The Balmar small frames will fit, and are hot rated; Pic shows a 6 series alt, available up to 150A Quote Link to post Share on other sites
Crazyhorse 47 Posted January 11, 2019 Author Share Posted January 11, 2019 Looks nothing like our old GM20. We have no third pulley. Would need to remove the orriginal fly wheel and stick a serpentine on? BXU12121a 120a universal. Quote Link to post Share on other sites
Island Time 1,230 Posted January 11, 2019 Share Posted January 11, 2019 That does not matter, Alts can be ordered with any foot config and any pulley. its a small frame, it would fit - small frames are a standard size. I had a bit of a look at that BXU12121a unit. Single fan, not hot rated, automotive or genset Alternator. Also duplicated in china, you would have to be careful you got the real unit. It is cheap though... If you are interested the balmar website has a configurator to work thru the get the right unit. By the way, I don't normally sell alts.... Quote Link to post Share on other sites
Crazyhorse 47 Posted January 12, 2019 Author Share Posted January 12, 2019 I have over 500 amps of AGms, plus a SLA for the engine. The engine bat to house has an isolator combiner between them. I run a small frame 35 amp alternator !! No problems... I live aboard and have TV fridge stereo computer and much more... Plus 2 solar panels (200 watts) . Never had a problem with lack of power or over heating... Just read this. 35 amp? It sent me looking on line as I didn't think you could get one that small but yep, there they are. Out of interest, what voltage do you charge at? Can you set it or is it internally regulated? Would take ages to charge up 500 Ah off a 35 amp alternator? Quote Link to post Share on other sites
Crazyhorse 47 Posted January 12, 2019 Author Share Posted January 12, 2019 Forgot to mention. We think we have found the problem! After some research, the alternator we had is a EARTH ISOLATED unit. Yanmar is earth isolated for use in any vessel keeping in mind electrolysis in metal boats boat in glass and timber boats not necessary. Didnt have to be earth isolated by thats what the supply decided to send us. The problem with earth isolated alternators is they can't dissipate heat through the chassis! Being timber, the engine is earth direct to the start battery and the new 120a alts are not earth isolated so the negative side of the alternator has much more capacity for heat conduction. We have 2 alts on the way, one bosch and one American (probably made in China) from a company called WIA, one as a spare. Hope to escape our muddy puddle for Houhora Wednesday... Quote Link to post Share on other sites
Island Time 1,230 Posted January 12, 2019 Share Posted January 12, 2019 Most alternator cooling is air via the fan/s. Most have a single fan, better marine units have 2. Ducting cool air over the alt can work... Quote Link to post Share on other sites
mcp 32 Posted January 12, 2019 Share Posted January 12, 2019 A lot of car companies in Europe use water cooled alternators. These run off the vehicles cooling system and are quite high current for there size. I'm looking at using one for a Renault Megane. Its about 150 amps. https://www.ebay.com/itm/ALTERNATOR-COOLING-WATER-RENAULT-ESPACE-MEGANE-SCENIC-GRAND-SCENIC-155AH/312211524893?hash=item48b141cd1d:g:AQQAAOSwYUlbbEhF:rk:23:pf:0 Quote Link to post Share on other sites
Island Time 1,230 Posted January 12, 2019 Share Posted January 12, 2019 Yep, true mcp. Would work just as well in a boat, but I've never seen one on any vessel I've been on... Quote Link to post Share on other sites
Crazyhorse 47 Posted January 13, 2019 Author Share Posted January 13, 2019 Interesting. A coil of copper pipe at the back of the alternator would do the same thing, allow air to be drawn through the coils cooling it, a T piece off the raw water pump engine feed (ours is straight sea water cooled) then returned into the exhaust mixer? I think a blower on a temperature switch drawing air in from outside the engine bay is going to be a lot easier and safer, probably cheaper too. I'd hate the copper coil to come in contact with the B+! Thought of putting heat sink fins on it too. Our engine does not get all that hot. Can put my hand on the exhaust elbow, rocker cover etc. Yanmar GMs were designed to run cool so having the earth from now on through the heavy engine mount should provide a lot more cooling. Time will tell once its installed and as soon as NZ Couriers works out that Mangonui is not a suburb of Kaitaia and redeliver the new alternator. Quote Link to post Share on other sites
idlerboat 116 Posted January 14, 2019 Share Posted January 14, 2019 Posted Yesterday, 07:45 AM Just read this. 35 amp? It sent me looking on line as I didn't think you could get one that small but yep, there they are. Out of interest, what voltage do you charge at? Can you set it or is it internally regulated? Would take ages to charge up 500 Ah off a 35 amp alternator? Hi CH,..yep 35 amp. A very standard small engine alternator. They are incredibly reliable due to the low loads. Charging output is the same as a car alternator. (reasonably dumb, internal regulator). ...and yes not very efficient...but... 500 amps of batteries (even AGMs like I am running) are (should) only being charged less than half of that amount, because you should never pull them down any further... The combiner isolator is between a single start battery and the main bank and is smart. It actually "pulses " the connections between the two banks until they reach near equilibrium (at which stage there is no huge charge load) The engine battery sort of acts like a capacitor, smoothing out things. More importantly my solar panels and wind genset, have never let me get to a situation where I have discharged so much as to put a very heavy load on the alternator. The whole system is in essence very close to balanced. (a bit of reasearch and a bit of luck ) Even though when I am not cruising I live at a marina, I really only need to use shore power in winter when I run a small ceramic box heater. I would like to go to my third generation of solar panels sometime soon as they have yet again decreased enormously in price and the efficiency has gone up a bit and the size down. Oh and the solar panels feed into the engine battery (that then shunts power across to the main bank via the isolator / combiner) so that if I go away working for extended periods of time the engine battery is always up. The wind gen goes straight into the main bank. (Fridge is an "EvaKool" 60 litre fiberglass camping fridge (chest type) and very low on power consumption and high on reliability. I even keep ice cream (and make it , as written about in posts a long time ago) Quote Link to post Share on other sites
Crazyhorse 47 Posted January 14, 2019 Author Share Posted January 14, 2019 I'm IMPRESSED!! ( no sarcasm!). Our Waeco freezer pulls on average 4 amps every 15 minutes for about 10m. Turbine a waste of money unless there is over 10kts, 15 plus preferable and the solars are great so most time there is no battery topping up via the donk. When I have to, usually there has been no problem as running at 1000rpm the 120ah alt gets things moving at 14.4v...unlike the weak although bullet proof hitach 55 ah that comes stock on yanmars. Incidentally, spent the arvo putting in the new WIA 120 alternator (comes with a chrome fan!!...jee..wow..). Got it all tested then gave it sheeit. 33deg c!! So the OEX cheapie was knackered. Doing 40ah so batts charged in 20mins. Thats stretching it because there is no equalization float charge but its enough to get through those windless cloudy days. AE Spares who supplied it said WIA warned not going over 180deg c. Thermal cut off is 90c so I think we are safe. Now for a well deserved glass of hooch! Quote Link to post Share on other sites
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