Alternators and Regulators
- Thread starter Malabarista
- Start date
PaulRainbow
Well-Known Member
Would be well worth looking into a modern replacement then Sandy. Especially with bluewater cruising in mind, increased charging and the old one would become a spare.
Iliade
Well-Known Member
In answer to a previous Q that I cannot see answered:
Yes do direct an engine compartment air intake to the alternator, it will make a marked difference to the temperature of the alternator.
Yes do direct an engine compartment air intake to the alternator, it will make a marked difference to the temperature of the alternator.
macd
Well-Known Member
Isn't it obvious? If the wheel had pointy bits, they'd batter the mudguards.
More seriously, as Paul writes, your ancient alternator is seriously prejudicing your charging potential.
Malabarista
Well-Known Member
? not mine but Sandys. Mine is so new I haven’t even started the engine yet. Anyway…mudguards on a boat?
Malabarista
Well-Known Member
Thanks for this. I will check with the supplier to check it doesn’t invalidate the warranty or anything. For clarity i was proposing taking a duct from the engine air intake to above the alternator. Also have a fan ( almost) fitted to withdraw air from the engine and battery bay compartments
geem
Well-Known Member
One thing to consider before you fit a ‘modern’ alternator with a charge voltage of circa 14.5v. These alternators are all well and good for most people coastal cruising. They are not sophisticated alternators they simply hit a 14.5v setting and stay there indefinitely. This works fine if you don’t run your engine for very long periods. Most batteries need typically 5 or 6 hours to charge assuming you are not charging a flat battery and you have only taken 15-30% out of the battery over night. An alternator with a smart regulator would go through the three phase charging cycle, bulk, absorption and then float. The so called modern alternator set to 14.5v wont do this. If you have your engine running for 12 or 24 hours you are seriously over charging your batteries.
My own alternator inbuilt regulator is set to 13.8v. The reason is the engine is a commercial unit normally fitted to fishing boats. The alternator on a fishing boat would be running all day so you dont need 14.5v. Batteries simply dont get discharged. Adding a smart regulator like a Sterling with 3 stage charging is far better than adding a ‘modern’ 14.5v alternator if you are going to be running your engine for many hours at a time. Trojan recommend a float voltage of 13.5v for their deep cycle 12v batteries. Running them at 14.5v constantly will do them no good at all. We have a switch on out Sterling alternator regulator. We simply turn it off if we don’t want to start an aggressive charge regime on our already charged batteries.
My own alternator inbuilt regulator is set to 13.8v. The reason is the engine is a commercial unit normally fitted to fishing boats. The alternator on a fishing boat would be running all day so you dont need 14.5v. Batteries simply dont get discharged. Adding a smart regulator like a Sterling with 3 stage charging is far better than adding a ‘modern’ 14.5v alternator if you are going to be running your engine for many hours at a time. Trojan recommend a float voltage of 13.5v for their deep cycle 12v batteries. Running them at 14.5v constantly will do them no good at all. We have a switch on out Sterling alternator regulator. We simply turn it off if we don’t want to start an aggressive charge regime on our already charged batteries.
Malabarista
Well-Known Member
Ok ( he said mulling it over) so now i am more confused. I was advised not to fit the A-B as the Cyrix did the job. But your point is a good one. How do i stop this overcharging without an A-B or similar?
pvb
Well-Known Member
The batteries in many millions of cars and vans happily tolerate around 14.5v for hours on end, and last for years. There's no reason why your batteries shouldn't do the same.
The Sterling A-to-B charger does have some advantages. It allows the start battery to be isolated and charges it at a lower voltage than the house bank. And it has a genuine multi-stage charge profile, with the ability to drop to a float voltage (most add-on "smart" regulators can't do that).
GHA
Well-Known Member
Hard to get an real data on overcharging, hundreds of thousands of white vans and cars have alternators running day in day out at 14.5+V. Possibly more of a problem if you have cheap thin plate batteries, there has been a detailed report (unavailable on the web unfortunately) recommending absorption voltage at 15.3v for solar as any detrimental overcharging seemed to be outweighed by the benefits of actually getting fully charged. (Sandia report from memory) though that was for daily solar , but certainly casts doubt on just how awful a few hours sitting at absorption actually is.
How often will you motor for 24h straight?
PaulRainbow
Well-Known Member
Read #17
Malabarista
Well-Known Member
? Cool thanks
Malabarista
Well-Known Member
Thanks for that. Isn’t it strange how at the edges of perception lie a multitude of doubts ?
GHA
Well-Known Member
Indeed
And next to no data to go on, plenty on here will blindly quote vague spec sheet 'don't overcharge' without having a clue if that's just manufacturers covering their bums. Mobile work platforms the world over often sit on cheap chargers day and night and seem to survive OK. But no real data....
This might be of interest, from someone who has probably done as much testing of boat batteries as anyone..
Musings Regarding External Voltage Regulation
geem
Well-Known Member
If that is correct then why do you run a bulk, absorbtion and float on your solar charger?
GHA
Well-Known Member
I don't. Well, float is set to 14.6v. Otherwise the regulator will cut out before the batts have a chance to get fully charged, it has no idea where the power is going. At a guess an awful lot of cruising boats go to float far too early on solar and just murder their batteries young unnecessarily .
But not really that relevant to 'but certainly casts doubt on just how awful a few hours sitting at absorption actually is. ' without some data, which is sadly lacking. Not surprising, huge amount of work and money and time would be needed. Though little doubt that sitting 14.lots all day every day isn't a good idea, the point was that people tend to run away scared very quickly about leaving charged batteries at absorption while a few hours here and there on an alternator may well have little detrimental effect, must be tens of thousands of them around the world that have that a lot. Without data no way to know for sure.
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geem
Well-Known Member
Dxi
I agree. But since I dont want to destroy my deep cycle batteries to find out I don't run at absorption voltages more than I need to to charge the batteries fully. Being able to switch the alternator to a lower charge voltage has its uses, certainly for us.
Malabarista
Well-Known Member
I spoke to the engine installer today who told me that redirecting my engine intake to just above the alternator is ok but that the alternator is designed to live in a hot engine room and shouldn’t need any help. He also got me to go on FaceTime and show him the connections i have made so far. All good but what kind of excellent service is that? On a Sunday afternoon helping out on a project he has long since been paid for his part in. Many thanks Simon of French Marine. Highly recommended
Iliade
Well-Known Member
The motor itself draws hot air out of the engine compartment at quite a lick. All that should be needed is for the engine compartment intake hose to vent onto the alternator and it will maintain itself at a sensible temperature. Blowers are really only needed to clear the air before start and now and then when then motor is not in use. Maybe in very hot climates.
If the alternator is allowed to get overly hot, it will inevitably produce less power (simple physics) and may be regulated to do so. Generally, engine alternators are not designed to charge vast banks of house batteries, unless a 'proper' marine one is used, but that will probably have temperature based regulation in addition to voltage regulation. [Sterling Instruction Manual PDF]
Apropos the float charging above, I have just observed that my 14.nnV alternator* has boiled off some of the electrolyte from the 2018 sealed house batteries such that the green eye is now black... I have just bought a used Sterling A-B.
* Assuming that the wind and mains chargers were not the culprits, but they are both sophisticated jobbies, Sterlingling and Marlec respectively, so unlikely.
rszemeti
Well-Known Member
I have a pair of these (or at least the prototypes for these). They work well enough, and get good output from a pair of regualr alternators. Alternators themselves have not chnaged much in the last 40 years, what has chnaged is the controller technocolgy.
WAKESPEED WS500 Advanced Alternator Regulator & Wiring Harness
WAKESPEED WS500 Advanced Alternator Regulator & Wiring Harness
