- Thread starter
- #21
Just ordered this Alternator so I will post up after installed which will be a few months from now
R
R
New 3B 80 amp 12V alternator with vacuum
- Thread starter Roberto
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Be very careful
Such high out put alernators can also over charge your batteries and make them useless
They can make your batteries over charge and useless
Waaz
???????
Carefull WaaZ we are talking amps here not volts. Batteries will only ask the Alt for what they need.
Granted that the alt size iis usually overcatered for, but cant do any harm except to your pocket and if not fused properly, can do more damage in the event of a short.
To be clear, a high current alt can NOT damage a battery form overcharging.
G
Such high out put alernators can also over charge your batteries and make them useless
They can make your batteries over charge and useless
Waaz
???????
Carefull WaaZ we are talking amps here not volts. Batteries will only ask the Alt for what they need.
Granted that the alt size iis usually overcatered for, but cant do any harm except to your pocket and if not fused properly, can do more damage in the event of a short.
To be clear, a high current alt can NOT damage a battery form overcharging.
G
- Thread starter
- #23
thanks, I have the National Luna Dual Battery Intelligent isolator smart system which prevents Alternator overload.
R
R
The NL system does not prevent overload, it isolates the batteries when the car is off and links them again a short while after starting.
Again the batteries will only take what they need. The concept is very much misunderstood, but rest assured a large alt will not fry your batteries. (Assuming all is working properly, but that goes for a small alt as well).
People always look at the max amps that an alt can produce, and, at which revs these amps are available.
The earlier the amps are available, rev wise, the better chance the batteries have to recharge at idle or very low speeds, so only important if you have parked for a long stay and want to use the engine (alt) to charge the batteries every few days. Again this takes longer than you think and it means idling a diesel for long periods of time with all associated problems. Better to up the revs with a hand throttle. ( IMHO)
The other good reason for a large alt is to feed all systems and auxiliaries AND have enough for battery recharge demands, in practice this seldom happens BUT if your alt can’t handle the demand then you stand more chance of alt damage and then battery damage due to UNDERCHARGING.
How much is enough???
90Amps for me, I run 2 100a.h batteries (1 system 1 aux), no extra running lights, no winch,no air con, led interior and camp lights, a fridge, and lots of camera and laptop battery recharging (with engine off). It's never been wanting even when the aux is flat and the head lights on.
Happy to discuss the matter further.
G
Again the batteries will only take what they need. The concept is very much misunderstood, but rest assured a large alt will not fry your batteries. (Assuming all is working properly, but that goes for a small alt as well).
People always look at the max amps that an alt can produce, and, at which revs these amps are available.
The earlier the amps are available, rev wise, the better chance the batteries have to recharge at idle or very low speeds, so only important if you have parked for a long stay and want to use the engine (alt) to charge the batteries every few days. Again this takes longer than you think and it means idling a diesel for long periods of time with all associated problems. Better to up the revs with a hand throttle. ( IMHO)
The other good reason for a large alt is to feed all systems and auxiliaries AND have enough for battery recharge demands, in practice this seldom happens BUT if your alt can’t handle the demand then you stand more chance of alt damage and then battery damage due to UNDERCHARGING.
How much is enough???
90Amps for me, I run 2 100a.h batteries (1 system 1 aux), no extra running lights, no winch,no air con, led interior and camp lights, a fridge, and lots of camera and laptop battery recharging (with engine off). It's never been wanting even when the aux is flat and the head lights on.
Happy to discuss the matter further.
G
Man! Some pretty odd advice being given out in this thread. Here are some more!
I have an Inova 3721 voltmeter ($13 on amazon), plugs into cigarette lighter socket and shows voltage very accurately (tested and showed same values as a fluke dmm). It is great to see that system is keeping a charge and alternator is working and batteries are well behaved. It shows voltage before you start the car (full charge is about 12.7), also shows voltage as you hit the glow (drops to 12 or so with my pair of batteries.) When rpms are up my steady voltage shows 14.2 but mine drops to 13.8 when headlights are on.
As others have said: don't worry about "high amperage" alternator, its the voltage that needs to be controlled. Insufficient amperage is a bigger problem as low voltage can do damage but mostly just won't charge your batteries.
Remember that its not good to recharge a deeply drained battery using the alternator, the high delta between battery and charging voltage can cause battery to take a false charge, battery will show 12.7 volts but voltage will drop quickly with use. Invest in a smart charger that will float voltage upwards as the battery charges. This takes several days for my pair of deep cycle batteries but gives a much better and deeper charge. Have been thinking it would be a good idea to be able to put a smart charger between the alternator and the batteries, but that's not how our cars are wired...
I have recently had two 1984 bj60 alternators rebuilt at Romaine Electric in Kent Washington. First alternator the seal between vacuum oil chamber failed and filled alternator with oil. They sandblasted, cleaned, repainted, replaced bearings, rectifier, seals and new voltage regulator for $270 US. They can rewind stators but in my case there was no need. The rebuilt unit is gorgeous and I feel good knowing it was rebuilt and tested by hand in the states. Second alternator had a bad diode in voltage regulator so wouldn't cap high voltage (BAD for batteries.) They replaced voltage regulator, rest of unit was fine so they didn't touch it. Cost $75 US. They rebuild alternators for small aircraft, armored cars, etc and seemed incredibly competent. In both cases the new alternators are rock solid at 14.20 volts.
I have an Inova 3721 voltmeter ($13 on amazon), plugs into cigarette lighter socket and shows voltage very accurately (tested and showed same values as a fluke dmm). It is great to see that system is keeping a charge and alternator is working and batteries are well behaved. It shows voltage before you start the car (full charge is about 12.7), also shows voltage as you hit the glow (drops to 12 or so with my pair of batteries.) When rpms are up my steady voltage shows 14.2 but mine drops to 13.8 when headlights are on.
As others have said: don't worry about "high amperage" alternator, its the voltage that needs to be controlled. Insufficient amperage is a bigger problem as low voltage can do damage but mostly just won't charge your batteries.
Remember that its not good to recharge a deeply drained battery using the alternator, the high delta between battery and charging voltage can cause battery to take a false charge, battery will show 12.7 volts but voltage will drop quickly with use. Invest in a smart charger that will float voltage upwards as the battery charges. This takes several days for my pair of deep cycle batteries but gives a much better and deeper charge. Have been thinking it would be a good idea to be able to put a smart charger between the alternator and the batteries, but that's not how our cars are wired...
I have recently had two 1984 bj60 alternators rebuilt at Romaine Electric in Kent Washington. First alternator the seal between vacuum oil chamber failed and filled alternator with oil. They sandblasted, cleaned, repainted, replaced bearings, rectifier, seals and new voltage regulator for $270 US. They can rewind stators but in my case there was no need. The rebuilt unit is gorgeous and I feel good knowing it was rebuilt and tested by hand in the states. Second alternator had a bad diode in voltage regulator so wouldn't cap high voltage (BAD for batteries.) They replaced voltage regulator, rest of unit was fine so they didn't touch it. Cost $75 US. They rebuild alternators for small aircraft, armored cars, etc and seemed incredibly competent. In both cases the new alternators are rock solid at 14.20 volts.