Originally Posted by tedsherrin
.....Why do I need a new alternator regulator?
You need a good EXTERNAL alternator regulator with multi-stage control that can raise the alternator output voltage and will then charge the battery faster. It will also reduce the output voltage to a Float mode when the battery is fully charged to prolong the battery life. There are many other very good reasons why you should fit a good external regulator, even if your internal regulator is producing 14.4 volts.
1. It should have multi-stage voltage settings for different battery types.
2. It should also be custom programmable to match the alternator and battery bank sizes. There are so many ‘new’ batteries now that don’t fit the standard charging profiles. Balmar's regulators allow many parameters to be changed, for example they may set the Boost voltage to 14.6v, hold that for 45 minutes and then reduce it to 14.3v, just below the gassing voltage, and hold it there for the duration of the absorption stage . They can be programmed to stay longer in the absorption stage without dropping down to float too early.
It is worth noting that with sealed batteries most battery manufacturers recommend that you use a multi-stage regulator to drop the charge down to float mode at 13.2-13.8 volts to avoid gassing and overcharging. This is a condition of the warranty on some batteries.
3. It will delay the charge current
for about a minute at start up until the engine oil
is well distributed. A 100 amp alternator draws 4 HP which is a heavy load on an engine when starting with a weak battery.
4. It will also accept a sensor to measure the alternator temperature and control the charge rate. Even a 100 amp alternator could be providing 15 amps to the boat systems, another 25 amps to say a watermaker
or an inverter
, and then a heavily discharged bank may be demanding 50 or 60 amps. In this situation the batteries may not get charged and the alternator will overheat and burn out from continually trying to deliver its maximum output if not protected by a temperature sensor. It is too easy for the alternator on a boat to get too hot if used for long periods.
5. It will also accept a sensor to measure the battery temperature which will rise with a heavy charge current
. At 25ºC batteries start to gas at 14.4v, at 40ºC they gas at 14v so the external regulator will reduce the charging voltage automatically to compensate for this. If batteries are fitted in an engine compartment it is very easy for them to get too hot and lose water
. This is fatal for sealed batteries. Sailing in high temperature regions may mean the batteries are already at 30C before charging starts.
6. It will have a voltage sensor at the batteries not on the alternator. This will compensate for split diodes or losses on cable runs to the battery.
7. A Balmar
regulator has a “small engine mode” that allows you to cut the output to 50% with a switch to reduce the alternator load on the engine when you suddenly need extra power in a big sea. It also has belt manager to reduce the load on the alternator. A 100 amp alternator set to 70% will run cooler and produce 70 amps at a lower speed