I've never noticed it until the other day ... my alternator seems to heat up when I am charging on shore power. Is this normal?
Some background. I have 400 ah AGM house bank (2 - 4D batteries). The house bank has an "always on" charging buss with fused cable connections for the alternator and charger. The charger is 60-amp Sterling & alternator is 125 amp upgrade with Balmar 618 external regulator. I have BSS DCP switch and ACR.
For the first time ever, I neglected to switch on the main AC breaker when I left the boat after sailing, so my charger wasn't charging! I left without verifying it was on. I always leave the switch "ON" to run the fridge and a few fans. After a week away from the boat, the house bank was drained. I arrived in the evening a few days ago and began charging. The charger initially began charging at around 56 amps. Noting that the SOC was improving through the evening, I went to sleep. In the morning, I glanced at the regulator face and wondered a bit why the alternator temp reading was 45 d C!
My job for the day was to replace the coolant. I turned the alternator disconnect switch to "OFF" (I was going to reach around the alternator to open the coolant drain) and placed my hand on the alternator. Yikes it was hot! Not hot enough to burn my hand but 45 d C is 115 d F and that got my attention! By that time, I had been charging for at least 12 hours and the monitor said about 90% SOC. BTW, the battery temp was 32 d C and the boat was very warm from daytime temps in the 80's-90's and overnight temps in 70's, so I was never alarmed by the battery temps.
From that point on, I switched the alternator off when charging on AC power and only switched the alternator on (with AC OFF) when running the engine. The alternator appeared to be functioning normally and it never heated up again when charging on shore power.
I assume that the alternator is "hot" when I switch on the charger due to the common buss. Disconnecting the alternator at it's own isolation switch prevents the heating. But is it normal or unusual that the alternator should heat up this drastically when charging on shore power? I've never noticed this before, not that I've ever even considered it. Does anybody make a standard practice of disconnecting the alternator at an isolation switch when charging on shore power?
Some background. I have 400 ah AGM house bank (2 - 4D batteries). The house bank has an "always on" charging buss with fused cable connections for the alternator and charger. The charger is 60-amp Sterling & alternator is 125 amp upgrade with Balmar 618 external regulator. I have BSS DCP switch and ACR.
For the first time ever, I neglected to switch on the main AC breaker when I left the boat after sailing, so my charger wasn't charging! I left without verifying it was on. I always leave the switch "ON" to run the fridge and a few fans. After a week away from the boat, the house bank was drained. I arrived in the evening a few days ago and began charging. The charger initially began charging at around 56 amps. Noting that the SOC was improving through the evening, I went to sleep. In the morning, I glanced at the regulator face and wondered a bit why the alternator temp reading was 45 d C!
My job for the day was to replace the coolant. I turned the alternator disconnect switch to "OFF" (I was going to reach around the alternator to open the coolant drain) and placed my hand on the alternator. Yikes it was hot! Not hot enough to burn my hand but 45 d C is 115 d F and that got my attention! By that time, I had been charging for at least 12 hours and the monitor said about 90% SOC. BTW, the battery temp was 32 d C and the boat was very warm from daytime temps in the 80's-90's and overnight temps in 70's, so I was never alarmed by the battery temps.
From that point on, I switched the alternator off when charging on AC power and only switched the alternator on (with AC OFF) when running the engine. The alternator appeared to be functioning normally and it never heated up again when charging on shore power.
I assume that the alternator is "hot" when I switch on the charger due to the common buss. Disconnecting the alternator at it's own isolation switch prevents the heating. But is it normal or unusual that the alternator should heat up this drastically when charging on shore power? I've never noticed this before, not that I've ever even considered it. Does anybody make a standard practice of disconnecting the alternator at an isolation switch when charging on shore power?
