Voltage drop

[gonesailing13]

back in spring I installed new batteries both house and start. Also had a new 100amp Balmar alternator and external regulator installed. When I start the boat the batteries go up to 14 volts. After an hour or so on the water I noticed the voltage start to drop off. First I notice the voltage drop to 13 then down to 12. Even noticed 11.9. Because of the low voltage the stop button will not work, have to manually shut it down. Next time we start her up it’s back up to 14 for the first hour or so before it starts dropping off again. I guess I’m wondering if it could be a problem with the regulator. Not sure.

 

[JackConnick]

Sounds like the alternator isn’t charging the batteries. With the engine running I’d check the voltage or amps coming to the batteries.

 

[ksanders]

Agreed, it looks like your regulator is for some reason telling the alternator to stop producing.

 

[O C Diver]

Did you program the external Balmar regulator? It seems to me that the alternator is working as it's reaching and maintaining 14 volts. There are essentially 3 stages to the regulator, bulk, absorption, and float. I would reprogram the regulator to make sure the float stage is programmed correctly.

Ted

 

[Portage_Bay]

14 volts initially, then less than 12 volts later points to the regulator.

 

[Bmarler]

Is this a new development or has it been this way since the balmar equipment was installed?
I can’t imagine anyone programming in voltage that low so I’m wondering about any temperature sensors you might have. If those are giving bad readings they can essentially shut down the alternator.

 

[gonesailing13]

Is this a new development or has it been this way since the balmar equipment was installed?
I can’t imagine anyone programming in voltage that low so I’m wondering about any temperature sensors you might have. If those are giving bad readings they can essentially shut down the alternator.

The boat sat for awhile, just noticed this problem in recently. I’m not sure about the temperature sensor but will check when i go down again. Do I need the temperature sensor ?

 

[DDW]

I'd say yes. It is there to protect the alternator from self-immolation.

 

[Comodave]

The first thing I always check when there is voltage drop is the connections. They can be loose, dirty on the outside or inside the connector. When doing new connections on large cables I use a copper conductive paste inside the connector. Helps them last longer without corrosion. Then use adhesive lined shrink tube over the connector.

 

[Don L]

its the regulator, but it could be programmed to do what it is doing

but OP are you sure your batteries are OK as the voltage shouldn't dropping so much

 

[TBill36]

As Comodave hinted, connection resistance increases with heat. As your engines heat up along with flowing current any questionable connection will heat up, increase resistance, heat up more from the increased resistance, and voltage will drop. Measure voltage directly off the battery with a voltage meter. If it's higher than what you're reading on the dash you have connection problems. 9 out of 10 it's a ground.

 

[SteveK]

Previously, you asked for input on new cable size.
What size cables did you end up using? Have you touched the cables to check if they are heating up and causing voltage drop.

Also, you have a single engine, how are start and house bank charging handled. Where is the regulator pulling the sense voltage.

 

[gonesailing13]

Previously, you asked for input on new cable size.
What size cables did you end up using? Have you touched the cables to check if they are heating up and causing voltage drop.

Also, you have a single engine, how are start and house bank charging handled. Where is the regulator pulling the sense voltage.

Used 2/0 cable , have to wait until I can get back down to the boat to see if they are heating up. Also have a Balmar Duo charger.

 

[SteveK]

Used 2/0 cable , have to wait until I can get back down to the boat to see if they are heating up. Also have a Balmar Duo charger.

OK, that is more info. Does the ALT+ go to the House or start battery and then to Balmar Duo charger. Also does the sense wire go to the same as ALT+?

 

[gonesailing13]

OK, that is more info. Does the ALT+ go to the House or start battery and then to Balmar Duo charger. Also does the sense wire go to the same as ALT+?

Going to have to check that when i get back down there

 

[Bmarler]

The boat sat for awhile, just noticed this problem in recently. I’m not sure about the temperature sensor but will check when i go down again. Do I need the temperature sensor ?

You need temp sensors to protect the alternator and the batteries. The temp sensor on the alternator can reduce the power output drastically if it’s overheating, the battery sensor adjusts the voltage a bit according to how it’s programmed.