LM 32 - WHERE DOES THE DC FROM THE ALTERNATOR GO?

[alisdairjohnston]

I've switched to using a trolling motor, with external battery pack for Nordlys' dinghy.  While I have managed to charge the battery pack from the 240 V battery charger, clearly on a longer trip (off grid)  this isn't a lot of good!

Exam question therefore: How do I charge the battery pack from the alternator?  I am unsure if the boat has a charge regulator between the alternator and battery bank (2 x pairs of 120 AH batteries). I can't see anything obvious - but LMs do have a habit of hiding things ! 

[Brian & Glenda]

My 1983 LM32 with Bukh DV36 SME came with a Paris Rhone 50A Alternator that had an external voltage regulator mounted high on the stbd forward end of the inside the engine compartment. This original (to me) voltage regulator was a Ford made product. Whether it was an OEM part or not, I cannot say. Sorry I don't have any photos of where it used to be. The voltage regulator in your alternator, may be built into the alternator.

I subsequently replaced the alternator with a Motorola 90A alternator and a Balmar ARS-5 external voltage regulator. (This particular voltage regulator doesn't have a charge program for lithium ion batteries, but does have programs for Deep Cycle Flooded, Gel Cell, Absorbed Glass Mat (AGM) and Spiral Wound Flooded (Optima) batteries.) I also added a Blue Sea System Automatic Charging Relay such that it will control the output of the alternator to the engine start battery first, and once charged redirect the current to the house batteries; and I wired my Solar Panel charge controller to the same inputs, such that my solar panels will work in a similar manner. It sounds however, that you'll probably end up with three battery banks ... house, engine start and auxiliary electric engine. Off the top of my head I'm not sure how you'd wire that, but I'm sure that can be done.

Brian.

[alisdairjohnston]

Hi Brian, thanks for the quick reply. My boat has a Beta 34 (or 35 HP) diesel - re-engined in 2006. Interestingly, the two battery banks (which have a make before break rotary switch) appear to be identical. That is, there is no quantitative difference between the capacity of both banks. I was looking for a device such as you describe, in the hope that I could simply run another set of connections to the Auxiliary battery. Nothing obvious! I will keep digging!

[Brian & Glenda]

Hello again. I was looking for further info regarding my ACR to determine if it can be used for three battery banks, and found the following link that I thought you may find useful. marinehowto.com/automatic-charging-relays/

It appears that I was wrong in my statement about how my ACR works. It doesn't charge one battery bank fully before switching to charge the other. It simply combines the two when a charge is required in either, yet somehow it won't overcharge one bank even if the other has a lower state of charge. I'll have to re-read this to better understand how it does that.

I didn't find in here, advice regarding how you could charge three battery banks ... but perhaps shoot Blue Seas a note, and they can propose a solution.

Brian.

[alisdairjohnston]

Hi Brian,

That's really helpful - because I have never altered my battery switch while charging under engine - and they have not gone flat in the last 6 years.

This would imply that there is some sort of charge regulator in the system - I just need to find it.

Sadly, it's not the weather for lying inside the bilges of an LM (she's still afloat)... Brrr!