BM-1 after Battery Replacement

[Lone_viper]

Hi All,

Before I go down to the boat to put things apart I thought I would post here.....

I have had a BM-1 installed for a while but this weekend it started to show some odd behaviour.

I have recently replaced my 180aH single house battery, with 3 x 90aH batteries wired in parallel, to give me more or less 270aH in pretty much the same volume.

Nothing in the connections for the BM-1 has changed, I just took the existing leads to the bank and connected in parallel with negative on battery 1 and positive on battery 3.

The batteries charge fine using shore power, and seem to also charge ok using the alternator, but here is where it starts to get odd.....

This weekend, while running the engine, I have noticed that the 'charge amps' on the BM were not very high. Firstly just after coming of the dock (with fully batteries) then charge was only bouncing between 0 and +1 amp. But I have never noticed that before and thought it would just show all the power being output from the alternator no matter what the charge level.
Then in the same vain when there was a far amount of discharge, the 'charge amps' were only showing between 20 and 30 amps, dropping down to about 10 after about 30 mins...... Again, I didnt think there would be any sort of regulation to stop putting the amps into the battery shown by the BM-1?

I am trying to put my mind at rest that there isnt anything wrong with my alternator..........

Any help gratefully received.

Jason

 

[Tranona]

Nothing wrong with your alternator. The monitor is showing what the batteries can accept, not what the alternator is capable of producing. What you are seeing is exactly what I see on my similar setup. I was on shorepower overnight last week and in the morning the BM1 was showing a charge of 0.4 amps - because the batteries are fully charged. Earlier after some discharge when sailing (and the batteries not fully charged) it showed 25A on engine startup, gradually dropping over 2 hours motoring to about 5A, then overnight with only the fridge on down to below 1A.

You have no noticed it before perhaps because your previous battery was never fully charged unlike your new ones.