[Amel Yacht Owners] Re: Batteries in Caribbean

Thomas Peacock

Agree with Mark’s excellent advice. However, some battery load testers may show a poor rating on deep cycle batteries, as they are designed primarily for starter batteries. They may claim to be good for deep cycle, but take that claim with a grain of salt. I would certainly isolate each battery and check individual voltages.

Mark Erdos



Your math is correct and you should be reading slightly higher voltage reads than you are getting.


A couple of thoughts:


Are you depending solely on the meter in the panel to monitor the batteries? If so, the meter may be out of adjustment of failing. Did you adjust the Peukert exponent when installing the new battery bank?


The best way to check the voltage of the bank is to disconnect the bank for a while by turning off the red handle switches, check the voltage with a good quality meter from the main studs in the battery well.

Do you have any load on the batteries when checking the voltage. A load such as a refrigerator running will cause lower voltage reads.


Have you load tested each battery to determine if you were sold a faulty or defective battery?


Hope this helps.



With best regards,





Sailing Vessel - Cream Puff - SM2K - #275

Currently cruising - Santa Marta, Colombia



From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Thursday, January 24, 2019 11:50 AM
To: amelyachtowners@...
Subject: [Amel Yacht Owners] Re: Batteries in Caribbean



I have a battery issue too, that I’d like opinions about.

I just bought 8 new series 31 120 AHr deep cycle marine batteries in August (while in Maryland). They were kept fully charged with solar before we headed S in late Dec. After only a month, they are not acting like 120 AHr batteries. They stay charged fully during the day with solar (900watts) but at night they discharge to ~24.7V and the monitor says I’ve only used ~45AHrs. I reset the monitor at dusk when the solar is no longer charging. 24.7V should be about 70% of capacity. That is where I’d like to set my minimum voltage before recharging, in the interest of battery life. But my 480 AHr battery bank shouldn’t get there until I’ve used 30% of capacity, which would be about 160 AHrs.

Am I thinking correctly about that?

I checked the batteries which consistently showed low specific gravity of 1..225 to 1.250 (in the”Fair” range). This didn’t change appreciably after running two equalization cycles with my Victron Skylla charger. It does seem that the batteries are a bit better in that they are now at about 24.8 V just before sunrise.

What do you think is going on here? Should I just keep running equalization cycles until the SG gets back to normal?

Thanks for any advice, thoughts, etc in advance.

Kent & Iris
SM 243
Still in Ft Lauderdale (We’re calling it Hotel California...you can check out but you can never leave.)