Battery testing/ replacement

[Yolodin]

Bought a 2018 29 RTCB last year. Previous owner replaced some house batteries in 8/23. Now noticing that I now need to turn on 1 and 2 banks and use parallel switch to start engine. Voltage after start is 13-14 . Is there a procedure for load testing house bank and engine start battery? Will I run into problems with disconnecting the house terminals ? Also any tricks to access the engine starter battery without having to pull out the house bank of batteries. Thanks in advance!

 

[Bosn Mate]

Ken and Cheryl:

I have a 2018 R29 Sedan and just changed all the batteries on the boat last year.

I am definitely not an electrical expert but will share some of my experiences:

* I did a lot of research on testing AGM house batteries and could not find any info that helped me.

* I was advised to replace all the house batteries at the same time as old batteries will draw down the new ones. This may be the case when the previous owner replaced some of the house batteries in 2023.

* When I disconnected the house batteries, I turned off all battery switches and covered the solar panel with a blanket. Also disconnected from shore power and turned off the switch for the inverter.

* I took photos of all the connections before I disconnected anything, labeled, and zip tied together as appropriate.

* I could find no tricks to access the starter battery without removing the house batteries. I did take the opportunity to better organize the wires/cables to make it easier the next time I do a battery swap.

* Before installing the new batteries, I took the opportunity to paint the cockpit locker deck plywood with Rustoleum Marine Topside. I want to avoid having to replace water damaged deck.

Hope this helps!

Mike

 

[Submariner]

I just replaced all 6 batteries on an R29.
There is no easy way to "test" a deep cycle battery other than using a battery monitor, draw about 10 amps, and wait to see if you can get down to 50% SOC wihle staying above 11.8 volts. It takes several hours to run this test and requires that a battery monitor be installed.

To get the engine battery, the 4 house batteries must be removed. I pulled out the first 2 batteries on the shelf. Then I removed the two screws holding down the starboard tray. Slide the remaining 3 batteries back about 10" so I could get the third, house battery out (the one on the inboard side to expose access to the negative post on the engine battery). Then I could reach the negative post on the engine battery (it has a short lead). disconnected it. Then I was able to pull the tray with the remaining 2 batteries all the way out.

Note: Before moving the shelf (made of starboard), use a sharpie to draw an outline on the two corners. That will help align the holes in the screws back to their original position when you slide the tray back into place. I sat in the port laz, and used my feet to push the battery tray with the batteries back into place. I also use electrical tape over all the connections I remove, to help prevent an accidental short from occuring with all the cables hanging loose.

The new battery also needs 5/16" posts to fit the existing cable lugs on the boat.
For a used boat recently purchased and the batteries are 3 years old, If I had to do the work to replace the engine battery, I'd replace all 5 batteries in the port lazarate. Start this boating season out right.

Assembly is the reverse of disassembly.