Half of house battery bank not charging? Cutwater30 CB

[skipper207]

Hello.

I replaced my batteries this season and am running into some trouble.

The first month things seemed to be ok. I was not at my usual slip and was turning off all batteries between uses because I did not have shore power and I had no problems. But, now I have been at my slip for roughly a week with shore power and been keeping the house batteries on to power fridge, etc.

When I came to the boat today I was getting alarms from my autopilot and Garmin of low voltage. Thrusters and engine batteries are reading good, 12.9.

When I load tested the house bank, the 2 outboard house batteries read 13.1 and the 2 inboard house batteries read 12.2 (this reading was with solar panel still connected but shore power disconnected).
My question is did I buy 2 bad batteries? Or is the house bank not charging adequately and those 2 batteries positioned inboard are being drained first for some reason?

If I am hooked up to shore power, which I am, why would 2 house batteries be being drained?

I am confused. The voltage readout on the Volvo display of the house bank jumps considerably when the engine is running. Just an added detail....not sure how it all fits together. My first thought is to try replacing the 2 batteries that are reading low, but after that I'm at a loss.

Any help would be amazing. Thank you.

 

[dbsea]

are your house bank batteries properly paralleled? If not, this can result in uneven charging. I found this to be the case with mine when the previous owner replaced the batteries in 2021. they should be wired like this (but with 4 batteries):

https://mlbrtmlyq4dz.i.optimole.com/WAF ... rallel.jpg

Mine were paralleled in a somewhat odd way, and I didn't like it so i redid it when I installed my battery monitoring shunt.

 

[Bobby P.]

Also recheck and re-tighten all connections.

 

[BB marine]

Yes confirm that the batteries are parallel correctly. The illustration that dbsea posted is not really the right way to parallel a bank but it does work. Daisy chaining the batteries is the preferred way to make sure the bank is charging as one battery.


This illustrates how the last two batteries are charging the least.
https://eadn-wc04-3361083.nxedge.io/cdn ... nced-2.jpg

This illustrates a better and the most common way to wire the batteries in Parallel
https://eadn-wc04-3361083.nxedge.io/cdn ... thod-2.jpg


This is the best but not alway the easiest to achieve in a tight compartment.

https://eadn-wc04-3361083.nxedge.io/cdn ... nced-2.jpg


I would check each battery with a volt meter while charging. The charge voltage should be the same. 13.0 V + . If they are not the batteries are not wired in Parallel. After all batteries are charged disconnect all negative leads from the batteries. Load test each battery. this will find a weak or weak battery in the bank if any. Replace the weak batteries and wire the batteries in a balanced parallel configuration.

 

[dbsea]

Yes confirm that the batteries are parallel correctly. The illustration that dbsea posted is not really the right way to parallel a bank but it does work. Daisy chaining the batteries is the preferred way to make sure the bank is charging as one battery.


This illustrates how the last two batteries are charging the least.
https://eadn-wc04-3361083.nxedge.io/cdn ... nced-2.jpg

This illustrates a better and the most common way to wire the batteries in Parallel
https://eadn-wc04-3361083.nxedge.io/cdn ... thod-2.jpg


This is the best but not alway the easiest to achieve in a tight compartment.

https://eadn-wc04-3361083.nxedge.io/cdn ... nced-2.jpg


I would check each battery with a volt meter while charging. The charge voltage should be the same. 13.0 V + . If they are not the batteries are not wired in Parallel. After all batteries are charged disconnect all negative leads from the batteries. Load test each battery. this will find a weak or weak battery in the bank if any. Replace the weak batteries and wire the batteries in a balanced parallel configuration.

Good callout Brian! Mine is wired the second way! Not most ideal but better than it was.

 

[CaptT]

Brian, thanks for posting these diagrams. I learn something new every time I read one of your posts.
Terry

 

[skipper207]

Hello all -

Thank you so much for chiming in! I disconnected all battereies and reconnencted them all. To be honest I am still not sure exaclty where things had gone wrong but my guess is the connection on one of the jumpers was loose. The diagrams were very helpful prior to diving back in to reconnect.

I am now getting the right readings, all batteries are charging and low voltage alarm is no more. Thank you all.