Time to replace batteries?

June 1, 2010

We have a typical sailboat setup – 2 battery banks on Reality Check, selected through a battery switch on the panel “2 – ALL – 1 – OFF”. The switch is always on ALL when plugged into shore power to keep all three batteries charged – yep, only 3 batteries.

The method is supposed to be to switch from ALL to Bank 2 (House) when sailing. That’ll keep the engine battery on Bank 1 isolated from the house batteries so there will always be enough juice to start the engine.

What’s that got to do with replacing batteries? Well, when you can’t start the engine on the dedicated engine battery, but have to switch to “ALL” , it’s a good indicator that batteries need to be replaced.

battery is bulging
Gel Cell 73 marine battery is bulging

I put Deep Cycle Gel cell marine batteries on the boat 11 years ago and now it was time to replace. Yikes! The price has tripled! Sure, 11 years is an unbelievable record for marine batteries, but after lots of battery experiences I had become a power miser when vacationing in Catalina – we used ice instead of running the refrigerator and used the portable generator to keep the house batteries charged.

Most people replace their batteries with the golf-cart batteries, like gel cell’s they can be repeatedly discharged and recharged. Looked into that, but… we weren’t going to change the way we used the boat so I didn’t really want to change a set-up that had worked so well for us for a long time.

Do I really need to replace all 3 batteries at the same time? That was the old rule, but a lot of time researching on the internet pointed out that wasn’t necessary. Sounds good to me – the 2 batteries on bank 2 (House) tested ok, the only bad one was the battery on Bank 1 (engine). Saved me a bundle.


Universal M25 Diesel

Heat Exchanger

Engine Compartment Insulation / Soundproofing

Anchor Locker





Bimini for the Boat



Edson Pedestal Controls