Costco Kirkland Marine Deep Cycle Battery

the butcher

the butcher

Well-Known Member
Does anyone know whether the Costco Kirkland Marine Deep Cycle Batteries are TRUE deep cycle batteries? My last set of batteries for my boat are the US Costco Marine/RV batteries made by Interstate and sold through costco US locations. The research I did on the Interestate RV/Marine batteries were they are NOT a true deep cycle battery but rather a hybrid and have characteristics of both a starting and a deep cycle battery. The US Interstate Marine/RV battery's don't have the Deep Cycle wording on their labels but the part numbers for the batteries have a DC in them which many people think it's a true deep cycle battery but it isn't. Canadian costco sells the Kirkland Marine Deep discharge batteries but someone on the internet says they are just the rebranded Interstate marine/RV batteries that they sell through the US costco locations.

Wondering if anyone has experience or knows whether the Kirkland Marine batteries are true deep discharge or not and whether anyone has any experience with them. Thanks.
 
get a northstar AGM - the 103Ah version is great for boats.
kirkland lasted me 18 months before going bad. the northstar is going on 2.5 years without losing capacity. costco did provide a full refund though.
 
zurk said:
get a northstar AGM - the 103Ah version is great for boats.
kirkland lasted me 18 months before going bad. the northstar is going on 2.5 years without losing capacity. costco did provide a full refund though.
Click to expand...
how much was your northstar and where did you get it from? Aren't AGM batteries typically 3-5x the price ?
 
Or you could try 2-6 volt golf carts batteries in series. They are true deep cycle, lots of amp hours and last well. I bought mine at Costco.
 
I only buy Interstate batteries for everything i own.. Just replace the one in my truck at 7 years and my buddy said it still had life left in it.. Never had a problem with one.
 
I use my batteries a lot for heavy prawn trap pulling everyday for a month or more and only charge them from the outboard (40 hp ) so they get abused. I have been running the Kirkland deep cycle group 24 marine batteries since February this year and they seem decent but I do notice they slowly drop in charge over time so keeping them topped up with a charger is recommended. I had AGMs before and they seemed to maintain a charge better.
 
I've used them for years in my ocean boat and in my lake tinny running my electric motor and electronics no troubles at all I just like the fact that they are returnable and costco honors returns up to 60 months I believe the rate is pro rated as the batteries get older so why wouldn't a person take advantage of the ability to return for new we pay for membership and membership has its privileges!
 
I would tend to not rely on the experience of others when it comes to boat batteries - way too many variables on how there are used/maintained; especially the deep cycles as they get damaged from improper charging (especially overcharging) easier than starting batteries.
AGM is popular as deep cycles in boats for a few reasons; they can be safely discharged to less than 50% & still maintain descent life, they don't self-discharge as much, and they can accept a faster charge, which is popular for sailboaters who often only run the engine to charge the battery. On the downside to maintain great battery life they need to be charged using a different charging profile than a standard lead acid battery & most if not all marine engine battery charging circuits are set to charge lead-acid. Buy batteries that can be properly charged with what your engine supports. Realize that your engine charger will most likely overcharge the deep cycle resulting in the battery not lasting as long as it would if charged ideally. This might mean replacing the battery every 3 years versus every 5. You COULD use a deep cycle bank large enough to satisfy your power needs while discharging to 50% or less & plug them into a shore charger using a charging profile for deep cycle/AGM and maintain the longer battery life. My 8d's weigh 150# or so & cost $800 (x2) so I baby them.
 
A few years ago, a buddy with an old cabin cruiser told me that he bought his batteries at West Marine. He would take the batteries back every year and exchange them for new ones. He made up an excuse and he was never refused.
 
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