Changing Cw30 Start Battery to a Stud Type Terminal Battery

[Shano]

I am considering changing our Ub121100 start battery to an upgraded start battery like a NSB-AGM31 or a Trojan ST1000. My conundrum is that both of these batteries have stud type terminals and the UB121100 has the L type terminals. Is there enough room on the studs for all of the cable ends that need to be attached and is there enough “twist” in the cables to twist the cables enough to attach them? Our batteries are going into their 4th season and unless the engine is warm I need to use the parallel switch to start the D6 and then I need to remember to switch it off again. I would change the thruster battery at the same time. Has anyone done this battery changeover on a CW30? Any tips or suggestions are appreciated. I’m hoping to not have to do too many modifications to make the changeover and I would really prefer to have a start battery with more cranking amps so I really don’t want to put a new UB121100 back in.

 

[BB marine]

The NSB-AGM 31M has Marine/SAE terminals. CCA 1150 MCA 1370. This is the same rating as the NSB-AGM 31 the difference is it does not have the Marine designation at the end of the model number M. The NSB have slightly more cranking amps than the Trojan ST1000. I have the NSB-AGM 27M installed in my boat C26. I had maintenance free original batteries when I purchased the boat from new. The difference between the maintenance free flooded and AGM was weigh, 20 lbs more per battery, cost was double (AGM). The CCA for engine cranking battery Maintenance free and AGM was the same, the duel purpose thruster and house (maintenance free) were 200 CCA less. I'm hoping to see the value AGM ( longevity ) after spending $1100.00, 550.00 more than maintenance free and carrying around an additional 80lbs. I will comment on the quality and reviews of the NSB is above average in my opinion. I don't think that the cable lengths will be an issue. You may have to do some minor rearranging of the cables. Cutting a few cable ties and then adding a few to arrange the cables to your liking for ease of future battery maintenance. I found on my boat there was ample battery cable length.

 

[Shano]

Thanks Brian, I just learned the difference between regular battery terminals and marine battery terminals! I appreciate your insight. I will post again once I make up my mind and get the new batteries installed. I’m also thinking that I will replace my house batteries either this year or next and I will likely upgrade them also to get more amp hours.
Shane

 

[bill46]

I changed original batteries on one 31CB to Sam’s Club Duracell 31 size AGMs. House and thruster fine with threaded studs. D300 would not always start without parallel. Found measured CCA on studs only 210A, SAE posts over 800. So added SAE post adapter, all fine now. Guess stainless studs have more resistance than lead posts.

 

[Shano]

I’m still learning! So if I was to go with the NSB-AGM31M for a start battery then I should use the posts with maybe a top post to side terminal adapter? The whole point is to be able to use the CCA’s so I want to get this correct!

 

[Cutwater28GG]

I have never had a problem with my universal AGM's starting the D4 260. these Northstars are almost double the price. Im trying to understand why you upgraded?

 

[Shano]

I have never had a problem with my universal AGM's starting the D4 260. these Northstars are almost double the price. Im trying to understand why you upgraded?

The UB121100 will not start our D6 when cold and barely starts it when it is warm. So I need to use the parallel switch to bring the house batteries in to start it. Also, our AGM’s are now 3 seasons old so...

 

[BB marine]

I changed original batteries on one 31CB to Sam’s Club Duracell 31 size AGMs. House and thruster fine with threaded studs. D300 would not always start without parallel. Found measured CCA on studs only 210A, SAE posts over 800. So added SAE post adapter, all fine now. Guess stainless studs have more resistance than lead posts.

When using the stud post you must confirm good surface contact between the battery cable terminal and the post base. Many times a flat washer and lock washer on the top and continuity washer on the bottom is needed in this application to provide a good connection. I like Marine batteries that provide both options( Marine/SAE ). Especially with the more complex battery configurations.

 

[Cutwater28GG]

I have never had a problem with my universal AGM's starting the D4 260. these Northstars are almost double the price. Im trying to understand why you upgraded?

The UB121100 will not start our D6 when cold and barely starts it when it is warm. So I need to use the parallel switch to bring the house batteries in to start it. Also, our AGM’s are now 3 seasons old so...

interesting: has that always been the case - even when the batteries are new?

I found after 3 years the same on the 260 buts thats because the batteries are aged: and caused by the charger on the boat treating these batteries pretty badly when on shore power all the time. I bet it would do the same for any AGM, so all you doing is end up spending more money every 3 years for a more expensive battery option.

if its always been the case; my guess is there is something else wrong: like poor connections and you are not getting the cranking amps to the starter effeciently.

 

[Shano]

I have never had a problem with my universal AGM's starting the D4 260. these Northstars are almost double the price. Im trying to understand why you upgraded?

The UB121100 will not start our D6 when cold and barely starts it when it is warm. So I need to use the parallel switch to bring the house batteries in to start it. Also, our AGM’s are now 3 seasons old so...

interesting: has that always been the case - even when the batteries are new?

I found after 3 years the same on the 260 buts thats because the batteries are aged: and caused by the charger on the boat treating these batteries pretty badly when on shore power all the time. I bet it would do the same for any AGM, so all you doing is end up spending more money every 3 years for a more expensive battery option.

if its always been the case; my guess is there is something else wrong: like poor connections and you are not getting the cranking amps to the starter effeciently.

When new the stock battery started the D6 but after 2 years we needed the parallel switch. The D6 has a huge amp draw to start, I think that Volvo recommends something like 1500 CCA to start when sub zero temperatures. I think that the stock battery only has 550 CCA.

 

[Cutwater28GG]

got it - you inspired me to do some more digging!

I just pulled up the Volvo manual specs for reference:

what a difference the temp makes between 41F and 23f!

yeah that universal at 535 CCA wont cut it!
https://www.1000bulbs.com/product/56373/BAT-UB121100FL1.html

has me pondering what I would buy next time. technically its not enough CCA for the D4 either.

 

[Shano]

Thanks for posting the requirement sheet Gavin - this has me thinking also, maybe I could get away with a Northstar group 27. We don’t use our boat in sub zero temps - the 27 is a little cheaper and lighter. It doesn’t have the 110 amp hour rating but it is way better than the Ub on CCA.

 

[Cutwater28GG]

yeah i started looking for other AGM battery options that arent close to $400 each. I just cant justify a $400 AGM battery price.


also not sure if there is anyway to insulate / heat the compartment: my guess is not easily.