Question regarding batteries

[Ronnie]

Hey guys,

I have a 2010 242 LS with the stock dual battery charging system (I.e., four modules, including main battery switch, house battery switch, combine switch and dvsr (?)). I also have a 2 bank on board charger maintainer by guest that puts out 5 amps per bank. Whenever my boat is not on the water the guest charger is plugged in doing its thing.

It's time to replace my batteries, I already bought two high cca/Mca cranking batteries but can exchange one or both of them for deep cycle batteries instead. The manager at the interstate battery store says keep a cranking battery for starting the engines and exchange the other one for a deep cycle to power everything else.

Questions:
1. Should I go with the advice above and run two different types of batteries?
2. Should I run the same batteries? If so what type, cranking or deep cycle? Why?

I like the cranking batteries because of the specs but read that our engines don't need it so I should go with deep cycle instead.

I also don't know if the stock or aftermarket charging systems require the same battery type / specs to operate properly.

Please reply.

 

[GiddYupJoe]

Ronnie, have you read up on all the DVSR discussion with the factory set up on our boat? Basically the smart charger has been playing dumb the whole time when charging them the way you and I have them set up in our boats (assuming you did not do the wiring loop mod, I have not).
I only mention this so that whatever new battery you purchase, it gets card for properly!


I'm interested in the response to you question as I need a new crank battery this season too.

 

[Ronnie]

@GiddYupJoe , yes I've read about the mod to get stock dvsr system to operate / charge both batteries properly. I can't say I fully understand what's wrong since I've used the system un modified for four season now but the easiest fix seems to be to add a switch to one of the lines to break the connection when on the water, if this is right I will just add that switch before next season.

Off the water I don't think it matters if I have the same batteries since the guest charger/maintainer has two separate banks which charge each battery independently but I'd like to hear what other members think before I go lugging one or two batteries back and forth. Once the new batteries are installed I would love it if I didn't see them again for at least another four seasons.

 

[Mainah]

There was a really deep battery debate a week or two ago. Pound for pound and dollar for dollar there are two top options. 6 volt deep cycle golf cart batteries will perform the best dollar for dollar and pound for pound if they are maintained. The downside is that they are wetcells that require electrolyte maintenance and could spill not to mention you will need 4 batteries to make two 12 volt banks. The winner IMO is twin group 31 AGM batteries. They are a just a tad more expensive but should last 7 years and have plenty of juice for whatever you need and are sealed. Sams club has a great deal on a duracell model amd I have interstates that I love but seem to be pricey at some dealers.

The whole cranking battery thing is moot with AGM as it will do both cranking and deep cycle very well. With deep cycle if the capacity is large enough the cranking issue is also moot.

If you have an onboard smart charger I very highly recommend cutting the red dvsr loop and connecting to engine on. Otherwise your smart charger only sees one bank and is tricked into being dumb.

If you have lots of money to burn then the grand daddy of batteries would be a pair of 100 amp or larger lithium ions starting at $1.5k each. For that money you save 1/3 the size and weight amd they last a few years longer with very little concern of discharging and leaving them that way. IMO we are better off waiting for hydrogen over electric power plants in our boats which would have a huge bank of these. Imagine the hole shot a jet boat would have with a couple of 150KW electric motors and big pumps.

 

[Ronnie]

Agm is out of my price range, the interstate branded agms are about twice as much cost wise as their cranking/deep cycle counter parts and I also don't want to wire up four 6 volts. Plus 7 years v 4, twice the cost for less than twice the life doesn't seem like a good trade off too me.

If electric boats follow the same path as electric cars it will be a while before a viable one is developed and it won't be for many years afterwards that I will be able to afford one. I plan to be back on the water within 6 months if not sooner. Just need to know whether is ok to mix cranking and deep cycle or just go with one or the other where the stock charging system is concerned and why.

 

[swatski]

@Ronnie x2 on AGM, marine deep cycle, or just deep cycle, FWIW. Maintenance free! (other than charging)
That red loop DVSR cut/reconnect trick is actually pretty strait forward, albeit took ME weeks to wrap my head around it, LOL.

EDIT: just saw your reply, if not Sam's club (for AGM pricing), I would go with two deep cycle, plenty of crancking power for our boats and def lower maintenance/longevity all other thigns being equal.
--

 

[Firehouse100]

I vote for your regular deep cycle battery. They are usually less expensive. Check the reserve capacity between a 29 series vs a 31. Also a 31 series may require a bigger battery box. The cost may not out wieght the cost difference. I know the interstate 29s are 210 min reserve capacity minutes. It will also depend on how well you care for them over the years. Jmo

 

[KXCam22]

What i discovered by accident is that our engines dont have the output to fully charge the large battery types. The on board charger is a must. When starting with a dead 27 battery and running all day it didn't get very far toward fully charged. Cam.

 

[Firehouse100]

I will agree. The motors/stators can only charge up to 15 amps at least that's the best I've seen on my chart plotter running wot with nothing on. I don't no what the motors are taking for the ignition system and how much the throw to charge. I would think it would take a good eight hours from dead to full even with a 5 amp charge.

 

[Ronnie]

Never mind, I changed my mind and bought matching agm batteries. Didn't like paying the price premium but dislike battery maintenance enough to justify the additional cost.

 

[MattFX4]

Never mind, I changed my mind and bought matching agm batteries. Didn't like paying the price premium but dislike battery maintenance enough to justify the additional cost.

What did you go with? I bought two of the Duracell group 31 agm's from sams club last week for $154 each. Using them as house bank and 1 deep cycle starting battery for engines.

 

[Ronnie]

2 interstate 34 agms for more than I want to admit. I checked my local Costco but they didn't carry any agms pepboys sells comparable Optimas but I already had a credit (not a refund) for the other batteries I bought from interstate a few months ago so i was bound to stick with them.

 

[Tobes]

I just picked up 2 Duracell AGMs for $360 w/ tax. Pretty sure I could have gone with 2 deep cycles like stated but I opted for a deep cycle for house and regular for the starting. Regular battery is I think 12 AH less than the deep cycle. Deep cycle has a 30 month warranty and regular is 48 month, both full replacement locally. Duracell's are made by East Penn so couple with the warranty/price, I feel it was a good buy.