Replacing Batteries

[Hot Rod Guy]

I have a 2003 National Islander 9402 DP ISL 400 HP and need to replace all 3 batteries.

They are 8-D 12v large bus type batteries, 1 is the starting battery and the other 2 are house batteries.

The 2 house batteries are deep cycle type and the other is the starting battery.

Question: Do I have to use deep cycle batteries for the house or can I install all 3 the same type, I am thinking of using Interstate 8D-MHD

The starting battery is a lot less expensive than the deep cycle.

We are usually plugged in to AC power and seldom dry camp.

Any advice would be helpful

Thanks, Hot Rod Larry

[FPengineer]

Larry,
House batteries should ideally be deep cycle type as that is their typical utilization. Starting batteries by plate design are primarily intended to momentarily provide high currents for starting engines, but are not intended to be appreciably discharged and recharged repeatedly, as a deep cycle battery is. (Conversely, a true deep cycle battery is not intended to provide large cranking amp capacity). Supposedly deep cycle batteries provide longer life in this service than does starting batteries. Have also read we should determine our amp hour requirement of our deep cycle battery bank, and size them at twice the requirement, whereas you will not be discharging them below 50% of their capacity (for best life expectancy).

All batteries should be keep clean and non-sealed batteries should have electrolyte levels checked regularly and topped off with distilled water only (never add electrolyte).

Lastly, I am a firm believer in keeping batteries on a four step charger/maintained to reduce sulfation. Most RV DC power supplies (chargers) and inverter/chargers provide this feature for your “house batteries”. An aftermarket “battery maintainer” should be provided for your chassis battery if not present in your rig. Care and battery maintainers go a long to prevent battery replacement from becoming a pricy seasonal expense.

[twinboat]

You can use the 8D-MHD starting batteries.
They will have the AH requirements needed for infrequent use.

If cost is a concern and you don't often dry camp, only get 2 batteries, one for starting and one house battery.

The 8D-MDH has 270 AH of capacity. That's more then most MHs have with 2 or 3 standard size house batteries. If you find, for some reason, that its not enough, pick up another one.

[Winemaker2]

Take a look at this link for the best info on true deep cycle that I've seen.
https://marinehowto.com/what-is-a-deep-cycle-battery/
Don't believe the marketing hype of dual purpose.
6 V GC golf cart battys are a best buy and readily available at Sam's Club & Costco. Sam's are Duracell made in USA by East Penn and good quality. You could likely get by w 2 GC2s hooked in series to provide 12V if you don't boondock often.

[FPengineer]

Winemaker2,
Thanks for the linked article, is what I have been hearing. Shopping for his recommended Duracell/East Penn golf course grade batter (CG2) I find an apparent very good value at Batteries +, their Duracell SLIGC125 with 235 AH of capacity for~$116 with on-line purchase discount (10%) and trade.
v/r,

W Taylor Hudson, Jr.
Black Creek, Florida (Jacksonville)
Clemson University class of ‘80
1998 Safari Serengeti (40’ DP)
(1997) Caterpillar 3126, 7.2L, 300 HP, 800 ft-lbs @ 1440RPM,
first generation HEUI direct injection
Allison 3060 six speed “World” transmission
Magnum chassis (Goodrich Velvet Ride rubber block torsion suspension)

[Gary RVRoamer]

I think twinboat gave good advice for Hot Rod's situation. He really doesn't need 540 AH if he rarely boondocks, e.g. just the odd overnight once in awhile.


As for using the starting batteries instead of deep cycle, it's mostly a matter of battery life. The deep cycle type should last longer than a starting battery when used for the house system. Whether a deep cycle lasts a lot longer of just a little depends on too many usage variables to make any prediction, though. If the MHD is enough cheaper, it's perhaps worth it.

[MSHappyCampers]

Hi ! Welcome to IRV2! We're sure glad you joined the gang!

I would stay with the deep-cycle! Have fun and keep her between the ditches!

Good luck, happy trails, and God bless!

[ThePowells]

Welcome to the forum!!

[Smitty77]

OP - For your intended usage, I too agree with Twinboat... Lower cost to get in, starter duty will be served, occasional house usage will be served. You will probably not get the same life out of these as a dedicated Starter and dedicated House batteries - but at that price point savings, will probably still come out ahead.

I personally, and that's just my way of doing things, like to have added contingency for 'just in case' situations. (We have a home in San Diego that the coach is at for about 3-5 months a year, depending upon our traveling schedule. We keep the coach fully stocked, fueled, and ready to go - even down to residential fridge is always on, and has frozen items as well as we carry many canned and dry foods too. We do this for the zones fire danger and we're also in an earthquake zone - so it is our families 'life boat' while we're in the area.)

I've also been in places where we had to hunker down for a few days to avoid weather patterns, while boon docking.

So my choice is to pay a little bit more, for contingency prep - and hope we never need it! (Keep an ample supply of Scotch too - one must be prepared!!).

Best of luck to you,
Smitty