ksanders
Moderator Emeritus
I'm thinking of replacing my boats house bank. This is not an emergency replacement, its part of what I am thinking of as a regular maintenance interval. The Batteries will be 7 years old next season, so this gives me some time to think about it.
The good thing is that I have a pretty good idea of how we use the boat, and our generator when on the hook which comprises of almost all of our cruising time.
I do not want to just re-create what the previous owner chose which were four L16HC Interstate batteries rated at 420 Amp hours, and making a 840 amp hour bank. I want to start fresh and determine what would be best for my cruising style. Perhaps that will be what the PO chose, perhaps it will not.
Starting with my loads...
With all our stuff onboard we draw between a low of 30 amps to a high of nearly 50 amps DC (not counting the microwave). We average somewhere in the low 40 amp range, with less during the sleeping hours.
Then we have our charging capacity...
We have a 150 amp smart charger built into our inverter/charger. We can limit the output as needed to match the batteries selected, but generally I see it max out as a little over 100 amps into the batteries since our loads are still there.
One of our engines is equipped with a Balmar 150 amp alternator as well. This has a smart regulator and we often see it at around 100 amps into the battery bank.
Now our style...
Our generator plays a vital role in our cruising style. Since it is very quiet, and our boat has allot of electric items we do not really really try to minimize its use. Generally speaking we need to run it in the mornings to make breakfast.
We need a couple hours to make water, and a couple hours to do a load of laundry. In the evening we need an hour or so to make dinner.
We do not sit in one place all day on the hook. We move around a bit, looking at things, moving from fishing hole to fishing hole, etc... I'm guessing three hours a day minimum is running the main engines.
My guesstimates....
Based on all this I'm figuring that we use approx 45 amps average or 1080 amp hours a day of energy thereabouts.
Our minimum recharge based on our style is
3 hours of generator time or 300 amp hours
3 hours of cruising time or 300 amp hours.
This leaves us with approx 7 hours (calculated) of additional generator run time that we will need on average to replenish what we use for a total of 10 hours a day.
My real-world generator run time has been only slightly less at around 8 hours a day total, so we're in the ballpark.
Now to the goals of the battery system...
Other factors...
I prefer to not parallel cells if possible.
I am not making price a factor in this equation at this time.
So... What would you do???
I'm thinking about the Rolls 4CS17P, or the 21P or the 25P as my first choice options.
The good thing is that I have a pretty good idea of how we use the boat, and our generator when on the hook which comprises of almost all of our cruising time.
I do not want to just re-create what the previous owner chose which were four L16HC Interstate batteries rated at 420 Amp hours, and making a 840 amp hour bank. I want to start fresh and determine what would be best for my cruising style. Perhaps that will be what the PO chose, perhaps it will not.
Starting with my loads...
With all our stuff onboard we draw between a low of 30 amps to a high of nearly 50 amps DC (not counting the microwave). We average somewhere in the low 40 amp range, with less during the sleeping hours.
Then we have our charging capacity...
We have a 150 amp smart charger built into our inverter/charger. We can limit the output as needed to match the batteries selected, but generally I see it max out as a little over 100 amps into the batteries since our loads are still there.
One of our engines is equipped with a Balmar 150 amp alternator as well. This has a smart regulator and we often see it at around 100 amps into the battery bank.
Now our style...
Our generator plays a vital role in our cruising style. Since it is very quiet, and our boat has allot of electric items we do not really really try to minimize its use. Generally speaking we need to run it in the mornings to make breakfast.
We need a couple hours to make water, and a couple hours to do a load of laundry. In the evening we need an hour or so to make dinner.
We do not sit in one place all day on the hook. We move around a bit, looking at things, moving from fishing hole to fishing hole, etc... I'm guessing three hours a day minimum is running the main engines.
My guesstimates....
Based on all this I'm figuring that we use approx 45 amps average or 1080 amp hours a day of energy thereabouts.
Our minimum recharge based on our style is
3 hours of generator time or 300 amp hours
3 hours of cruising time or 300 amp hours.
This leaves us with approx 7 hours (calculated) of additional generator run time that we will need on average to replenish what we use for a total of 10 hours a day.
My real-world generator run time has been only slightly less at around 8 hours a day total, so we're in the ballpark.
Now to the goals of the battery system...
- A minimum of 10 hours at our low usage time of approx 35 amps, or 350 amp hours is our overnight goal.
- I want to keep approx the same weight at 480 lbs. I could go a couple hundred pounds higher but don't really want to.
- We need to keep the same approx footprint. We currently have two boxes side by side of 12X14X 18". We could go a few inches higher
- The cells need to be individually movable at no more weight than our current 120 lb unit weight.
- The goal is to match or do better than the current 1475 rated discharges of our L16HC cells. (this number comes from US batteries data sheet at 40% discharge on a L16HC battery.
Other factors...
I prefer to not parallel cells if possible.
I am not making price a factor in this equation at this time.
So... What would you do???
I'm thinking about the Rolls 4CS17P, or the 21P or the 25P as my first choice options.
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