Shore power chargers don't make any sense to me ... - SailNet Community
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post #1 of 48 Old 05-18-2019 Thread Starter
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Shore power chargers don't make any sense to me ...

I figured I'd start a new thread for this. It's a topic related to my batteries being dead but a bit standalone.

I've found a supplier that can get me Firefly Oasis batteries in a reasonable time frame, so I'm planning to go that route.

As a result, I need to replace some of my charging infrastructure, as it's old, not designed for anything other than FLA, and not programmable. FYI: I'll be replacing my alternator, but that's not really what I'm confused about.

The first thing I'm noticing is that a lot of these programmable chargers don't seem to really be programmable. It's tough to get details, but (as an example) the FF batteries don't require float charge, and the manufacturer recommends that you don't float them. I can't find any confirmation for any of the vendors I've checked that it's possible to disable float charging. To make matters weirder, the vendor recommends floating at 13.4v if you do decide to provide float charge. The chargers I've found don't seem to provide any way to adjust the float voltage.

Next, size recommendations. Given that my house bank will be about 300AH, I'm seeing most recommendations to buy a charger of at least 30 amps. This is ridiculous to me. If I'm plugged into shore power, it's going to be plugged in constantly. 10 amps seems perfectly fine since all it has to do is keep things topped off. Hell, the only thing on the boat that draws more than 10 amps is the windlass. I think if I turned on everything else all at once I might barely exceed 10 amps. I'm wondering if these sizing recommendations are based on usage patterns different from mine? People who make popcorn off their 12v system? Or people who rely solely on shore power for charging and therefor need fast charging between trips? (I have 300w of solar and am planning to upgrade my alternator so ... ?)

I'm kind of sick of talking vendors ... I usually get them trying to push stuff that feels massively oversized, and when I resist they say things like "what if you need to run an electric chainsaw off your inverter?!" (note, this is also a major factor for why I'm doing the work myself ... if I could find someone local that I trusted to do the work correctly and not sell me stuff that I didn't need, I'd probably pay to have the work done)

I'm also frustrated with product offerings. When I get down to chargers in the 10A range, they seem to be hack-jobs with a NEMA 5-15P plug on the end, as if any shore power pedistool takes that (the cable wouldn't be long enough either).

The most promising unit I've found so far is the Blue Sea 25A unit, which seems to have excellent programmability. It's very expensive though ... I guess if I'm going to dump the $$ into the FF batteries, it's worth it?

I guess this is as much a rant as anything else ...

Update: here is the information I'm using to plan the charging system: https://www.emarineinc.com/Shared/pd...ers-Manual.pdf

Last edited by BillMoran; 05-18-2019 at 05:00 PM. Reason: Add document link
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post #2 of 48 Old 05-18-2019
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$500 for a charger really is not that much.
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post #3 of 48 Old 05-18-2019 Thread Starter
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Re: Shore power chargers don't make any sense to me ...

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$500 for a charger really is not that much.
Probably not. Unless I buy a charger that can't be programmed sufficiently to match the batteries. Or if I'm forced to buy something bigger than what I really need.

I'm sitting here ... on the fence to just placing the order, but I just thought I'd rant a bit first Psychologically, it makes me feel better sometimes to rant before I fork out a bunch of $$.
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post #4 of 48 Old 05-18-2019
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Re: Shore power chargers don't make any sense to me ...

I am using a 4 amp auto trickle charger for my battery charger when at the dock (and it's night).

Cost about $20.

Shore power is an extension cord off the dock, through a hatch and into some powerboards.

Cheap. Good. No lossy.
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Mark do you have it hardwired and mounted or gator clipped use
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Re: Shore power chargers don't make any sense to me ...

No Float on Firefly is a best case optimal reco for longevity, as with LFP

Many owners do not want the complexity designing their infrastructure to accommodate that.

In which case 13.2V is really better than anything higher, when the Indian parent co took over they raised the spec for "drop-in" marketing purposes.

Sterling Power ProCharge Ultra and ProMariner Pronautic P

are fully adjustable.

A 0.2C charge rate availability (20A per bank 100Ah) is also better for longevity, with all quality AGM, some spec 0.4C **as a minimum**,

but lower should not be that big a deal if you never have a need for shorter runtimes.

And if you're usually charging of alt, maybe they get high amps that way?

BTW if you go with Sterling BB series for precise custom-voltage DCDC charging off a regular VR that will also deliver what you want off any old shore charger - indeed any old DC source - no need to double up on the investment in fancy gear for every type of energy input.
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Re: Shore power chargers don't make any sense to me ...

We have a Mastervolt 30 amp for our 660 amp house bank. 330 usable Echo charge the blue top spiral starter,.

300 ah seems small for your usage. How much actual ah on the bank of fireflies ?


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post #8 of 48 Old 05-19-2019
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Re: Shore power chargers don't make any sense to me ...

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Mark do you have it hardwired and mounted or gator clipped use
It's hard wired.

A few years ago I added a 'jumper' cable from my house bank that comes forward through the engine room and has a few extra feet. It was for an emergency starter battery jumper, or a temporary power supply for anything.

So this (fused) charger connects to that. It's just 'temporary' as it it's used in winter at the dock. Any other time of year Solar panels keep the bank charged.

The shore power just comes in direct through a sheltered hatch, behind the settee cushions to the mast base and splits into 3 power boards: forward cabin (mine), saloon TV, and main saloon heaters, Nav and the charger.

It avoids going through the boats system entirely. One reason is electricity in London US .32 cents per kWh! So I wish to have as little loss as possible.

It might not be as pretty a solution than some boats, but it provides me with a huge number of PowerPoints exactly where I want them.

As the shore power is only 13 amps it's vital to keep an eye on it. The charger at 4 Amps @ 12 volts means I can still run lots of heaters.

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Re: Shore power chargers don't make any sense to me ...

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We have a Mastervolt 30 amp for our 660 amp house bank. 330 usable Echo charge the blue top spiral starter,.

300 ah seems small for your usage. How much actual ah on the bank of fireflies ?
Well, the FF batteries claim that they can be deeply discharged, so about 240AH useable if I trust their numbers.

Since I'm new at this cruising+livaboard thing I have a lot more math than I do actual experience. When I try calculating what I expect to be a typical day's power usage, I get between 100 and 150AH depending on whether I'm being optimistic or pessimistic. Actual experience with the solar panels has been has been hindered by the fact that I don't trust the current batteries to have enough power to survive the night, so the solar panels are floating all day and thus throttling the wattage. Theoretically, they should generate about 100AH on a day with partial clouds and a few thunderstorms rolling through. I'm actually seeing about 1/2 of that, but again, it's all float charge throttling the amperage. In theory, a perfectly sunny day should crank out at least 150AH.

Am I missing something that I should be assuming my power needs will be significantly greater?
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post #10 of 48 Old 05-19-2019
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Re: Shore power chargers don't make any sense to me ...

10A, fully programmable, just turn float voltage down very low and it is the same as off. $200. A bit cheaper in other places.

https://www.sterling-power-usa.com/s...-two-bank.aspx

Mark

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