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Old 27-03-2011, 10:38   #1
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Questions about replacing battery charger

Hello:

My boat has a permanently installed ProMariner charger which I have every reason to believe is ~30 years old. It crackles and buzzes quite loudly and while I understand that the buzzes are normal, I was told the crackles could indicate that the charger is at end of live and should be replaced.

I haven't done an energy audit yet but my rough guess is that we use about 90Ah per day although when I add up the number of electrical appliances I wonder if that is accurate. I currently have three no maintainance batteries (age, type and amperage unknown). We only have our engine alternator (no genset) and shore power to charge the batteries but I had thought of purchasing a small portable generator to top up the batteries while at anchor. Typically shoreside charging would be overnight.

I actually purchased a ProMatic 3-30A charger that was on sale but it doesn't physically fit in the space where the existing charger resides so I am thinking of returning it). For roughly the same price, I found a ProMariner 3-20AMP waterproof charger that may give me more flexibility in placement.

I have to admit I am a bit clueless being more of a battery slayer than a electical guru so perhaps you can provide some guidance on the following, please:

1. Does it sound like my existing charger should be replaced? If not, how would I know?

2. If so, how many amps should the replacement provide or rather, how would I make that determination?

3. Do water proof chargers have any issues that I should be aware of (for example, I heard they run hotter than vented chargers). If I purchased a water proof charger I thought of putting it next to the batteries but that would place it near the bilge in an enclosed space. Would heat and lack of circulation be an issue there?

4. At this time I see no need for an inverter and figure I can buy a stand alone unit in the future if need be. Is that a prudent choice?

5. Are there specific features in a replacement charger should look for? For example, will they all run off of a small portable generator?

6. Any other points I should consider?

Thank you for any guidance you can provide,

Andrew
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Old 27-03-2011, 11:08   #2
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Re: Questions about replacing battery charger

Andrew, a 20 amp charger is a bit miserable, yes I know they cost the earth but you could go a bit bigger. We have a modern Sterling 4 stage 40 amp charger for 220 amp house bank (2x 110) and the engine start battery.

Somewhere on CF is a suggestion not to exceed 25% of the total bank but that is for flooded lead acid, I think.

What we did notice was whilst it started out giving 42 AH actually, this quickly drops after 15 minutes to mid 20 amps for a while and then as the batteries are reaching fully charged the voltage drops to a trickle.

Others will have to recommend a cost effective make, I am on the wrong side of the pond for you.

Pete
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Old 27-03-2011, 11:56   #3
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Re: Questions about replacing battery charger

A lot depends on what kind of portable generator you have. A Honda EU2000 is rated for 13 amps continuous. Check the AC input specs on the 40 amp charger you are considering. It will be close, but close is good as you are using the maximum capability of your generator which will minimize running time. If you have the EU1000 then you need a much smaller charger, maybe a 20 amp would work.

The sparks in your current charger are a good indication that it is in need of replacement. Also a 30 YO charger may not have three stage capabilities.

David
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Old 27-03-2011, 14:01   #4
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Re: Questions about replacing battery charger

Whatever you decide to buy, deep six that charger. Don't even give it away to your worst enemy.

They're ferroresonant and known as "The Endless Hummer".

They consistently overcharge batteries.

I used to work for a yacht maintenance company and several boats with those chargers needed battery replacement almost yearly.

We tried to convince the owners to replace those chargers, but they couldn't afford to do so because they were always buying batteries !
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Old 27-03-2011, 14:29   #5
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Re: Questions about replacing battery charger

nb the honda is at a much higher voltage a 1000w gen will easily run a 40 amp 12v charger (600w max draw) don't compare amps at different voltages.
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Old 27-03-2011, 17:06   #6
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Re: Questions about replacing battery charger

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Originally Posted by Pete7 View Post
Andrew, a 20 amp charger is a bit miserable, yes I know they cost the earth but you could go a bit bigger. We have a modern Sterling 4 stage 40 amp charger for 220 amp house bank (2x 110) and the engine start battery.

Somewhere on CF is a suggestion not to exceed 25% of the total bank but that is for flooded lead acid, I think.
Hi Pete:

40AMPS! Wow. Ya know, that isn't really the answer I was looking for but thanks... .

What is the consequence of not having enough charging Amps? Just longer charge times or is it possible to damage the charger and/or batteries? I know at this time that going with a more expensive charger is not an viable option so I then need to decide to wait for next season or get what I can afford for now.

If I understand your statement about the 25% total bank in my case, assuming I also had a 220 amp house bank then I could theoretically consider chargers up to 50 AMP. Is that correct?

Thanks, Andrew
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Old 27-03-2011, 17:23   #7
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Re: Questions about replacing battery charger

Andrew,

Assuming you have a diesel boat, I'd look into the Iota line of chargers. They come in various sizes up to 90 amps, and are far and away the best bargains on the market. A good source of supply is Northern Arizona Wind and Sun. http://www.solar-electric.com/bach1.html

When your three "no maintenance" batteries die, replace them with real deep-cycle batteries. Golf-cart size deep cycle batteries are perhaps the best bang for the buck.

The charger capacity should be 20-25 percent of the total amp hours of the (flooded) batteries to be charged. So, if you had four golf-cart batteries in series parallel, that would be 450AH capacity, and you'd want a charger capable of putting out nearly 90 amps. But, if you're planning to use a small generator like the Honda EU2000i, you'll want to use a charger no larger than 75 amps, because that's all it will drive.

BTW, the Iota chargers are very tolerant of voltage input fluctuations, and work very well with small generators.

Bill
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Old 27-03-2011, 17:30   #8
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Re: Questions about replacing battery charger

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Originally Posted by djmarchand View Post
A lot depends on what kind of portable generator you have. A Honda EU2000 is rated for 13 amps continuous. Check the AC input specs on the 40 amp charger you are considering. It will be close, but close is good as you are using the maximum capability of your generator which will minimize running time. If you have the EU1000 then you need a much smaller charger, maybe a 20 amp would work.

The sparks in your current charger are a good indication that it is in need of replacement. Also a 30 YO charger may not have three stage capabilities.

David
Hi David:
Thanks. I mistakenly thought that the charger would use very little and so any generator would be sufficient. Good to know. Do you know the calculation that I would need to do determine the size of generator (looking over the specs for the charger I purchased does not seem to indicate the input requirements)?

I seem to recall reading that some chargers would not run well from a generator. Would this simply be a factor of output AMPs from the generator or could it also be the quality of the current that is being generated?

The charger which I picked apparently does support three stage charging:
Products :: Battery Chargers :: Promatic 30-3 12 Volt

Thank you for your response,

Andrew
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Old 27-03-2011, 17:33   #9
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Re: Questions about replacing battery charger

Quote:
Originally Posted by senormechanico View Post
Whatever you decide to buy, deep six that charger. Don't even give it away to your worst enemy.

They're ferroresonant and known as "The Endless Hummer".

They consistently overcharge batteries.

I used to work for a yacht maintenance company and several boats with those chargers needed battery replacement almost yearly.

We tried to convince the owners to replace those chargers, but they couldn't afford to do so because they were always buying batteries !
I guess that makes me lucky so far in that I haven't fried my current batteries yet. Are the newer chargers silent?

Andrew
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Old 27-03-2011, 17:35   #10
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Re: Questions about replacing battery charger

Quote:
Originally Posted by stevensuf View Post
nb the honda is at a much higher voltage a 1000w gen will easily run a 40 amp 12v charger (600w max draw) don't compare amps at different voltages.
That is good to know. Thanks!
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Old 27-03-2011, 17:45   #11
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Re: Questions about replacing battery charger

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Originally Posted by btrayfors View Post
Andrew,

Assuming you have a diesel boat, I'd look into the Iota line of chargers. They come in various sizes up to 90 amps, and are far and away the best bargains on the market. A good source of supply is Northern Arizona Wind and Sun. Iota Regulated Battery Chargers, 12 to 48 Volt

When your three "no maintenance" batteries die, replace them with real deep-cycle batteries. Golf-cart size deep cycle batteries are perhaps the best bang for the buck.

The charger capacity should be 20-25 percent of the total amp hours of the (flooded) batteries to be charged. So, if you had four golf-cart batteries in series parallel, that would be 450AH capacity, and you'd want a charger capable of putting out nearly 90 amps. But, if you're planning to use a small generator like the Honda EU2000i, you'll want to use a charger no larger than 75 amps, because that's all it will drive.

BTW, the Iota chargers are very tolerant of voltage input fluctuations, and work very well with small generators.

Bill
That is great information, Bill. Thank you. Also,the Iota chargers are very well priced as you indicate. Yes, I have a diesel engine. Why is that significant?

It sounds like I should consider my future charging requirements then. If I purchased a 75A or even 90A charger, would there be any problem with my existing batteries (i.e. would exceeding 25% damage my existing batteries)?

Andrew
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Old 27-03-2011, 17:54   #12
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Re: Questions about replacing battery charger

admprtr just work out the watts, ie 14v for charger times amps say 50 amps =700w + add 30w or so for losses at the charger. if using a generator you want to drive it as close to its limits as possible, not under run them, the 1000 honda will be near its limits on a 50amp charger (they always rate generators for peak and not continuous use)

btrayfors 75 amps is barely 1100w well within the operating range of 2000 honda, i think they are rated about 1600 or 1800 continuous should be good for about 100amp at 14v dc + charger losses.
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Old 27-03-2011, 18:02   #13
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Re: Questions about replacing battery charger

andrew charging the batteries too fast heats them up, can boil the fluid, changes the internal resistance, now it depends on how discharged the batteries are as to the current they will suck in.
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Old 27-03-2011, 18:17   #14
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Re: Questions about replacing battery charger

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andrew charging the batteries too fast heats them up, can boil the fluid, changes the internal resistance, now it depends on how discharged the batteries are as to the current they will suck in.
I thought 3 cycle new chargers would be "smart enough" not to overcharge (or charge too quickly). Or do I still need to adjust the charger with the size of batteries? For example, if I have 200Ah bank now I would not want a charger more than 50AMP based on the maximum of 25%

Basically, what I a trying to determine is if I was planning on upgrading to deep cycle batteries as suggested by Bill, would I also need to plan on upgrading my charger at that time (instead of upgrading to the larger charger now)?

Thanks,
Andrew
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Old 27-03-2011, 18:42   #15
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Re: Questions about replacing battery charger

stevensuf,

No, you can't compare watts DC with watts AC. A Honda EU2000i can (barely) handle an Iota DLS-75, but cannot handle a DLS-90. And, certainly NOT a charger of over 100 amps.

Also, batteries will only take what they will take. You could hook a 150 amp charger up to a 450AH flooded battery bank, and it would still only take about 90A initially, then would dial back as the charge came up.

The only way to push up the amperage beyond the battery's safe charging rate is to raise the charging voltage higher than about 14.4VDC for a 12V battery. Smart chargers and regulators prevent this from happening.

Bill
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