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-   -   Are portable generators safe? (http://www.sailnet.com/forums/electrical-systems/96436-portable-generators-safe.html)

sstuller 02-07-2013 02:39 AM

Are portable generators safe?
 
I am thinking about installing AGM's because of their fast charging capability. However I would need a portable generator and charger with enough output to take advantage of fast charging. Any thoughts on how to do this safely underway and/or at anchor? Thanks. Steve S

Minnewaska 02-07-2013 07:24 AM

Re: Are portable generators safe?
 
You'll just need a battery charger that is designed for AGM output and a generator that can provide the proper capacity for its input. Portable gens do not put out tremendous watts/amps and almost always less than their model number suggests.

In the end, this can be done. The downside to an AGM's ability to take an enormous charge, is they can burn out a charger, if it isn't properly regulated. That's why you need one specifically designed for AGMs. However, that could also mean that between the low input and regulated output, you don't really get the full benefit of having that style batt.

sstuller 02-08-2013 04:50 AM

Re: Are portable generators safe?
 
Good advice. Thanks.

Stumble 02-08-2013 09:02 PM

Re: Are portable generators safe?
 
Almost all marine battery chargers made in the last five years can handle AGM, gel, and lead acid. I wouldn't consider this an issue.

But having a larger charger where the generator can't meet demand would be a waste.


As for safety, so long as you are cautious about the exhaust and have a carbon monoxide detector they are fine.

Maine Sail 02-08-2013 09:16 PM

Re: Are portable generators safe?
 
Quote:

Originally Posted by sstuller (Post 986915)
I am thinking about installing AGM's because of their fast charging capability. However I would need a portable generator and charger with enough output to take advantage of fast charging. Any thoughts on how to do this safely underway and/or at anchor? Thanks. Steve S

How big is your bank in Ah's? Even a 300 Ah bank of wets can often exceed in acceptance what a portable gen can charge at..

sstuller 02-09-2013 04:18 AM

Re: Are portable generators safe?
 
I'm thinking that a 100 AH bank of AGM's could provide the same output as a 200 AH bank of wet cells because of their lower resistance. In combination with a generator and a charger (Samlex) that can be used as a power supply you would be doing the work of a wet cell bank with half the weight and half the space. The gen/charger combination that you would use with a 200 AH bank would be just about right for a 100 AH AGM bank. Thanks. Steve S.

Maine Sail 02-09-2013 05:32 AM

Re: Are portable generators safe?
 
Quote:

Originally Posted by sstuller (Post 987890)
I'm thinking that a 100 AH bank of AGM's could provide the same output as a 200 AH bank of wet cells because of their lower resistance. In combination with a generator and a charger (Samlex) that can be used as a power supply you would be doing the work of a wet cell bank with half the weight and half the space. The gen/charger combination that you would use with a 200 AH bank would be just about right for a 100 AH AGM bank. Thanks. Steve S.

It does not work that way. Both banks can still only be drawn to 50% depth of discharge and getting either bank back much above 85% state of charge while off cruising is nearly equally as difficult. Once AGM or FLA batteries hit "absorption" voltage they begin taking less and less current. This is just a fact of life with all lead acid batteries. Some AGM's will charge slightly faster in absorption but not enough to go from a 200Ah bank to 100Ah. Yes the time spent in bulk mode will or can be shorter with AGM but you are only talking about replacing 30-35Ah's in bulk mode.......

hellosailor 02-09-2013 04:16 PM

Re: Are portable generators safe?
 
Steve-
"I'm thinking that a 100 AH bank of AGM's "
A 100Ah bank of AGMs would be called one group31 AGM battery. Not much point in cobbling together a "bank" to do that, at all.
Battery makers typically say that AGMs can be charged at 25%C and wet cells at 20%C so there is not a whole lot of difference there, four hours for AGM versus five for wet cells, half of that (2 hours compared to 2.5 hours) if you are doing a 50% charge cycle.
Hardly a deal breaker for most genset users. AGMs will also be maybe 30% more expensive and more sensitive to overcharging as well. Not that I don't like them, but it sounds like someone sold you on the magic without going into all the fine print.
Gensets in general will just point out one regulated voltage, not following a more advanced charging protocol either. That's also going to hurt, and hurt more with higher-priced AGMs.

wind_magic 02-09-2013 06:33 PM

Re: Are portable generators safe?
 
Can be safe with a carbon monoxide detector.

Size generator and charger to the bank size for best value.

sstuller 02-10-2013 03:40 AM

Re: Are portable generators safe?
 
It's fun comparing a battery bank to your savings account. If you have a regular income your savings account doesn't have to be as big as the case of the fellow whose income is intermittent. He needs an account big enough to cover the times when there is no income. A generator is similar to a regular income while relying on solar/wind is like the fellow who gets temporary employment and has to put a lot in the bank to cover periods of unemployment. Trojan Battery calls that time period the "days of autonomy". It recommends five days of battery capacity if you are relying on solar only while saying two days of autonomy is sufficient for dependable charging. The battery consumption in both cases may be the same but the charging frequency determines your battery capacity. Thanks. Steve S.


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