On Board Charger

[sundowner205]

Hi All,

I was attempting to answer this myself with the search function as to not bother my fellow boaters, but I can't seem to find an answer anywhere.

I've decided that I need to purchase an on board charger. Here is the issue. The boat stays moored from April until the end of October, and obviously there is no shore power in the mooring field. I really hate having to remove the batteries and bring them back home to charge them every couple of weeks. The alternator doesn't seem to do a good enough job of maintaining a charge on the batteries and I'm starting to suspect that it may need to be replaced...

So here is my question: If I purchase a good 30 amp on board charger, will it charge the batteries while the engine is running, or do they only operate on A/C current?

As always, thank guys.

-Mark

 

[sundowner205]

Re: On Board Charger

I suppose something like this:

http://www.cabelas.com/link-12/product/0053960019683a.shtml

But I was thinking something along the lines of a Promariner...

 

[blueoval1]

Re: On Board Charger

I would think that that would work for you. I have found with a alternator that the motor needs to run around 2000 rpm just to start getting a good charge on a battery. That sounds like it would work for you as long as you don't mind going out and firing up the boat once in awhile. And it makes me wonder how long you would have to run the engine to get a full charge.
I'm sure that some of the guys with multiple batteries have a set up like that. They're bound to chime in.

 

[sundowner205]

Re: On Board Charger

Well we usually cruise around for about 45 mins before we drop anchor so I would assume that it would deliver a somewhat decent charge to both the batteries.

It is just becoming too much of a hassle to lug those 2 batteries back to the house to charge, especially that group 27 Trojan - it's a monster

 

[Silvertip]

Re: On Board Charger

On board chargers require shore power for operation and have nothing to do with the engine or its electrical system. "On board" merely means it is a waterproof battery charger intended for permanent installation in the boat. It still requires shore power for operation. If you don't have shore power available you would need a reaalllllly long extension cord.

 

[sundowner205]

Re: On Board Charger

... If you don't have shore power available you would need a reaalllllly long extension cord.

Yeah I would . I'm going to try that Minn Kota dual bank 12V alternator charger that I posted a link to earlier with a high output alternator, maybe around 85 or 100 amps. I've been doing some research on it and it has gotten very good reviews.

I'll let everyone know how it performs.

 

[Beefer]

Re: On Board Charger

What about a solar maintenance charger? Just a thought.

 

[sundowner205]

Re: On Board Charger

What about a solar maintenance charger? Just a thought.

I was thinking about that as well. However, most that I have seen only have a 2.5 or 3 amp output and I'm not sure if that would be sufficient to maintain the charge, and are about $200-250....not sure if it would be worth it...plus, I don't know where I would mount the damn thing. The 3 amp version I saw was pretty large - around 12x24 inches...I know alot of the wind powered guys use them though...

 

[Beefer]

Re: On Board Charger

I've seen 5w solar maintainers at major boating stores (not iBoats, so will remain nameless) for under $80. I use a 1.8w that I paid $30 for. Haven't had to charge my battery once all summer/fall.

 

[sundowner205]

Re: On Board Charger

I may look into one of those as well...couldn't hurt.

 

[jlinder]

Re: On Board Charger

Remember that the solar charger runs for many hours. If you got 1 amp for 10 hours a day for 6 days a week (boat on the 7th day) that is a lot of charging.
If you are talking about only needing a charge every few weeks that is even more.

 

[Beefer]

Re: On Board Charger

Maintenance chargers do not over charger, so that isn't/should be a concern.

 

[Silvertip]

Re: On Board Charger

A 5 watt charger delivers about 0.38 amps so your 10 hour a day, 1 amp example must be expanded by a factor of three. Solar panels are also a target for thieves.

As for the on board DC charger, I fail to see how that would be of any benefit. Your problem is battery discharge during periods of non-use. These chargers do nothing to solve that problem siince the engine needs to be running. If you have two batteries, iinstall a battery switch or isolator and both batteries can be charged while running. If the engine alternator can't keep up with one battery, it certainly can't keep up with two.

 

[sundowner205]

Re: On Board Charger

A 5 watt charger delivers about 0.38 amps so your 10 hour a day, 1 amp example must be expanded by a factor of three. Solar panels are also a target for thieves.

As for the on board DC charger, I fail to see how that would be of any benefit. Your problem is battery discharge during periods of non-use. These chargers do nothing to solve that problem siince the engine needs to be running. If you have two batteries, iinstall a battery switch or isolator and both batteries can be charged while running. If the engine alternator can't keep up with one battery, it certainly can't keep up with two.

I'm thinking of purchasing an 18 watt solar charger made by Coleman to use as a battery maintainer. I can place it on the dash in good view of the sun.

I already have a dual battery switch. While underway I usually keep it on "Both", however it does not seem to do much as far as keeping the batteries topped off. Perhaps I'll test my alternator out this weekend.

And I think I'll also get either the Minn Kota DC charger or a dual bank isolator to add some charge to the batteries while we are cruising. I don't see how it can hurt.

 

[Silvertip]

Re: On Board Charger

Before spending money on anything, you are advised to verify alternator output. Even a 60A alternator should have no trouble keeping two batteries topped off.. However, if you leave the battery switch in the BOTH position when the boat is left unattended, a weak battery will suck the life out of the good one until both are equal.

 

[mthieme]

Re: On Board Charger

What about a solar maintenance charger? Just a thought.

I use solar panels for my stuff successfully.
This includes the tractors and the golf cart too.

 

[sundowner205]

Re: On Board Charger

Before spending money on anything, you are advised to verify alternator output. Even a 60A alternator should have no trouble keeping two batteries topped off.. However, if you leave the battery switch in the BOTH position when the boat is left unattended, a weak battery will suck the life out of the good one until both are equal.

I'm going to test the alternator today. And I never leave the battery switch on when we are not at the boat. My auto bilge is wired directly to the deep cycle so no need to leave the power on.

 

[sundowner205]

Re: On Board Charger

I use solar panels for my stuff successfully.
This includes the tractors and the golf cart too.

Just out of curiosity, what is the wattage of the panel you use for the boat?
Thanx.

 

[cprince]

Re: On Board Charger

Just curious... but how old are the batteries? Are they the kind you need to top up?

The auto bilge may also be something to look at... not sure about what kind of draw they have but if it is going off at all hours of the day... that may be hard on the batteries is it is at a low level for a good part of the week until you start up again and charge them with a 45 minute run.

Just throwing it out there!

 

[sundowner205]

Re: On Board Charger

My group 27 Trojan deep cycle is a little over a year old, and my group 24 Interstate cranking was bought in May.

The float switch for the bilge only activates when there is about 2 inches of water in the bilge, which is only after heavy rains.