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Go Back   SailNet Community > On Board > Gear & Maintenance > Electrical Systems
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  #1  
Old 08-24-2009
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HELP: Battery Charging Question

I have a new AE 38. I have 3 Batteries. Bank 1 is the house with a 200 amp and a 100 amp. Bank 2 has a 200 amp Engine Battery.

I have a 110 amp generator.

I have a meter that shows how many amps have been used in each bank and how many amps are being either consumed or when the engine is on or I am plugged into shore power, how many amps are going into the battery.

My problem is that i never seem to have much more than 10 amps positive going into either battery bank when I am charging. And unless I run the engine for 3 or 4 hours I can't get the batteries up to even close to 100% charged. And that is when the indicator says that the battery is 25% depleted.

I mentioned it to the dealer that I bought the boat from and he gave me some mobo jumbo about how batteries charge and that I shouldn't worry about it.

Is this normal?

Thanks for any help.
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Old 08-24-2009
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You may have gotten a good deal from your dealer but you are not getting good advice. Most importantly, if you really have two different size batteries (a 200 amp and a 100 amp as bank1) connected in parallel, you have a problem even before considering the charge rate.
Change this first so you have equivalent batteries. Should be easy enough to just switch out the 100 amp o be used as a start battery and connect both 200's in parallel.
Next, can we assume by "generator" you mean alternator?
If so, what is the regulator? Is it set too low? Need more info as the regulator determines the charge rate.
Next, what is your shore charger? Rating? Ability to control bulk charge rate?
Lastly, What meter are you referring to? Is it calibrated? when?

Also, understand that a good regulator or shore charge will sense existing battery state and adjust charge rate accordingly - that said, a fullly charged bank will not have a high rate of charge as you described.
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Old 08-24-2009
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Quote:
Originally Posted by k1vsk View Post
Most importantly, if you really have two different size batteries (a 200 amp and a 100 amp as bank1) connected in parallel, you have a problem even before considering the charge rate.
Change this first so you have equivalent batteries. Should be easy enough to just switch out the 100 amp o be used as a start battery and connect both 200's in parallel.
There is no problem having two different sized batteries in a single bank. They just need to be the same type - AGM, wet cell, or gel cell.
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Old 08-24-2009
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The monitor is a Xantrex Link 20 which was calibrated 2 months ago.
Yes, it is an Alternator.
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Old 08-24-2009
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Quote:
Originally Posted by pprimont View Post
I have a new AE 38. I have 3 Batteries. Bank 1 is the house with a 200 amp and a 100 amp. Bank 2 has a 200 amp Engine Battery.

I have a 110 amp generator.

I have a meter that shows how many amps have been used in each bank and how many amps are being either consumed or when the engine is on or I am plugged into shore power, how many amps are going into the battery.

My problem is that i never seem to have much more than 10 amps positive going into either battery bank when I am charging. And unless I run the engine for 3 or 4 hours I can't get the batteries up to even close to 100% charged. And that is when the indicator says that the battery is 25% depleted.

I mentioned it to the dealer that I bought the boat from and he gave me some mobo jumbo about how batteries charge and that I shouldn't worry about it.

Is this normal?

Thanks for any help.
From what you describe you have a battery monitoring system. I think you would be well served by getting a copy of the system's operating instructions and reading it carefully. It's hard to tell what's happening from your description.
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Old 08-24-2009
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Quote:
Originally Posted by pprimont View Post
My problem is that i never seem to have much more than 10 amps positive going into either battery bank when I am charging. And unless I run the engine for 3 or 4 hours I can't get the batteries up to even close to 100% charged. And that is when the indicator says that the battery is 25% depleted.
The plot of the curve that defines battery acceptance over time becomes extremely flat for the the last few Ah charged. Bringing batteries up to a truly full charge takes an inordinate amount of engine charging because the batteries are not accepting anything like the potential of your alternator: probably as little as 1A for the final few Ah. Plug the boat in to shore power if you have an internal charger and let the charger top off the batteries.

It sounds as if you are charging 75Ah into a house capacity of 300Ah. 10A sounds low for the bulk or absorption phase. If you never discharge the bank greater than 50% (and you shouldn't) then you will likely never see the Alternator (or shore power charger for that matter) supply a very large load to such a relatively small capacity bank.
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Originally Posted by SteveInMD View Post
There is no problem having two different sized batteries in a single bank. They just need to be the same type - AGM, wet cell, or gel cell.
When you pull a given load from two dissimilar batteries, the effect upon each is different. As an example, if he pulls 100 amps out of a bank consisting of one 200 amp and one 100 amp battery, he lowers the available capacity of each differently - 50 amp from each but 25% of one and 50% of the other all else being equal.
That's the first problem.

The second problem created is in recharging both - the regulator or shore charge doesn't see each battery separately and starts pumping at a rate of the avg which will undercharge the larger battery and over-charge the smaller.
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Old 08-24-2009
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Whoa...

Can we back up a minute before beginning recommendations?

The Alerion Express 38's new come with gelled house batteries, I believe.

PPrimont: could you please give us some more precise details on your setup?

Specifically:

1. Type of house batteries and AH capacity (I'd be surprised if AE put a 200AH and a 100AH gel battery together for the house bank);

2. Type of start battery and AH capacity (is it really 200AH? sounds like overkill. Is it flooded? AGM? Gelled?);

3. Type of regulator on the alternator (internal or external?);

4. Type, model and capacity of battery charger?

5. How are these wired to the battery switch(es)?

These details are important before one can be reasonably sure of what's going on and/or where to look.

Bill
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Old 08-24-2009
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Understood.... I don't have all that info at my fingertips. I will get the info tonight from my manuals and get back to you.

thanks,

peter
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Quote:
Originally Posted by k1vsk View Post
When you pull a given load from two dissimilar batteries, the effect upon each is different. As an example, if he pulls 100 amps out of a bank consisting of one 200 amp and one 100 amp battery, he lowers the available capacity of each differently - 50 amp from each but 25% of one and 50% of the other all else being equal.
That's the first problem.

The second problem created is in recharging both - the regulator or shore charge doesn't see each battery separately and starts pumping at a rate of the avg which will undercharge the larger battery and over-charge the smaller.
We are going to disagree on this one, but since it's not at the core of this thread I'll not go deeper here other than to say that the voltage remains the same in both batteries, so the percent discharge of each is also the same. Charging works the same way.
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