Batteries - Mixing capacity and Charging

jarcher · #1 (**permalink**) 03-31-2010

Hi All...

I am planning to replace my walmart batteries and add a battery charger. Nothing fancy, I have shore power at the slip so I just plan to plug in. I don't need solar panels and wind machines.

I'm wondering if I get something like an Iota charger (which is seems to be a simply, 1 output dumb charger) and a Echo Charger or a combiner, will the charger be able to properly charge each battery? The two batteries won't be in the same bank, as one will be for house and the other for starting, so they won't drain at equal rates or charge at equal rates. I probably need a lower capacity starting battery then house battery, so i can save some size, weight and money.

But I am thinking that this might confuse the battery charger. Even if the batteries were the same capacity, being in different banks they would discharge at different rates, but I guess that what the Echo Charger is supposed to handle.

If i do mix capacities, am I better off with something like a 15A Dolphin, that has 3 stages and two outputs? Cost seems comperable to an Iota and an Echo Charger.

btrayfors · #2 (**permalink**) 03-31-2010

The Iota and an Echocharge device would be an excellent solution to your situation. The Iota with the IQ-4 option isn't a "dumb" charger....it's a smart multi-stage charger. The EchoCharge won't confuse it at all.

Wire the Iota to the house bank, with the appropriate CPD (fuse or breaker). Wire the EchoCharge between the house bank and the start battery. Voila! No more problems.

Size the Iota according to the size of your house battery bank....about 25-30% of total AH capacity. Be sure to use adequate size wire, and to do everything as best you can: quality wire, crimp connections with a proper crimper, adhesive heat-shrink tubing, etc.

Bill

jarcher · #3 (**permalink**) 03-31-2010

Quote:

Originally Posted by btrayfors

The Iota and an Echocharge device would be an excellent solution to your situation. The Iota with the IQ-4 option isn't a "dumb" charger....it's a smart multi-stage charger. The EchoCharge won't confuse it at all.

Wire the Iota to the house bank, with the appropriate CPD (fuse or breaker). Wire the EchoCharge between the house bank and the start battery. Voila! No more problems.

Size the Iota according to the size of your house battery bank....about 25-30% of total AH capacity. Be sure to use adequate size wire, and to do everything as best you can: quality wire, crimp connections with a proper crimper, adhesive heat-shrink tubing, etc.

Bill

Hi Bill, thank you very much!

What do I do with the alternator?

Maine Sail · #4 (**permalink**) 03-31-2010

Quote:

Originally Posted by jarcher

Hi Bill, thank you very much!

What do I do with the alternator?

Run it directly to the house bank if you are installing an Echo Charger..

tager · #5 (**permalink**) 03-31-2010

Why not use something like a two bank smart charger? The ProMariner one I have works well so far.

Maine Sail · #6 (**permalink**) 03-31-2010

Quote:

Originally Posted by tager

Why not use something like a two bank smart charger? The ProMariner one I have works well so far.

Often times dual bank chargers don't assign amps by need but rather 10 amps for bank one and 10 amps for bank two. This is regardless of whether or not the start bank actually needs any amps. The bank that needs amps (house bank) only gets half the capacity even if the other bank is still only using 1 amp....

With an Iota and an Echo your house bank would get face value minus up to a max of 15 amps that the Echo may borrow to send to the start battery. Usually, with a basic starting battery they are at 99+% SOC and the Echo will barely borrow any amps to satisfy the starter battery so the house bank gets the full output, or darn close to it, of the single bank charger..

davester · #7 (**permalink**) 03-31-2010

I have a related question, so I'll ask it here: does the use of an echo charger (and never combining the banks) make it ok if the house and starting batteries are different types (agm house and gel starting battery, for example)?

Maine Sail · #8 (**permalink**) 03-31-2010

Quote:

Originally Posted by davester

I have a related question, so I'll ask it here: does the use of an echo charger (and never combining the banks) make it ok if the house and starting batteries are different types (agm house and gel starting battery, for example)?

No, not really, but better than using a combiner. The Echo is a voltage follower. This means it will output the voltage +/- a small % that the alt or charger is putting out. If your alternator regulator or shore charger is set up for wet cells then your gel battery will see wet voltages, which is not good for gels.

The Balmar Duo Charger (LINK) can be used with different battery types as it can be programmed for two different output voltages. I prefer the design of the Duo Charger over the Echo but both are very good designs. the Duo charger can also output or "borrow" up to 30 amps as opposed to 15 amps...

hellosailor · #9 (**permalink**) 03-31-2010

"if the house and starting batteries are different types "
Dave, that's usually a bad idea. If nothing else, every battery type usually requires a different charging voltage and by mixing types you'll wind up with the right voltage for ONE of them and the wrong voltage (either overcharging or undercharging) everything else.

davester · #10 (**permalink**) 03-31-2010

Thanks. I wasn't aware of the Duo Charger. My shore charger is an Iota with the IQ-4, and my alternator is probably stock (engine is a ~1986 yanmar 2gm20f) so I don't really know if my charging system is optimized for a particular type of battery. I bought an Echo Charger last week, but haven't installed it yet. Right now I have two different size gel batteries in two banks and I was thinking about increasing capacity this season.