Charging Batteries with Generator

[ArtJ]

I have just purchased a new Honda eu1000 generator. It has a 8 amp
output for charging batteries. I looked at the schematic and it doesn't
look as though there is any capacitorfiltering and the dc 8a output comes
directly from a diode bridge.
I have added a second bank of deep cycle group 27 batteries.
I have connected the second bank via a new a/b/both switch. I have
ganged this output with the original primary bank of 2 batteries.

In this way, I can select any or all or none of the batteries .

I plan to use the batteries for a small refrigerator. I plan to recharge
with the honda generator when at anchor and the atomic 4 60
alternator while under way.

The question is that I plan to connect the hard wired outlet for the

Honda generator directly to the output of the combined a/b switches.
Will the alternator be harmed by the dc generator output being
appllied to it (engine is off of course). Will the diodes be damaged
by spiking from the generator? Will the field of the alternator get
screwed up somehow?

I don't really have room for a 3rd a/b switch to disconnect the battery
banks from the alternator, besides this could leave the alternator
without a load if forgot to turn it back on.

Any suggestions appreciated

Thanks,
Art

[ArtJ]

I just spoke with Honda. They said they do not recommend using the
DC output to charge batteries other than in a emergency. The reason
they gave was that it will continously put out 12v at 8 amps. They
recommend using a battery charger powered by the ac output of
the generator. However; the same question arises regarding the
alternator possibly being damaged.

[ArtJ]

The other alternative is go turn the a/b switch to off position and
using clip leads (ugly and inconvenient due to location of batteries)
charge a isolated battery at a time with no alternator or anything
else connected.

Is there another way to accomplish this?

[tenders]

How do you charge your batteries now? You might find it advantageous to mount a permanent battery charger in the boat that's wired into your AC system. Patch the generator into your AC system with a short "shore power" cable, and you'll charge the batteries at the same time you power the rest of the AC on the boat.

I've been disappointed with the DC output from my generator (not a Honda). 8 amps is essentially a waste of time and fuel considering what the generator can really do.

[ArtJ]

I just spoke with tech support at schumaher battery chargers inc.

He said that there will be no problem using my (currrently owned)
sc7500a battery charger ac powered from the Honda. He also said
that the Alternator always being connected is no problem at all.
He said that my sc7500a microprocessor controlled charger will be
able to fully keep my deep cycle batteries charged and (assuming
4a draw for 6 hours from freezer, would be able to recharge both(using 2)
batteries in a couple of hours. He also said that if the batteries
have been used separately to charge them separately to begin with,
but ( assuming same age, model of batteries) they could be discharged
and recharged in parallel without any problem.

I also asked him how my sc7500a ( automotive charger) differed from
the marine version. He said fundamentally, it would be identical with
very similar charging algorithms and no more resistant to rust.

Regards
Art

[ArtJ]

How do you charge your batteries now? You might find it advantageous to mount a permanent battery charger in the boat that's wired into your AC system. Patch the generator into your AC system with a short "shore power" cable, and you'll charge the batteries at the same time you power the rest of the AC on the boat.

I've been disappointed with the DC output from my generator (not a Honda). 8 amps is essentially a waste of time and fuel considering what the generator can really do.

I don't use shore power regularly as the boat is on a mooring. I charge
batteries when using the boat usually. On trips I will supplement the
atomic 4 with a generator and microprocessor based charger.

Thanks for the info

Regards

Art

[ArtJ]

I have 2 Sears die hard group 29 HM Deep cycle batteries specs are:
675 CCA, 200 minutes reserve capacity, "amp hrs at 20 hour rate 115"

After charging both batteries to 100% with 3 stage charger, I connected
the new Dometic cf25 freezer (spec sheets says draws 7.5amps) I also
connected a new thermoelectric cooler as well (spec is 3.4 amps) .
So they total draw is around 10 amps.

I monitored the % charge with the schumacher charger's meter and
the battery (single used at a time) discharged to 50% in around an hour to 1.5 hours. I read that it is best not to discharge below 50%
I repeated the test with the second battery and got similar results.

I repeated the charging process again on both batteries to try and
eliminate something called sulfuration which I am told gives a false
full charge reading until partially drawn down and recharged.

What kind of capability should I be expecting from these batteries?
I was expecting to be able to draw 10amps from a single battery for
at least 5 or 6 hours.

These batteries are 2 seasons old and have only been used for engine
starting and low power accessories. I have used this type of battery
for 10 years.
But never for refrigerator or relatively heavy continuous current draw.

Comments appreciated

Thanks

Art

[Administrator]

Do you by chance have an isolator installed?

Bill

[ArtJ]

Bill

The batteries are sitting in my cellar and I am using them separately
only as a test prior to installing in boat.

As a aside, I have added provisions for 4 of these batteries to be selected
via 2 a/b both switches with outputs tied. I have installed a 40amp
breaker by the input from a external charger. I do not have the relay installed.
I was planing on keeping track of the batteries separately by observing
on charge meter and charging either pairs or single battery. I was also
going install a 120 amp alternator from indigo with 3 stage regulator, but
wanted to test how good the batteries are by themselves first. So that
I can get a feel for what kind of capacity I will have.

My concerns are as follows:

1. how much currrent and for how long can I expect draw from a single battery?
2. will 65 amps ( from indigo alternator at 1600rpm) be excessive?