# Honda ES6500 K1 overcharges battery



## Joisey (Oct 18, 2018)

I have owned this generator since it was one month and 24 hours old. It has always overcharged the battery, in the range of 15 to 15.2 volts. 



I found the charging coil on the parts list and wiring diagram, I cannot find any mention of a voltage regulator, which I assume this unit is equipped with.


I have been thru 8 batteries, plus the original Yuasa. I've used Yuasa premium and a variety of sealed and unsealed batteries of equal or more amp hours than original. Cables are excellent, no high resistance, and all connections are clean.



The idle and maximum rpm are spot on. Any ideas?


Thank you.


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## tabora (Sep 6, 2018)

There are several variants of the ES6500K1 (note serial number ranges). Which one is yours?


 ES6500K1 A/A *-* EA1-1000001-1072228
ES6500K1 A/B *-* EA1-1072229-1099999
ES6500K1 AR *-* EA1-1000005-1099999
For example, if it's the AR variant, the voltage regulator is #13 in the Rear Housing Drawing here:
Honda Power Equipment - Parts Look Up - Official Site
And you can see it in the wiring diagram below.

If your AC output is in spec, a charging problem may be a bad rectifier #12 , not the AVR.
The charge circuit is rated for 3amps when running, but the manual specifies adding an external 1.4amp charger for maintaining the battery between uses. Have you done that? See pages 43-44 of the owners manual: http://cdn.powerequipment.honda.com/pe/pdf/manuals/31ZA0724.pdf

Your charge voltage doesn't sound excessive. My BMW charges the battery at 14.9V, and the "recovery" recharge voltage on a 12V battery is up to 16V. It's really the amount of current being applied that's critical. You can test that easily with a good multi-meter or auto battery/alternator charge tester.


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## Joisey (Oct 18, 2018)

Where would I find the seriel number on my generator? I bought it in 1984 or so. On the horizontal bar under the engine cover there is a number that reads EA1-1033221. It is on a foil sticker with black numerals on it.


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## Joisey (Oct 18, 2018)

I will check the output amperage in the meantime. Yes, the battery is kept on a battery minder in it's off time to keep the battery up.


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## Joisey (Oct 18, 2018)

I received a reply from Honda. My generator is an AR unit.


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## tabora (Sep 6, 2018)

Joisey said:


> I received a reply from Honda. My generator is an AR unit.


So, the info I already posted above is correct for your unit. 

A typical 12-volt lead-acid battery must be taken to approximately 14.2-14.4 VDC before it is fully charged. If taken to a lesser voltage level, some of the sulfate deposits that form during discharge will remain on the plates. Over time, these deposits will cause a 200 amp-hour battery to act more like a 100 amp-hour battery, and battery life will be considerably shortened. Once fully charged, batteries should be held at a considerably lower voltage to maintain their charge - typically 13.2 to 13.4 volts.

Next steps I would take are:

1. Check the battery voltage when hooked up to your maintainer. Should be about 13.2 to 13.4 volts.
2. Check the battery voltage with it disconnected from everything. Should be about 12.5 to 12.9 volts.
3. Hook the battery up to just your maintainer without plugging it in to AC. Check the battery after 15 minutes. If the voltage has dropped, the diode in the maintainer may be bad.
4. Repeat steps 2 & 3, but with the battery hooked up to the non-running generator. A significant voltage drop may indicate a bad isolation diode in the genset.
5. If the above checks pass OK, check the charging current when running 15 minutes+ after starting, without the maintainer in the mix. Should be under 3 amps, according to the manual.
6. Check the voltages pre/post rectifier. The charge coil should emit ~30 VAC, and the rectifier should send 1/2 of that to the battery ~15 VDC. If the math doesn't work exactly, probably a bad rectifier.


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## Joisey (Oct 18, 2018)

I will do all of those checks as soon as my back permits movement in the necessary directions. Currently just changing position is a major ordeal.


Thank you very much for your help. I did check the battery maintainer when I first installed it. It holds the battery at 13.4 volts, zero drain when the maintainer is unplugged and left connected to the battery.


I'm using this 12V 2A Desulfating Battery Charger Maintainer | Worldwide Use


Best unit that I've ever seen.


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## tabora (Sep 6, 2018)

Joisey said:


> I'm using this 12V 2A Desulfating Battery Charger Maintainer | Worldwide Use
> Best unit that I've ever seen.


That *IS* a good one!


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## Joisey (Oct 18, 2018)

tabora said:


> So, the info I already posted above is correct for your unit.
> 
> A typical 12-volt lead-acid battery must be taken to approximately 14.2-14.4 VDC before it is fully charged. If taken to a lesser voltage level, some of the sulfate deposits that form during discharge will remain on the plates. Over time, these deposits will cause a 200 amp-hour battery to act more like a 100 amp-hour battery, and battery life will be considerably shortened. Once fully charged, batteries should be held at a considerably lower voltage to maintain their charge - typically 13.2 to 13.4 volts.
> 
> ...



OK, I am back among the living. I checked the generator and this is what I found.


1. Battery on maintainer is 13.4 volts


2. Battery disconnected from everything is 12.8 volts.


3. Zero voltage drop, so maintainer is good.


4. Isolation diode in the genset tests OK. Less than .03 volts dropped after one hour.


5. Ran the generator five separate times, maximum amperage charged was .98 volts. Cranked generator off and on until battery read 11 volts, started the generator and the max charge was 1.0 amps. So I feel it is safe to say that the battery isn't being overcharged, at least in my limited grasp of the problem.


6. Checked the diode as you recommended. Fun laying on a sheet of cardboard on a cement floor playing with AC current. But, all checked out fine.


One thing that Honda did mention in their email was that the generator charging system works best with a Yuasa Yumicrom battery. I assume because they can handle higher charge voltage than a standard battery.


One odd thing I noticed today. It's about 35 degrees outside and the battery never rose above 14 volts, even after an hour running at governed speed. I'm beginning to think it is haunted.


Thank you everyone for all of your help.


Merry Christmas to all.


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