North Star generator not charging battery - but wait!

[sblg43]

A local lumber yard has me service their rental equipment.

This latest unit is a North Star generator with a v twin Honda 20.0 engine. I was told that the battery to start the unit does get charged and eventually fails to turn the engine over. The battery is fairly new.

Here is what I found - I put the multimeter on the battery and it reads 12.5v. I start the unit, and the reading slowly climbs to 15.2v. I repeat the process several times. Sometimes the reading increases quickly and sometimes very slowly.

I checked the engine alternator and it is putting out 17.4v AC.

So of course, it's working now! But I can't bring it back until I do something!

I suspect the rectifier is going bad. I don't have much experience with rectifiers/regulators. When they go bad, is it all at once, or sporadic?

Any thoughts?

[KE4AVB]

Electronics can develop cold solder joints and give strange results. If I remember correctly these regs are seal in epoxy so repair is nearly impossible with replacement the best path.

As for standalone rectifiers yes they become leaky and intermittent. Long time ago I use a heck of circuit coolant and heat application to find things like this. Office personnel would often times find a machine in the frig or oven that i was testing at breaktimes as was duplicating the failures.

I had a new office salesman one time ask me about it and I said oh I just roasting a calculator for lunch.

[Fulltilt]

I checked the engine alternator and it is putting out 17.4v AC.
Any thoughts?

Seems a bit low to me. Not totally familiar with honda alternators, but most other brands put out something like 26VAC or more at 3600rpm or so.

Edit: This just in : http://www.sharkpw.com/Upload/CPDCategoryDocuments/Shark_Honda%20Engine%20Charging%20System.pdf
I just gave it a quick glance, up to you to thoroughly read/ interpret it, right?

[Arkie]

In a charging issue like you describe I would check or monitor the charging AMPS. (I usually use a clamp on DMM that will read DC amps)
If you will post the model number of the unit we would have a better idea of the size and type of charging system.
Some emergency generator chargers only charge at wide open throttle and at about 2-5 amps.

Another thing that is priced reasonable is a 100 amp load battery tester/analyzer. (to check fairly new batteries)

I do not like to brag on HF tools but their 100 amp 6/12v battery load tester for less than $25 is good for testing lawn mower and smaller automotive batteries. (especially when a engine is cranking slow and acts like a weak or bad battery)
I prefer to charge a battery and then load test the battery after it has rested for at least 24 hours if it checks ok right after it's charged.

Safety note: Be very careful and take safety precautions when load testing batteries, they can explode in your face and Sulfric Acid in the eyes is not a good thing.

[sblg43]

Whoops Sorry!

Generator: Northstar 13000PPG Item#165923R

Engine: Honda GX620 - 20.0 V-twin

[sblg43]

Edit: This just in : http://www.sharkpw.com/Upload/CPDCategoryDocuments/Shark_Honda%20Engine%20Charging%20System.pdf
I just gave it a quick glance, up to you to thoroughly read/ interpret it, right?

Beautiful! This is a wonderful piece of information! Thank you!

[Fulltilt]

Edit: This just in : http://www.sharkpw.com/Upload/CPDCategoryDocuments/Shark_Honda%20Engine%20Charging%20System.pdf
I just gave it a quick glance, up to you to thoroughly read/ interpret it, right?

Beautiful! This is a wonderful piece of information! Thank you!

You're welcome.

[KE4AVB]

The equipment number always help. With this generator the battery charging is provided by the engine's alternator and not generator's alternator which does make difference in troubleshooting the problems.

Arkie, I have been testing the digital battery analyzer from HFT and it seems to fairly on the money when testing, just got wait for at least 15 minutes after charging to test a battery. Then after overnight to see if the batteries are holding a charge at the spec CCA. Not as low cost as that resistive load tester but I don't need to wait the unit to cool down either. Now I know the battery CCA of ones I testing when the labels are gone.

[Arkie]

KE4AVB

What model or part number of the HFT digital battery analyzer are you playing with and do you have any good/bad/ or indifferent opinions yet? I'm little bit gun shy at buying electronic type HF stuff if it costs more than around $15 due to being a disposable item if it craps.

I see this one from HFT at around $70 is why I'm asking.
Digital Battery Analyzer
Cen-Tech® - item#66892

I've got all kinds of electrical testers, but a battery load tester/analyzer cane save lots of time and hassle when engine is cranking slow and could be anything from a bad cable connection, dragging starter or a little bit weak battery, no ground wire or bad ground from the engine to frame. (or all 4)

A clamp on (clamp around the wire type) DC ammeter that will auto read from 1 amp to 400 or 600 amps is also good/user friendly and fast for checking charging and cranking amps.

[KE4AVB]

It is Item # 66892.

So far it has work good but I only had it since July. To be honest I just don't get too many battery problems. I only replaced about 10 batteries since I got it. The last battery I replaced it said was good although the customer said was bad. Well it rated 190 CCA and test at 210 CCA. I install that battery in the mower with a Kawasaki 25 hp and it is starting it fine so I'm fairly confident the last test on it was good and unit working as expected.

This week I got in a 300CCA battery that I charged via my solar charger. It still reading 12.51v but with internal resistance of 18.93 meg ohms and a capacity of 139 CCA. Basically a bad battery. So a 100 amp tester probably would have passed it. I think I going to try a few days on the charger to see if it is just badly sulfied plates. I save my tractor battery this way as I was fully discharge for several years.

As you know HFT things is a hit or bad miss. I did read of some out of the box problems but I see that in all things at one or other. I had those bad misses too like the set of taps and dies that were nothing but junk that why I get and keep every receipt from them.