Last fall, after the voltage regulator failed I got a replacement circuit board from Luke for my GM PD4106(12v)
Now, the alternator appears to be charging intermittently(like it switches every second or two) So it goes from battery voltage of 13.5 to 15v or so.If you turn on the headlights you can see the lights alternately go bright then dimmer every second or so.
Any suggestions on what to look for.
Thx
Fred
Is this at idle or at speed? With an electrical load? Still does it with blowers on? Are batteries fully charged? Make sure connections at batterys are clean and tight. Same at Alternator.
Yup, x2, confirm the batteries are sound.
Cheap load tester is a busnut's good friend, multimeter is not the tool for deciding if batteries are sound.
Happy coaching!
Buswarrior
Whats a decent load tester on a budget?
+1 on checking the connections, particularly anything you touched while changing the regulator. And don't neglect the grounds - in fact my money would be on a bad ground.
My alternator does that too-even with new digital regulator, new batteries, etc.
A decent load tester on a budget is the underfloor blower motors. Those suckers can load the system quite well.
Old school automotive tester.
Amazon for example: $32 https://www.amazon.com/dp/B015EEWURW?ref_=Oct_CARAsinC_15707371_3 (https://www.amazon.com/dp/B015EEWURW?ref_=Oct_CARAsinC_15707371_3)
Never guess whether a battery is good or not again.
Not suitable for Nasa grade OCD, but good enough for a "normal" busnut?
Happy coaching!
Buswarrior
Quote from: buswarrior on April 28, 2018, 10:12:31 AM
Old school automotive tester.
Amazon for example: $32 https://www.amazon.com/dp/B015EEWURW?ref_=Oct_CARAsinC_15707371_3 (https://www.amazon.com/dp/B015EEWURW?ref_=Oct_CARAsinC_15707371_3)
Never guess whether a battery is good or not again.
Not suitable for Nasa grade OCD, but good enough for a "normal" busnut?
Happy coaching!
Buswarrior
(https://cloudfront.zoro.com/product/full/Z1tCG-jcpEx_.JPG)
That works good for car batteries, but you need more of a load than that can produce. Here is some info on other items that will work you may already have.
https://www.homepower.com/articles/solar-electricity/equipment-products/load-testing-batteries-without-load-tester (https://www.homepower.com/articles/solar-electricity/equipment-products/load-testing-batteries-without-load-tester)
it isn't the load, it's the duration of the load that matters.
you can hold the load longer than the suggested.
and get an answer that will tell the tale.
i seriously doubt that the blower motors draw 100 amps running.
Low possibility, but might it be a continuously tripping and immediately resetting automatic resetting circuit breaker? Headlights or tail lights comes to mind. You may or may not hear it during driving depending where it physically is.
Blower motors, defroster motors and headlights all on will get the job done, while you check the voltage at batteries. Done with automobiles for years. Now they use electronic testers to check condition of batteries.
"Low possibility, but might it be a continuously tripping and immediately resetting automatic resetting circuit breaker? Headlights or tail lights comes to mind. You may or may not hear it during driving depending where it physically is."
It may well have always been like that and I never noticed it before. I think Tom C mentioned that his bus does the same thing. I recently added a voltmeter to my dash and that is where I first noticed the fluctuation. And because the bus is undercover I could see the effect on the headlights. I almost NEVER drive at night so wouldn't have noticed that.
A constantly resetting circuit breaker can be detected with an ir gun, another reason to have one of these babies. Btw, on sale at HF now, $17.99.
Not to be argumentative, how is the busnut going to get the blowers to come on to test the batteries?
And how does the busnut isolate the bad battery from its partner using the coach's own loads?
The cheap tester will quickly indicate a strong or weak battery, without any further work than attaching the clamps? We're after a go,no go answer for this diagnosis.
There is way too much time and money spent unnecessarily on battery and charging systems, when there are adequate economical tools available to get immediate answers for diagnosis?
Infrared heat gun, cheap battery load tester and a decent multi-meter. With all the electrical issues a busnut faces, and the various skill sets on the Board ranging from engineer to nothing, we can help a busnut who knows little, but has those tools so we can direct their diagnosis?
Some of us are good at electrons, many are not.
Happy coaching
Buswarrior
turn the start switch on. turn blowers on. turn on headlights. If you have caps on the batteries, use a hydrometer to check specific gavity differences between cells. You can crank engine from rear with engine stop held in for a large load test. after loading, diconnect one cable between batteries and do a voltage test at each one. that load tester is nice, but there are ways to easily accomplish the same outcome if one is on a budget.
http://ezgo.smartmanual.biz/using-a-hydrometer/using-a-hydrometer_en.html (http://ezgo.smartmanual.biz/using-a-hydrometer/using-a-hydrometer_en.html)
https://www.amazon.com/OTC-4619-Professional-Battery-Hydrometer/dp/B0050SFVHO/ref=sr_1_3?ie=UTF8&qid=1525009922&sr=8-3&keywords=battery+hydrometer (https://www.amazon.com/OTC-4619-Professional-Battery-Hydrometer/dp/B0050SFVHO/ref=sr_1_3?ie=UTF8&qid=1525009922&sr=8-3&keywords=battery+hydrometer)
here's an even bettee priced load tester if you go that way.
https://www.amazon.com/dp/B000AMBOI0/ref=sxbs_ktp-hero_bs_tr_lp_1?pf_rd_m=ATVPDKIKX0DER&pf_rd_p=3534580262&pd_rd_wg=qWSs2&pf_rd_r=MHQMY4VW5WW4X881KXBJ&pf_rd_s=desktop-sx-bottom-slot&pf_rd_t=301&pd_rd_i=B000AMBOI0&pd_rd_w=2FOaL&pf_rd_i=battery+analyzer&pd_rd_r=21e69614-0ab1-4e0b-8a11-8cd6a0568807&ie=UTF8&qid=1525010269&sr=1#customerReviews (https://www.amazon.com/dp/B000AMBOI0/ref=sxbs_ktp-hero_bs_tr_lp_1?pf_rd_m=ATVPDKIKX0DER&pf_rd_p=3534580262&pd_rd_wg=qWSs2&pf_rd_r=MHQMY4VW5WW4X881KXBJ&pf_rd_s=desktop-sx-bottom-slot&pf_rd_t=301&pd_rd_i=B000AMBOI0&pd_rd_w=2FOaL&pf_rd_i=battery+analyzer&pd_rd_r=21e69614-0ab1-4e0b-8a11-8cd6a0568807&ie=UTF8&qid=1525010269&sr=1#customerReviews)