AC ripple?

OK. There's a thread going on over on RVnet about charging house batteries with the vehicle's alternator, and something came up over there that I haven't run into before. Wonder if any of the electrical gurus here know anything about this? Parts of two separate posts:

"I don't like causing a slow death to my alternators diodes which increases the AC voltage ripple thru the dc system. Which in turn can slowly destroy the ECM, PCM and other electronic circuitry. It can play havoc with sensors as well. Smaller wires to the batts from the truck will help slow the amperage demands that sometimes are too much for the trucks alternator and cause damage to the diodes.

Best to charge slow off the truck (not big wires) or use Solar collector and/ or a small Quiet Generator. My camper walls are thin and you can hardly hear the honda 1000 watt gen even when raining and underneath the camper its quiet.

I suggest that all truck/ car owners check for AC ripple occasionally to keep dc system healthy. Esp. after installing a rebuilt alternator. Even new has been tested with too high of AC noise in the system."


And:

"Checking for AC ripple in your charging system is as simple as taking your digital volt meter and setting it on the AC scale and touching the test leads to your batteries while the truck is running.

.05v is a about as much as you want to see, .1 is generally considered a “fail”.
Depending on the alternator it may take some searching but you can get new diodes for most. Those are what stops the AC ripple.

Having an alternator tested at most auto parts places won’t help, they don’t usually check AC ripple, just 12v output. An alternator that flunks an AC ripple test will still pass their 12v load test.
 
From: https://en.wikipedia.org/wiki/Ripple_(electrical)
"Ripple (specifically ripple voltage) in electronics is the residual periodic variation of the DC voltage within a power supply which has been derived from an alternating current (AC) source. This ripple is due to incomplete suppression of the alternating waveform after rectification. Ripple voltage originates as the output of a rectifier or from generation and commutation of DC power."

"Smaller wires to the batts from the truck will help slow the amperage demands"

Or cause a fire? Either way, no more ripple voltage. I'd look into maybe a capacitor or a better voltage regulator / charging relay? Maybe a Blue Sea automatic charging relay?
 
Yeah, not a fan of running smaller wires that will just overheat. Which is a general problem with charging trailer batteries with the vehicles alternator anyway, the wire that runs from the fuse block to the 7 pin trailer connector is 10 gauge, fusing in the block varies.

10 gauge wire is enough to trickle some voltage to that rear battery, but it will never charge it to full due to voltage loss over the wire length.

I have also seen where a customer had a 40 Amp DC to DC charger in his trailer, feeding power off the 7 pin connector, and the wire failed within his jeep. The Redarc DC to DC charger BCDC1240D model draws around 30-40 amps, and being at the end of that line, that is way too much draw. When voltage drops - amps increase. And it overloaded his vehicle wire, blowing the fuse (thankfully only the fuse).

I recommend to my trailer customers to either run dedicated charging wires to their trailer, using a smart device like a DC to DC charger, appropriately selected gauge wire and fuses. I do not recommend ACR's (not even Blue Sea) because they're non-intelligent, completely unaware of rear battery voltage (if your alternator is spinning, the ACR is sending power to the rear battery whether it's full/no longer in need, or not). OR set the trailer up independent of the vehicle; permanent solar, or shore power charging, or both.
 
I'm sure most of you know my standing on dual batteries these days. The issue stems from the alternators that are sold with our vehicles are for the standard workload the manufacturers designed them for.

In the past, building government vehicles (surveillance vans, fire battalion chief vehicles, supervisor/commander police vehicles), in many cases upgraded/additional alternators are installed to handle increased power requirements. Alternately, shore power chargers are added to maintain the auxiliary battery bank, and they're used religiously - when the vehicle returns to the station, it's plugged in, and either the shore power is unplugged or automatically ejected from the vehicle when its deployed to the field again. None of these vehicles rely on alternator alone to deal with the auxiliary battery banks.

Can we get by with our alternator alone, considering our stress loads are much less than those commercial vehicles?

From what I'm seeing with my own battery, I would have to say no. accounting for the time it sits parked, the amount of time driving back and forth, shopping trips, etc.

As a test after our last outing, using the CTEK Battery Sense as a gauge, I let the battery drain to 75%, at this point I cut the loads by opening the circuit breaker to all my aftermarket constant-hot items leaving only the sPOD (in deep-sleep mode) and the standard vehicle draws.

After a week of routine driving/sitting, using only the alternator to charge back up (this DOES include a Diode Booster on the Alternator Voltage Sense fuse in the fuse block so that bulk charging is around 14.2 volts), the battery got back as to 85% capacity.

When I'm camping, I have no problems keeping the battery 100% full using my Renogy Eclipse 100W panel, and overnight fridge loads and a couple hours use of camp lights only take about 15% out of the battery. After sunrise, the battery is back to 100% by 10am with the solar panel charging it.

But in order to keep that expensive Odyssey 2150 in shape for the long haul, I may consider upgrading my alternator at this point.
 
I'm sure most of you know my standing on dual batteries these days. The issue stems from the alternators that are sold with our vehicles are for the standard workload the manufacturers designed them for.

In the past, building government vehicles (surveillance vans, fire battalion chief vehicles, supervisor/commander police vehicles), in many cases upgraded/additional alternators are installed to handle increased power requirements. Alternately, shore power chargers are added to maintain the auxiliary battery bank, and they're used religiously - when the vehicle returns to the station, it's plugged in, and either the shore power is unplugged or automatically ejected from the vehicle when its deployed to the field again. None of these vehicles rely on alternator alone to deal with the auxiliary battery banks.

Can we get by with our alternator alone, considering our stress loads are much less than those commercial vehicles?

From what I'm seeing with my own battery, I would have to say no. accounting for the time it sits parked, the amount of time driving back and forth, shopping trips, etc.

As a test after our last outing, using the CTEK Battery Sense as a gauge, I let the battery drain to 75%, at this point I cut the loads by opening the circuit breaker to all my aftermarket constant-hot items leaving only the sPOD (in deep-sleep mode) and the standard vehicle draws.

After a week of routine driving/sitting, using only the alternator to charge back up (this DOES include a Diode Booster on the Alternator Voltage Sense fuse in the fuse block so that bulk charging is around 14.2 volts), the battery got back as to 85% capacity.

When I'm camping, I have no problems keeping the battery 100% full using my Renogy Eclipse 100W panel, and overnight fridge loads and a couple hours use of camp lights only take about 15% out of the battery. After sunrise, the battery is back to 100% by 10am with the solar panel charging it.

But in order to keep that expensive Odyssey 2150 in shape for the long haul, I may consider upgrading my alternator at this point.

I have become a fan of the permanently mounted solar panel. My daughters 4Runner has a 100 watt Renogy with a PWM controller and one group 31 battery. The next rig we mounted the same panel on the roof rack but upgraded the controller to a MPPT Victron with Bluetooth for monitoring. This vehicle has the ARB fridge in it and running 100% of the time. Its parked outside 100% of the time and has a dual battery set up using National Luna system and Odyssey group 35 (If I remember correctly). The solar is wired to the house battery that runs the accessories. Next truck has the same panel, same controller, same dual battery system but is parked in the garage and or at his work for log periods of time. When in the garage its plugged into a CTEK shore power dual battery charger.

All three systems stay topped up. My next build will have a permanently mounted solar with the CTEC as shore power as I like to have my truck parked in the garage.
 
@WashingtonTaco just remember to keep those panels clean: Trail dust + morning dew = mud, and a mud covered solar panel is useless.

Another thing to consider making it easier to keep the battery load down, take that national luna battery monitor and throw it in the trash. Your victron is superior, and the power consumed by that NL monitor is way more than it needs to be.
 
I have become a fan of the permanently mounted solar panel.

I initially was planning of putting 100w permanently mounted solar panel on the roof of the camper shell. But during the summer given the choice of parking in the sun on in the shade I'm going to want to park in the shade.

Already have a spare 12AH AGM motorcycle battery. Going to have the OEM toyota battery from the taco soon too. I'm thinking of making my own power cube from one of them. Independent of the vehicle power. Have it maintain the fridge w/ solar keeping it topped off during the day. I'm thinking of using the motorcycle battery. Nice and small. Sneak it into Starbucks, Panera, etc.. Sit down. Have a coffee and maybe a sandwich. Use their free wi-fi. Charge my overlanding battery hidden in a backpack from the power receptacles provided for laptops... :lol
 
Learning that NL is not all that it’s cracked up to be!
Yes, I wish more people would ignore the hype it gets. It really isn't what it's sold as being.

Tear it apart, and you'll find a cheap controller on top of a very common and inexpensive relay, that you could have built better yourself for less than $50.00
 
I initially was planning of putting 100w permanently mounted solar panel on the roof of the camper shell. But during the summer given the choice of parking in the sun on in the shade I'm going to want to park in the shade.

Already have a spare 12AH AGM motorcycle battery. Going to have the OEM toyota battery from the taco soon too. I'm thinking of making my own power cube from one of them. Independent of the vehicle power. Have it maintain the fridge w/ solar keeping it topped off during the day. I'm thinking of using the motorcycle battery. Nice and small. Sneak it into Starbucks, Panera, etc.. Sit down. Have a coffee and maybe a sandwich. Use their free wi-fi. Charge my overlanding battery hidden in a backpack from the power receptacles provided for laptops... :lol

A 12 AH AGM battery with a fridge load will probably get you halfway through the night.

The factory battery is a flooded cell type, with no "reserve capacity". They're designed for delivering high levels of amps for very short periods of time, like the kind needed to start an engine then sit back and recover with help from the alternator. They don't do very will with low/moderate amp draws for long periods of time. Which is why leaving your dome light on overnight will cause a dead battery by morning. They'll perform the task a few times, before those draws start to damage the battery.

I use the track and field sport to describe the differences as "Sprinters" (Flooded Cells) and "Long Distance Runners" (AGM's/Lithiums).
 
This was all very interesting, but I was actually wondering more about whether ac ripple from the alternator is something I really need to be concerned about, as far as it damaging engine control computers. Is this really something I should be concerned about? Is it really possible to easily check for this by using a DMM set on ac and measuring at the battery posts? Anybody here found significant ac ripple from their alternator?
 
This was all very interesting, but I was actually wondering more about whether ac ripple from the alternator is something I really need to be concerned about, as far as it damaging engine control computers. Is this really something I should be concerned about? Is it really possible to easily check for this by using a DMM set on ac and measuring at the battery posts? Anybody here found significant ac ripple from their alternator?
I guess that depends on the quality of your alternator to begin with?

Sure it's a problem, if present, it can cause dirty DC power, which could affect some sensitive electronics. Modules could reset or self-trigger, computers could get odd readings from sensors when they’re not supplied with constant, clean power, or are getting hit with too much EMI.

Is an auxiliary battery system capable of creating that? I have no idea. In my 10 years experience building these systems, It's never come up.

One thing I can assure you of, when someone says use smaller wires to control current, whatever you read before that, and after that, can probably be disregarded.
 
I don't know much about car wiring, but I am a licensed electrical contractor in the State of NC and the electrical foreman for Moore County schools.... controlling current with smaller wire is what makes the smoke come out.
 
Checking for AC Ripple. Multiple sources say testing at the alternator gives a more accurate result.
 

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