Alternator charging House Lithium battery

[vanagonjr]

[jimf909]

[MarkWard]

[DanHoug]

[Kdj]

I'm running mine without a Dc/Dc charger. I use the bluetooth app to monitor
and most I've seen it draw was 14amps. I have not run the battery below 25% yet but the BMS in battery should control charge draw ! Kinda playing the wait and see game. Might bite me in the ass but will to experiment.

[MarkWard]

I get my amp/voltage information from the BMS built into the lithium battery. It is Bluetooth enabled and I have the battery app on my phone. Might want to look at your battery features.

[CarstenR]

The idea of having an ameter gauge and alternator temperature gauge next to the oil temperature and oil pressure gauges should almost count as 'distracted driving'! I know I'm SERIOUSLY dating myself, but it reminds me of the 70's UHF channels in northern Michigan that, when they went off the air, would have a camera pan slowly back and forth between a thermometer, barometer, and wind speed indicator gauge all night. With muzak playing in the background...

I think I found the solution I'm going to try- a Ctek D250SE charge controller that has a solar input along with the DC-DC charger. I like the trickle charge for the starter battery from the solar panel and the 20A pull from the alternator. If I do upgrade to the 'beefier' alternator I can always add their Smartpass 120.

Downside: No bluetooth and no app.

- Carsten
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Carsten Ramcke
Allen Park, MI
1981 Aircooled Westfalia: the 'Opa Bus'

[MarkWard]

Personally, I would prefer to not have my alternator running at 100% duty cycle.
Also, there is not a one size fits all solution. Everyone's requirements are going to be different. Type of use, geographic locations, climate etc. There is also no limit to what you can spend. My wife and I are minimalists on the road. We take road trips maybe 4 times a year. Others are living in their vanagons full time. Some are doing the remote office thing. Then their are those documenting their VanLife uploading content as often as they can edit it. I expect in those instances their power requirements are greater than ours.

It would likely be more helpful to those seeking advice to know what their actual loads are and for those of us giving advice to remember on size does not fit all.

And yes, solar is neat, just not necessary for some. I prefer the bare look of our stock vanagon. The van can be left attended at trail heads, parking lots, etc. Install a solar panel, cargo box, cellular booster, hardware hanging off every panel and I can't help, someone is not going to wonder what is inside? Ours will blend in at the ferry parking lot as just an old beater. Again, no one size fits all. At least that is my logic.

[Sodo]

[jimf909]

[Sodo]

How would you know if your alternator is overburdened?
It seems rather strange to me that an alternator specified as "110A" should not be loaded to 110A.

So lets say you have a 110A alternator and your DCDC charger is limited to 30A.

What is there that might ever draw 80A?
I have 400 watts of headlights, that's 33 amps.
How much can a start battery ask? Maybe 25amps, for a little while.
OK now - on my van we have 33+25=58amps.

So Headlights on high, start battery is hungry, house battery is hungry, windshield wipers on high, and Defrost on high, and A/C on high and it's 105°F summertime and the Rad Fan is on high-speed for the moment.

I suppose that would do it. But it's not likely.
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'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[jimf909]

Given all the options for user-defined parameters in the various solar/inverter/charger devices I'm surprised that DC-DC chargers don't allow the user to set a max charge rate to allow for some flexibility in battery bank or alternator capacity.

- If the battery capacity is reduced for some reason the charge rate may need to be reduced to not exceed the max. charge rate of the battery.
- If the alternator capacity is reduced for some reason the charge rate may need to be reduced to not overburden the alternator.

Victron offers endless pages of configuration options on their devices but DC-DC charger output is not one of them. Maybe there's a technical reason?
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- Jim

[vanagonjr]

Despite having a higher capacity alternator (1.8T), limiting amperage is one reason why I snagged a Victron 18A DC-DC charger off FaceBook market place. ($100, and had never been used, still in box).

Love the Bluetooth interface and Victron app on my Victron DC-DC and MPPT solar controller! (Just bought a Victron meter that also will work with the app.)
_________________
John - 86 Wolfsburg Westfalia "Weekender"
Flint reversed 1.8T W/Passat 5-Speed

Complete SA Grill Set-up for sale!
https://www.thesamba.com/vw/classifieds/detail.php?id=2748907

FAQ thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=525798

[Howesight]

Hey Carsten:

I agree with the posters above who recommend a lower current DC-DC charger in the 20 amp range. This will protect your alternator and also be just fine charging your 100 A/h LiFePo4 battery. 30 amps or 40 amps would be too much.

We have a 280 A/h DIY LiFePo4 battery and use the Redarc 40 amp (nominal) DC-DC charger which also acts as a solar charge controller. The actual alternator charging output is around 43 amps. I am careful not to have the Redarc switched on for long periods when the engine is idling and other large electrical loads are also pulling current on the alternator. At normal driving RPM's I do not have to limit in this way. We have a 1994 Subaru SVX 3.3 engine which came standard with a high-output alternator, although I can't recall the rating at the moment.
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'86 Syncro Westy SVX

[Crooked Designer]

I have a 110A alternator (subaru) and was advised to do the 20A vs 30A Renogy. Not sure if that was the right advice, but the 20A has been plenty for my 100Ah House battery. I almost never turn on the DC to DC charger tbh.. (I have a toggle switch on the D+ signal wire) because I have 200w of solar up top and that does an amazing job of charging while I drive. (I too camp in the shade in the summer) But, if its raining, or if I need both to charge faster, I love it. I don't think I've ever wished for the 30A. Fridge, stereo, and 3-4 devices charging constantly.
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'85 Westy full camper, Subaru 2.5L, 5 speed SubiGears + 5speedbus shifter kit

[CarstenR]

[MarkWard]

We have a Lithium 100 amp battery. We use the Dometic on propane. We have an oscillating 12 volt fan and have converted the kitchen light to LED. For reading we use out rechargeable head lamps. Maybe some stereo when camped. The biggest hitter is probably our diesel heater.

The most we have used in 24 hours is 20 amps. Our Renogy DC to DC 20 amp charger recovers the battery in an hour of driving. It sounds like your use would be similar to ours. We have not been able to justify adding solar. We always camp in shade when possible and often set camp end of the day.

Having done a few versions of cabin batteries, combiners, switches, I have found the 20 amp Renogy dc to dc charger to be the best setup so far. I can see where an AGM battery would also benefit, because you can set the output voltage and it’s stable and conditioned. Your results may vary.

[E1]

Thank You for that experienced view… I’ll never think about that “mod” again!

The above post about your alternator upgrade is also awesome!

And Yes, when our rebuilt alternators’ voltage regulators failed, I’d see fleeting spikes at over 17 volts. Once, a battery got hot, so no more NAPA rebuilts for us (although, our spare is a fresh version of exactly that, will only temporarily use until replacing with new).
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If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[GoEverywhere]

[E1]

Hi, Carsten:

The guy who installed the house system on our first van really knew what he was doing… and yet, he insisted our starter and house batteries not only had to both be AGMs to charge well, but the *exact same* batteries. So we put in two $300 AGMs, 1100 Ah each. He had nothing to gain from this, as he didn’t sell batteries.

If you can’t upsize the alternator, there are aftermarket voltage regulators (from Volvos, I think) that can enable sending 14.4 volts to the batteries instead of in the 13s.

A couple years later, we heard otherwise over and over — from other full-time travelers — so replaced the AGM starter battery with a typical, 650 aH lead acid and the other AGM became a second house battery. No problems keeping all three charged, but we’d also added a new Bosch 75 amp alternator and never lost another regulator as we’d been doing on rebuilt 60-amp NAPA alternators. But using two house batteries was a constant battle, in never being identical in charge and performance, and why we will never run two instead of a larger single again.

I, too am very skeptical on this topic. Lots of theories and complications, mostly sold by the industry and well propagated online.

Admittedly, I’ve never run a lithium for a variety of reasons, but will next time — partly to add capacity, but mostly to lose 60 lbs. It could turn out we do need a more-precise method to do so, but until then I will remain skeptical… but so far, lots of use in the wilds has proven me right (been over maybe a thousand high passes under load, too).

Please let us know what you do and how it all works. And Yes, Sodo’s ground information is on my To Do list, sometime.

Another tip is to not buy a large inverter like we first did, an 1100 watt based on a bus parts supplier’s posted advice. It sucked battery power endlessly and ruthlessly. Ours is 600 watts now and can run a blender.

So far as power needs, we run a Macbook and a 27” monitor most days, all day, plus a powered speaker, then we watch videos at night with the speaker, and 200 watts of solar keeps up even in winter. But, we’re in the desert, and use an ice chest, so being in the East like you would probably have me wanting a lithium for more storage on cloudier days.

It all comes down to what level of power you need — and some serious thought to power conservation as well. Worth noting is we run only portable panels, they’re miles more efficient, our last one lasted 125 months of constant use (Zamp), and we like to park in the shade. We just bought two 100w portable Zamps a month ago, and they’re spectacular.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”