TheSamba.com :: View topic - Alternator charging House Lithium battery

Wed Jan 10, 2024 8:59 pm

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.)

Wed Jan 10, 2024 9:23 pm

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?

Wed Jan 10, 2024 9:33 pm

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.

Wed Jan 10, 2024 10:05 pm

Sodo wrote: 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.
.

True, alternator duty-cycle is not made clear to the consumer. Can I run my 105 amp alternator at 105 amps 24/7? Probably not. Can I run it at 50% 24/7? I don't know.

I'm not too concerned that the 105 amp alternator on my zetec will be stressed by the 30 amp DC-DC charger attached to it along with high beams, fan on high, etc. (possibly to my future detriment).

However, if I was the OP with a 65 amp alternator I'd prefer to buy a 30 amp DC-DC charger, dial it back to perhaps 15 or 10 amps and then dial it up to 30 amps when I add a high output alternator, do an engine swap, etc.

nocreditnodebt may have the best answer we've seen so far. Maybe we'll all soon have alternator temp gauges right next to our trans oil temp gauges. :wink:

nocreditnodebt wrote: I cycle a group31 Northstar TPPL AGM. Very similar to Odyssey.

Thin plate pure lead, 103 AH and 1050 CCA

It is a beast. I have fed it 134 amps of plug in charging source when depleted to just under the 50% range, and that was not enough to instantly bring its voltage to 14.7v.

After several minutes of voltage climbing towards that, the breaker feeding the 134 amps of charger blew and I then continued with 94 amps for several minutes before voltage did climb to 14.7 at which point amps tapered.

Since I can manually control the voltage my alternator is told to seek, this battery can easily max out my 120 amp alternator as it will take ~65% more amperage when told to seek 14.7 compared to 13.6v.

Alternators get very hot very quickly when maxed out, or nearly so
Above 220F is the danger zone.

My Non VW van, at highway speeds keeps the maxed out alternator under 140f, but under 25mph maxed out, and temp quickly shoots towards 180f+.

Parked idling it can only make ~50 amps but still temp shoots up quickly as well as does the temperature of my external voltage regulator as it sends maximum field current to the rotor.

I've No data on a VW alternator when it is working hard feeding depleted
healthy battery capacity, but if you intend to work it hard, then force feeding it/ Ducting coolest possible ambient air to keep it cooler will help its output and longevity to some unknown degree.

I use this Northstar AGM as it has no Issues with huge recharging amperages, and seems better off when it regularly receives them from a well depleted state. It can and does push the charging sources to their limits, and All I can do is insure they and the battery do not get too hot, then twist my voltage dial down when they do.

So knowing when and where they do needed to be established.

Heat generated is the limiting factor, whether it is alternator, cabling, Dc to Dc converter, or bttery or its BMS, if Lithium.

There are K type thermometers, like which come with many digital multimeters. I use Arctic silver thermal epoxy to adhere the sensor to the alternator casing, then use Nashua Flex fix and a reflextix like product to insulate it from airflow.

Actual Data is so much better than guessing. Without tools to actually collect data, all one can offer is a guess.
With so many variables, guesses even when well intentioned, can be wildly inaccurate, and cause failures.

Sometimes seeking maximum safety, compromises function. I'd be quite annoyed if I had to limit my charging sources to save the battery, or limit the charging sources to save themselves. or both.

Wed Jan 10, 2024 10:30 pm

jimf909 wrote: Sodo wrote: How would you know if your alternator is overburdened?

True, alternator duty-cycle is not made clear to the consumer. Maybe we'll all soon have alternator temp gauges right next to our trans oil temp gauges. :wink:
Probably could test it with the wifi-meat thermometer method.
I wouldn't mind having an Alternator amps gauge.

Here's one for $21 at Amazon.
The hole is 3/4" - I suppose the ring on the alternator will fit thru.

Thu Jan 11, 2024 7:46 am

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.

Thu Jan 11, 2024 7:50 am

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

Thu Jan 11, 2024 8:07 am

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.

Fri Jan 12, 2024 7:52 am

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 :roll: ! Kinda playing the wait and see game. Might bite me in the ass but will to experiment.

Fri Jan 12, 2024 8:11 am

Kdj wrote: 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 :roll: ! Kinda playing the wait and see game. Might bite me in the ass but will to experiment.

even the super duper $800 Battle Born battery BMSs do not limit charge current. you may be playing with fire, literally.

Fri Jan 12, 2024 8:26 am

Kdj wrote: 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 :roll: ! Kinda playing the wait and see game. Might bite me in the ass but will to experiment.

All types of batteries have a preferred charge voltage. Not a big deal for a cheap lead acid battery. When you progress to AGM and Lithium it becomes more important. Our Renogy 20 DC charger was around $100 from the big A. With dip switches you can set it for your batteries desired charge voltage. It’s also externally fused in and out. It doesn’t require big cables and is an automatic isolator. If it extends the life of my Chinese battery it pays for itself. Easy decision for us. Our previous AGM when it failed internally got too hot to touch driving all day. So, S happens. Fortunately it’s housed in a fireproof aluminum box.

Mon Jan 15, 2024 8:14 pm

jimf909 wrote: 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?

Okay, it looks like Victron is responding to the potential need for user configurable charge currents in a DC-DC charger with their new 12-12 | 50 amp charger.

Sure, it costs more but it does offer flexibility not previously offered in DC-DC chargers.

https://www.victronenergy.com/dc-dc-converters/orion-xs-12-12-50a-dc-dc-battery-charger
Stay in charge with configurable input and output currents, and rest assured that your Orion XS will run at full capacity up to 40°C. The innovative aluminium circuit board cooling technology delivers an astonishing 98% efficiency without the need for fans.

Tue Jan 16, 2024 11:28 am

jimf909 wrote:

Okay, it looks like Victron is responding to the potential need for user configurable charge currents in a DC-DC charger with their new 12-12 | 50 amp charger.

Sure, it costs more but it does offer flexibility not previously offered in DC-DC chargers.

https://www.victronenergy.com/dc-dc-converters/orion-xs-12-12-50a-dc-dc-battery-charger
Stay in charge with configurable input and output currents, and rest assured that your Orion XS will run at full capacity up to 40°C. The innovative aluminium circuit board cooling technology delivers an astonishing 98% efficiency without the need for fans.

Thanks for posting that! While I am happy with my set-up, that flexibility might be nice for others. Victron stuff is such good quality, it's my go to now.