Is the 190A alternator adequate to charge 2 Lithium batteries via two Victron 12/12 18A DC->DC chargers

Thanasis

Active member
I am considering the use of two Victrons 12/12 18A DC to DC chargers to simultaneously charge each of my 2 house Lithium batteries ( one charger per battery).
My T1n came with a 190A alternator (not a smart one)
My question is: could the alternator be capable to support this configuration? I do not wish to overload it.
Am I correct to assume that the 2 chargers combined will limit the Amp draw for charging these batteries to 36A (2x18A)?
Thanks
 

borabora

Well-known member
The current draw from the alternator will be more likely around 45 amps because of efficiency loss and because voltage in will be lower than voltage out but your alternator should have no issues with that load. Why two chargers rather than one bigger one? Also, since the batteries are likely in parallel, you don't charge the batteries separately but you charge the battery bank as one (maybe that's why you thought you need 2 chargers -- you don't). If the two batteries are in series then you need a single 24V charger.
 

Cavah

2002 Hymer RV, 2500 chassis
I would just install a single 40 or 60 amp dc2dc, your alternator will not even notice it as many of our T1Ns came with a 90 or 120 amp alternator. Running a 4 gauge power cable to the battery is simple and you can use an open slot at battery fuse block (usa only) to install the required proper fuse rated for your unit. we assume your two house batteries are connected as one.
 

autostaretx

Erratic Member
190 amp for a T1N alternator is an odd duck.

The usual sizes were 90, 115 and 150, and it was possible to get a 200 amp.
Showing on the datacards as:
(silent) the 90 amp
M35 14 V/115 A ALTERNATOR
M39 14 V/150 A ALTERNATOR
M40 ALTERNATOR 14 V /200 A
(also reported from the field: 614K ALTERNATOR 14V 150A )

You might double-check the rating (and/or please tell us what the datacard option number was, so i can update the list)

--dick
 

Thanasis

Active member
Thank you all for responding.
1. reason for 2 chargers is location. One battery is under the passenger seat and is already being charged by a Victron charger in the same location, while the second battery is in the back of the van under the bed, I want to add the second charger near the other battery in the back.
2. Alternator size is : 14 v/ 150A ( Dick, you caught me lying :))
 

Midwestdrifter

Engineer In Residence
Are both batteries attached to the same DC bus (in parallel)? If so there is almost no reason to have two chargers. Particularly with LFP which is much less sensitive to charge voltage than lead acid.
 

owner

Oz '03 316CDI LWB ex-Ambo Patient Transport
I've actually just upgraded to 2x 50A Renogy DCDC chargers for my new 400Ah bank (with 200A stock alternator). 100A charging is needed on a bank that big.

50A was the sweet spot in terms of cost per A on the DCDC chargers I had access to. It also gives me some redundancy if one craps out.

It also means I can split the load via a switch. So if I run my rooftop aircon (up to 100A 12V draw) off the alternator directly, I can still also charge the bank at 50A via one charger. If I try to charge at 100A (while also powering the aircon) the van voltage drops too much at idle, so 50A is about right.

So there is reason to run 2x DCDC, but I guess its pretty niche.
 

Bill B.

Active member
Seems to me there is a lot of what I got, what I want, and maybe not enough information to answer a complex question.
Vehicle/engine loads + auxiliary charging loads + auxiliary loads while charging = total alternator loads
Unless you have already figured that out it's impossible to say Yay or Nay on the 150 but if I had to guess I'd say, Meh...
Personally, I wouldn't load these more than 50% for extended periods and definitely not unless I'm at freeway speeds. They get unimaginably hot as do those dc-dc converters. Your batteries(Li) will take all you can feed them until they are full which means without away to regulate the current they will be maxed for the duration of the cycle and we still don't know what the total load on your alternator will be. Just some things to think about. I big horse you work half as hard will work 10x longer than the same load on a small one working twice as hard.
 

Midwestdrifter

Engineer In Residence
If your van was factory fitted with a 150A alternator, then you typically will have 50A or so available above engine/chassis loads. Especially above idle.

So if you upgrade to a 200A unit, then you would have about 100A for charging. Just make sure your DCDC is setup to turn off when the voltage on the vehicle 12V bus drops below 13V or so, in order to avoid draining the starter battery if the loads exceed the alternators max current.
 

SilverRocket

Active member
If your van was factory fitted with a 150A alternator, then you typically will have 50A or so available above engine/chassis loads. Especially above idle.

So if you upgrade to a 200A unit, then you would have about 100A for charging. Just make sure your DCDC is setup to turn off when the voltage on the vehicle 12V bus drops below 13V or so, in order to avoid draining the starter battery if the loads exceed the alternators max current.
That's why I went with the Ecoflow. Their 800w dedicated DC/DC charger was $240 and a Delta 2 1024wh power pack was $400. (thank you Black Friday) So $640 for an initial system including all the cables. The charger has auto shutoff and also does starter battery maintenance, back-fed from the power pack. The power pack has built in solar charge management too.

The build out will be modular and I don't want a fixed cabinet with the typical mass of component spaghetti, so this should work well.

DC charger will be tucked away in a panel with a shore power inlet and solar cables installed nearby, with a harness loomed together that will stash into the same panel. Pop in the power pack, pull out the harness and plug it all in. Alternator, shore AC and solar inputs, AC output to power strips, DC and USB outputs to misc devices.

If at some point I need more capacity I'll just get a bigger power pack or add and additional one.
 

autostaretx

Erratic Member
A major part of what can kill an alternator is heat.
At idle, you're not getting the full cooling effect of its own fan.
At 2000+ rpm, you are
BUT
The alternator is also designed to be cooled by the ram air of vehicle forward motion.
If you're just sitting there, even at 2000+ rpm, you're still lacking what air cooling the alternator would love.

The 150 amp rating is probably adequate for the "sitting, 2000+ rpm" model ... but may be marginal.

MB has always offered a "high idle" switch (option) for uses like ambulances.
But they're also offered mounting points for a 2nd alternator to carry excess loads (they didn't sell a 2nd alternator, they left that task/risk to the secondary market)

--dick
 

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