New Lithium-based Sprinter Build

[arctictraveller]

I'm really looking forward to your build, but my mind refuses process a battery system supporting A/C, electric cooking and all the other loads with just 10 to 20 minutes idling every few days. I know you have done the math though, I guess I'm just stuck back in 2015. I really want to see this work....

[Wrinkledpants]

Originally Posted by arctictraveller

I'm really looking forward to your build, but my mind refuses process a battery system supporting A/C, electric cooking and all the other loads with just 10 to 20 minutes idling every few days. I know you have done the math though, I guess I'm just stuck back in 2015. I really want to see this work....

My energy budget doesn't account for running the AC off the battery as it's not something we'll really be doing. The AC is there for driving, when we're plugged in, or when we need to work for an hour. AC while boondocking is not a priority for us. But, we can run the AC off the batteries. It just becomes a math game between current from the AC and the amp hours available on the battery. A 400 Ah lithium could support AC for about 3 hours with nothing else running (cooktop, etc). But, you'd have a dead battery at that point.

The induction cooktop can boil enough water for coffee in 4 minutes. Then another 14 minutes of use in the evening for dinner. This combined with the fridge, lights, etc - I figure around 80 AH a day for average use (more in lower elevation hot summer temps, and more in high elevation cold winter temps). The battery system gets 150 amps at idle, 230 at high idle. This after all the efficiency losses. If we have 400 AH, we'll get around 4 days going down to 85% depth of discharge (340 AH usable). That's 22 minutes at high idle a day to maintain 100% charge. Or, go 4 days of boondocking and then drive for a little over an hour. We could easily go 3 days (fri-sun) without needing to idle, and just the commute to and from the mountains will ensure we're topped up before parking the van.

We're never boondocked for that long as there is always some driving needed to get from a camp spot to a TH or parking area. So, the "20 min of idling every few days" is with the assumption that we are driving some distance each day, even if it's just 10 minutes. It's idling above our typical commute time.

Even if we do boondock for 4 days without any solar, 20 min a day at high idle will keep us topped up. I don't think I would want to go more than 1 hour total on high idle without driving some distance at hwy speeds. Though, MB said that high-idle will keep the emissions system cleaner and the heads better lubricated compared to just idling. And the block heater will ensure the block and oil always get up to temp when we do use high-idle.

[JoeyNick]

Originally Posted by Wrinkledpants

The battery system gets 150 amps at idle, 230 at high idle. This after all the efficiency losses. If we have 400 AH, we'll get around 4 days going down to 85% depth of discharge (340 AH usable). That's 22 minutes at high idle a day to maintain 100% charge. Or, go 4 days of boondocking and then drive for a little over an hour. We could easily go 3 days (fri-sun) without needing to idle, and just the commute to and from the mountains will ensure we're topped up before parking the van.

Does the battery system get 150 amps at idle or is it that the alternator puts out 150 amps at idle? There is a difference. Just running the van takes up a lot more power than you would expect.

My Ford E350 came with the "heavy duty" 140 amp alternator. In the summer with the Starcool on, even driving on the highway, the alternator could not keep up with the power demands. I often had to let the van run for 20 minutes after parking, A/C off, to ensure there was enough charge put back in the batteries to start it.

I finally upgraded my alternator and wiring to 270 amps and it's no longer an issue.

A 2800 watt A/C is drawing 233 amps at 12 volts. If your alternators are putting out only 240 amps total, you're not going to have quite enough power run the A/C all day once you factor in the electrical demands of the vehicle itself. At the end of the day, you will have run at a deficit.

For everything else you list, you'll be fine electrically and I think you're on a good track. It's only the A/C that puts a really big draw on the electrical system for hours at a time.

-Joey

[Wrinkledpants]

Originally Posted by JoeyNick

Does the battery system get 150 amps at idle or is it that the alternator puts out 150 amps at idle? There is a difference. Just running the van takes up a lot more power than you would expect.

My Ford E350 came with the "heavy duty" 140 amp alternator. In the summer with the Starcool on, even driving on the highway, the alternator could not keep up with the power demands. I often had to let the van run for 20 minutes after parking, A/C off, to ensure there was enough charge put back in the batteries to start it.

I finally upgraded my alternator and wiring to 270 amps and it's no longer an issue.

A 2800 watt A/C is drawing 233 amps at 12 volts. If your alternators are putting out only 240 amps total, you're not going to have quite enough power run the A/C all day once you factor in the electrical demands of the vehicle itself. At the end of the day, you will have run at a deficit.

For everything else you list, you'll be fine electrically and I think you're on a good track. It's only the A/C that puts a really big draw on the electrical system for hours at a time.

-Joey

The vehicle alternator is 220 amps and the secondary alternator installed by SMB is 270 amps - so 490 amps total coming from the engine (no efficiency loss). Since the coach batteries will be lithium, the vehicle alternator will be purely for the vehicle, and the 2nd alternator is just for the lithiums. 150 amps at idle is at the battery, 230 at operating speed from the 270 amp alternator when the various losses are factored in. The Fit RV blog has the same setup (same lithiums, same alternator), and these numbers were measured at their battery gauge.

Maybe I'm not calculating my A/C voltages correctly, but the Dometic A/C unit that SMB mounts only pulls 12.7 amps for the compressor and 2.6 amps for the fan at 120 volts. That's 150 amps at 12 volts, and figuring around 80% duty, maybe 120 - 130 amps effectively. We should be able to run the AC while also supplying 100 amps to the batteries if we're driving.

The only issue is that the locked amps is above the max rating for the 2800W inverter. To reliably start the A/C unit, we'll need to get the Dometic Smart Start that lowers the locked rotor amps to about 40. I think it's an additional $500 for this part.

https://www.thefitrv.com/rv-tips/our...-and-inverter/

[JoeyNick]

Originally Posted by Wrinkledpants

The vehicle alternator is 220 amps and the secondary alternator installed by SMB is 270 amps - so 490 amps total coming from the engine (no efficiency loss). Since the coach batteries will be lithium, the vehicle alternator will be purely for the vehicle, and the 2nd alternator is just for the lithiums. 150 amps at idle is at the battery, 230 at operating speed from the 270 amp alternator when the various losses are factored in. The Fit RV blog has the same setup (same lithiums, same alternator), and these numbers were measured at their battery gauge.

At 490 amps total, you'll be in terrific shape! I misunderstood when you said you'd have 240 amps, I was thinking that was your total output.

I look forward to seeing your build. Over the years, I've come to believe the all electric SMB is one of the most hassle free ways to go.

-Joey

[Wrinkledpants]

We got notified that our van will be pulled for production in May.

We ended up adding the parktronic sensors since we notice how much we use it at ski resorts on our daily driver. Backup cam was always covered in road grime, so the sensors will help with those packed lots.

We also added the overhead storage compartment that usually houses the CB radio. It comes pre-wired for power, and I can foresee using that spot for a few different ideas - like the aux tank switch and gauge.

Attached is the build sheet with option codes for anyone interested.

I had a conversation with Agile about an aux fuel tank they're starting to install for the Sprinters. It mounts along the driver side space, is aluminum, weighs around 40 lbs, and holds 20 gallons. The filler is in the wheel well, so no drilling needed on the side of the van. It's a transfer system, so you flip a switch that has a built-in 20 minute timer to transfer fuel into the main tank. This may change some of our plans as we originally wanted to have a gray tank over there. But, having the aux tank and doubling our range is pretty high on our list of desires.

We're also heavily leaning towards the Rixen D5 setup for heat. The biggest selling point would be the 110V option, which would help keep our van warm when in storage for the week. We can also route the glycol lines around the edge of the van to keep water lines warm when it's really cold. I spoke with Rixen at length about the system, and it's pretty well thought out. Since we have the engine coolant line extension option, we can hook up a flat plate heater to allow the engine to heat the lines, and provide heat to the rear while driving.

I haven't heard any details from SMB about how they're doing the lithium build, but I'll keep this updated as we iron out more details.

[PvT]

Thanks for the continued info share, super interesting and much appreciated! Congrats on the decisions and progress (even if it might feel gruellingly slow at times for you.). I'll just hang out in the peanut gallery here.

[Fitz]

Originally Posted by Wrinkledpants

We got notified that our van will be pulled for production in May.

CONGRATULATIONS!

I had a conversation with Agile about an aux fuel tank they're starting to install for the Sprinters. It mounts along the driver side space, is aluminum, weighs around 40 lbs, and holds 20 gallons. The filler is in the wheel well, so no drilling needed on the side of the van. It's a transfer system, so you flip a switch that has a built-in 20 minute timer to transfer fuel into the main tank. This may change some of our plans as we originally wanted to have a gray tank over there. But, having the aux tank and doubling our range is pretty high on our list of desires.

Very interesting build you have going, following along with great interest.

Does Agile have any kind of a picture/diagram of the Sprinter fuel tank? My grey tank is already mounted on that side, but I am always interested in the details.

[Sprinter4x4]

Wrinkledpants: A couple of thoughts below on your build spec sheet. Very similar to what I spec'd on my 3500 a few months ago:

- Consider switching to axle ratio code AR3 4.18 Axle Ratio. It's better in the mountains (I'm up the road from you in Winter Park and it makes a difference having driven both).
- Nice choice on the FF8 Overhead Storage Slot - the pre-wire of 12v+ constant, 12v+ ignition, and ground is well worth it. I'm running Nav, 360 camera monitor, and future rear view mirror mounted electronics off of it.
- Two items on my "I wished I had added now that I own it" list are F49 Heated Front Windshield and H88 Rear Heater coolant lines - both of which you already have. You'll especially like F49 when there's ice on your windshield. The van takes a while to heat up even with the aux heater in really cold weather.
- LB9 Illuminated Exits are also money well spent. The height of the van does not allow the overhead lights to cast much light on the ground when the doors are opened because of the angle. This is a great solve and well worth it in muddy or snowy areas.
-T12 - Sliding Door- Two Stage Opening - I would instead just go with one of the aftermarket door track mounted stops. The factory one is mounted overhead of the door and really gets in the way of a clean ceiling over the door or interferes with an overhead cabinet if you so choose.

I would also consider adding the following:
- JW2 - Deactivation Lamp Monitoring Failure ($21). This allow you to switch the fog lights to LED units without having to add resistors or other "fixes" to avoid throwing a code.
- ED4 - no cost option to swap the starting battery to a higher quality AGM battery. Same output, but much better vibration resistance.
- SZ7/SZ8 - adds cargo nets to both front seat backs (this may already be included in a 2500 van, but I had to add to my 3500.
- RM1 - Tires Mud & Snow - These are actually full on snow rated tires vs M&S tires. $123 is the cheapest set of snow tires you'll ever buy and make a great winter set on the factory wheels for those upgrading to off-road tires and rims.

I too am going all electric (A/C, water heater, microwave, induction cooktop, etc) and have worked directly with a battery manufacturer, inverter / charger company, and alternator / regulator company to design a fully integrated system that (hopefully) avoids the pitfalls so many others have had going to a high capacity Lithium system. Happy to discuss off-line but might be helpful as we have very similar intended uses for our Sprinters.

Hope some of this helps. Look forward to following your build.

[Sprinter4x4]

JFlo - Would love to hear about your experience with LinDen. I'm looking to have the same items completed.

Thanks in advance.