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2017 Interstate GT Lithium Upgrade Completed!
Interstate GT ’17 Lithium Upgrade Completed
It’s been a long three weeks part time to upgrade my van from 4 Lifeline 80AH AGMs to 1 300AH LiFePo battery. I spent a lot of time planning the install by reading everything I could get my eyes on including watching the Iron Irene videos a dozen or so times. I’ll keep the article brief and to the point. Hopefully, this will inspire someone else to try this upgrade as it is attainable by the average Joe.
1) Situation – My AGMs were dying a slow death. The time for Lithium had arrived. Since I am not sponsored, I could not afford the top tier batteries, so I investigated other offerings while always maintaining an eye towards safety. My van had been upgraded by Airstream at the time of purchase to 4 Lifeline 80AH AGM batteries installed underneath the coach in metal brackets riveted to the frame. This configuration provided 180AH of usable capacity. This usually provided a weekend of running the Fridge/Freezer even with 3 solar panels. Since purchase, I had upgraded the 3 100W flexible Go-Power solar panels from Airstream to 3 Glass Renogy solar panels. The difference was very noticeable. I also removed the crap PMV solar charger with a Victron MPPT with Bluetooth. This configuration served us well for 4+ years.
2) The Goal – We need to upgrade the batteries since the degradation was very noticeable. We wanted to be able to stay out a 3 + days without fear of losing our food when a hookup wasn’t available or we couldn’t run the generator due to campground rules. Any uypgrade would want to see a 2x increase in capacity. We also wanted to be able to brew a coffee with our inverter. This was not possible with the Magnum 1012 as its barely 1000 watts.
3) Planning – We decided right away to first decide on a battery and inverter then the other bits would fill themselves in.
a. Battery Selection – The existing battery boxes under the van are for Group 24 sized AGM batteries. The new LiFePo 100AH batteries do not fit as they are too long. You would need to move down to a 50AH LiFePo battery to come close to fitting the existing bracket. So the decision was either….go with 4 x 50AH LiFePo batteries (not enough capacity) or change the brackets (expensive) or go with a single 300-400AH battery. A single battery would mean bringing it inside the coach and giving up storage space. Well heck, LiFePo doesn’t like charging under 32 degrees…we live in the Bay Area….ok, move ‘em inside. Now for the blasphemous part, I purchased a single 300Ah Amphere Time LiFePo battery off Amazon. It arrived in 2 days. $1,000. I know it’s not BattleBorn or the other brand names….but, like I said…I’m not sponsored so no discount or free. Gotta spread my limited funds around. It’s warranty is for a year and it came with an AC charger. Charged right up.
b. Inverter Selection – Easy choice for our needs. The Xantrex XC 2000. Why? We wanted it to fit under the rear jump seat where the Magnum hung out and power just the outlets circuits (TV x2 , AV, Coffee, Outside, Rear Inside). This inverter has plenty of power to do that and then some. It has enough wattage to brew coffee in the morning : ). We also purchased the Xantrex remote for the front panel. In hindsight, I should have purchased the Bluetooth version. Additionally, the Xantrex has a Lithium charge profile which the Magnum does not.
c. Charging – This is a big topic. Charging totally changes. The new 300AH LiFePo battery charges differently that the Chassis AGM (starter battery). This means the existing BIM (battery isolator) and the SB 164 solenoid have to be removed. A charging method for each battery needs to be designed. I though about the Battle Born LiFePo BIM to replace the stock BIM. I read too many stories about alternators failing or batteries being overcharged and went in a different direction. It would have been a much simpler install with the BB unit. Instead, I went with a Victron Orion Non-Isolated Charger for the Alternator charge to the house battery. While driving, this setup will charge the AGM chassis battery from the alternator and then pass the current to the Victron Orion to manage the correct charge to the House LiFePo battery. Another casualty of the two camps of batteries is the solar arrangement. The existing Victron MPPT controller connected to the 3x 100w Renogy panels would now only charge the house LiFePo battery. I needed a solution for the chassis battery since Mercedes pulls a small current and will kill the battery if the van is not drive often. To solve this, I installed a 4th solar panel on the roof forward of the Fantastic Fan unit. The new solar panels are available in every shape and size these days. I went with a 50 watt narrow rectangular panel that was rigid fiberglass and 1/8” thick. I reused the existing Airstream wiring entry on the roof to bring that power down to a new Victron BlueSolar PMV controller connected to the chassis battery. The existing 3 Renogy panels were rewired and routed through a new wire gland installed on the roof. These wires went to the Victron MPPT. The final charging set up has the Xantrex XC 2000 providing a LiFePo charging profile to the house battery when connected to shore power or with the generator running.
d. Where to put everything – The new LiFePo battery is small and lightweight. I had to re-think where to locate everything while minimizing storage space loss. I decided to build a battery box to hold the new LiFePo and have all the related bits in / near the same box. The box would also protect the battery from touching anything, be accessible, give a neat appearance, and be secured in a (god forbid) accident. I dusted off the woodworking machines, made some measurements under the rear van seating and Poof! – out popped a box (See Pics. I had a compartment for the battery and another for the Orion and connection points. I selected connection points that provided shielding incase of anything coming loose no contact would be made. I also fused EVERYTHING. Another necessary was the inclusion of a cooling fan since the Orion has a reputation for running hot while cranking out the charge Amps. A computer fan was installed (thank you useless ignition wire from old BIM) that turns on when the van starts (same as Orion). The “battery box” was screwed to the floor and has strapping keeping everything secure and in place. The rear cover is removable and covered in carbon fiber auto film.
e. Controls – The existing control panel in the front of the van need ed to be entirely replaced. The space space for the Magnum remote would not accommodate the Xantrex remote. I purchased a sheet of ¼” ABS plastic and laid out a new arrangement of all the gauges and etc. After fitting the new panel, I also covered it in carbon fiber auto film. Looks really nice.
4) Installation – I’m not going to go into the details here….but, it really sucked dealing with all new cables. Advice – get a hydraulic lug crimper. A manual operated crimper does not have the guts to give a solid crimp. One surprise during the installation was where is the positive lead for the generator starter? FYI – Airstream connected it directly to the AGM batteries underneath the van. Now one thing I learned, LiFePo batteries do not like to start ANYTHING. This means the Generator positive wire has to go to the chassis battery. Another item is the battery combination switch on the dash no longer works. Combining batteries of different chemistries and LiFePo to another starter is all bad new. If I ever need a jump start, I purchased a Hulkman jump starter rated for a 6L diesel - $100. It’s the size of a small book, incredible. Another item I put in was a BlueSea switch between the battery positive and the Inverter. This will eliminate any Inverter draw during storage.
5) Aftermath – Van is running like a champ. Was it expensive? Yes, but less than if I went all out on the batteries. I can also add another battery if need be. I took some pictures of the install and added my wiring diagram. By no means am I a Lewster (respect dude) or professional installer. I am sure someone will find fault somewhere. I don’t mind as feedback always gives a learning experience.
6) I’ve have now added this upgrade to my list. I am running out of projects. I want an Atlas, but the wife says no.
a. Upgrades (see Pics)
i. Lithium
ii. A real sink with custom cutting board
iii. Custom wood Bath mat
iv. Replaced drawer under sink
v. Mac mini install in front seat workarea
vi. Fridge/Freezer digital controls and cooling
iv. Fit a 32" tv in the rear by modifying the existing bracket so it rotates
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