My Interstate Lithium Battery Adventures

[InterBlog]

This example furnished the best laugh we've had in a while (LB_3 was considerably more animated in his reaction off-Forum). A crap frozen pizza for about $3.99 and a $20,000 system to cook it, LOL. At least I legitimately do paying work out of our van. My use supplies a partial justification.

But like I said, if these redditors and IGers and the rest of them weren't spending all their time, money, and energy on van design, then they'd be out drinking hard liquor and robbing banks and chasing tail instead.

[rmkrum]

Frozen pizza and all that overkill—kinda out of range even for me, the “overkill engineering “ department head.
I caught a lot of flack just for proposing going to power operated WD jacks! [emoji3]

[Mattirs]

Originally Posted by InterBlog

A crap frozen pizza for about $3.99 and a $20,000 system to cook it,

Military Defense Contractor?

[rmkrum]

Giggle!!
Seen even less sensible things than that—just sayin’

[polarlyse]

I do perfectly good pizza on my charcoal Volcano grill. Surely somewhere out there is a suitable cooker running on propane I should think.

[LB_3]

Originally Posted by rmkrum

Giggle!!
Seen even less sensible things than that—just sayin’

I’m scratching my head trying to figure out whether that was intended as a pun or not. #nerdhumor

[rmkrum]

No pun. Observation from too many years of being involved with the military as both active duty and as a defense contractor.

600 dollar hammers, anyone?

[TheCabin]

Originally Posted by Mattirs

Military Defense Contractor?

I like that question.

[LB_3]

I got a question about how I configured the battery and how I wired the sense lines on the Electrodacus battery management system. Pictures are worth a thousand words so here’s a pic:

It may be a bit confusing but the positive and negative terminals of the battery are on the right side. The bottom right is the positive (red) terminal. The top 3 cells on the right have a band across them putting them in parallel. When 3 100 AH cells are configured in parallel, they are functionally serving a one larger 300AH cell. The battery is configured from 12 100AH cells with 4 cells in series and each of these cells consists of 3 individual cells in parallel, yielding a 12v 300AH battery.

Banding the individual cells into larger groups ensures that these individual cells are always at the exact same voltage so they only need 2 voltage sense wires instead of 6. One sense wire is measuring the negative terminal of the top right cell which is also the negative terminal of the entire battery. This is the reference voltage for all the other cells and it should be at 0 volts. The other sense wire on the red cell terminals of the top right group is measuring the voltage contributed from the 3 individual cells grouped together (~3.6v).

Since the positive cells on the top right are connected to the negative terminals on the top left group of 3 individual cells, they are at the same voltage (~3.6v) and can share the same sense wire. In all, only 5 wires should be needed to measure the voltages on a 4 cell battery.

But if you look closely, we’re using 6. This is because the electrodacus BMS is designed to also support 24 volt batteries with up to 8 cells (9 sense wires) and when only sensing a 12 volt battery(actually 14.4 volts), it uses cells 1, 2, 7, 8 so the wire shared between cells 2 and 3 (~7.2v)is not the same wire used between cells 6 and 7. Thus the redundant pair of sense wires on the left side of the battery measuring the exact same voltage.

There is a better pic in the BMS manual. I’ll try to post that shortly.

[uncle_bob]

Hi

I'd suggest grabbing a tube of RTV and sticking the sense wires down to the top of the batteries. It doesn't take much, you don't need to glue the entire length. A glob by the end and one or two along the length of the wire is plenty.

Bob

[LB_3]

Originally Posted by uncle_bob

Hi

I'd suggest grabbing a tube of RTV and sticking the sense wires down to the top of the batteries. It doesn't take much, you don't need to glue the entire length. A glob by the end and one or two along the length of the wire is plenty.

Bob

Thats a good idea. The tops of each cell has a little groove that holds the wires but where I had to cross over the connecting bands I added electrical tape for a bit more friction protection.

[LB_3]

Graphic from the manual:

[InterBlog]

After a long hiatus, I finished the third of my four-part electrical system summary description. Link and reference photo below.

LITHIUM BATTERY UPGRADE, PART 3: CHARGING / INVERTER SYSTEM



EDIT: My tardy completion of this description was inspired by a Sprinter Forum thread titled Can a lithium pack be charged by alternator alone?

Given our recently-failed alternator and the PSA I published in response to it, of course I had comments to make about that topic. There were enough good ideas emerging on that thread that I decided to advance my own summary descriptions for general consideration.

[gmillerok1]

Originally Posted by polarlyse

I do perfectly good pizza on my charcoal Volcano grill. Surely somewhere out there is a suitable cooker running on propane I should think.

Roccbox. Worth every cent.

[amirm]

Originally Posted by InterBlog

Given our recently-failed alternator and the PSA I published in response to it, of course I had comments to make about that topic. There were enough good ideas emerging on that thread that I decided to advance my own summary descriptions for general consideration.

Sorry to hear about your troubles with your alternator IB.

I don't think this is an issue with stock Interstates today. Every stock Interstate comes with charging system that pulls in excess of 100 amps to charge the AGM batteries. The Bosch alternator is rated at 220 amps and actually delivers almost 240 amps. If the clutch were to fail at these currents, we would hear about a ton of such problems from sprinter owners yet we don't.

As with all things mechanical, there are different products with different reliability metrics and ability to handle load. I suspect the 200 amp alternator you used is not as robust as what ships with Sprinter NC3s now.

Personally I have had my alternator charge the Lithium cells multiple times with no sign of any trouble. The load from the Sterling battery to battery charger is just a hair above what I used to measure with AGMs so I think durability is the same.

[InterBlog]

I wish there were a way I could determine it conclusively, Amir. Of course we simply could have gotten a $500 lemon alternator. Unfortunately, the way to test out that hypothesis to its logical extent might lead to loss of property and/or life, so I can't do it.

In other words, if I were to replicate the original operating conditions and I DIDN'T get a failure of the new Bosch, then that outcome would support the "lemon alternator" null hypothesis.

If that exercise instead led to another clutch pulley failure, I could also get the van destroyed and/or myself killed in the process of proving the alternate hypothesis.

There are enough anecdotal reports of clutch failures in a wide variety of high-demand operating scenarios that I can't accept "lemon" on its face, though. Failures seem to be endemic to the newer alternator designs, at least outside of a certain poorly-defined operating envelope. And so there we are.

You can bet your booty, though, that I will be posting back here if I discover more lithium users reporting this same failure mode in the future.

[InterBlog]

Some clever bugger on Sprinter Forum was largely the inspiration behind the design of this, a circuit that my husband stayed up way too late last night to work on. It never ceases to amaze me how much influence people we've never met and don't even know the names of have on our lives. Much of the time, I don't even know what countries they are located in. It's a true hive mind scenario.

Anyway, I already have a mechanism that can effectively manage alternator charging and which is protective of the clutch pulley. The corresponding circuit is embedded in my prefrontal cortex and the mechanism is attached to my shoulder and there are 5 digits at the distal end of it - WITH an opposable thumb to boot. This existing mechanism of mine affixes organically when needed to a switch on the panel which toggles between "on" and "off".

But that's not good enough for my husband, who decided to kick off his entire week with a too-late night. Once he gets this designed, he can have it commissioned as a build. It better not be the kind of circuit board that can develop tin whiskers, though.

[InterBlog]

Post-script on the solar facet of our electrical system --

A T1N Interstate owner contacted me off-forum (via my blog) and emailed me some pics of his rig. We (meaning LB_3) spent a veritable boat-load of money on the 80/20 frame that straps our panels to the existing T1N Interstate roof rack. A boat-load of money!! Ours is not the only viable design, however. If someone doesn't wish to spend a boat-load of money on a custom-fit frame, and alternatively, doesn't have the tools to do metal cutting and welding, there are other design options, such as this one.

[mineralfarme]

or mine:https://www.dropbox.com/s/lu6siemp1l...65718.jpg?dl=0

IMG]http://https://www.dropbox.com/s/lu6siemp1la03kq/20161112_165718.jpg?dl=0[/IMG]

[mineralfarme]

I have 640 amp hours of victron lithium batteries as well as 640 watts of solar on the roof and I've had no trouble with my stock alternator for a year now. I do not use a battery to battery charger, just a victron control system. Works great. If anybody wants to check it out my van is for sale on the Forum :-) we are looking into a Leisure Vans Unity.