But Weight, there's Less!
So Elon Musk has parked his Tesla in the Milky Way or wherever. Just imagine having the capability and resources to do that, and the mind boggles at the thought of what else you could dispose of up there in the big blue yonder. I presume that he removed the battery before take-off, because those things are heavy.
Yes, I know they are Lithium Ion (LI) batteries, but those are not as light as some imagine. I know this from when I drive my Chevy Volt to my office in Tesla Drive (a bit ironic don’t you think) and feel how solid and sure-footed it is on the highway. That’s because it weighs about 800 pounds more than a similarly sized Chevy Cruze due to the hefty battery pack. But thanks to that 17kw lump, I have sizzling, silent acceleration and decent range in a very stable platform.
Talk is that there’s soon to be an Electric GT motor racing series featuring a modified Tesla. This will no doubt have phenomenal out-of-the-box performance, but weighs in at about 200 pounds more than my road-going Volt, and where less weight = more speed (i.e. on the race track) that means a lot of lithium to be grappling with lurching around the bendy bits.
I started tinkering with LI batteries six years ago, and even made my own 100 amp/hr pack from bits and bobs I bought online. I did it primarily to investigate whether that might be a viable alternative to the few expensive and complex marine LI systems available back then, but soon realized that the safety aspect was paramount.
Those specialized marine LI systems featured external Battery Management Systems (BMS) that could cut loads and/or charging devices if anything got slightly out of whack, and when you’re in the middle of an ocean that’s a pretty important feature. Most of the online offerings I came across were for auto use, where it’s assumed that if something goes wrong you can pull over to side of the road, hop out, and run away. Not so good for a yacht where the closest land may be a just mile away, but happens to be straight down, on the ocean floor.
And that’s where I left it for a few years while I concentrated on selling high quality energy-dense AGM batteries while keeping an eye on the Lithium scene for new developments. I did flaunt some ideas at boat shows, etc., to gain feedback on how boaters perceived Lithium Ion batteries, and below is a brief summary.
- Reduced Weight - Not seen as a major buying point for large-scale battery banks. Many sail-boaters said they actually need the weight of batteries for ballast.
- Extended Cycle-Life - Many understood the concept of the protracted cycle-life of LI, but were not willing to pay the premium for that fact alone when they would probably be selling their current boat in the near future.
- More Useable Capacity - Many seemed slightly wary of being able to draw LI batteries down to at least 80% Depth Of Discharge (DOC) on each cycle without any detriment other than slightly reduced cycle life. Most understood that drawing down lead-acid batteries lower than 50% DOD was not advisable.
- High Discharge Load Capability - This feature, where the available capacity of a LI battery is the same whether the discharge current is 1 amp or 100 amps was especially attractive to those looking at high load applications like electric propulsion.
- Faster Charging - This fact seemed to be pretty well known, but many were focused on the absolute maximum charge rate possible while not considering being more conservative, both for safety’s sake and also to extend charging equipment life.
- Cost - Ah yes, the cost. Actually, once all the benefits of LI batteries were fully explained, the relatively higher initial cost of LI was typically perceived to be less of a detriment. Most respondents had not considered other associated costs such as alternator and charger upgrades, monitoring system, etc.
I’d always envisaged that eventually we would have LI batteries in the same case sizes as lead-acid versions, and with simple, standard positive and negative terminals, just like we have all been used to for so many years. So no real surprise then that these started appearing a few years ago, but more as single-battery replacements, i.e. for auto’s, motorbikes, quad bikes, bass boats, etc. I dallied with one or two manufacturers, but never saw the safeguards or technical back-up I’d deemed a priority in being able to utilize their products in high-energy marine LI battery banks. But that was then, and this is now.
Recently I have been working with one manufacturer of LI batteries that has so far ticked all the boxes on my wish list:
- They have LI products in all popular marine group sizes, with just a positive and negative terminal.
- Their batteries contain an internal BMS and incorporate comprehensive safety mechanisms.
- Their batteries have passed very stringent tests, where other manufacturers test the cells only.
- The products are backed up with a comprehensive and worthwhile five year warranty, the first three years of which is replacement or repair free of charge.
- This company fully understands the particular needs and requirements of a multi-battery marine cycling bank, and offers specific guidelines and detailed charge/discharge instructions.
- Their engineers and sales persons are very knowledgeable, and quick to respond to questions and inquiries.
- 24v and 48v products are available, along with custom designs.
There remains just one very important box to tick: a monitoring and control system. But then we have that already.
- The Philippi PSM system has components that can be configured to give all of the monitoring, safeguards, and switching functions that have been standard on the complex specialized marine LI systems mentioned earlier. As an example, the PSM can be set up as a dual-bus system that will cut charging during over-voltage and high battery temperature conditions, and cut heavy loads in the event of low voltage or low battery capacity. This leaves the internal safeties in the batteries as final fail-safe devices.
So, there we have it. Soon Coastal will be offering Lithium Iron Phosphate (LiFePO4) batteries in Gp 24, Gp 27, Gp 31 and 8D case sizes, and can configure a Philippi monitoring and switching system to the customers’ requirements, from simple to comprehensive. And all this backed by Coastal’s extensive experience and renowned customer service.