Battery+Chargers,+Charging,+&+Storage

toc There are many excellent alternatives for batteries and chargers for electric assist BFER Velomobiles, abbreviated here as eVelos. Here are some which have been reported as working extremely well for current BFER and other velomobile and Light Electric Vehicle (LEV) owners.

Charging While Not Home
Have you ever realized you were leaving home and hadn't fully charged your battery pack? That's ok, you say to yourself, the trip is short and your battery pack can handle it. Oops, it couldn't. It wasn't long ago that you could stop many places and just ask to plug into their outside wall outlet. The growing popularity of "plug-in EVs" now has many businesses and people thinking this may cost them or somehow this isn't right, so there is increasing resistance to just "plugging in" everywhere you go.

There are many areas of the world where Charging Stations are sprouting up and you can plug in your charger for your Light Electric Vehicle (LEV). Throughout the US, the L1 120VAC NEMA 5-15P connector is the most common way to connect and charge your LEV. BUT if you want to use those charging stations in North America, almost all now have the standard SAE J1772 handle; the thing looks remotely like a Star Trek phaser but with a gas pump size cable attached to it as shown in the photo to the right.

Most LEVs and even many Neighborhood EVs (NEVs) don't have the special inlet connector and associated controller to mate with these J1772 handles. The J1772 standard includes a special signaling protocol which enables the charging station to start current flowing into the LEV's battery pack. For about $100 you can have an adapter that allows you to use the J1772 equipped charging stations with your 120VAC or 240VAC charger and NEMA cable.

One option offered by at least two vendors and possible to build yourself is detailed in the diagram below. A J1772 outlet is wired to a NEMA 6-20R outlet adapter. This in turn is connected to the eVelo/LEV charger and may include a drop down transformer if the battery charger is wired for 120VAC cannot be switched to accept 240VAC power (North America). As of September's 2013 the J1772 adapter is still a pricey part at about US$200 assembled into a UL approved box. Add a 500W transformer for about US$30 sufficient for a 120VAC to 48VDC@8A charger.

For those who are competent with high voltage electricity, an entire solution as diagrammed below fits into a shoebox and weighs about 10lb/4.5kg if the transformer is required, half the size and just over 3lb/1.5kg if no transformer needed. The parts can all be had for under $120.



J1772 to NEMA 6-20/5-15 Charger
Photos of an OT ELF with all parts needed to connet to a J1772 charging station:

Battery Packs
Several vendors alternative LiFePO4 battery packs have been tested in ebikes and eVelos. Battery packs from Ping Battery onlinehave fared well, as have packs from AA Portable Power, which does business online as batteryspace.com. More detail on batteries are reported in the Velomobile Compatible Components page. Note that many velomobiles are using 48v battery, motor, and controller systems and these are largely moving to LiFePO4 battery chemistry.

Chargers[[image:bfer-velo/Int-48v-5a-charger.png width="317" height="217" align="right"]]
Most of the inexpensive LiFePO4 chargers included one or two LEDs for indicating battery and charger status. Until recently, meters were reserved for the over $300 chargers for LiFePO4 packs. Here are some relatively inexpensive, high performance, metered chargers:

Intelligent Series Chargers, 3A to 25A, 12VDC to 72VDC
The Intelligent branded series of chargers which are currently marketed in the US by the Electric Car Parts Company include multi-function meters into the design of most of their chargers. These meters measure more than a WattsUp or GT Power inline meter as the user can program in charging time and battery capacity. The chargers are about 1/3 to 1/2 more than the cost of chargers not equipped with meters and timers.

These Intelligent branded chargers are all single voltage, single current rating models. The figure above and right shows the display capability of the 48VDC 5A Intelligent Charger tested. Note: these chargers include integrated 110-120VAC or 220-240VAC power supplies, you specify which version when ordering. A few of the chargers rated 15A and over are available with switchable 120-240VAC power supplies built-in.

KP Series chargers
The EVassemble company has been a very reliable source of direct from China products for at least the past 3 years. One of the best of the "simple" two LED chargers available today is the KP series of chargers which are basic, inexpensive, reliable LiFePO4 chargers. The most popular and durable of the 48V chargers is listed in the Velomobile Compatible Components page.

RC Battery Pack Chargers
There is one limited production charger, the Pulsar 3, available from Europe that handles up to 60v eVelo battery packs and handles up to 1500W (25A) charge or 100W (2A) discharge testing. So if you have a spare US$750+, this is the battery charger/analyzer to buy! The Pulsar 3 has many different charge/discharge cycles setup for multiple battery types and chemistries and includes custom Windows based software as detailed on the Pulsar 3 web site. This and other relatively high current Radio Control (RC) battery pack chargers **//do not//** include AC conversion built-in and require a moderately high current AC to DC power supply or DC power source: 28A@48-60V DC.

For 24v or less eVelo, LEV, or ebike systems (increasingly rare in newer models) there are many high end RC chargers which are mult-voltage and multi-chemistry as is the Pulsar 3, at a much lower price. The GT Power A8 is a fantastic multi-chemistry charger for up to 24V systems and available for less than US$70 (incl shipping). Like the Pulsar 3, the GT Power A8 includes custom charge/discharge cycles for Lead Acid, Lithium Ion, LiFePO4, NiMH, or NiCd based batteries.Like the Pulsar 3 the GT Power A8 requires an external AC to DC power supply (13.6V @ 10A) or DC battery power.. Both the Pulsar 3 and the GT Power A8 may be connected to a laptop or desktop computer and form part of a computer controlled battery charge/discharge station.

Battery Analyzers
There are many simple battery testers but none of them available in the under $500 price range comes close to features available from the West Mountain Radio (WMR) Computerized Battery Analyzer (CBA). For almost a decade the CBA and it's software have evolved, initially in response to the ham radio community requirements. For the past few years the CBA software and accessory amplifiers for high power and high discharge rate testing (hundreds of amps at 100+ V at 2C or greater discharge rate. Note: charge/discharge rates are often listed as the letter C prefixed by a number as multiplier or divided by a divisor. The CBA and accessories have become the standard discharge based battery analyzer tool for the Electric Vehicle Community.

Charging & Storing
LiFePO4 battery packs are much more stable than other Lithium chemistry battery packs. BUT there are still reports of LiFePO4 packs heating during charge cycles and causing items around them to catch on fire or melt. Since many velomobile/ebike owners have both LiFePO4 and other Lithium Ion packs, it makes sense to charge them and store them in a space that is fire retardant if not on the bike itself away from any susceptible materials. Lacking a spare oven as many have used in the past, instead some of us are now using fireproof safes such as the ones described below and on the Components page.

Fire Safe Battery Storage Boxes
Many of the current generation (2013) of "fireproof" home safes are built with a very thick fire resistant thermoplastic case inside and outside the safe instead of metal. Given the large number of horror stories from Lithium battery fires on the web, adding a battery storage box, such as this is great because:
 * 1) Though thicknesses can be greater than an inch, the plastic can be drilled to allow cables to be run in for tester and temperature probes.
 * 2) Plastic cases are non-conductive, which is an enormous plus if there is some sort of event where a connection comes loose on the battery and thus drastically reduces the chances of short circuit problems due to contact with an external metal container

The main idea: place the battery in the charging box so that some opening exists to allow for heat dissipation when charging, then close the box no earlier than 30 minutes after charging ends so that heat from the balancing process is largely dissipated. I sit the charging battery on a large heat sink which is a larger version of the heat sinks on desktop PC CPUs. When closed, this "battery safe" is a sealed, firesafe unit which you can attach thermal probes that are externally accessible to monitor heating if desired.

Some of us have found inexpensive plastic encased fire safes from Craigslist at a fraction of retail value. For instance, in Central NC a Sentry H3300 safe was found for under $50 in great condition. The H3300 safe has interior dimensions of 11-1/2 inches by 13-7/8 inches by 14 inches, great for installing a rack to separate multiple LiFePO4 and other Lithium Ion batteries stored after charging. Wires pulled in through the drilled holes use connectors appropriate to the monitoring tasks such as PowerPole for the open circuit pack voltage. Diagrams will be included once completed. Note: all holes must be filled with a fire retardant sealant after the wires are installed. Great Stuff Fireblock Foam Sealant works well to plug the holes as well as creating inserts as noted below.

Creating a Fire Resistant Battery Storage Box
Though a large safe like that is great for velomobile battery pack storage in the garage or home, carrying a 65lb safe around isn't practical for the times you'll have to store batteries after charging on the road. If you carry currently carry a spare battery pack in a plastic box, it probably has a lot of airspace and is not fire or heat resistant; consider using a portable firebox and creating a custom fireproof foam insert by creating a replica "box" using cereal box cardboard or the like.

//NOTE: the process that follows is NOT advisable for the velomobile active battery box as these foams are thermal insulators, and you need to allow for heat to dissipate from the battery. For high C rate charging (greater than 2C continuous) contact between the bottom of the insulated battery case and the velomobile battery box is important for heat dissipation.// If your onboard battery case is sized for a much larger or multiple batteries and you have fewer, you may wish to make custom spacers using the same material in small sections so that the battery doesn't "bump" around in the battery case. A thin, cushioned and chemical spill resistant mat such as the JEGS mat listed here, can be used to both cushion the bottom of the battery and protect against corrosion if a battery leaks (which is rare).

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Creating Foam Battery Spacers
Here is a simpler process for creating battery spacers which is not as good as creating custom inserts but much easier: Here are directions to make a solid. custom fire proof foam spacer:
 * 1) Use a mister to put a thin coating of water spray on the inside of a ziploc sandwich bag into the space you wish to pad batteries.
 * 2) Spray a small layer of Great Stuff Fireblock Foam into the bag, push the foam to the bottom, them put the bag with spray foam into place in the battery pack
 * 3) Spray some water over the foam with a minister and allow the foam to rise in place with batteries in the battery space
 * 4) Add another layer if needed within 10 minutes. Leave at least a couple of inches at the top of the bag
 * 5) Arrange the bags to alternate filling space as the foam expands 50-60% when setting up. Try to avoid the expanding foam pressing from all sides on the battery or the battery case.
 * 6) After a few hours remove the plastic bags which usually peel away. The foam will shrink back about 5% as water vapor leaves the solidifying foam
 * 7) Final sizing can be done with fine tooth hacksaw blades
 * 1) Makes a great solid foam unit: Coat the inside of the replica cardboard box with a thin layer of petroleum jelly and create another replica "box" the size of your battery pack. Coat the outside of the smaller inner box with petroleum jelly as well. Use Great Suff Fireblock Foam sealant to create first a base layer in the larger box up to 1" or so below where you want the battery pack to sit. Use a spray water mister to hasten the foam setting, but allow at least 2 hours. NOTE: clean out the nozzle and the Great Stuff can tip with acetone in between uses or the foam will block the openings and not allow re-use. Acetone works as does acetone based cleaners such as some Goof Off products.
 * 2) Put in the replica box and continue spraying foam to fill the space between the boxes in layers. [Photos to be added...] After you have built up the layers just a few inches at a time to within 2" or so of top of outer box, allow the boxes to sit and cure for at least 4 hours (with misting) 8 hours without. Then cut away the inner box and outer boxes. You may find it easiest to cut the whole thing in half and then peel away the two boxes. Now you have a custom insert for either your firesafe battery box or your velomobile active battery box, omitting a bottom spacer for the active battery box. If you are fitting 2 batteries, then cut two boxes and sit them in the larger box and create your layers. At the end you can drill the foam, cut it with a fine tooth hacksaw or use a surform to smooth out parts of the foam inserts.

Portable Firesafe Battery Storage Box
You might also create inserts for a portable Firesafe Battery Storage Box as well. For transportability off the eVelomobile, we are modifying a small Honeywell 1101 fire box that has at least 1/2" to spare in every dimension of our largest velomobile battery.

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Summary: Safe Battery Charging, Testing, & Storage
An outline of a safe charging, testing, & storage process. Though lead based "gel cells" are far more stable than Lithium based batteries, the hints and tips below apply to all rechargeable battery types:
 * Select a battery sized appropriately for your velomobile and your use, nominal total current carrying capacity is critical for both the battery and attached battery management system (BMS). This topic merits a whole separate wiki page!
 * Use low rate charging, preferably C/2 or less whenever possible. Solar panels are great for this, and the OT ELF's built in panels are sized appropriate for 48V 10AH pack.
 * When a high rate of charge (1C or greater) is used, allow the battery to sit for at least 30 minutes after disconnecting charger before use instead of charging up to the very last minute, then unplugging the charger and jumping onto/into the eVelo.
 * Create a heat, flame, and spill resistant space for charging batteries (yes including lead based gel cells, too).
 * Charge batteries while monitored, set timers to turn off chargers at night or when unmonitored and/or create a separate charging space that will be isolated from your living space if a battery disaster happens. //NOTE: many chargers may discharge the attached battery when turned off with an external timer.//
 * Put charged batteries that are not in use in a sealed fire resistant and chemical spill resistant container. Commercial battery boxes are OK, especially if a custom liner is made for them as documented above.

When handled with respect rechargeable battery packs will provide long lived power to your velomobile or LEV.

Copyleft: Mark Smith, W4CHL DBA 7tronic