Battery Backup Project

[awefulspeller]

Hi all,

I'm about to spend about $5,000 on a battery backup for my 2013 Ford Focus Electric. I would have gave this money to Ford in order to increase the range in my FFE, but its not an option so I'll develop myself.

The plan is to use a module from a Tesla battery, inverter and EVSE in order to provide about 6kW to the FFE. This equipment will easily fit in the trunk of the FFE and will allow me to charge anywhere I park. Very handy for me. I'm thinking about enclosing in a Pelican case so it is portable. 6kW is about all I need to add to compensate for the loss of range experienced during the winter. I'm sitting in my car charging my FFE as I type this. Cant make it to family's house and back on a full charge in my 13 FFE. Refuse to buy a 17 FFE.

Wish Ford would offer a battery upgrade option. I would have paid up to $7500 in order to add capacity to my current FFE battery.

 

[fbitz777]

seems like it would be heavy? what size Tesla module are you thinking ( I have a Tesla on order but not familiar with module sizes)?
or are you talking more like the powerwall (which would require not inverters)

seems like a 6-7KW generator with 220V output would be less heavy (and cheaper)...maybe you could live with a 3kw 220V?

there are a lot of very small 110V generators that are no bigger than a gas can but 220V are quite bulky.

I like the idea of the BMW i3 range extender but now that they have a larger 33KWh battery I am not sure they still offer that option.

I know you are not interested in doing the 2017 FFE but with your 5k budget and 7.5K in tax credit plus some trade in you'd be quite ahead?

 

[awefulspeller]

It will only weigh about 100lbs after inverter and module. I'll post pictures once complete.

Generator too smelly for me. Would at least need 220V, don't want to be sitting around forever waiting for a charge. Level 2 charge already takes forever compared to fast charger.

I'm most defiantly interested in the 17 FFE. Thats a good car. The range and price is just about right, and easy with fast charging. But, if I sell my FFE today, I would be giving away the $20,828 I've already paid into the car and have nothing to show for it except a new car with even more negative equity. Better to do the small 5k upgrade now and still be able to pay my car off on the final payment date.

Just saying... this 5k could be in Ford's wallet, and customer satisfaction would increase. "And wow! Look at all these neat options they offer! So my investment won't be completely obsolete once I pay it off".

 

[michael]

How often is the lack of range an issue for you? Most days? Or occasionally?

Is there a place (friend, relative, business) along your regular route where you could install a charging station? Or even a 220 V outlet? I did that at a friends house...used that as my private auxiliary charging station. it worked so well that they bought their own EV. All you need is a 220 outlet and a Turbo Cord, you're all set.

If it happens all the time and you can't come up with a simpler alternative, I'd dump the car, take the hit, and get something with longer range. And this time lease, don't buy.

 

[Robert123]

6 kWh and only 100 pounds? What voltage?

Is your plan to invert back to 240v then charge the FFE from the spare battery in the trunk? Have you got all the equipment sourced and spec'd out?

 

[awefulspeller]

6 kWh and only 100 pounds? What voltage?

Is your plan to invert back to 240v then charge the FFE from the spare battery in the trunk? Have you got all the equipment sourced and spec'd out?

That is my plan precisely. Maybe a bit more than 100lbs, but no more than 130lbs.

Here is the inverter:
http://www.ebay.com/itm/Magnum-Energy-Pure-Sine-Wave-4024-PAE-Inverter-Charger-/262750278531?_trksid=p2141725.m3641.l6368

EVSE:
https://store.clippercreek.com/level2/level2-12-to-15/lcs-20-lcs-20p-16-amp-level-2-ev-charging-station

24v Tesla Module:

 

[fbitz777]

How do you charge a Tesla 24Vmodule...I thought it takes a lot of electronics to do so and the module is in liquid and that needs to be regulated?

Not to sound simplistic but how about using Lead Batteries instead and maybe go to 48V ...heavier but safer.

As an example:

I have two Raven MPV7100 hybrid mowers and they have a 48V battery (1kwh only) what I can drive the mower for many miles on battery mode....the 48 V pack itself is quite small and can be charged with a 48 charger in a few hours.

http://www.ebay.com/itm/Raven-MPV-7100-Generator-Mower-48-Volt-Battery-Kit-Assembly-31140-H200100-0001-/182264798011?hash=item2a6fd41b3b:g:wJkAAOSwMgdXyOZK

 

[michael]

Upon further thought, I think yes,this could work. However I still don't think it's the way to go.

You can charge it easily enough, it's only a 6S unit. Off the shelf battery management charger with balancing capability would work. The efficiency will be low, since you are charging one battery pack from another, each with inefficiencies. plus inefficiency of the inverter. Cooling may be an issue. I didn't see on the inverter data sheet the Voltage range for operation. You will need a protection circuit to make sure you don't over discharge the battery pack. But it could work.

I'd still suggest spending the money to install an EVSE at some place along your route. For $1K you can buy one and have it installed. Find someone who will let you use it in exchange for installing it at your expense. Easier, faster, safer. I'd try this approach first. Or, as I suggested, just a 220 outlet.

 

[EVA]

fbitz777 - in the Chicago area, you can't buy an i3 without the range extender. The new bigger battery version absolutely do have the range extender option. BMW kept that around.

The horrible part of that nonsense - you lose the EL plates in Illinois. If there is a gasoline engine in the car, doesn't matter why, you can't have EL plates.

Oh I saw somebody do the math on using a gasoline generator to charge an electric car. It is reprehensible, from just about every viewpoint possible. Charging is super slow, the generator is noisy, you have to carry around gasoline, and it pollutes. A generator is an all around bad idea. Unless you will be somewhere in the middle of absolutely nowhere, with no electric plug anywhere - that's the only time one of those makes even a remote amount of sense.

 

[EVA]

fbitz777 awefulspeller - good luck dude. Obviously you have made the decision to do this. Hopefully you have fun building it and don't kill yourself with a fire, or electricity.

Can't wait to see your pictures and description of what you end up doing. I take it from the picture, you managed to already buy a portion of a Tesla battery pack? Because that is a very small chunk of the full size battery.

Sorry about that fbitz777 - bad copy and paste earlier.

 

[fbitz777]

It's not me! awefulspeller is the originator of the topic. and no I would not do such a project.

But yes you can buy lots of teslas 24V modules on ebay. They seem to be around $1250 for a nominal 6kw. That's is pretty cheap around 200/kwh. weight is around 55lb. Four of these would do an FFE (except the voltage would only be 96V)

 

[Robert123]

Not dissing on your project. I have that exact inverter in my barn powering my incubators. Use it as a UPS on a 240v home line. It's a great inverter and that's a good price. So, here are some observations / watchouts ....

Charging the Tesla Battery will be very easy. Simply use the Magnum to charge it up. The issue you are going to have to battle with is amperage and heat.

A bit overly simplified is that to deliver 16 amp to the Clipper Creek, you are going to have to pull 160 amps from the 24v source. That's a lot of amps and the wire you should use will be very impressive indeed (I use 000 wire on the battery side). I don't thing the Tesla battery can deliver that amount of amps continuously. That why EVs run extremely high voltage. It keeps the amps down and the wiring reasonable.

Assuming you beat the amps, the Magnum is going to get quite hot inverting that 4 kwatt load. You have to dissipate that heat somewhere. You'll need some fans to move the air out of the car.

Whatever you do, be careful!! Amps kill - even at 12 volts.

 

[ATL-FFE]

I hate to say this -- but you're using a hammer to drive a screw. The FFE is a city car, not meant as a road car. If you dont have the range, then you've picked the wrong car. Why not a $3k-4k used car? At least with that you could turn around a sell it for at least 80% of what you paid.

 

[Robert123]

you can buy lots of teslas 24V modules on ebay. They seem to be around $1250 for a nominal 6kw. That's is pretty cheap around 200/kwh.

You have my interest in these as I'd like to look at adding them to my barn setup. Have you got any idea what the recommended maximum amp draw is on these cells?

 

[fbitz777]

6S74P so that is 24V 250AH

I am sure 250amp+ is possible (1C discharge) although when I read about the Powerwall modules they talk about getting 2KW out of the starter version with about the same capacity battery.

 

[Robert123]

Thanks for the reply. Did some looking into it myself as well. Looks like these packs are built using 444 Panasonic 18650 cells? Looking at those specs I got about 173 amps at 1C with respectable performance at 2C. That's in the range of your numbers, so that answers that question.

Next question I have is .... Curious if the battery frame was built to sustain such a continuous amperage draw? Seems like it might, but then again perhaps that is the source of the Tesla fires? Can the Tesla be driven such that it runs outta juice after 30 minutes or an hour? IDK?

 

[fbitz777]

Thanks for the reply. Did some looking into it myself as well. Looks like these packs are built using 444 Panasonic 18650 cells? Looking at those specs I got about 173 amps at 1C with respectable performance at 2C. That's in the range of your numbers, so that answers that question.

Next question I have is .... Curious if the battery frame was built to sustain such a continuous amperage draw? Seems like it might, but then again perhaps that is the source of the Tesla fires? Can the Tesla be driven such that it runs outta juice after 30 minutes or an hour? IDK?

Tesla has them running at over 1500AMP in Ludicrous mode! but again this is for a few seconds while do 0-60 or drag racing.
at most a Tesla will do 100-150AMP average if you consider that it has a 2 hour range at 80mph.

My main issue is how is the liquid cooling handled?

 

[awefulspeller]

Great information in all of these comments. Thank You! I'm going to have to take a look at what the heat will do inverting 24vdc to 240vac @ 4kW. It might be too hot.

 

[awefulspeller]

Thanks for the reply. Did some looking into it myself as well. Looks like these packs are built using 444 Panasonic 18650 cells? Looking at those specs I got about 173 amps at 1C with respectable performance at 2C. That's in the range of your numbers, so that answers that question.

Next question I have is .... Curious if the battery frame was built to sustain such a continuous amperage draw? Seems like it might, but then again perhaps that is the source of the Tesla fires? Can the Tesla be driven such that it runs outta juice after 30 minutes or an hour? IDK?

Tesla has them running at over 1500AMP in Ludicrous mode! but again this is for a few seconds while do 0-60 or drag racing.
at most a Tesla will do 100-150AMP average if you consider that it has a 2 hour range at 80mph.

My main issue is how is the liquid cooling handled?

Plan is to bypass the liquid cooling because I dont know how it works :lol:

Worst case scenario with that inverter I can simply just charge 120v. Oh yea, and the car goes up in flames. Thank god for GAP insurance!

 

[EVA]

The more I think about this the more confused I am. Have you actually thought about opportunistic charging - scavenging where you can?

You go someplace in the car during the day, and stay there for some time. Then return home. You seem to be charging on your way home and spending a lot of time doing that.

Why wouldn't you try to find a 110V outlet where you leave the car during the day? Most light poles have 110V outlets at the bottom of them. Almost every workplace has a 110V outlet outside for doing yard work. I'm thinking an extension cord and you would be in perfect shape. 8 hours of 110V charging will get you 30 miles of range.