Any Experience with Plug-in Supply?

No, I think you are asking the right questions. I have no personal experience with Plug in Supply, but can tell you the owner Robb seems to be well respected on the plugin hybrid discussion list. I like their pop-up battery box a lot, as it keeps the spare tire in place. On the downside I asked some of these exact questions a few months ago and didn't get any answer back. I don't believe they are doing anything different than the standard cal-cars conversion with regards to battery balancing or over-discharge. Based on that I am a little skeptical of their battery life claims.

Lead acid is cheaper up front, but will probably cost more in the long run. Count on a new $1000 pack every year to year and a half. If the lower upfront cost is the only way you can afford it, it might still be worth while. I'm still considering it for that reason. I think there are likely to be ways to improve the battery life on PbA conversions, but I do not think anyone is really looking at this at the moment. Another strategy is go ahead and do lead acid, and in 12-18 months when you need a new battery pack maybe something better will be available. The only challenge at that point is how much of your conversion will be compatible. For the most part the controller and basic setup should be ok, but the charger may or may not work with the new batteries. I do like that Plugin Supply is thinking in this direction, planning for a future Li-ion upgrade path.

Have you gotten a price from them recently? They were advertising $5k, but there is no price on the website now.

Rob

 

I hear you. I would very much like to do one just on principal, but the realities of having to come up with the cash have so far prevented it. As an engineer I would also like to make some technical contributions, particularly in the area of the low end market, but the realities of having two small children and no spare time have so far prevented that. Some day.....

My thoughts on extending the life of the lead acid packs are two fold.

First, I would really like to try the "stack of isolated 12V chargers" approach used by several of the BEV conversion folks using AGM batteries. You can get the individual smart chargers for ~$30, which would come to $600 for 20. This has the advantage that every battery gets exactly as much charge as it needs, so it is inherently a balancing charge mechanism. You can see an example of this sort of thing here:
Soneil Battery Chargers
http://www.econogics.com/Soneil/son914-1.jpg
I believe these chargers are made by Soneil, but re-badged by battery mart at a much better price. Would need to make sure they are the isolated version though, although I believe someone has already used these successfully in an EV.
Battery Defender 12 Volt 3 Amp Battery Charger: BatteryMart.com
The downsides to this approach are that the chargers are lead acid only, so not reusable later, and there is a complexity concern. Since you have 20 individual chargers, there are twenty chances for something to go wrong. I believe these chargers are less likely to go wrong than a big 240V monster, so I'm not sure where that settles out reliability wise. Ideally you'd want some sort of safety catch, that wouldn't let you use the pack unless all the batteries were successfully charged. Engaging the pack with 19 good batteries and one flat would kill the pack very quickly.

Second, I would monitor the voltage of every battery and disconnect the pack any time any one battery falls below a certain voltage. This could probably be done in a brute force way for under $10 per battery, or ~$200 total with a simple adjustable comparison circuit. More elegant solutions would shuffle current around to compensate for the weakest battery and get as much range out of the pack as possible, but that would cost a lot more. Theoretically this could be used to catch an uncharged or undercharged battery if the above stacked charger scheme was used, as the battery that didn't charge properly would hit the limit first. This approach comes at the expense of reducing mpgs a bit after the pack is depleted. Right now the depleted pack is kept in parallel which adds some regen capacity and lowers the effective internal resistance of the battery which improves efficiency. Its believed this effect just about cancels out the 1-2 mpg loss you would expect from carrying around 300 lbs of dead batteries in the trunk. You'd have to give that up if you disconnected the battery, but I expect the life improvement would be well worth it. The pack get run down to 180V (9V per battery, 1.5V/cell) or less when its left connected, which is a huge no-no according to the BEV folks. Depending who you ask, they consider 100% DOD (a completely empty battery) around 10-10.5V (200-210V total, or 1.67-1.75V per cell). This is particularly bad news for a pack that is not well balanced, as the weakest cells will be far less than 1.5V per cell, and can even end up reversed. This is the surest way to kill a battery from what I've read.

These problems are all compounded because all the batteries in the pack must be decently matched and age together. Once the weakest battery fails, you pretty much have to buy a whole new pack. Trying to replace one or two failed batteries results in all kinds of mismatch issues and quickly leads to many more failures.

Rob

 

Hi all!
I have been an owner of a 2005 Prius for 3 years and love it! We are now becoming a two Prius family and my second Prius is a 2007 PHEV with a plug in supply package. Now, I haven't received this car yet but I have enjoyed watching it being built by Auto be Yours. I hope to upgrade to Lithium when this battery pack needs to be replaced. Anyhow, I am adding a 4 kwh hour solar array to our residence and thus...I plan to plug into the sun daily! I'll let you know how things go once I actually have the car. I have posted a picture album of the car being built. It is at the painters now and then will have the PHEV kit installed.

saintjerome

 

In their latest ad, from their website, they are calling the pack future proof as it will be able to be upgraded to Lithium. Also, when reading their site, they are talking about 800 charges with an upgrades lead acid pack vs. the 300 or so recycles you previously received.

 

That is not very many charges compared to what Hymotion A123 Systems is projecting. Their 5 kwh lithium pack is projected to last several thousand charges.

A123Systems :: Home

According to their chart, they are still at 85% of original capacity after 3,500 discharge cycles. That is 10 years of regular use every day, which means that the Hymotion battery will likely last for the life of the car.

 

Hi AlanK,

I just had the Hymotion mod done about a month ago and I was curious about the recharge durability of the pack over time. I was told by Scott, the Hymotion install manager at Burt Toyota here in Denver that the L5 pack has been lab test cycled to 8000 full charge/discharges. I believe he said the pack at that point still had about 75% capacity, so I'm not too worried about replacement costs at this time. BTW, 8000/365 = almost 22 years of daily usage. The mod did add 10K to my cash outlay for the car, but over the next several years I do hope to recoup part of it through both the higher mileage and no battery replacement costs (I'm not expecting to make up the full cost of the pack, and that was never a criteria for the purchase - but hey, if that does happen I won't complain)

If/when you have the Pba PHEV mod done to your car, please share with us the details and costs - I'm sure there are a lot of members here that would like a less expensive option to join the PHEV club!

 

In general PbA batteries need to be recharged as often as possible. The more heavily they are discharged, the fewer cycles you will get out of them so you never want to go more than one day before recharging if possible. If you have the option to recharge more than once a day that might be even better. Here's a quick numerical example to illustrate. Lets assume the range of the pack is 15 miles at 100% DOD. From the datasheet linked below, the EB20-12 batteries are good for 800 cycles at 50%, 500 cycles at 70%, and 300 cycles at 100% DOD. Putting that in terms of miles:

50% = 7.5 miles * 800 cycles = 6000 miles
70% = 10.5 miles * 500 cycles = 5250 miles
100% = 15 miles * 300 cycles = 4500 miles

http://www.bb-battery.com/productpages/EB/EB20-12.pdf

I think that makes it pretty clear why you would never go more than 1 day without recharging just because you didn't use all of the charge in the pack. These curves also apply to a battery that is discharged and immediately recharged. If a lead battery is left in a partial or full discharged state it will further degrade, which is another good reason never to do this. The original battery used in the cal-cars was the EVP20-12, which illustrates the difference even better as it includes a 30% DOD number:

30% = 4.5 miles * 1500 cycles = 6750 miles
50% = 7.5 miles * 600 cycles = 4500 miles
100% = 15 miles * 300 cycles = 4500 miles

http://www.bb-battery.com/productpages/EVP/Evp20-12.pdf

My biggest concern with the cal-cars based PbA conversions at the current time is that they do nothing to prevent the supplemental battery from discharging to 100% or beyond. When/if I can ever get my conversion going (and I don't get talked into trying some cheap Chinese Li-ion) this is one of the areas I want to try making some improvements as outlined above.

Even with improvements, you have to be realistic about the cost benefit. The best case above of 6750 miles if you recharge every 4.5 miles still works out to ~15c/mile for the battery assuming ~$1000 for the pack. This is not price competitive with gasoline unless you assign additional value to reduced oil consumption, reduced CO2 output, supporting the development/publicizing of PHEV technology and/or reduced pollution output.

Rob

 

Hi! Yes, I just had a 2007 salvage Prius converted to Plug in Supply's kit. I love it! Plug In Hybrid Electric Vehicle PHEV converted it for me. Steve Woodruff was the installer. He's the one who made the installation videos for the Plug in Supply website. Check out my blog at Our New PHEV Prius! Don't hesitate to ask any questions.

 

Thanks saintjerome, I've enjoyed checking out your conversion. We also got our first Prius from Steve a while back, he does really nice work. Should be able to start my PHEV conversion this spring, looks like I'll probably be going with the Plugin Supply kit for the most part, with a few mods of my own

Rob