Floodie / Lithium hybrid battery experiment

40197 Views 93 Replies 16 Participants Last post by dougingraham, May 24, 2013

Ziggythewiz

Discussion Starter · May 25, 2012 (Edited)

I'm starting an experiment to test the effects of using lithium LiFePO4 cells in parallel with cheapo lead acid batteries.

Lithiums are 40 AH Calbs, and they'll be boosting 29HMs (formerly known as 29DC) and GC8s. My current frankenpack consists of 3 29HMs and 11 GC8s.

Phase 1 of FLHE will put 8 calbs in parallel with 2 29HMs with a JLD404 to monitor AH usage and control charging. The calbs will be charged in parallel with the floodies until approx entering gassing phase where the JLD will cut the lithium contactor while the floodies finish their cycle. 1 29HM will remain unboosted as a control.

Phase 2 will add 8 calbs in parallel with 3 GC8s and tested as above.

The experiment will try to gain info about how the current sharing works out as well as how lead cycle life can be prolonged with the aid of a lithium booster.

A successful experiment would demonstrate an increase in lead cycle life sufficient to justify the cost of the lithium booster.

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TexasCotton

· #81 · Mar 3, 2013

may use something like this
http://www.ebay.com/itm/UNIVERSAL-1...US_Rechargeable_Batteries&hash=item5d37d0a874
to boost. I may try solar panel wired to solar controller wired to SLA battery wire to diodes to 24vdc Lifepo4 80ah and see what I get on my Prius, I am hoping to charge the Lifepo4 via SLA mainly kinda of a solar charger on wheels.

Ziggythewiz

Discussion Starter · #82 · Mar 3, 2013

Don't expect mobile solar to do much charging, and be wary of buying batteries that have been sitting around unused.

Ziggythewiz

Discussion Starter · #83 · Mar 14, 2013

2

Finally got around to hooking up my split pack meters and switches, 1 for each 13 cells. They're not calibrated (the last one I touched fried and set me back a couple months) so they'll rarely ever match but if they ever spread by a couple volts I'll know there's a problem.

Here's my latest spaghetti board prototype:

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Ziggythewiz

Discussion Starter · #84 · Mar 24, 2013

With warmer overnight temps I don't need the charger floating overnight anymore, so I've reduced booster charge voltage to 132.6 (3.4 vpc), giving a rest ~130.5V.

TexasCotton

· #85 · Mar 30, 2013

dtbaker said:
lead sags more under high load, and suffers from peukart's.

Hello
OP I was wondering in my application 24vdc lifepo4 80ah and 24vdc 100ah lead acid . Would a 80ah rated battery isolater between them work?

Ziggythewiz

Discussion Starter · #86 · Mar 30, 2013

Usually an isolator is made for two or more batteries to charge together but discharge separately. That's not the case for a hybrid pack. You could use a heavy diode to separate them but that would make the discharge balance vary significantly.

As for ratings, you'd need to be rated for the peak or average current depending on the device. Capacity (AH) is irrelevant.

TexasCotton

· #87 · Mar 30, 2013

Ziggythewiz said:
Usually an isolator is made for two or more batteries to charge together but discharge separately. That's not the case for a hybrid pack. You could use a heavy diode to separate them but that would make the discharge balance vary significantly.

As for ratings, you'd need to be rated for the peak or average current depending on the device. Capacity (AH) is irrelevant.

Has anyone consider like a ultracaps booster pack for lifepo4 battery pack

Ziggythewiz

Discussion Starter · #88 · Mar 30, 2013

Yes, no need. Lithium is pretty good already and for the same weight is much more useful than supercaps, not to mention the price.

PStechPaul

· #89 · Apr 3, 2013 (Edited)

Today I just happened to pass by a local BatteriesPlus store and I asked them what their price would be for 12V 12Ah SLA batteries such as I recently got on eBay for about $22 each including shipping. I think theirs were about $49/1 and the best they could do for 20 pieces was $35 each. But their 8Ah batteries would be just $16.50 each. So, for my tractor, I could get 240V 8Ah or 1.92 kWh for $330 plus $20 to make the governor happy, so just about $350. I have demonstrated that my small riding mower with me aboard will run at 24V 15A or 360 watts, so I may be able to expect 1 HP or 750 watts to go faster or climb hills or do some work, and at that level I'd draw about 3 amps (0.4C) Peukert says I'll have 5.1 Ah and I should get a run time of about 1.5 hours. That seems pretty good.

If and when I get back to my project (after my scheduled hip replacement April 22), I'll start a build thread. But this seems like a pretty good deal at $0.17/Wh (more realistically about $0.25 with tax and Peukert). The batteries have a 1 year guarantee and should be fine for occasional use, and I think they weigh about 5.25 lb each and an equivalent on eBay is about $17.50. But the batteries from BatteriesPlus are made in USA rather than China so I feel better about that.

For an electric car as an adjunct to lithium cells, the 55 Ah deep cycle battery might be appropriate, and at a list price of $150 it's not bad at $0.23/Wh. In quantity they are probably much less, maybe under $100, or close to the smaller battery's $0.17/Wh. These are 42.5 lb so a 240V 55Ah 13.2 kWh pack would be 850 lb and about $2000.

EDIT: I found out that the Werker brand from BatteriesPlus may be produced by Deka/East Penn but also could be from elsewhere, including some Mexican sources. There are some local reps for Deka/East Penn.
http://www.dekabatteries.com/default.aspx?pageid=844
http://www.dekabatteries.com/ZipSearch.aspx?pageid=843

Their factory is about 2 hours north of me in Lyons, PA.
https://maps.google.com/maps?saddr=Cockeysville,+MD+21030&daddr=Lyon+Station,+PA&hl=en&sll=40.187267,-75.311279&sspn=2.135889,5.218506&geocode=FYFvWgId7IFu-ylngO2kZxLIiTEDNpvSwWL1mg%3BFfe0aQIdggd8-ynF9kpUf9PFiTG6EDsTNxblAw&oq=21030&mra=ls&t=m&z=9

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Ziggythewiz

Discussion Starter · #90 · Apr 10, 2013

Finally got around to doing a range test. I drove 41 miles before I got tired of going in circles. I cut out the booster ~27.5 miles in at 80% DOD. The floodies were probably still ~70% DOD when I stopped, so I have ~45 mile range to 80% DOD.

Average efficiency was 242 wh/m from the batteries, 332 from the wall.

I'll have to do another test soon without the booster to try to measure the increase in Peukert effect.

TexasCotton

· #91 · May 23, 2013

Hey OP
I have a question .What difference(if any) would there be in the discharge of these two examples.
two 12volt AGM 200ah lead acid
or
four 6volt 200ah golf cart deep cycle

The discharge rate would be 5ah
I am thinking the 6volt deep cycle may be the better performance

Ziggythewiz

Discussion Starter · #92 · May 23, 2013

Depends on the exact batteries. I've heard some AGMs perform better, but others don't like high current as well.

I assume you mean a rate of 5A? Either should handle that fine.

TexasCotton

· #93 · May 24, 2013

yeah a discharge at a rate of 5ah/aka amp hour . ....I found 6 volt golf cart battery 200ah on a local basis and also thinking they may withstand my application not that the AGM would not but both closely price but the purchase of 6 volt deep cycle golf less footwork

dougingraham

· #94 · May 24, 2013

TexasCotton said:
yeah a discharge at a rate of 5ah/aka amp hour . ....I found 6 volt golf cart battery 200ah on a local basis and also thinking they may withstand my application not that the AGM would not but both closely price but the purchase of 6 volt deep cycle golf less footwork

At 5 amp discharge rate both cells will give you the full 200 ah as this would be a 40 hour rate. The real problem is that once you get below about 50% state of charge the plates start sulfating at an accelerated rate so while your battery will do this once it will be hurt by doing so. I don't know which of the cell types you mention would survive this better. Some of the Lead Acid batteries would do this only a handful of times and they would be completely ruined.

If you only discharge to half (about 20 hours) either type should last a couple of years.

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