Bill - even though the packs are made of 'D' cells, I believe they are 'welded' together somehow so that there is no chance of connection resistance that could cause issues. Do you know the make/model of these D cells? This would be a great project for my old battery pack.

 

Roger the welding issue...

I'll go lookup the cells and edit this post when I find them. My hybrid is a Ford Escape. Its cells are 5,500 MA-hour D cells. I looked around awhile ago and found some D cells on the market rated at 11,000 MA-hour.

Since these are really just "market available" cells I am thinking that if push comes to shove when my pack dies I just might try your work and see what I can do. My FEH was manufactured in May 2005 & purchased in Dec 2005. So far the battery pack is working just fine.

Having spent 30 years driving nuke subs (they have a really, really big DieHard), I have some idea of how these things work, along with just how you have to care & feed a battery. Your efforts are inspiring, , so I just may take on this battery swapout when the time comes as you've provided much good groundwork.

Here's the source:
http://www.allelectronics.com/make-a...rgeable/1.html

Look for the D cell NiMH batteries. These are 10,000 MA-hour instead of the 11,000 I saw awhile ago.

Here's a place that advertises a 12,000 MA-hour NiMH cell:
http://www.batteryjunction.com/dnireba.html

I believe the "welding issue" has to do with the battery connections not melting under load as they would if they were just soldered. In the end, it is a big hurdle.

When I brought this up over on the FEH side I got razzed. The razzers thought I didn't understand the welding thing.........

 

Thanks Fuelmieser. Wouldn't you know it, while cleaning up I found a pigtail with power pole connectors on it. **razzberry**. So... my bad! I take back the slanderous words I spewed! Haven't hooked it up yet. Repairing my sons' computer, edging the yard, building a Langstroth bee hive. So many projects... so little time!

Hunter:

Thanks for taking the time to do that. I suspected this was going on. I'm hoping that individual sticks are discharging faster and not the whole pack. When I start testing with the CBAII I hope it will also shed some light on this. Cudos!

Bill:

I just had some Jack Daniels on the rocks and while reading your post I got lost after the word calculation! LOL Too tired and too late in the day for formulas... I'll look at that when I'm not so tired. :-)

As for using D cells and building my own pack... the question was brought up earlier in this discussion... I encourage you to read it... I gave a nice long winded answer. :-) But the short answer is even Chinese cells are expensive when you add them up. They have to be welded together to carry many many amps (I don't know exactly how many but if the size of the cables connected to the pack are any indication, I'd venture somewhere around sixty amps)... so the welded connections have to be "sick" (to use my teenager's verbage).

The current pack has threaded connections on each of the "sticks" of cells. I'd either have to figure out how to put threaded ends on the battery sticks I made or come up with a whole new way of connecting them all together... and lastly, if the cells internally can't handle the loads we're talking about, I've wasted a whole lot of money! I don't know how the pack cells are manufactured... but I bet they're specially made to take the punishment... maybe thicker electrodes... something... I just don't know.

If I find a definite bad stick of cells, I have every intention of cutting one of those babies open and dissecting it for class discussion. Maybe I'll get a regular NIMH D-cell off the shelf and dissect it as well. It won't answer the question of chemistry but it might shed some light on any differences (if any) on how it was made. Pictures of course will be included!

I'm a Wally World guy. If I can't find it there, I just do without it... ya know? :-)

I really want some rich dude to try this so we can all know if it works!

Thanks all for the feedback and compliments on this thread. I really enjoy the discussions.

Ross

 

Don't worry about the Jack... It took me a couple of days after you asked the question for the thought to gel for me... and I didn't have the jack motivator!

Based on my experience with Submarine batteries (admittedly Pb-Acid...) where currents of several thousand amps can be drawn, if the chemistry is right I don't think the amperage will be a problem. They chose the higher voltage (330VDC for the FEH) to reduce the amperage.

The issue I'd be more concerned about is the ability of a cell to handle the heating & possible gas generation that NiMH batteries see.

I saw your discussion and read it... I'll go back & read it again.

So where's that rich guy... we could use him!!!

 

Be aware that the advertised capacity of those cells, it is a capacity that cannot be delivered as the capacity of the hybrid vehicles batteries.

The internal resistance on a hybrid is so low that it will allow to discharge at 10 times the rated capacity, 65 Amps at full assist and charge at up to 8 times the capacity.

The internal resistance translates in lower coeficient of heat, and believe, the heat you will generate with a household battery will be enough to start sparks.
Do some reading in the internal resistance of NiMH and you will understand what I mean.

 

Don't understand your post.

If it was in reference to my method of calculation it doesn't make sense. Please explain some more.

 

This place sells the 'Betterbattery' for HCH I's - they claim 23% increase in capacity for the pack (8.0 amp/hr vs 6.5 amp/hr), they stay 5% cooler, and have lower internal resistance (less charge/discharge wasted in heat)

http://www.hybrid-battery-repair.com/hch/new.html

They don't say what the make/model of the individual cells. It would be interesting to see if something like this can be done to increase the HCH-II 5.5AH to a higher capacity.

I believe HCH I and HCH II use the same Panasonic batteries, however, the HCH-II has a few more so the voltage is higher.

 

Bill, it was in reference to the batteries in the links, Thenergy, D-cell, 10Ah capacity and others.
I have questioned the validity of the claims by others that a higher capacity cell runs cooler. The math does not add up.
Electricity is a fairly exact science. Power stored and power delivered generate heat in a battery. More power in and more power out equals more heat. Now, if you can find a battery with lower internal resistance, you may get away with more capacity, but not much. Heat builds up exponentially.
If we could see the data sheet of such miracle cells, then we would be able to validate the claims.

I have contacted all the battery manufacturers for a replacement battery for the OEM and the first thing they tell me is that individual cells are not produced for retail. The low internal resistance batteries are only produced for the automotive industry for now. Hence the high cost.

 

OK, got it. Skepticism is always appropriate.

Be aware that the chemical reaction generates heat in one direction and absorbs heat in the other. I'll have to look up the NiMH chemistry.

Then there's the I squared R loss which always generates heat in either direction.

This is from Wikipedia and may be part of the availability issue:
Stanford R. Ovshinsky invented and patented the NiMH battery and founded Ovonic Battery Company in 1982. General Motors purchased the patent from Ovonics in 1994. By the late 1990s, NiMH batteries were being used successfully in many fully electric vehicles, such as the General Motors EV1 and Dodge Caravan EPIC minivan. In October 2000, the patent was sold to Texaco and a week later Texaco was acquired by Chevron. Chevron's Cobasys subsidiary will only provide these batteries to large OEM orders. General Motors shut down production of the EV1 citing lack of battery availability as one of their chief obstacles. The Cobasys control of NiMH batteries has created a patent encumbrance of large automotive NiMH batteries.

 

Personally I believe that finding GOOD (non failing better quality) batteries would be a better goal than higher capacity, since when you use assist, you must restore the energy anyways. The higher capacity would buy you more assist time, but you'd have to restore it using the ICE unless you do lots of braking and have down-hills.

higher capacity batteries would make sense for a plug-in hybrid or mod, since you could use additional assist and drain the batteries and charge it at night.