Has anyone ever looked at what is in the battery pack?

Is it really 120 D-Cells (as reported in the FEH forum)?

If so then a DIY battery change/upgrade might be possible.

Our pack is rated 6000 mah, it is possible to buy D-cells up to 11000 mah at the moment (for $10 ea, see www.amondotech.com), so for about $1,200 we could almost double the size of the pack.

Buying batteries with solder tabs limits it to about 9000 mah and drops the price to about $1,000. I don't think I would use non-soldered batteries for the high-drain application that is the HCH.

The idea of a DIY battery change five years down the road and/or increased IMA is really appealing, and it's half the price Honda will charge and a 50 percent increase in electrical storage. My battery routinely drains on the hill to work. I would love to have a bigger pack so I could ride the battery longer.

And batteries are likely to get better (and cheaper) over time.

 

The problem is the computer controls the charging of the batteries and it reports the level of the batteries. I'm not sure if it would automaticaly compensate for the additional capacity.

 

Hi Kmh3:

___Those D-Cell’s in the hybrid’s are supposedly CAP matched. I have no idea how a capacity match test is performed but Sanyo, Panasonic, whoever just doesn’t reach into the pile and pull out 120 D-Cell’s and says here you go.

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

 

CAP matching does sound like a problem, perhaps it would not be that bad, it would be an expensive test to find out however.

The computer can compensate for reduced capacity as the batteries age, and it will recalibrate when a new battery pack is installed (people have reported this) so it seems likely that it could compensate for a larger battery pack.

Good to know they are D-Cells anyway.

We shall see if in a few years I am adventurous enough to try it. :-)

Note: CAP matching is simply a charge/discharge test, they measure how much the battery holds. I don't know what normal variation is, nor how much tighter the HCH's requirements are. You can do it yourself with a stopwatch and a discharge circuit. You need a highly accurate charger (they are not that expensive), or you could make do with a trickle charger and let it overcharge slightly. Hard to imagine doing this test by hand with 120+ cells.

 

http://www.amondotech.com/index.asp?...ROD&ProdID=402

Currently 8.00 each for a total of $960.00

 

Yeah I am an Amondotech fan, "titanium pow power" is so ridiculous it is funny. :-)

I did more research on our batteries after those posts.

The cells in the HCH-I are slightly larger than a D-Cell, and are custom manufactured by Panasonic. I found a pic on howthingswork.com wrt hybrids. Don't know about the HCH-II, but probably similar.

They are also appear to be rated at many more charge/discharge cycles than consumer NiMH's (1000 typically). I couldn't find anything on why however.

I heard here that they generate about 100 amps at full assist, and take about 50 amps at full charge. Doubt those little spot-welded tabs on the Amondotech batteries would take that. The picure I saw of the HCH batteries showed very large connectors at the + end of each battery.

The idea of a 50% increase in the mAh capacity of my pack for $1k was very attractive however. :-)

 

I expect that when people get close to the 8 years or 80,000 (or 120,000 in some states) miles that Honda will have switched over to Lithium batteries at half the weight and potentially twice the capacity.

That would be a worthwhile upgrade to be sure!!

 

When I was into RC car racing we would do cap matching to build our NiCad battery packs all of the time. I can't imagine it would be that much different to cap match NiMH.

I'm guessing that, as mentioned earlier, the BCMs & ECMs might not be able to harness the extra capacity due to their programming.

 

Bjaardker, to do cap matching don't you need a surplus of batteries? If you have to
cap match 120 batteries how big of a pool would you need to buy?

This should give us an idea how much a create your own pack would cost.

 

The software has to deal with reduced capacity over time, so I was hopeful that a recal would pick up increased capacity too.

wrt cap matching, you have to define an acceptable variation between cells, an upper and lower bound, and reject (throw away) cells that don't fit. The tighter your limits (compared to the variation in your source) the more you have to throw away.

Trouble is, I don't know what variation limits are acceptable to the HCH computer.