battery charger advice needed

[Mark Vieselmeye]

I'm interested in building a new battery pack for my 6-volt Vistalite, mainly to increase the run
time because I can't run both lights for my full round-trip commute, and even just on one light it
starts to get dim. Also, I'm considering over volting to 7.2v.

One option I'm interested in is using 13 amp hour F cell NiMH cells. My problem is I can't find the
right NiMH smart charger for 6 or 7.2 volts. I found one for an RC car, but it specified a max of 2
amp hour battery pack. Also, there are lots of hand tool chargers that maybe I could adapt, but I
don't know if that would work, e.g. would those also have limits on amp hours? I'm also wondering
how the "smart" aspect would be affected. I believe most of these chargers use temperature change
rather than current change to sense a full charge, so if I hooked up an external connection I don't
see how it could sense the temperature.

Another option maybe is to use ten D cells and a more readily available 12 volt charger. Is it
possible to retrofit 12 volt bulbs to a VistaLite?

What about hooking up two 4.5 amp hour NiCd packs in parallel to get 9 amp hours? Nothing I've read
has suggested that as a possibility, so I'm wondering if there's a reason why that's not done.

The days are getting shorter, so any help is greatly appreciated!

- mark

 

[Per ElmsäTer]

Mark Vieselmeyer wrote:
> I'm interested in building a new battery pack for my 6-volt Vistalite, mainly to increase the run
> time because I can't run both lights for my full round-trip commute, and even just on one light it
> starts to get dim. Also, I'm considering over volting to 7.2v.
>
> One option I'm interested in is using 13 amp hour F cell NiMH cells. My problem is I can't find
> the right NiMH smart charger for 6 or 7.2 volts. I found one for an RC car, but it specified a max
> of 2 amp hour battery pack. Also, there are lots of hand tool chargers that maybe I could adapt,
> but I don't know if that would work, e.g. would those also have limits on amp hours? I'm also
> wondering how the "smart" aspect would be affected. I believe most of these chargers use
> temperature change rather than current change to sense a full charge, so if I hooked up an
> external connection I don't see how it could sense the temperature.
>
> Another option maybe is to use ten D cells and a more readily available 12 volt charger. Is it
> possible to retrofit 12 volt bulbs to a VistaLite?
>
> What about hooking up two 4.5 amp hour NiCd packs in parallel to get 9 amp hours? Nothing
> I've read has suggested that as a possibility, so I'm wondering if there's a reason why
> that's not done.
>
> The days are getting shorter, so any help is greatly appreciated!
>
> - mark

I'm into trying pretty much the same thing you are. NiMh batterys are a little different than lead
acid and there seems to be lots of things to learn. One technician I talked to said that it is not
as easy or good to hook up NiMh in parallell as you propose 4.5 Ah + 4.5 Ah. However Silva sells
such a batterypack 10 cells at 1.2V and 4.5 Ah hooked up to make 6V and 9Ah. There is also at least
two different ways to make NiMh cells. The same person told me that foamed cells where good enough
for a bike lightning system. I was recommended a charger called "Ansmann, type ACS410P Traveller"
However it seems to charge only a battery pack of up to 9 Ah. I haven't figured out what that
implies and what happens if you connect 13 Ah batterys???

Let's hope somebody can make these things clear for us.

--
Perre

You have to be smarter than a robot to reply.

 

[Per ElmsäTer]

Per Elmsäter wrote:
> I was recommended a charger called "Ansmann, type ACS410P Traveller"

Here's a link to the charger above
<http://www.elfa.se/elfa-bin/setpage.pl?http://www.elfa.se/elfa/produkter/en /4279.htm>

--
Perre

You have to be smarter than a robot to reply.

 

[N2vx Jim]

On 7 Oct 2003 18:54:55 -0600, Mark Vieselmeyer <[email protected]> wrote:

>I'm interested in building a new battery pack for my 6-volt Vistalite, mainly to increase the run
>time because I can't run both lights for my full round-trip commute, and even just on one light it
>starts to get dim. Also, I'm considering over volting to 7.2v.

Overvolting was done to death earlier. Try a google newsgroup search. Probably not worth it due to
greatly reduced bulb life.

>One option I'm interested in is using 13 amp hour F cell NiMH cells. My

Seems like NiMh F cells are in the 3.5-3.8 amp-hour range. Nice capacity and you can get them
from some laptop PC packs cheap. I use a bunch of them in some test equipment. Ebay is a good
place to look.

>problem is I can't find the right NiMH smart charger for 6 or 7.2 volts. I found one for an RC car,
>but it specified a max of 2 amp hour battery pack. Also, there are lots of hand tool chargers that
>maybe I could adapt, but I don't know if that would work, e.g. would those also have limits on amp
>hours? I'm also wondering how the "smart" aspect would be affected. I believe most of these
>chargers use temperature change rather than current change to sense a full charge, so if I hooked
>up an external connection I don't see how it could sense the temperature.

Try the Maha MH-C777+. It charges NiCad, NiMh and lithium packs. Great piece of equipment that
charges nearly everything safely. There are R/C chargers that work with a wide range of packs, too.

Many smart chargers just use voltage detection. I wouldn't worry about temperature too much.

>Another option maybe is to use ten D cells and a more readily available 12 volt charger. Is it
>possible to retrofit 12 volt bulbs to a VistaLite?

Many D cells are just sub-C's in a plastic shell. Real NiMh D's are expensive. Don't know about the
bulb. You still want a smart charger with it. No point in frying some really expensive batteries.

>What about hooking up two 4.5 amp hour NiCd packs in parallel to get 9 amp hours? Nothing I've read
>has suggested that as a possibility, so I'm wondering if there's a reason why that's not done.

Use two identical packs; don't mix and match. Voltage from each pack has to be very close.

>The days are getting shorter, so any help is greatly appreciated!
>
>- mark

A useful exercise is to figure out how many amp-hours you need for your trip. Multiply bulb current
draw and trip time. You won't get full capacity out of the battery so bump it up by 25-50%.

Perhaps you could post details on commute time and bulb current draw or wattage.

Good luck with your quest, Jim

 

[Mark Vieselmeye]

Per wrote:
: Mark Vieselmeyer wrote:
:> I'm interested in building a new battery pack for my 6-volt Vistalite, mainly to increase the run
:> time because I can't run both lights for my full round-trip commute, and even just on one light
:> it starts to get dim. Also, I'm considering over volting to 7.2v.
:>
:> One option I'm interested in is using 13 amp hour F cell NiMH cells. My problem is I can't find
:> the right NiMH smart charger for 6 or 7.2 volts. I found one for an RC car, but it specified a
:> max of 2 amp hour battery pack. Also, there are lots of hand tool chargers that maybe I could
:> adapt, but I don't know if that would work, e.g. would those also have limits on amp hours? I'm
:> also wondering how the "smart" aspect would be affected. I believe most of these chargers use
:> temperature change rather than current change to sense a full charge, so if I hooked up an
:> external connection I don't see how it could sense the temperature.
:>
:> Another option maybe is to use ten D cells and a more readily available 12 volt charger. Is it
:> possible to retrofit 12 volt bulbs to a VistaLite?
:>
:> What about hooking up two 4.5 amp hour NiCd packs in parallel to get 9 amp hours? Nothing
:> I've read has suggested that as a possibility, so I'm wondering if there's a reason why
:> that's not done.
:>
:> The days are getting shorter, so any help is greatly appreciated!
:>
:> - mark

: I'm into trying pretty much the same thing you are. NiMh batterys are a little different than lead
: acid and there seems to be lots of things to learn. One technician I talked to said that it is not
: as easy or good to hook up NiMh in parallell as you propose 4.5 Ah + 4.5 Ah. However Silva sells
: such a batterypack 10 cells at 1.2V and 4.5 Ah hooked up to make 6V and 9Ah. There is also at
: least two different ways to make NiMh cells. The same person told me that foamed cells where good
: enough for a bike lightning system. I was recommended a charger called "Ansmann, type ACS410P
: Traveller" However it seems to charge only a battery pack of up to 9 Ah. I haven't figured out
: what that implies and what happens if you connect 13 Ah batterys???

If it's anything like the Maha universal charger, then it means it takes a heck of a long time to
charge. That one can charge up to ~10 Ah before the timer cuts off (i.e. 15 hours). It charges at
~650 mAh rate. If I'm going to use it every day, I'd need to alternate two battery packs, and then I
wouldn't be able to leave it on the bike for charging.

- mark

 

[Mark Vieselmeye]

Jim, N2VX <[email protected]> wrote:
: On 7 Oct 2003 18:54:55 -0600, Mark Vieselmeyer <[email protected]> wrote:

:>One option I'm interested in is using 13 amp hour F cell NiMH cells. My

: Seems like NiMh F cells are in the 3.5-3.8 amp-hour range. Nice capacity and you can get them
: from some laptop PC packs cheap. I use a bunch of them in some test equipment. Ebay is a good
: place to look.

I think we're talking about different cells. I'm referring to these ones:
http://www.rabbittool.com/frames/NiMH2.html

[ ... ]
: Try the Maha MH-C777+. It charges NiCad, NiMh and lithium packs. Great piece of equipment
: that charges nearly everything safely. There are R/C chargers that work with a wide range of
: packs, too.

Yes, I just googled that one up today, and was excited for a bit until I realized it would take ~20
hours to charge a 13Ahr battery pack.

: Many smart chargers just use voltage detection. I wouldn't worry about temperature too much.

That's what I was hoping, but I've read some things that indicate Dv/dt is much less reliable for
NiMH than for NiCd. This seems to be one of the better references:

http://www.powerstream.com/NiMH.htm

:>Another option maybe is to use ten D cells and a more readily available 12 volt charger. Is it
:>possible to retrofit 12 volt bulbs to a VistaLite?

: Many D cells are just sub-C's in a plastic shell. Real NiMh D's are expensive. Don't know about
: the bulb. You still want a smart charger with it. No point in frying some really expensive
: batteries.

Proper D cells are up to 9Ah, and can be had for $7-8 apiece. Still pricey, but ten of those would
only cost a little more than five F cells.

:>What about hooking up two 4.5 amp hour NiCd packs in parallel to get 9 amp hours? Nothing
:>I've read has suggested that as a possibility, so I'm wondering if there's a reason why
:>that's not done.

: Use two identical packs; don't mix and match. Voltage from each pack has to be very close.

[ ... ]
: A useful exercise is to figure out how many amp-hours you need for your trip. Multiply
: bulb current draw and trip time. You won't get full capacity out of the battery so bump it
: up by 25-50%.

: Perhaps you could post details on commute time and bulb current draw or wattage.

I haven't calculated it, but based on experience I figure I'll need more than 9Ah. My current setup
is 4.5 Ah, which isn't enough to keep my 15watt light going for the whole 1hr 40 minute round trip.
So I think I'll need at least to double it if I want both the 15 & 10 watt lights. Also, I was
thinking if I could get a 13Ah battery, I could also wire in a pretty decent tail light array.

- mark

 

[N2vx Jim]

On 8 Oct 2003 17:58:14 -0600, Mark Vieselmeyer <[email protected]> wrote:

>Jim, N2VX <[email protected]> wrote:
>: On 7 Oct 2003 18:54:55 -0600, Mark Vieselmeyer <[email protected]> wrote:
>
>:>One option I'm interested in is using 13 amp hour F cell NiMH cells. My
>
>: Seems like NiMh F cells are in the 3.5-3.8 amp-hour range. Nice capacity and you can get them
>: from some laptop PC packs cheap. I use a bunch of them in some test equipment. Ebay is a good
>: place to look.
>
>I think we're talking about different cells. I'm referring to these ones:
>http://www.rabbittool.com/frames/NiMH2.html

You're right, those are big honkin' batteries. I must be thinking of
5/4 A cells or something like that. The Maha would time out with something that size.

A charger for something like won't be cheap. If you're really handy check the Maxim MAX-712 NiMh
charge controller chip. I made a charger using the MAX-713 (NiCad) and it worked OK.

I once saw a charger that plugs into your PC. It also measures capacity and can be used to match
individual cells for making packs. Don't remember who it was but it was reasonably priced and a good
place to start Given the low current draw of contemporary drives you should be able to take a few
amps off the +12 supply. ...
>: Many smart chargers just use voltage detection. I wouldn't worry about temperature too much.
>
>That's what I was hoping, but I've read some things that indicate Dv/dt is much less reliable for
>NiMH than for NiCd. This seems to be one of the better references:
>
>http://www.powerstream.com/NiMH.htm

They are right. The usual recommendation is minus delta V for NiCad and 0 delta V for NiMh. The
Maxim chips can use temperature, too. ...
>I haven't calculated it, but based on experience I figure I'll need more than 9Ah. My current setup
>is 4.5 Ah, which isn't enough to keep my 15watt light going for the whole 1hr 40 minute round trip.
>So I think I'll need at least to double it if I want both the 15 & 10 watt lights. Also, I was
>thinking if I could get a 13Ah battery, I could also wire in a pretty decent tail light array.
>
>- mark
>

It's in the 4 to 7 amp-hour range depending on the bulbs you have on. At high current draw you will
not get full battery capacity. Look for a graph of battery output vs. discharge time.

You also mentioned 1:40 round trip time. Does this mean it's 50 minutes each way? I used to use
lead-acid gel cells and had a charger at work and one at home. I'm not a weight weenie, but it adds
up fast with clothes, shoes, lunch, etc. A smaller pack keeps your cost down, too.

Jim

 

[Mark Vieselmeye]

Jim, N2VX <[email protected]> wrote:
: On 8 Oct 2003 17:58:14 -0600, Mark Vieselmeyer <[email protected]> wrote:

: A charger for something like won't be cheap. If you're really handy check the Maxim MAX-712 NiMh
: charge controller chip. I made a charger using the MAX-713 (NiCad) and it worked OK.

I'm always up for DIY projects. How complicated would this be? I can solder parts together, but
generally my elctronics knowledge is more on the level of installing car stereos. One thing I'd
wondered about was whether I could build a temperature sensor (or maybe the controller itself) into
the battery pack and connect to the rest of the charger with an external cable.

: I once saw a charger that plugs into your PC. It also measures capacity and can be used to match
: individual cells for making packs. Don't remember who it was but it was reasonably priced and a
: good place to start Given the low current draw of contemporary drives you should be able to take a
: few amps off the +12 supply.

Sounds interesting. I'll have to do some googling on this.

: ... It's in the 4 to 7 amp-hour range depending on the bulbs you have on. At high current draw you
: will not get full battery capacity. Look for a graph of battery output vs. discharge time.

: You also mentioned 1:40 round trip time. Does this mean it's 50 minutes each way? I used to use
: lead-acid gel cells and had a charger at work and one at home. I'm not a weight weenie, but it
: adds up fast with clothes, shoes, lunch, etc. A smaller pack keeps your cost down, too.

One thing I'd like to do is minimize how much I have to fiddle with the system once it's installed.
Ideally, I'd leave it attached to the bike for the whole winter, and just plug it in each night when
I get home. Weight and size aren't much of a concern, since I'd be attaching this to my rack.

- mark

 

[N2vx Jim]

Links for a couple kits.

http://www.hobbytron.net/R-DN-1.html
http://www.vectronics.com/vectronics/products.php?prodid=VEC-412K

For a power supply use your PC +12 line. I ran a 25 watt mobile radio (draws 7 amps) off a PC
running software for the radio with no problem. The case had extra cutouts for DB-9 connectors. Put
a female connector made by Molex in one of them.

I think that's about the cheapest setup you will find for a smart charger.

Jim

On 10 Oct 2003 12:43:59 -0600, Mark Vieselmeyer <[email protected]> wrote:

>Jim, N2VX <[email protected]> wrote:
>: On 8 Oct 2003 17:58:14 -0600, Mark Vieselmeyer <[email protected]> wrote:
>
>: A charger for something like won't be cheap. If you're really handy check the Maxim MAX-712 NiMh
>: charge controller chip. I made a charger using the MAX-713 (NiCad) and it worked OK.
>
>I'm always up for DIY projects. How complicated would this be? I can solder parts together, but
>generally my elctronics knowledge is more on the level of installing car stereos. One thing I'd
>wondered about was whether I could build a temperature sensor (or maybe the controller itself) into
>the battery pack and connect to the rest of the charger with an external cable.
>
>: I once saw a charger that plugs into your PC. It also measures capacity and can be used to match
>: individual cells for making packs. Don't remember who it was but it was reasonably priced and a
>: good place to start Given the low current draw of contemporary drives you should be able to take
>: a few amps off the +12 supply.
>
>Sounds interesting. I'll have to do some googling on this.
>
>: ... It's in the 4 to 7 amp-hour range depending on the bulbs you have on. At high current draw
>: you will not get full battery capacity. Look for a graph of battery output vs. discharge time.
>
>: You also mentioned 1:40 round trip time. Does this mean it's 50 minutes each way? I used to use
>: lead-acid gel cells and had a charger at work and one at home. I'm not a weight weenie, but it
>: adds up fast with clothes, shoes, lunch, etc. A smaller pack keeps your cost down, too.
>
>One thing I'd like to do is minimize how much I have to fiddle with the system once it's installed.
>Ideally, I'd leave it attached to the bike for the whole winter, and just plug it in each night
>when I get home. Weight and size aren't much of a concern, since I'd be attaching this to my rack.
>
>- mark

 

[B.C. Cletta]

Mark Vieselmeyer <[email protected]> wrote in message
news:<[email protected]>...
> I'm interested in building a new battery pack for my 6-volt Vistalite, mainly to increase the run
> time because I can't run both lights for my full round-trip commute, and even just on one light it
> starts to get dim. Also, I'm considering over volting to 7.2v.

most newer Vista are "overvolted", HOT bulbs.

> One option I'm interested in is using 13 amp hour F cell NiMH cells. My problem is I can't find
> the right NiMH smart charger for 6 or 7.2 volts. I found one for an RC car, but it specified a max
> of 2 amp hour battery pack. Also, there are lots of hand tool chargers that maybe I could adapt,
> but I don't know if that would work, e.g. would those also have limits on amp hours? I'm also
> wondering how the "smart" aspect would be affected. I believe most of these chargers use
> temperature change rather than current change to sense a full charge, so if I hooked up an
> external connection I don't see how it could sense the temperature.
>
> Another option maybe is to use ten D cells and a more readily available 12 volt charger. Is it
> possible to retrofit 12 volt bulbs to a VistaLite?

i've stuffed NR bulbs in a Vista head after removing the heat shield. the pot metal Vista heads
will get hot if you get too unreasonable.

> What about hooking up two 4.5 amp hour NiCd packs in parallel to get 9 amp hours? Nothing
> I've read has suggested that as a possibility, so I'm wondering if there's a reason why
> that's not done.

i'd be more inclined to run one then the other. consider getting a Willie Hunt LVR to protect both
the bulb & BP. <http://www.cs.indiana.edu/~willie/lvr.html> consider running 6 cells & not 5. 6
cells starts at 7.2-V and "ends" at 6-V so you'll have a constant uniform light. (5 cells will
start at 6-V and end at 5-V.) consider just bringing a wallwart to work and recharge there. i use
a DeWalt w/ my NiCads. i'm under the general impression that NiCad last many more charge cycles
than NiMH and can take much more abuse. if weight is not an issue (and rarely is on a commuter
sled), i'd use NiCads.

> The days are getting shorter, so any help is greatly appreciated!

...since June 23rd, what's taken you so long?
>
> - mark

the NiCad Lady has a great reputation and can set-up your BP: <http://nicdlady.com/

 

[Mark Vieselmeye]

B.C. Cletta <[email protected]> wrote:
: Mark Vieselmeyer <[email protected]> wrote in message
: news:<[email protected]>...

:> Another option maybe is to use ten D cells and a more readily available 12 volt charger. Is it
:> possible to retrofit 12 volt bulbs to a VistaLite?

: i've stuffed NR bulbs in a Vista head after removing the heat shield. the pot metal Vista heads
: will get hot if you get too unreasonable.

What's unreasonable? I'm thinking about going with two 20watt MR11 12volt bulbs (one wide angle and
one medium angle).

:> What about hooking up two 4.5 amp hour NiCd packs in parallel to get 9 amp hours? Nothing
:> I've read has suggested that as a possibility, so I'm wondering if there's a reason why
:> that's not done.

: i'd be more inclined to run one then the other. consider getting a Willie Hunt LVR to protect
: both the bulb & BP. <http://www.cs.indiana.edu/~willie/lvr.html>

That's an interesting possibility. If I'm reading that right, I could run 6 volt lights off a 12volt
4.5 amp hour battery pack and get increased runtime (it's not clear if it would be double or what).

: consider running 6 cells & not 5. 6 cells starts at 7.2-V and "ends" at 6-V so you'll have a
: constant uniform light. (5 cells will start at 6-V and end at 5-V.) consider just bringing a
: wallwart to work and recharge there. i use a DeWalt w/ my NiCads. i'm under the general
: impression that NiCad last many more charge cycles than NiMH and can take much more abuse. if
: weight is not an issue (and rarely is on a commuter sled), i'd use NiCads.

I tend to agree, but I've been looking at NiMH just so I can increas amp hours without having to
parallel connect the batteries. The voltage regulator approach probably solves that. On the other
hand, I'm really liking the idea of having those two twenty watt lights blazing away.

:> The days are getting shorter, so any help is greatly appreciated!

: ...since June 23rd, what's taken you so long?

Are you kidding? Most of the summer I don't wake up 'til the sun's blinding me through my eylids.

- mark

 

[B.C. Cletta]

Mark Vieselmeyer <[email protected]> wrote in message
news:<[email protected]>...
> B.C. Cletta <[email protected]> wrote:
> : Mark Vieselmeyer <[email protected]> wrote in message
> : news:<[email protected]>...
>
> :> Another option maybe is to use ten D cells and a more readily available 12 volt charger. Is it
> :> possible to retrofit 12 volt bulbs to a VistaLite?
>
> : i've stuffed NR bulbs in a Vista head after removing the heat shield. the pot metal Vista
> : heads will get hot if you get too unreasonable.
>
> What's unreasonable? I'm thinking about going with two 20watt MR11 12volt bulbs (one wide angle
> and one medium angle).

i felt that the 10-W bulb that came with it got the head too hot to the touch. if you have one,
give it a try.

> :> What about hooking up two 4.5 amp hour NiCd packs in parallel to get 9 amp hours? Nothing I've
> :> read has suggested that as a possibility, so I'm wondering if there's a reason why that's not
> :> done.
>
> : i'd be more inclined to run one then the other. consider getting a Willie Hunt LVR to protect
> : both the bulb & BP. <http://www.cs.indiana.edu/~willie/lvr.html>
>
> That's an interesting possibility. If I'm reading that right, I could run 6 volt lights off a
> 12volt 4.5 amp hour battery pack and get increased runtime (it's not clear if it would be double
> or what).

both NiCd & NiMH are considered discharged at about 1-V, you don't get much below that & the risk of
ruining the cells is too great. look up the discharge curves on the w-pg of the various battery
companies, Panasonic is one.

> : consider running 6 cells & not 5. 6 cells starts at 7.2-V and "ends" at 6-V so you'll have a
> : constant uniform light. (5 cells will start at 6-V and end at 5-V.) consider just bringing a
> : wallwart to work and recharge there. i use a DeWalt w/ my NiCads. i'm under the general
> : impression that NiCad last many more charge cycles than NiMH and can take much more abuse. if
> : weight is not an issue (and rarely is on a commuter sled), i'd use NiCads.
>
> I tend to agree, but I've been looking at NiMH just so I can increas amp hours without having to
> parallel connect the batteries. The voltage regulator approach probably solves that. On the other
> hand, I'm really liking the idea of having those two twenty watt lights blazing away.

"watt" is a unit of power, "lumen" is light. maybe you need one good lamp rather than two OK ones.
my old 'Bicycle Lighting Systems' used emergency lighting bulbs, 8-W/PAR 36(? it's been awhile, like
the ones you see in stairwells, the 6-V bulbs became difficult to find), and had more light than a
NR 20-W. the trade-off is bulb life. the NR is rated at 2000-hrs, i think the other was around
100-hrs. i'm using a NT Storm HID now.