Printing charging equipment

Very nice! I've been thinking about putting some of my old Geodimeter batteries into service for GPS use, but I'm reliant (for now) on the Geodimeter charger. I've never understood the multiple charging connections for each battery; why do they need more than two points of contact? Is there a monitoring circuit involved as well as a charge circuit?

More than likely you are looking at a battery that uses a third wire to get signal from a temperature probe. That is a method of determining when a NiMH is fully charged as it's temperature rises sharply. The R/C industry predominantly uses the curve at the top of the charge curve. A NiMH cell has a very flat curve top in comparison to NiCD and you need a very actuate charger to use this method.

Could be a full charge circuit and trickle circuit? or a charge circuit and a slow release circuit for battery optimization.

Jim, if you post a picture of the battery I can probably tell you as I am way too familiar with them. If the wire is in use, I am positive that it is a temperature probe as that was the only technology I can remember them using prior to the Trimble take over. If you are speaking of the big 7 amp NiCD batteries with two Hirosi ports then only two wires are used. I created a charge port on the side on mine years ago and do not charge through the ultra wimpy Hirosi ports. Memory says I was getting 14 amps from those converting to NiMH.

Regardless, my next project is going to be a fix for the broken tabs on these large batteries for hanging on the legs. Print a girdle or something. I will model the case to do that, any guess how rude that will be with the little one being $50? http://shpws.me/pUOc

Norm

I designed a girdle for the big Geodimeter batteries this morning. It is the 571-202-194 or 571 125 272 battery. These are nice cases when they do not have the tabs broken off. I did do a little designers license and add area to the back of the hookup area for easier wiring. It will still fit a stock case.

First the battery model, it came in at the shocking cost of $300 for a full print:excruciating: If someone actually wants one, I can easily cut a pattern into the sides making it an exoskeleton and easily cutting half or more of the cost. It is all about material used.

Those of you that have these batteries know that their crews well carry multiple batteries in a chain and break the tabs off. It is a shame to let these go to waste, so, hopefully this little design can add the tabs back onto them

Decided to add another cross brace. For $2 +/- it is worth it

I decided that I was placing to much moment on the supports for the hanger. They were both to the side and had no way of absorbing the twist. I dropped the anchors down on a 45° and had to move the hanger out to make room for the new braces. Since I already moved it out I placed in a new cross brace

It is not as cheap as I thought it would be ($40), but, I did very strong supports and I am very reticent to shrink them. I also gave it a lot of land area to meet up with the area where the stock case will be broken. I want a good meeting area, so, I am going to leave it. The supports are the same diameter as my gear knobs and you really have to squeeze to get any movement on them. I am thinking both of these designs are good to go for a test. I will sit on them for a week though

I have converted all my equipment to Lipo and charge them with
a Hi Tech X 4 charger which has four charging channels this is the fourth model airplane charger wore out the others . Charges any
chemistry under the sun.

I you are adverse to lipo there is LiFePo cells that are more rugged
Nimh is a crappy battery due to the charging algorithm used and 10 cell to
get 12 volts.
I use to order loose Lipo cells from battery space.com but have found the local
electric model car/plane shop has complete wired LiPo packs at less cost and
no shipping and good brands like thunder power

I just go to the local Hobby shop and buy 5000+ mah 11.4 volt LiPO packs in shrink wrap and then dip them in liquid polyurathane or silicon.

The biggest selection of lipo is at battery space dot com.

Go Lipo you will glad you did and ditch NiMh

Peter K

The hanger appears to be one piece, same with the case handle. How do you get a new hanger onto an old case?

OK, I will look at LiPo. As I said i do not know too much about it yet. Have there been fire hazards like li-ion?

Glad to see someone else using R/C tech!!!!

It is two pieces. In the digital world that means they mate so well they look like one, LOL. Here is an exploded pic with a really ugly color combination

I have not had or seen a Lipo fail to fire and I crashed my YAK 45 Carbon Z into the
ground bent the Lipo battery in half " no fire or Smoke" and destroyed the plane salvaged one wing.

I think there is more risk from a car fire than a LIPO battery.
Heck I plug my lipo cell phone in at the house all the time

Peter K

A sign of the times I guess. What local hobby store ... All the ones that I knew of are now gone. It does look like there is one in the biggest mall area in the State, man I hate shopping at Christmas, LOL

I hate running two chemistry's. I ran NiCD and NiMH together when NiMH came out and I have some good working NiMH now. I will probably do the old Tamiya connector is one chem and another connector is another thing, again. Thanks for the tip

Norm

From what I have read LiPo come in 3.7v packs, so, three is 11.1 and four is 14.4. Obviously, a four pack would leave a static charge higher than I would be comfortable with. I haven't played with LiPo, so, just guessing based upon what I know of NiCD and NiMH voltage levels would be 3 packs 13.7v and 4 packs 18.3 after a full charge on new cells. Most of the surveying equipment I have tested shuts down when the static level gets to 12.0v, GPS appears to go a few tenths lower. I don't know the curve shape on the LiPo battery to know how much life is between 12.0v and 13.7v of the stated capacity. Based upon percentage it would be 65%. I am going to build a LiPo as everything I have read says they are significantly lighter. Even if the usable amperage is even or less than NiMH, light weight is a huge factor. I have the ability to discharge at a specific rate to a given voltage and see the amperage used, so, being the way i am, I will test the usable level. Can't help being me ...

Are you speaking of LiFePo4 cells?

Lipo Peak voltage per cell 4.2
Nominal / average is 3.7
so you have 0.5 volts per cell to power your survey gadget this
0.5 volts is about 90.0 % of the lipo cell capacity anyways=good

Lipo weight wise are the way to go still today

The other chemistry Like LiFiPo are for car/bike aka racing at extreme battery outputs. nothing to do or could be used with survey type gear.
PLUS LIPO still beats LiFePo in the weight category...

Most about 99.9% of survey gear protects the battery by Shutting down itself
at 10.8 volts well you guessed it the minimum volts per Cell NICD and NIMH or lead acid in a large pack is 1.1 volts per cell at total discharge or something like that

10*1.1=11.0 if I remember right the shut down for crap NIMH or NICD
is (n+1)*1.0volts = something of that sort look it up

IE GPs/Robot are a bit of legacy to these old chemistry battery/cell volt levels that
linger today.

But 2.74-3.00 v cell is the lowest level from memory that lipo should be taken to
this is good for there little chance of LIPO cell damage due to low voltage cut off damage
and I have cell(packs) that are around 7 years +- due maybe to the 3.6 cut of voltage
but at 3.6 volts if you look at the discharge curve remaining capacity for LiPo the cell is 90% discharge +- anyways so that last 10 percent is a nice safety buffer to protect the
Cell pack

So in summary a 3 Cell LiPo is fine for 99.9 percent of survey gear that
shuts down at 10.8 volts due to legacy lead acid voltage protection

Peter K

Peter,

Where are you getting the 10.8 figure as my testing has shown shutdown, or rather inability to continue to use, well prior to that level?

I have read about the damage that can happen is the voltage is taken below an established level on LiPo. Sounds like almost complete right off if discharged. Three cells could never be close and four cells would be too close. Lots of good stats regarding LiPo, the reason I asked about LiFePo was that appears to be what the www.batteryspace.com carried. If those are the racing cells then yes I want the bulk working stuff. Must have been in the wrong area, maybe I was blind, but, I didn't see straight LiPo there. I will go back and look.

You are correct on the 11 volt minimum level for NiMH(CD), at least I think, as it matches what I remember. From my experience if your take either one of those chems there very often the life is really shortened.

So the minimum operating voltage will play heavily into the decision if or if not to use LiPo. Thankfully, that is an easy enough test to do.

Good info, thanks for sharing!!

Norm

Hello Norm

Yes Batterspace.com site could use some work... the single
Lipo cells are there they are a BIT of a search to find...
way to hard to find to be blunt.

My third charger/discharger a Orbit made in Germany "very thick aluminum"
as a shop test I would discharge a battery connected to the orbit and powering
a 12 volt lead acid/nimh/nicd survey device and the device "survey gadget" would
start to shut down at okay 10.8 - 11.0 volts.

the 10.8 volts is from specifications for large nimh/nicd ie 10 cell count
packs back in the good old days..

Best advice is to drive to the nearest electric airplane hobbies
shop and Get a TWO channel Hitec X2 the X4 has a built in power supply
which has a bit of a Noisy Fan so I power the Hitec X4 with a 12 volt
switching power supply from a computer shop.

Don't get overwhelmed by the huge selection of chargers but if the drive
is long Go Hitec 4 or 2 channel charger say goodbye to battery issues.

When your in the the hobbies shop don't get hooked get a nice electric RC plane
get a big basic model like a Eflite Apprentice big = easy to see

And the crash the plane I know it can take it...

Peter

I have a couple of friends with quadcopters and I keep thinking about them, ... which is bad. Very bad. Like any self respecting self charging guy, I have my own power supplies, so, I am good there. The Tekins for the most part had their own power supplies, but, after time they would hum and buzz and had to be placed far away from my desk.

When I did all of my voltage point tests, I used the appropriate battery until function would cease. I would them use a meter to sense battery level with no load. As I am sure you know, load changes the numbers a lot. You might be talking voltage at draw, I never tested that. I did test with several batteries and I remember getting results of 11.8 to 12.0 static battery level after shutdown. This was long enough ago that it had to all be Geodimeter equipment, prior to any Trimble.

You will appreciate this, my receptionist made me discharge batteries at her desk so she could heat her hands on the discharger. Dischargers have such a limited use anymore and they are superbly inefficient hand warmers.

Factory chargers suck don't they. I have received twice the useful life from both NiCD and NiMH cells using R/C chargers and they have more useful charge with very little memory issues.