Re-celling to LiPo

Norm, I was going to respond this Am and forgot.

Top notch work! I can see the attention to detail in your work. You should consider re-celling batteries for other surveyors...

There is a market for after market battery upgrades on some of the high end gold metal detectors. A few people are selling kits and they are very popular...and expensive.

I was just getting the old mothballed stuff up and useful. I actually never intended on coming up with my own battery system, but, I found it kind of fun. If you need a functioning Geod 600 or Trimble 5600 they are very awesome. The big battery would be an excellent choice for any instrument or GPS though. The little orange batteries have got to be hard to find at this point, but, I had a stack of them on the shelf. If I had to do it with the black radio batteries I would have used the 5 amp cells and it would weigh more and last forever with the pole battery in use.

3D printing charging adapters and cases was fun and I enjoyed it. That is the part I could get dragged into, re-celling is more like um,... work. I am still laughing at using a disc golf disc for the top of pole battery and not printing a top, but, it is a very pliable bumper and saves a few bucks.

I will certainly help anyone that has any questions to the best of my ability

To beat this to death, this is a link where I posted to add a regulator and a off / on switch after the PCB was already wired. https://surveyorconnect.com/index.php?mode=thread&id=270808. The only thing I do differently with larger batteries with a regulator is tape off everything around it and leave the regulator out in the open. Don't tape up the regulator is what I am saying, as you will create a heat related shutdown. Instrument or GPS current create noticeable heat in higher step up or step down situations

What is the cost of supplies? Thanks for posting! Jp

Old case sitting on shelf = $0
3 LiPo's 2.0 amp = $23.97
Old speaker wire = $0
PCB = $6.05
3S Smart charger = $24.95 (I don't have as many chargers as batteries, though)

Total = $54.97 plus some shipping

We have been getting 1.5 days out of these radio batteries running the radio and the 360° prism. I don't have the data yet on how long they last now that we are powering the 360° at the 360°. I know the 360° draw is around 175mA, so, I am guessing I will find out two things the crews day and a half is exaggerated slightly and my 175mA might be a little high. It does show very little draw from the radio and since they were first designed with 700mA batteries and went for days on them, I am guessing these will go forever. This particular battery is from a Geodimeter 4402 I think and it will work on the Geodimeter 600 series which of course is the same as a Trimble re-badge (5600)

Thanks! I have a robotic 5600 sitting in my garage that I don't use. I just knew when I went to use it I would have to spend 400$ on a new internal battery. And now not so much on the instrument radio batteries. Thanks, Jp

I have some worn out S6 batteries, so, I cracked them open to have a look.?ÿ They are six cells that are 3.7v, 2.2 amp, 18.3mm dia and 65mm long.?ÿ Basically they are 18650 cells.?ÿ I have some 3.0 amp 18650's from another project, but, they are button cells and do not have tabs.?ÿ You have to be very brave?ÿ(or stupid) to solder a tab onto a button cell.?ÿ I found some Samsung 18650's that are 2.6 amps that will fit, so, I guess that I am re-celling and not buying new.?ÿ As Trimble goes these batteries are not that bad at $150.00 retail as it will cost a little less than $50.00 to re-cell.?ÿ Their ratios are usually much worse than 3:1.

LiFePO4 are a good choice these days and should be safer than LiPo. I run some pre made external packs from Bioenno Power and see they do have cells too. You may be able to rebuild with these:

https://www.bioennopower.com/collections/lifepo4-lithium-iron-phosphate-cells

BE AWARE OF THE CHARGING REQUIREMENTS IF SWAPPING FROM OEM CHEMISTRY!!!!!!!!!!!

I have found that LiPo are safe, as we do not use them the way the RC industry does.?ÿ We don't routinely crash them or charge and discharge at very high rates.?ÿ With routine surveying use, I have packs that are right at three years old and no issues.?ÿ With that said, if I see a dropped / cracked pack, I take it apart to inspect.?ÿ Is LiPo as safe as LiFePO4, no they are not, I am not kidding myself.?ÿ It is a balancing act though, as LiFePO4 are heavy for the amperage they produce.?ÿ Take a current 18650 LiFePO4 cell and it is 3.2 volts, 1100mAh and 38 grams ( https://tinyurl.com/ycuw7th8), while a typical 18650 cell is 3.7 volts, 2600mAh and 47 grams ( https://tinyurl.com/ybbht6uv).?ÿ Higher amps examples of both exist, I took what were more moderate working cells for samples

Interesting fact became apparent during the re-cell of the S6 batteries.?ÿ Their PCB or protection board has a lower cut off set around 11.0 volts.?ÿ Basically they are li-ion cell being limited to NiCd lower levels.?ÿ A 3 cell li-ion should have a cut off around 9.0 volts so half of the voltage is wasted by design.?ÿ Did some voltage tests and out of four S6 batteries I got 2.4Ah, 2.5Ah, 2.7Ah and 2.7Ah out of cells labeled as 4.4Ah because of the 11.0 volt cut off.?ÿ The S6 batteries do not have the room to place a regulator to get the lost voltage, so, unless I printed a new case that could use flat cells and a normal PCB and a regulator, I am not going to get the lost voltage.?ÿ No way worth the effort when the batteries are $150.?ÿ My guess is that the instruments were designed around NiCd way back when and Trimble did not place a regulator inside the instrument to capture all of the energy.?ÿ More than likely there were some NiMh packs released early in the instrument life cycle and having a 9.0 volt cut off in the instrument would have caused definite issues by killing those un-regulated packs

But capacity remaining isn't linear to the indicated voltage.

By the time you discharge to around 3.6 volts per cell, you've used about 80% of the rated capacity. Multiple discharges below 3.6 will likely?ÿ shorten the overall battery life. Also, the voltage sorta falls off a cliff once you start getting below 3.6. Personally, I'll only take LiPos below 3.5-3.6 volts only in urgent situations, knowing I've probably spent one of the battery's nine lives.

Tom

I never said capacity remaining was linear, that's why I tested it.?ÿ For one thing voltage fall is greater in older used cells.?ÿ Regardless, I think you are missing my point.?ÿ 11.0 volts is just too high a cut off, I do agree with you on taking it down to 9.0 volts, but, there is a lot of amperage between 11.0 and 10.0 and then it usually falls very quickly to 9.0.?ÿ If you are saying it is detrimental to longevity to take them down to 10.0, then I don't agree with you.?ÿ At an 11 volt cut off you ARE limiting how much you get out of a battery li-ion or lipo battery as their base voltage is 11.1 volts.?ÿ

I just looked up the specs for the PCB's cut off voltage in the instrument batteries we have been using for years.?ÿ They are all 2.4v per cell which IMHO is way too low.?ÿ In every case the are routed to the instrument through a regulator stepping the voltage to 13.6.?ÿ The regulator is going to go through the voltage below 10 very quickly stepping it to 13.6, but, they work and have for more than three years used every work day.

Just replacing the pictures from the imgtree.net that seems to be gone now:

@norm-larson

Much obliged.

*right-click, save-as*