battery replacement for SOLA 1200

[fmerkel]

That's my thinking. The indicator (green to yellow to red to blinking red) is just some electronic circuit, as is the "it's dead, jim" light turn off function. What I did was re-calibrate the electronics, but if it restores the 'time on' that's all I want. I'm pretty sure the important part was taking the light down as much as possible before charging it.

Eventually it won't work and new batteries will be needed, but this did extend the working time.

Agree. If it's already dying, or appearing to be well down that path, you don't have a lot to lose.
Normally that kind of charge/discharge to end points works OK for NiMh, and just takes some life out of the lithium battery.

I have seen a couple of Li-on packs 'go bad'. When I pulled them apart the individual cells were good. The protection circuit was doing it's job but the cells had gotten WAY out of balance. The PCB was stopping the pack when the strongest cell got charged, and the weakest cell got discharged. This effectively crippled the pack.

PCB circuits generally DO NOT balance, they merely limit. There are higher end PCB circuits that limit and balance but I've never seen one in field use. They are much more expensive. (I think quality Li-on tools do use this arrangement).

I have a 2S2P (2 series, 2 parallel) Li-on canister light and I make packs with balance plugs, no PCB. If you know how to take care of Li-on it's a much better arrangement. I always know exactly what each cell is doing and it never gets out of balance with a balance charger.

 

[psychomatrician]

Sola offered to replace my battery and service the unit for $150.

Thanks Sunnyboy for the burn test idea. Doing it right now. (Why didn't I think of that?)

The battery pack for the Sola from England from above is about $85 (if they are still using Euro's?)..So maybe in the $100 range including shipping and you have to do the install yourself; whereas it's $150 from Sola and they do other servicing (and take the responsibility for doing it correctly).

Here is precisely what they said: "The service cost for a Sola 1200 dive is $150 which includes a new battery, circuit board, updated firmware, and new O-rings." I'll probably go that route if the burn test goes south but so far, so good!

 

[fmerkel]

Trying that burn test myself.
Did you gather any data? So far for 2 cycles I got total 62" for the first, 67" for the second.
Maybe most important is the high burn: 35" first try, 45" second try. Minor improvement.
So far, not working all that well for me. I'm at 64% of claimed specs. Most of the time use at at lowest setting as a focus light so this is not critical yet, but it's a trend.

I did get it 2nd hand in a camera rig purchase from here so don't know much about it's working history.

 

[sunnyboy]

Did you gather any data?

Not really. This was over a year ago, and I was just getting very frustrated at how quickly the light was going from green to 'really flashing red' on a dive (like within 15min). I did the burn test / charge cycle I think 3 times total. It did make a significant difference to how soon the light went from green to red on subsequent dives.

I've owned since new, from Nov 2011. I tend to use it in spot mode, power 2 (2 leds on), and use it as a primary dive light. It's on my camera, but then my camera is in front of me most of the dive. When I want to take a photo or video I switch to flood mode, power 1 or 2 leds showing. I almost never use high power as it washes out the photo or video. I use the light as focus/backfill in photos.

Based on that, I can easily get a 72 min dive out of the light with it blinking red by the end. On longer dives it lasts 90min OK, but has shut off near the end of 2hr dives. I do find when it shuts off you can turn it on again if you wait maybe 10 sec and go for low power.

I also charge the light as soon as I get home, and then leave it unplugged. Just before the next dive I plug it in to verify it's fully charged then go diving.

 

[psychomatrician]

Trying that burn test myself.
Did you gather any data? So far for 2 cycles I got total 62" for the first, 67" for the second.
Maybe most important is the high burn: 35" first try, 45" second try. Minor improvement.
So far, not working all that well for me. I'm at 64% of claimed specs. Most of the time use at at lowest setting as a focus light so this is not critical yet, but it's a trend.

I did get it 2nd hand in a camera rig purchase from here so don't know much about it's working history.

(1) At the highest flood level I get 45 minutes, then immediately 20" at power level 2 and 20" more at power level 3. I did this twice so I think this is a consistent result.

(2) I did a third test at flood level 2 and got 75 minutes and then immediately got about 2 more hours out of the spot (lowest level I think).

Don't know if that helps... I asked if Sola would recommend a rebuild after 4 years and whether they would be more concerned with the battery degradation or with possible flooding due to not replacing the O-rings. No reply yet.

 

[fmerkel]

I'm charging up for test #3.

Based on all the experience I've gained working with rechargeable lithium chemistry for ~10 years I'd recommend not fully charging the light and letting it sit unless you are going to use it within 24 hours. Since there is no good way to determine the exact level of charge I think charging it until it's blinking in the [orange] color range would be about mid-charge. Based on Sola instructions there must be some kind of low parasitic drain, so I'd check that monthly if not being used for awhile.

The 2nd fastest way to degrade a lithium cell is storage at full charge, especially in a warm environment, the warmer the worse. I store my 18650's at 50% charge, in zip-locs in the fridge.
(I'm actually doing a freezer test, which is not recommended. So far, 2 monthly cycles, I've found no damage or degradation. But that could change.).

What happens with storage at full charge (and just plain age and use) is the internal resistance goes up, which compromises it's ability to sustain amp draw. The actual capacity might still be almost within spec but only if used at a very low amp draw. The Sola obviously pulls some amps on high.
The ability to support the amp draw shows up as you go from high>med>low. The cut-off is the same, but with less demand the voltage can stay up above the cut-off until the level being used cannot support that demand anymore and the voltage drops.

The fastest way to ruin cells is over discharge. The lower you go below ~3.0v, the worse. Below 2.0v permanent damage starts to accrue, actual changes in the cell chemistry with breakdown.
The Sola obviously has a protection circuit and cut-off to prevent that. No telling how low or how accurate that is. I would also suspect it does not balance the cells. If the cells get out of balance, the PCB circuit is only as good as the weakest cell.

 

[fmerkel]

Did test #3 and 4:
#3: 3-50" - 2-15" - 1-5": Total - 70"
#4: 3-52" - 2- 15" - 1-9"; Total - 76"

Seems I worked my way up from 62" total to 76" total.
Of maybe more interest is that the high beam went from 35" to 52", a decent improvement. Diminishing returns at this point so time to quit I think.

Appreciate finding this new technique out. From what I've previously learned it should not have worked. Obviously some other factors at play which I strongly suspect is circuitry, the drivers and protection.

 

[psychomatrician]

Aside from battery degradation the other concern Sola mentioned is O-ring deterioration and potential flooding. The good news is that if it floods for the same $150 service fee for a new battery and updated circuitry they will completely restore a flooded unit. Given that I might squeeze another year out of my 4-year-old Sola 1200.

 

[fmerkel]

I opened up my unit to see what was inside. The setup is clean and the light as a whole seems well put together. Cells are LG LGDAS31865 2200mA 18650 attached to a PCB circuit. The cells are OK but for an expensive top end light I think we are getting short changed by not having a similarly top end Panasonic, Sanyo, or Samsung 3400mA in there. The cost difference for L&M would maybe be $4-6. I've ordered a couple Sanyo NCR18650GA 3500mAh 10A Flat Top Battery for a whole $12.

Test/Review of LG 18650 S3 2200mAh (Blue)

I ran the individual cells through my Liitokala 500 analyzing charger. They are well matched still @ about 2050mA (~93% of new) with a 350mA draw, which is WAY less than the circuit pulls on high (~2A), but I don't have any way to test that. It's got skinny little wires with a tiny semi-proprietary plug.
I also tested the internal resistance with an Opus analyzing charger and got 110, not a great number on a 18650, but certainly not terrible. The time of ~50" on high with a fresh charge is consistent with these findings. I don't know if the cells were out of balance as all I could test was individual voltage when I pulled them out and that's a pretty rough indicator.

 

[fmerkel]

Both batteries charged I thought I'd do a discharge test from batteries individually charged from a known good charger. Putting it back together is a bit fiddly, getting all the parts in the right place. Once assembled I put it on the Sola charger. I got the green blinking lights indicating near full. 15 minutes later it was still doing that so I stopped it anxious that it might be over charging. Turned out not, at least at this point, but with just blinking lights you really don't know quite what it's doing.

So put it back together again. This time I got all red blinking lights like it was near empty. What was going on? Opened it up again but couldn't find an obvious problem. Back together I decided to do a burn test. It did 55" on high, 3 red lights blinking the whole time., right from the start. So I didn't make any battery capacity progress. Not sure what to do about the blinking red lights. It's on the Sola charger now to see if it will straighten itself out.

Addendum: After ~3 hours charging the green lights came on and it finished. Now when I turn it on I get green indicator lights like I should. Doing another discharge test now on high. At 15" the 3 green lights all went red but still going. Same at 30". Died at 46" on high.

Charge follow up: Took 2 hours 10 minutes to charge on the Sola charger. Pulled the battery and tested the individual cells, both were 4.04v. If you go with Li-on voltage charts that's about 85% of full. In the long haul it's better for the batteries, especially for the folks that tend to charge after the dive and leave it that way. For an immediate dive you are losing some 10-15% of your burn time.