[BarryE]

I've several Pentax batteries for K-1/K-3 cameras which I rotate.

Today my K-1 died with the mirror up (in MUP mode). Switching off/on made no difference. Pulling the battery, replacing it and switching the power back on reset the mirror and all was well. I suspect the battery might have been the cause. I tend to swap my batteries over when power display goes off full. I was a bit slow this time and I suspect this old battery was probably approaching one bar on the display. I rotate my batteries around my cameras. So I'd like to be able to measure their capacity without having to fire hundreds of test shots. Is their a way of metering the batteries condition?

Thanks

[jatrax]

I have a battery tester that works for AA & AAA but no idea how to test a L-i90. Curious if there is an answer as well. I have an assortment of L-i90s dating back to 2010 or so. Would be interesting to test them.

---------- Post added 10-01-20 at 01:07 PM ----------

Just found these:
Universal Battery Checker Tester with Leads LCD Display, Battery Capacity Voltage Resistance Tester for AAA AA C D 9V Digital 12V 3.7V Li-ion 18650 CR123A CR2032 Button Cell Batteries More - - amazon.com?tag=pentaxforums-20&

amazon.com : PRO Lithium Battery Tester : Digital Camera Batteries : Camera & Photo?tag=pentaxforums-20&

No idea if they will work though.......

[AstroDave]

If you have an accurate voltmeter available, you could use the battery discharge graph in this post of mine: Some Pentax D-LI90 Battery Charge/Discharge Measurements - PentaxForums.com and other relevant comments (particularly from C.A.M.; go look at his results, too) in that thread. If you don’t have a voltmeter (doesn’t everybody?! - I must have a dozen or so spread around the house!), go get one. You should be able to find something decent for $10-$20 at a local hardware store (cheaper than even most knock-off batteries).

Using the measured voltage, determine where on the discharge circuit your battery is. Then take the relevant time value from the graph and compare that to the end-of-useful-charge voltage (somewhere around 6.8 V) time (720 minutes). The ratio will tell you about what fraction of the battery charge you have used up.

For example, suppose you measure your battery at 7.1 V. The time value at that voltage is about 480 minutes.

The ratio 480/720 = 0.667 , indicating you have used about 2/3's of the batteries capacity.

If you normally get, say, 450 shots from a fully-charged battery, then you have about 150 shots left.

More simply, just measure the voltage, and if it is less than about 7 volts, it’s time to start thinking about charging it and/or changing to your back-up battery.

[BarryE]

If you have an accurate voltmeter available, you could use the battery discharge graph in this post of mine: Some Pentax D-LI90 Battery Charge/Discharge Measurements - PentaxForums.com and other relevant comments (particularly from C.A.M.; go look at his results, too) in that thread. If you don’t have a voltmeter (doesn’t everybody?! - I must have a dozen or so spread around the house!), go get one. You should be able to find something decent for $10-$20 at a local hardware store (cheaper than even most knock-off batteries).

Using the measured voltage, determine where on the discharge circuit your battery is. Then take the relevant time value from the graph and compare that to the end-of-useful-charge voltage (somewhere around 6.8 V) time (720 minutes). The ratio will tell you about what fraction of the battery charge you have used up.

For example, suppose you measure your battery at 7.1 V. The time value at that voltage is about 480 minutes.

The ratio 480/720 = 0.667 , indicating you have used about 2/3's of the batteries capacity.

If you normally get, say, 450 shots from a fully-charged battery, then you have about 150 shots left.

More simply, just measure the voltage, and if it is less than about 7 volts, it’s time to start thinking about charging it and/or changing to your back-up battery.

Many thanks. From a brief scan - can only be a brief scan as my wife's just reported we've a leaky roof - buckets out. Looks like I'm on the roof tomorrow. What fun :-( .

Are you saying that 7V for a fully charged battery suggests it needs replacing? I suppose this suggests the charger's circuitry will detect when a battery can take no more charge up to a maximum designed voltage. I was supposing an older cell would reach the 8.5V (approx), but drain quicker.

For ref, the three pins are +, - and a probe/detector pin? Yes/No? In what order?

Back to the buckets ...

[AstroDave]

Are you saying that 7V for a fully charged battery suggests it needs replacing? I suppose this suggests the charger's circuitry will detect when a battery can take no more charge up to a maximum designed voltage. I was supposing an older cell would reach the 8.5V (approx), but drain quicker.

No - I meant that when your battery reads ~7V, you need to charge it or put a different one in the camera. I suppose if the battery is indeed near the end of its useful life (i.e. it will no longer hold much, if any, charge), then it might just never charge up to anything approaching 8+ volts.

Yeah, I think the old/nearly no longer useful battery will drain quicker.

For ref, the three pins are +, - and a probe/detector pin? Yes/No? In what order?

Look at the contacts on the back of the battery (the flat side). There are + T - symbols in little circles (a bit hard to read unless you've got the light just so) in that order, with the + nearest the edge of the battery.

GOOD LUCK on the roof! bummer.

[Mooncatt]

So I'd like to be able to measure their capacity without having to fire hundreds of test shots. Is their a way of metering the batteries condition?

Thanks

Are you asking about knowing estimated capacity for a given instance (I.e. When the camera gauge shows 50%, is the battery really at 50%), or the overall health and total capacity of the battery (I.e. The mAh when full) as it ages?

For the former, a simple voltage meter will suffice.

For the latter, you'll need a load tester. To properly test the available capacity, you have to charge the battery to full. By "full," I mean until the charging circuit shuts off, not just when the light goes green. If you don't have a way to verify this, charge until the light is green plus an additional hour. Then you connect the tester, which applies a constant load on the battery and monitors the power consumed until it is drained. Something like this is what you would need.

PEMENOL DC Electronic Load Tester 35W 5A Adjustable Constant Current Aging Tester Discharger Voltage Current Power Battery Capacity Display with Cooling Fan LCD Display - - amazon.com?tag=pentaxforums-20&

That isn't a recommendation, just a random listing I found as an example. I personally don't bother load testing my batteries. If the device is shutting down well before the gauge shows empty, it's simply time to replace the battery.

[photoptimist]

What Mooncatt said!

One major issue with aging batteries is that their internal resistance increases with age and use. That means that even if the voltage of the battery seem decently high (as measured by a voltage meter or the camera's displayed battery bars), that voltage will plummet if the camera tries to draw a high current. The result can be a lock-up like you experienced or an unceremonious shut-down of the camera (and even the potential for loss of data or corruption of the memory card if the camera was writing data when the battery glitched).

Old, erratic batteries can be more trouble than they are worth.

P.S. It's also a good idea to clean the power contacts of the battery and camera -- grease and dirt add to the resistance and lower the available voltage when the camera demands high power.

P.P.S. Best wishes with the roof, too!

[photogem]

A simple and yet well working method:
- battery charged fully
- Pentax switched on, SD-Card with photos on it in, Auto-Power-Off: Off!
- Select to view one of the photos

- Leave it on and measure the time until it switches off (due to low battery).

Somebody I know measured with this method:
7 hours with his K5IIs and a 3 years original Pentax battery
6 hours with a burned in (recharged 3 x) brandnew no-name battery

[BarryE]

Lots of helpful advice buried in this thread. I have a multi-meter so this will help. I was surprised how much original Pentax batteries have increased in price. I thought they're were about £50, but it seems they are over £70.

I'll need to look in more detail when that 'other thing'is not pulling on my time. I've just put a new bucket out and the drip, drip is more insistent as it's falling on the plastic base. Can't ignore it now it's morning here in the UK ...

[jatrax]

I found this thread that has some interesting information: Some Pentax D-LI90 Battery Charge/Discharge Measurements - PentaxForums.com

[stevebrot]

By "full," I mean until the charging circuit shuts off, not just when the light goes green. If you don't have a way to verify this, charge until the light is green plus an additional hour.

With the Pentax-brand charger, the light goes from green to "out" and the charger shuts off. I believe my Wasabi quick charger behaves the same.


Steve

[stevebrot]

That means that even if the voltage of the battery seem decently high (as measured by a voltage meter or the camera's displayed battery bars), that voltage will plummet if the camera tries to draw a high current. The result can be a lock-up like you experienced or an unceremonious shut-down of the camera (and even the potential for loss of data or corruption of the memory card if the camera was writing data when the battery glitched).

This ^ ^ ^

When issues present that are likely power-related, best to retire the battery.


Steve

[Mooncatt]

With the Pentax-brand charger, the light goes from green to "out" and the charger shuts off. I believe my Wasabi quick charger behaves the same.


Steve

I don't recall how my Pentax OEM charger works, so I'll take your word on it. I have a Wasabi too, but it goes from orange (charging) to green (full).

[photogem]

Good Li-Ion battery-chargers (such as the orig. Pentax) use the delta-peak-detection. Just before the battery is fully charged, it's voltage falls slightly (about 5-10mV).
A good charger can measure this and switches off and thus protects the Li-Ion which shouldn't be charged all the time.

A Li-Ion battery ages quicker when low or high charged (beneath 30% capacity it is dead, when a cell has reached 3V, the internal resistance has risen and that can't be reversed). Because of this the protective circuit switches of when 3,5V are reached (we have that with Pentax). So the Li-Ion ages quicker when near those 3,5V and full.
That is why it is recommended to store them about half charged, they age the least in that state. Best for storing is 3,9V and a cool place.

Charging a Li-Ion when it has reached just 50% of its capacity also lets it age quicker, because it has a maximum of cycles it can be charged.
But charging more often does age less than storing the battery long when fully charged!

So best is to have 2 or 3 batteries and let them discharge by use until the camera warns and then recharge right away.

I don't use any non-Pentax batteries anymore. I have seen famous no-name batteries changing size and getting warm, no way that I have that danger in my house or in my cameras.

[Mooncatt]

Charging a Li-Ion when it has reached just 50% of its capacity also lets it age quicker, because it has a maximum of cycles it can be charged.
But charging more often does age less than storing the battery long when fully charged!

Li-ion batteries like a happy medium, and partial discharges/charges are better than full cycles.

How to Prolong Lithium-based Batteries - Battery University

From the article above:

"Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life. "

Their Table 2 is a chart that shows the cycle count increase as the depth of discharge is decreased. I maintain about 40-80% in my phones because it's a sealed battery, but not so much in the camera. When I'm on a shoot, the time between charges is more important so I'm not changing batteries as often, plus the chargers are rather gentle when it comes to charging them to full. I can buy new camera batteries and replace them easily when needed, not $150 plus shop time with a phone battery.