I’ve been thinking about getting something that would be able to test the capacity (at least current charge, but ideally, how much the battery can hold), mainly for Li-Ion batteries, but potentially also with NIMH.
I am not looking for a hobby charger-type setup.
I’m aware of the MBT-1, but it seems a bit expensive, and I’ve seen this:
“GT Power Lipo/Life/NiMH Battery Pack Controller Checker Capacity/Voltage Meter”
So I was wondering if anyone here has used that?
Also, it says “remaining capacity in your battery PACK”, and I’ve seen somewhere else where it said “2 or more batteries”, so I was wondering does it work to check the capacity for a single battery, rather than for a battery pack with multiple batteries in it.
Finally, it doesn’t look like it comes with any cables, but has a connector on the side, similar to hobby chargers, so, to use it to check a battery, would I need to purchase additional cables, harnesses, etc.?
Thanks,
Jim
P.S. If anyone knows of some other device that works well, and is relatively inexpensive, please post.
That doesn’t do a discharge test, which is the only reliable way to measure capacity. It uses cell voltage to estimate remaining charge, as a percentage only.
For the same price, you can get a full hobby charger/discharger like an iMaxB6, Accucel6, or similar. www.hobbyking.com sells a lot of different models for decent prices. Shipping in the US is reasonable too.
I know I said the MBT-1 was expensive, but how is that? Is it any good? I know that it only shows gross percentages, like 20, 40, etc., but is it at least grossly accurate (a contradiction in terms, I know)?
You can use a multimeter and member HKJ’s table to estimate remaining capacity.
A hobby charger will let you do a discharge test to find true capacity. A cell voltage measurement is just a estimate of remaining capacity.
I guess the thing with hobby chargers is a “mental” thing for me, when I’m looking for a “capacity tester”.
What I mean is that I HAVE a charger already, so I don’t need a charger, but everytime I look into “capacity tester”, “hobby charger” keeps coming up :).
Hi Jim,
It doesn’t do a discharge test so, to evaluate a particular cell’s storage capacity, I would not recommend it. To estimate the remaining capacity of a cell where the storage capacity is known, it does the job.
However, moderator007’s suggestion would work good too, since HKJ has done the heavy lifting and profiled the cells for us.
You have to discharge to find true capacity. A hobby charger does a discharge test revealing the capacity on the display. You can even set the current to do the discharge test at. Some batteries do well with low currents some are better for high currents.
OK, I also misunderstood what you wanted. When I hear capacity, I always think storage capacity, not remaining capacity. The reason for this line of thinking is simple.
I measure the storage capacity of every cell I purchase and keep a record of it. When putting cells in series, I only put same-brand cells with similar capacities and ages in the same light.
I have a very crude way of measuring remaining capacity. if I measure below 3.9V on a resting cell, it’s time to charge it. I don’t care how much that translates to in capacity, it’s somewhere in the middle, so I swap it out with a fresh cell. I have extras that are always charged and get rotated into lights.
I hope that helps, at least to understand why I pushed you towards a hobby charger.
Edit: I don’t charge much with my Accucel6; it’s a discharger only for me.
Wow, there are some huge differences within some rows, e.g., 3.7V? If I’m reading that chart correctly, if a battery measures 3.7V, it could be at 12, 52, or 50%, depending on which type of cell is in the battery? And oftentimes, you don’t know whose cell is being used?
If it was only a couple of % difference, then it might not be so bad, but between 12% to 52% seems a big difference.
Yes, it greatly depends on the cell you are using.
This voltage to capacity guide was what most people I know used before the newer cells became available and the chart was no longer valid as it depended on the cell used. This was the capacity guide with the cell measured at rest.
Voltage Capacity
4.2v………100%
4.1v……….87%
4.0v……….75%
3.9v……….55%
3.8v……….30%
3.5v…………0%
