Current thoughts on 9V rechargeables

I realize not many, if any, lights use 9v batteries. That said, batteries are often a discussion point here and consider it fairly relevant to bring them up on this forum.

My question is what the community thinks of rechargeable 9v batteries at this point. I have some EBL 600mah which I use in multimeters, inferred thermometers, and a scale. I also use them in some of my smoke/CO alarms though not all in the event they fail. As a precaution I use alkalines in my bedroom and in one alarm downstairs. I have been using them for about a year though and haven't had any failures or issues in smoke alarms or any of my gadgets.

The EBL's seem well reviewed on amazon, and have not given me any issues. I've read they are two Lipo batteries soldered together and come out at 8.4v charged, which hasn't been a problem for me so far, though it would be nice to see a true 9v with high capacity. I find them surprisingly light compared to my other batteries.

I have not measured capacity as I don't know how.

A concern of mine is the charger, as I use the 2 slot one that came with them and it gives off a burning smell while charging that seems to be permanently imprinted now. I only charge them during the day and keep them right next to me, and haven't had any issues regardless of the smell. It seems they have a line of different chargers now and am interested in getting a higher quality one, safety first and all.

Anyone know of good aftermarket 9v chargers or are we kinda forced into EBL's? From what I can tell the major competitors with EBL and Tenergy and perhaps Maha, though none of those are as well reviewed.

I would like to see some high quality reviews for either of these, but unfortunately can't find any nor know if they exist at this point.

Sorry about the missing EBL review, but I have not been able to get any.

You can find all my 9V reviews here: http://lygte-info.dk/review/batteries9V/Common9Vcomparator.php

I have some 9V too, let's call them packs. I use them in multimeters and infrared termometers. Because of that low current requirements, its more important for them to be LSD.
At least for me they last at least 6 months, even one year, so performance and charge/discharge cycles does not count that much, i guess they self-discharge as much as the energy consumed from them.
I use to charge them with hobby chargers, which can go as low as 100mA and programmable minus delta V. Anyway, the minimum 100mA is close to 1C for most of them, not much choice about that.

As I mentioned before, I have over 15 EBL 2S Li-ion 9V 600mAh batteries that have been working splendidly for a couple years. I too use them in multimeters, smoke alarms, etc. For further discussion see here and see here.

Just as for cyclindricals, once you switch to Li-ion you will never look back to inferior chemistries such as NiMh.

Do not use cheap hybrid Nimh+Li-ion 9V chargers that rely on Li-ion batteries OVP termination to terminate the charge. Besides greatly degrading life and exacerbating imbalance, they can also fry the protection circuit since some supply up to 12V after protection trips (this problem is described in a review iirc). Instead you should use a true 2S CC/CV Li-ion charger, e.g. a hobby charger. It is possible that one of the Opus or Soshine 9V chargers may be a true 2S Li-ion charger, but they have not been tested by anyone yet as far as I know (a major omission imho).

Beware also that a small number of EBLs arrived unbalanced from the factory, and you have to open them to balance them to achieve the rated 600mAh capacity (which is accurate - not exaggerated). You can easily recognize when they are unbalanced because they will charge to (much) less than 8.4V.

In summary, they are great if you know what you are doing, but probably not yet a good choice for novices or those who want mindless plug-n-play solutions (at least until a good charger is available and tested).

How do you open & balance them?

To open use a utility knife to carefully score and break the glue seal around the top, then carefully slide out the pack as in the photo below. Don't pry too hard on the top portion since it is connected to the pcb only by tabs. Once the PCB is exposed use that to pull out the pack.

Then with the exposed tabs you can use a normal 3.7V (1S) Li-ion charger to recharge the low cell to match the voltage of the high cell. It is best to do this when the higher voltage cell is fully charged (i.e. top-balance), which it will be if you just charged the pack. Finally push the pack back into the case (and add a little glue/tape if desired). It's quite easy to do (but rarely necessary).

Thank you very much for that.
I use the soshine v2 charger for mine ,they charge to 8.4v according to the charger but with testing with a multimeter some drop to 8.35v ,is this normal or do they need balancing ?

The charger usually put in somewhere about 580mah

It's hard to say without knowing more about the charger. If they are unbalanced enough the charge will be terminated by the HYCON HY2120-CB 4.28V OVP (OverVoltage Protection) tripping, and if at that time the lower cell is below 4.12V then the pack voltage will be less then 8.40V when the protection trips (so the charger may have not entered CV phase, so it will not yield a full charge). You can infer how much they are unbalanced from the pack voltage when the protection prematurely terminates the charge, e.g. if it terminates at 8.20V then the lower cell was only charged to 8.20 - 4.28 = 3.92V, so the cells are 0.36V unbalanced. The unbalance will get bigger as time goes on since the high cell is continually being overcharged (to 4.28V) so it will degrade faster than the lower cell (which will eventually lead to nontrivial capacity differences between the cells if they are never rebalanced).

dupe - ignore

Thanks,
I'll try and balance one battery & see if it differs from the others.
The charger is soshine H2 ,v2.

Your batteries don't need balancing if they're charging up to 8.40V.

Thanks gauss, I think these EBL battery's are very good ,I tested them against some Duracell 9v battery's & they lasted about 3 times longer.
I wired three 12 v computer fans together & ran them with each battery until the EBL's tripped at 6 v & the Duracell stop working.
I paid £15 for 6 EBL's from eBay , I think I got lucky because they're now about £30.

The price does seem to have gone up a bit, but you can still get the EBLs cheap on the USA eBay site, about $3 each in quantity (about $0.50 more than I paid a couple years ago). That's still a steal considering that other unscrupulous companies are charging more that 10 times that for similar batteries with no apparent advantages.

Gauss163 said:

As I mentioned before, I have over 15 EBL 2S Li-ion 9V 600mAh batteries that have been working splendidly for a couple years. I too use them in multimeters, smoke alarms, etc. For further discussion see here and see here.

Just as for cyclindricals, once you switch to Li-ion you will never look back to inferior chemistries such as NiMh.

Do not use cheap hybrid Nimh+Li-ion 9V chargers that rely on Li-ion batteries OVP termination to terminate the charge. Besides greatly degrading life and exacerbating imbalance, they can also fry the protection circuit since some supply up to 12V after protection trips (this problem is described in a review iirc). Instead you should use a true 2S CC/CV Li-ion charger, e.g. a hobby charger. It is possible that one of the Opus or Soshine 9V chargers may be a true 2S Li-ion charger, but they have not been tested by anyone yet as far as I know (a major omission imho).

Beware also that a small number of EBLs arrived unbalanced from the factory, and you have to open them to balance them to achieve the rated 600mAh capacity (which is accurate - not exaggerated). You can easily recognize when they are unbalanced because they will charge to (much) less than 8.4V.

In summary, they are great if you know what you are doing, but probably not yet a good choice for novices or those who want mindless plug-n-play solutions (at least until a good charger is available and tested).

Click to expand...

You wouldn't trust something like this? They claim cccv. I am using it now and find it charges them only to 8.3v while the little white ones that comes with them charge to 8.4-8.5.

https://www.amazon.com/gp/product/B00RL7E2MC/?tag=cpf0b6-20

And certainly not the one here then?

https://www.amazon.com/gp/product/B00EQ3U2AA/?tag=cpf0b6-20

What voltage have you found unbalanced cells to be at? I've got a new one that I can't get above 8.3v even on the charger that brings them up to 8.4-8.5.

The 2 and 4 cell EBL NiMh+Li-ion chargers are widely said to be crap, but I don't know about the circular 8-slot unit. The 2 slot Soshine charger is also reported to fry Li-ions, e.g. see this youtube review (and see Soshine's reply there). Until we have competent comprehensive tests of these chargers it's difficult to discern the truth from random scattered snippets on the web.

I suggested to HKJ that these would be very useful reviews, but I don't know if he plans to test them. Pehaps more folks need to submit requests before he will consider pushing them onto his queue.