TrustFire charger with 3.7V 5000mAh Li-Ion batteries



I just received OpenROV #128 (woot) and with it came the TrustFire TR-006 multifunctional charger and 5000mAh batteries. The charger on the side has two settings, 3.0V and 4.2V, the instructions on the package call it a "transfer switch". Which setting do I use to charge the 3.7V 5000mAh batteries (TF26650) ?



you want to charge it on the 4.2v setting. The batteries are IMR cells (Lithium Maganese Nickel), and their chemistry calls for a charging cutoff voltage is 4.2v. the 3.0v cutoff setting is for charging LiFePO4 batteries.




Could these batteries be used with the openrov? I post in this thread because I did not want to start a new one!


Hi Joel.

I can't see why not...
They have the same form factor and have the added
bonus of having the ability to store more energy.



Hi Joel:

You can use pretty much any battery technology with OROV, as long as it provides between, say 8 and 15 volts. The vehicle is currently set up with two parallel packs of 3 size 26650 cells in series (this configuration is called 3S2P). Any generic LiCo or LiMn 26650 battery will provide about 11V to the ROV, and thus will work fine.


The reason we recommend the cells that we do is that they have a built-in protection module, that protects against over-current, under-voltage, and also over-voltage while charging. If you decide to use bare cells in your ROV, then you the user have to make sure that none of these conditions occur. Allowing the cells to over-discharge (under-voltage) will ruin the cells, and over-voltage during charging, or having a short-circuit in your wiring which causes an over-current, can lead to a ruptured battery or worse.

So, if you decide to use the cells that you linked, be cautious in all phases of the battery operation.

The TrustFire protected cells that we recommend are not a perfect solution- the protection modules will sometimes trip during hard driving, and the connection between the cell and the protection board is rather fragile- so if you drop the battery or flood the battery tube, you can end up ruining things. Here at OROV HQ we're starting to experiment with some other battery configurations that hopefully will be more rugged.

Hope this helps.



We have had a bad marriage with trustfire TR-006 and the UltraFIre 6000mah batteries that came with it. I ordered them about 6 months ago and we have had very few charge cycles <50. I really don't understand the charger characteristics and the failure rate of chargers and batteries has been very high. Out of the three chargers one is still working, and probably half of the 6 batteries will not take a charge. Maybe all my chargers are bad... not sure because the LED/ voltage seems somewhat random depending on which battery or slot is used. I uploaded an excel data file that shows a snapshot of where I stand today as I try to get at lease three working batteries to 4.2 volts. It has been a source of frustration and Algalita was not too impressed when I left them with two working chargers and 6 six batteries that seemed to work and after one use that came back with another dead charger and probably only three working batteries.

So....question. I need to get a good working battery/charger set for the July voyage that I can trust a little. I think Bestfire company who Amazon supplies through will replace the chargers for free but not sure on the batteries. The lead time are getting tight. Any ideas or explanations of what I am seeing on the excel sheet/



PS... It seems that we are doomed to keep the Li batteries alive or they go sour with low voltage discharge over time. I suppose all batteries are like this but i'm beginning to favor deep discharge batteries as a long term solution even if we give up on some of the battery life.

1453-BatteryChargerEvaluation.xls (20.5 KB)


I had a poor experience with TrustFire TR-006 charger and TrustFire batteries I bought from Amazon. I couldn't understand the behavior of the charger; whether I put in a discharged or a charged battery, the LEDs didn't change color. Sometimes the LEDs blinked, sometimes not. At one point I checked the voltage it was applying to the batteries: 4.9 V (way too high!).

I ended up replacing the charger with a NiteCore IntelliCharger i2 which so far seems to be working well.

I also returned the batteries to Amazon; see my thread about that experience here:


a good test for this charger



Hi Steve:

Thanks for the link- it’s an interesting review.

Around OpenROV we also use some Trustfire TR-008 chargers - they are 3-bay chargers, so they take up less plugs on the power strip, and they will also handle 32650 cells if you are building a bigger ROV. There’s a review for this charger as well: