Question about battery/breaker issues

[Jofaur86]

For your information, in electricity, for the same appliance, if you use a device of a certain power at 12 volts, it will consume a high current, but if you operate it at a higher voltage, 36 volts (for example), you will consume less current (amperes).

[tankme]

I was thinking about this further and I'm wondering, how are you charging this battery? Charging an SLA is a lot different than charging a lithium based battery. Did they supply a charger or are you using your own? I guess if it were me I would be cutting that blue cover off to see what's underneath... It can always be taped back together if it's multiple batteries under there. I know it's not going to be pretty, but batteries aren't cheap these days. I usually prefer not to blow them up while charging them. Usually....

[Jofaur86]

That's what I suggested in one of my previous messages, because we're going around in circles here... but Tankme is absolutely right... open that blue thingy box so we can determine exactly what's underneath? Even though I remain convinced it's lithium-ion, because for lead-acid? Is there some new technology I'm unaware of? Furthermore, in some countries (except certainly China?) lead-acid batteries are banned, and in any case, they're obsolete due to their very high discharge rate. And wouldn't a 36-volt, 15 Ah battery fit in your car?
And following up on Tankme's question: what type of charger do you use, what voltage and charging current do you apply, and what type of battery are you using? It seems, based on your explanation, that this method is working well, since you're getting 40 volts at the end of the charge and haven't exploded yet. It's also important to know that this type of battery (certainly a low-cost one) will never perform as well as a better, more expensive, and higher-quality battery. I've seen this with older NiMH batteries advertised as 2000 mAh that barely reached 1600 mAh, and with a charger that was only a charger in name

[Jib]

Well, I am sorry for dragging this out.

If I wasn’t an absolute dumb dumb I would've looked at the special charger they sent with it a year ago. I use this to charge the battery every time, but never thought to actually look at it.

In my defense, it was all in Chinese, but that took Google Translate all of 1 second to solve…

So, the charger indicates it is for a 36v Li-ion battery, charging at 42V @ 5A

My bad. Mystery solved. At least I didn’t go through the work of digging it out of the model and stress of cutting into it before looking at the charger…

[tankme]

So now that we can say definitively that the battery is Li-Ion, Li-Ion is not known for it's high discharge rates like Li-Po batteries can provide. It may be possible that under high load it draws more current than the battery can provide. Removing the cover of the battery would still reveal the BMS if present. Knowing the model of the BMS might also shed some light into how much current it can provide as it would further limit the actual output current of the battery. I like Li-Ion over Li-Po batteries as they tend to be a little more fire resistant when the Li-Ion battery is in a hard cell format. You might want to consider a small amp meter connected right after the main breaker to see how many amps the whole system is consuming. Maybe something like this: https://www.amazon.com/DROK-4-5-100V-Vo ... 9hdGY&th=1

[Jib]

So it has a voltmeter built in, but this would be nicer. I may look into replacing it with one of these in the future.

I’m still pretty hesitant to cut into the wrapping unless I really have to. I’m kind of over troubleshooting the electronics, I want to get to work on the exterior. I can work with, when the voltage drops below 38v it’s time to bring it home. I got plenty of use out of it the other day, went from 40.2 to 39.4 in about 30-45 minutes.

One last question, there seems to be a lot of debate on charging Li-ions, I’ve seen just charging to 100% all the time and wear and tear is negligible, other say charge to 80% to lessen wear and tear. What has been your experience? I know getting the battery to charge that last little bit takes a lot longer than charging to 39v.

Also keeping a storage charge around 3.75v per cell would be 37.5V over all, which is where my model starts pooping out on me. Would you all still recommend this? Or is it not a big deal if I’m running it every week or every other week?

[tankme]

I haven't really had any issues just keeping my Li-Ion batteries topped off, but mine are all less that 24V with most of them being 12V or 7.4V for my 1/16 scale tanks. They also hold a charge for a long period time unlike the older NiMh or NiCD batteries.