Test discharging/charging my AntiGravity ATZ-10 Lithium motorcycle battery. - Page 1
Forum section: electronics / projects

author: djsb
author_rank: Super Contributor
timestamp: August 11, 2024, 11:49:10 am
content: I have a new Antigravity™ ATZ-10 (12.8V 12 Amp Hours (PbEq)/ 6.1Ah (Actual)/ 78Wh) Lifepo4 Lithium battery. I want to test discharge it and then carefully charge it. I have NOT tried it on the actual motorcycle (a Royal Enfield™ Himalayan 411 2021) yet.This link describes how to charge/discharge a lithium battery with a 4 stage process (stage 1 constant current, stage 2 constant voltage, stage 3 charge ends, stage 4 topping charge)https://www.power-sonic.com/blog/how-to-charge-lithium-iron-phosphate-lifepo4-batteries/I am going to DISCHARGE the battery first using a TENMA™ 72-13210 DC Electronic Load, 300 W, Programmable, 0 V, 120 V, 30 A. It has a constant resistance, constant current and constant voltage mode. I would like some guidance on at what rate and over what period of time should I firstly DISCHARGE this battery and to what level of charge to avoid any damage to it. Also, after discharge, does there need to be a refractory/rest period before recharge?I will do the recharge later on in this topic. Does the Tenma have an ability to RECORD or send data via a serial port/Ethernet connection? Maybe I should RTFM? Any advice welcome. Thanks.PS What does the term "12 Amp Hours (PbEq)/ 6.1Ah (Actual)/ 78Wh" that I copied from their website actually mean?Link to topic on communication with the Tenmahttps://www.element14.com/community/thread/64903/l/need-windows-usb-driver-for-tenma-72-13210-electronic-dc-load-30a120v-300w

author: SteveThackery
author_rank: Super Contributor
timestamp: August 11, 2024, 05:00:55 pm
content: I'm afraid I can't help with your questions, but I just want to make an observation. I very much doubt that you need any kind of multi-stage charging system, because that battery is designed to operate in a motorcycle. Modern motorcycles employ a simple rectifier/regulator, which basically acts as a current-limited constant voltage supply. I expect there will be an appropriate battery management chip inside the battery, although I've never dismantled one to find out. In my experience the regulator is set to around 14.4V, sometimes a little higher.The page you linked to does suggest that a current-limited constant voltage supply should be fine (despite describing a more complex method), so maybe a battery management system (BMS) inside the battery isn't needed after all.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 11, 2024, 05:20:29 pm
content: Quote from: djsb on August 11, 2024, 11:49:10 amThe recommended Ah capacity of LiFePO4 motorcycle batteries is typically around half that of the standard lead acid battery. You can believe that it is actually 6.1Ah. The questionable part is claiming "equivalence" to a 12Ah lead acid battery. What parameters, exactly, are we talking about?I'm pretty sure the answer will be in the cold starting amps; a 6.1Ah LiFePO4 will meet whatever cold start test a 12Ah lead acid battery will meet.I want to point out that no motorcycle actually needs 12 amp-hours. There is nothing on a motorcycle that needs to draw 1 amp for 12 hours, or 100mA for 120 hours. Rather, in order to meet the cold starting current tests, a lead-acid battery sized for 12Ah is typically required. The amp-hour capacity is just a side effect of sizing a lead acid battery to meet the current delivery tests.Starting a motorcycle uses a small fraction of one amp-hour (work it out: 150 amps (say) for 5 seconds (say)). So it doesn't matter at all that the lithium battery is only 6.1Ah. There's enough capacity for dozens of cold starts.There is one advantage to a larger capacity battery (ie in sticking to lead acid). Most modern motorcycles have a small residual current drain on the battery, typically for the clock and any anti-theft electronics. That is often enough to flatten the battery over a winter lay-up. Your 6.1Ah battery will go flat in half the time. That might be important, but in reality any motorcycle layed up for winter ought to be connected to a charger regardless of whether the battery is lead-acid or lithium.

author: djsb
author_rank: Super Contributor
timestamp: August 11, 2024, 05:25:16 pm
content: You're right, it has a simple regulator/rectifier. Not sure if it works properly, though. And the battery is claimed to have a built-in BMS. I'd rather see for myself at close quarters how the battery behaves, rather than assume everything is set up to work together.I also don't know if my optimate dual lithium/lead acid charger can charge the battery as well as maintain it on a trickle charge.I have also asked about the battery on the forums and there does not seem to be much enthusiasm for the battery (mainly because of the cost I suspect).

author: SteveThackery
author_rank: Super Contributor
timestamp: August 11, 2024, 05:42:02 pm
content: Quote from: djsb on August 11, 2024, 05:25:16 pmNot sure if it works properly? In that case you shouldn't connect either type of battery to it until you know for sure.Quote from: djsb on August 11, 2024, 05:25:16 pmOK, understood.Quote from: djsb on August 11, 2024, 05:25:16 pmUnderstood, although you might end up "fighting" the internal BMS if it's expecting a constant voltage supply. Even so, you might learn something.Quote from: djsb on August 11, 2024, 05:25:16 pmNo, me neither. Could you ask Optimate?Quote from: djsb on August 11, 2024, 05:25:16 pmHaving used LiFePO4 batteries myself, I agree. Both types of battery are fit-and-forget. Both start your bike reliably. Both need a top-up over the winter lay-up. So why pay twice as much for something that does the very same job? You could say you get a kilogram or so of weight saving. But be real - your weight probably varies that much day-to-day anyway. There is another downside to a LiFePO4 battery: it is half the size of the lead-acid battery, so you need to mess about putting packing into the battery enclosure to ensure it doesn't bounce around in there. Not a big deal, but still something you need to think about.

author: djsb
author_rank: Super Contributor
timestamp: August 11, 2024, 09:22:17 pm
content: Thank you for your comments. This battery actually physically fits very well, so that's a non issue. I would still like some guidance on how to SAFELY (to prevent any degradation to the battery) this battery in a controlled manner. I can then monitor the discharge on the electronic load. That is the first task I have set myself. Could someone please help me with this? Thanks.PS Is it better to discharge the battery at 0.5 amps for 6 hours to 50% charge or can it be discharged a little more. In theory, it should be able to be discharged at a rate of 1 Amp for 6 hours. Or is it not as simple as that.

author: BrokenYugo
author_rank: Super Contributor
timestamp: August 11, 2024, 09:58:35 pm
content: See the battery's datasheet for max continuous discharge currents, or treat it like a SLA since that's sort of the whole point of the product.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 12, 2024, 12:04:13 am
content: By the way, you haven't said why you want to discharge and recharge it. What is the purpose?

author: djsb
author_rank: Super Contributor
timestamp: August 12, 2024, 05:04:18 am
content: 1/ I need to partially discharge it BEFORE I can recharge it. Easier to measure the discharge rate on the bench than on the actual bike.2/ I want to make use of the Tenma DC load. It's a nice piece of equipment.3/ I'm curious as to how stable the voltage is over a period of time when it's new.4/ I will then have some data/experience I can share on the motorcycle forum and some evidence in case of a dispute with the manufacturer.5/ Shits and giggles.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 12, 2024, 10:03:13 am
content: Hmmm... nothing important, then.