LiPo and LiFePo batteries for use with voltage references??? - Page 1
Forum section: electronics / general

author: branadic
author_rank: Super Contributor
timestamp: June 01, 2022, 04:34:15 pm
content: Batteries of type NiMH and lead acid (VRLA, valve-regulated lead-acid) batteries are known to be used in voltage references, such as Wavetek/Fluke 7000 (NiMH) and Fluke 732A/B/C (lead acid). They work reliable, but come with drawbacks, limited time of operation and heavy weight. What about modern battery types, such as LiPo or LiFePo?I know there are several arguments against one or the other such as:1. Shipping restrictions, but not all of us live in a country with the only reasonable way to ship goodies by plane and ground shipping is still a valid method2. Flameability, here is where a good BMS comes into focusI already bought some parts to experiment myself:LiPo:HRB 4S 6000 mAh 14.8 V 50 CBMS:YH2204B, 4S 50A w/Balance 3.7V 18650 Lithium Battery Cell PCB BMS Protection BoardThe BMS is based on BM3451 3/4/5 Cell Battery Protectors. I had a bit of luck to find one of the chips not fully laser etched so I was able to identify the part number and found the datasheet.Hint: this BMS is equiped with a 51 kΩ resistor for the temperature setpoint and thus intended to be used with a 100 kΩ thermistor. In case you want to use a 10 kΩ resistor instead you have to relace the setpoint resistor to 5.1 kΩ.LiFePo:SLPOC3.2-6000 (Modell: 32700), Sunstone Power Industrial GmbH, 32700, 3.2 V 6000mAhBMS:Eremit LiFePO4 12V 10/30A safety circuit, balancedThe BMS is based on R5436T508BA by RICOH.Both ICs account for overcharge, overdischarge, charge overcurrent, discharge overcurrent, short circuit, temperature and feature a cell balancer.While I’m not planing to ship a reference with the LiPo pack, it can still extend time of operation for a voltage reference during transport from one place to another and can act as a low noise power supply for noise testing of references at home.Different story with LiFePo, which can be integral part of a voltage reference design intended to be shhipped for "lab" intercomparisons.But what is the experience within the community?-branadic-

author: james_s
author_rank: Super Contributor
timestamp: June 01, 2022, 04:39:42 pm
content: LiPo is a poor choice, at least the type you have chosen which is optimized for high current rapid discharge. Those will degrade rapidly when left fully charged and they are notorious for bursting into flame if they are overcharged or physically damaged.Good quality NiMH and lead acid batteries can last many years, aside from the weight I don't really see any great disadvantage to using them in these instruments.

author: tunk
author_rank: Super Contributor
timestamp: June 01, 2022, 04:57:27 pm
content: In addition to battery pack and BMS, I think you will need a charging circuit,i.e. CC/CV/cut-off. You may also want look into how much unbalance theBMSs can handle.

author: MK
author_rank: Regular Contributor
timestamp: June 01, 2022, 09:05:12 pm
content: With Lithium cells you do have to disconnect before the voltage drops too low or you can never charge them again. But for quite a lot of kit they could be quite useful.

author: thm_w
author_rank: Super Contributor
timestamp: June 02, 2022, 12:46:38 am
content: Quote from: MK on June 01, 2022, 09:05:12 pmOP specified the BMS they are using, and that it has overdischarge protection already.Quote from: james_s on June 01, 2022, 04:39:42 pmDecent lipo 3-10 years, and good quality LiFePo will last decades, more than lead-acid for sure.But I agree, OPs choice of an RC style battery isn't ideal. No reason to go cheap here and not use LG/Panasonic/Samsung at the very least.You can often find medical grade packs here, with built in BMS:https://batteryhookup.com/

author: MrYakimovYA
author_rank: Regular Contributor
timestamp: June 02, 2022, 01:00:28 am
content: Hi!I'm also interested in the issue. I have an additional question: what's about metrological things with the batteries? I mean an additional noise, for example. I don't work with LiPo and other types of batteries. So I don't know anything about using them in the precision measurement.

author: bdunham7
author_rank: Super Contributor
timestamp: June 02, 2022, 01:20:11 am
content: One issue that may or may not matter depending on the specific instrument and how much you will modify it is that lithium secondary batteries cannot be float charged and therefore would need to be switched in and out of the charging and power circuits as necessary. That's going to result in a blip in the power supply.Another issue is that having them sit in a warm enclosure at 100% charge is not a good life for them. You might want to consider a 'range' switch where they charge to about 3,9V normally on line power so there is some ability to ride out power outages and then a 'long-range' mode where they charge to 4.15V or so for maximum run-time for shipping.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: June 02, 2022, 01:59:24 am
content: what about those LTO ?those 2.4v crazy 10 year batteryhttps://www.aliexpress.com/item/1005003097552029.html?algo_pvid=2d8894d9-b5a0-49af-ac53-fd8112ca625a&algo_exp_id=2d8894d9-b5a0-49af-ac53-fd8112ca625a-2&pdp_ext_f=%7B%22sku_id%22%3A%2212000024068455003%22%7D&pdp_npi=2%40dis%21AUD%21%2143.22%21%21%21%21%21%402101d64d16541330428913168edab3%2112000024068455003%21sea