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gwindhurst
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# Posted: 3 Aug 2025 09:26am
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Just received a Humsienk 12v 314Ah Mini BT ($339 AMZ), and Form Industries 12v 30a charger. As far as I can tell, the battery and charger performed as they should. The battery reached 100% at 13.58v and peaked at 14.25v. Then settled in at 13.61v roughly 7 hours after charge completed. Is this normal? I'm new to this LifePo4 world and was wonder if this is normal and/or if anyone has any comment. Thank You.
The following are my results:
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Steve_S
Member
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# Posted: 3 Aug 2025 10:23am - Edited by: Steve_S
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Take the voltage and Divide by 4 to get average cell voltage.
LFP has 2 Voltage Ranges like all batteries. (see chart @ bottom)
Gross Range = 2.500 -> 3.650 Volts per cell.
Working Range = 2.800 -> 3.400 VPC.
NEVER EVER Exceed 3.650 VPC and NEVER go below 2.500 VPC as that WILL harm the cells.
* Working Range is the optimal working performance range where the cells chemistry is Optimal and delivers the Actual AMP HOUR rating as labelled on the cells.
** NB: LFP has a very flat Voltage Curve compared to other chemistries and they are Millivolt & Milliamp "sensitive" and so must be measured accordingly.
13.6 = 3.4V per cell. PERFECT as that IS 100% and the best "settled" voltage.
14.25 = 3.56 VPC is a Perfect Cutoff Voltage for charging and leaves the room to settle to 3.400 +/- 0.15 V
** All Lithium Based cells will settle slightly lower after charge, this is normal & expected, LFP is pretty consistent with the amount the cells settle.
YOUR Battery can take a MAX of 157A (0.5C-rate) for Charging and can handle up to 314A (1.0C-Rate) for Discharging. *NB: The internal BMS (Battery Management System) controls this and will limit that lower to 100A protect the battery. (Per your product info as posted on humsienk site spec data) BE AWARE that should a Full Short Fault occur, a 314AH Battery can DUMP @ 5C which is 1570A (a serious kick in the pants). There is a HEAP OF JUICE lurking in there and so RESPECT IT !
WARNING ! NEVER EVER Charge a Battery when it is below 2C/35F Temp ! THAT WILL DAMAGE the cells ! LFP will discharge fine down to -25C/-31F and will charge safely up till 50C/122F The BMS in that battery has Temp Protection for Hi & Lo Temps, so it is safe
Here is one of my charts that shows the voltages etc.
Hope it helps, Good Luck
Steve
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gwindhurst
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# Posted: 3 Aug 2025 10:51am
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Thank you very much for the very informative response. I will print this out for future reference... As, for the cold weather and Low-temp cut-off, that's been one of my contentions to NOT buying a LifePo4 however, with the newer built in safety features I felt more comfortable with this purchase. Also, I plan on building a well insulated box out of 3/4" plywood with 2" closed cell foam (Owens Corning Foamular 200) and adding a thermostatically controlled RV Tank Heater like this as a safety net:
https://www.amazon.com/gp/product/B0DNTGLPMQ/ref=ox_sc_saved_title_8?smid=A1U5K42UL16 JP0&th=1
Thoughts on that?
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Steve_S
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# Posted: 3 Aug 2025 11:24am
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I know many people use battery heaters, usually the silicone ones with the element within and there are many versions with temp controllers. Depending on type (aluminium plate vs silicone embedded) you need to have some protection between the insulation material (foam with aluminium can carrey current) and even battery bottom pending on type of casing etc.
IF a Manufacturer sells you a battery with built-in heater (there are many) they are almost always the silicone embedded ones as they are the safest and most affordable from manufacturers perspective.
It's important that "whatever heater" have it's own temp sensors and that it will cut off all draw when not required and that it will not heat too much, but rather keep the batt at +5C/41F to +7C/44F so not to "cook" the batt or waste energy trying to bring it to a higher temp which is not needed.
I should point out, that during Carging, the chemical interaction generates heat, the warmer the cells, the more heat they will generate as they charge.
The Batt Specs say it has a BMS with BlueTooth and APP that let's you interact with the BMS and to monitor the internal state of affairs. That BMS does NOT have Internal Cell Balancing (not mentioned in description) so this means the batt is playing the "Averages" game meaning there can be a difference in cell voltage, ie: One high say at 3.500 while another maybe at 3.330. Now if ONE CELL drops to cutoff point, the BMS will shutoff the batt... Same if one cell reaches Overvolt setting (most often they set that to 3.650 as the default) the while thing will stop till that cell settles down & the BMS unlocks the charging.
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gwindhurst
Member
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# Posted: 3 Aug 2025 11:42am
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Got it. I think I will leave it as is in an insulated box this winter, and see how in performs on its own. And if necessary, I will add a silicone heating pad with a programable thermostat. Winter usage is minimal, weekend a month in central Vermont. It does get pretty cold at times... Thanks again.
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gwindhurst
Member
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# Posted: 29 Mar 2026 01:07pm
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Made it up several times this winter and had good success with the new battery. However, on one trip in mid February I arrived to a dead battery. With sub-zero temps, battery heater left on, cloudy days and snow covered solar panels it was expected I guess. So I brought it into the cabin from the power shed to warm up before reconnecting it, fired up the generator and charger... Good as new!
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Steve_S
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# Posted: 30 Mar 2026 08:25am
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The BMS did a very good job of cutting off at 2.8 Volts per cell. That is "proper" protection because it did not bottom the cells. THAT IS REASSURING ! The fact that the cells were very close together with only 0.039V differential shows they used quality matched cells within.
As an FYI, I have yet to see any complaints of consequence about Humsienk and your experience backs that.
Enjoy and have a Great Spring season.
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paulz
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# Posted: 30 Mar 2026 09:57am - Edited by: paulz
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Good deal. Today will be interesting for me. When I left Friday for a weekend at the grid, I wired 2 of my new Humsienks (12v 100ah) in parallel to the WiFi and trail cams, leaving the bank alone, so I could monitor from afar. I got a photo or two first day, but messages saying they were offline after that. Those batteries should have easily handled the load. Going back out this afternoon will see what happened, hopefully just an alligator clip popped off. At least the bank batteries are sitting with no load and on the solar..
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paulz
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# Posted: 3 Apr 2026 02:48pm
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Re above post: so when I got back to the cabin Monday, both Humsienks were dead. They both read half a volt, unhooked. A bit surprised as I thought the BMS would have shut them off sooner. Good news is they both charged right up to 13v. Still haven’t figured out what happened, must have left something else draining them, but they both passed the car headlamp test afterward.
So they are going back in storage. I read best Lfp storage voltage is 3.2-3.4 per cell, pretty wide. I want them at the ready if needed so wil go for the high end.
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Steve_S
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# Posted: 3 Apr 2026 11:20pm
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1/2 V means the BMS set discharge to Off. Of course the moment you put the charger on it started accepting juice as charge was set to On. That's exactly how a BMS should behave. Had there been 0.0V then the cells would have been depleted & the BMS would have shut down.
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paulz
Member
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# Posted: 4 Apr 2026 10:31am - Edited by: paulz
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Quoting: Steve_S Had there been 0.0V then the cells would have been depleted
Thanks Steve. So at a half volt the cells are in no danger, should it be some time that way?
When they quit a week ago, I had both batteries connected in parallel powering both the cabin WiFi and the shop cameras. Today we are going to our Saturday breakfast in town so I’m trying agai, this time one powering the WiFi and the other the shop cams, to see which one dragged them down. The shop, in addition to the cams, has a couple of motion detection led lights inside connected. They have their own little batteries inside and will run the lights for a few minutes without external power, but with the doors closed while gone should never have come on. Maybe even in that state they take some external power just keeping the usb batteries charged?
Be back in a few hours for a check.
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Steve_S
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# Posted: 5 Apr 2026 06:57am
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The BMS was still active because the cells were still above Full Shutdown which is likely set at 2.600V per cell. That is why it showed 0.5V at the terminals. The BMS will prevent (supposed to) cells from going below 2.500V. As long as the cells are above 2.5V they can sit like that without issue or concern.
Note that many "advanced" chargers will first try to sense a voltage before starting to charge and will not start if there is no voltage present.
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paulz
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# Posted: 5 Apr 2026 09:03am
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Ok got it. Bit more on my testing yesterday: the one battery hooked to the shop cams and lights went all day without signs of discharge, even took a couple photos. On the other hand the other one was running the WiFi. Late afternoon the WiFi died. Battery showed 11.25v. Switched it over back to the bank. The WiFi only draws one amp by my meter. I hadn’t fully charged the Humsienk prior. So how long should a 100ah battery deliver one amp, 100 hours? My plan is to try again next week with a full charge.
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FishHog
Member
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# Posted: 5 Apr 2026 10:02am
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yup, 1amp, should last 100hrs, but that's 12v. Is the 1amp you measured on the wifi 120? If so that should be drawing 10amps at 12v, so then your down to 10 hours.
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Steve_S
Member
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# Posted: 5 Apr 2026 10:29am
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 @FishHog
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gcrank1
Member
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# Posted: 5 Apr 2026 02:13pm
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And that doesnt count the other associated losses, although small they are still there.
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paulz
Member
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# Posted: 5 Apr 2026 05:28pm - Edited by: paulz
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WiFi is 12v. It came with an AC power supply, it’s in the pile with 50 other 110 power supplies.
My battery bank lead runs through a hall affect ammeter. When I run the Meanwells 40amp charger it does read about 40.
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paulz
Member
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# Posted: 8 Apr 2026 10:35am - Edited by: paulz
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Little update. Yesterday morning I put the WiFi on a freshly charged Humseink sitting at 13.3. Ran all day, down to about 12.85 last night. Early this morning the WiFi died, battery showing half volt again. Hooked to the bank and it’s charging right up so far.
So only got about 20 hours out of the Humsienk . Upon close look the WiFi may be drawing 1.5 amps. And not sure how fully charged that 13.3 reading was. What’s that tool mention that tells you true charge? Something with a shunt..
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Steve_S
Member
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# Posted: 8 Apr 2026 11:22am - Edited by: Steve_S
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A proper shunt with 3 decimal accuracy is really the only way to get accuracy after it has been calibrated with a high quality DVOM. Now a shunt this accurate is NOT cheap whereas a 2 decimal one is cheaper & 1 decimal one is cheapest.
13.3V = 3.325V per cell which is 0.075V below 100% SOC. Remember that 0.200V represents almost 50% if using factory spec that says 3.000VPC=0% and 3.400VPC=100% with 3.200VPC being 50%...
I have "set" my software including shunt to register my voltages as follows:
2.800VPC = 0% and 3.400VPC as 100%
That allows for a 0.600V range from 0% to 100%.
Every 0.060Vpc = 10%
0.150V + 2.800=2.950VPC for 25% in my system.
0.300V + 2.800=3.100VPC for 50%.
0.450V + 2.800=3.250VPC for 75%
0.600V + 2.800=3.400VPC for 100%
!*! Remember to multiply VPC (Volts Per Cell) X4 for 12V, X8 for 24V and X16 for 48V.
Confused ?
If that router is directly wired (through a fuse) to the battery system and pulling only 12V and 1.5A something really doesn't add up. There has got to be something else going on or the label is bogus. An in-line ammeter would be able to tell you that, some DVOM's will let you clip on their leads to act as an ammeter but most limit volts/amps so check yours.
Hope it helps, good luck.
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paulz
Member
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# Posted: 8 Apr 2026 12:07pm
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Thanks Steve. My clip over DVM only list AC amps. The cheapo clip on meter shows about 1.3. I’ll charge the Hummer to 14.x today and try again.
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paulz
Member
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# Posted: 9 Apr 2026 07:39pm
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So yesterday I took the Humsienk up to 14.6 with the meanwell charger. Took a long time in the higher 13s but went through the 14s more quickly. Manual says 14.6 charge max. So then it sat at 13.6 for an hour before putting the WiFi on it, then 13.3 before bed.
This morning still at 13.3, WiFi up strong. I’m back to the house for the weekend, WiFi still going.
The short story is I apparently never got the Humsienk up to 100%. With the WiFi on I can look at the cabin from afar. I doubt it will last all weekend but maybe 100 hours.
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gcrank1
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# Posted: 10 Apr 2026 01:40pm
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Ime it is good to give the LFP's a few 'working cycles' to get them into the idea of what they are supposed to do and us into the idea of what they can do.
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paulz
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# Posted: 10 Apr 2026 04:25pm
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Ok sounds good. Well I’m back at the cabin. Got to the house yesterday and forgot my meds (living in two homes gets to be a pain). WiFi been on and going, about 50 hours now and the Humsienk still at 13.16. Going to spend at least tonight since we’re here. I’ll leave the WiFi on when we go to see how close we get to 100.
I bought 4 of these around new year in case the old bank finally gave out, they were all over 13 but I don’t think I ever fully charged.
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Steve_S
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# Posted: 11 Apr 2026 05:16am
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That explains part of your Batt weirdness. You just charged to 14.6 or 3.650Vpc and fully activated that battery pack provided the Amps being taken dropped down to like 7A.
As I said in other posts related to LFP, if cells/batts are new or have been in storage for 6 months or more, the Batts "settle" and must be fully charged to fully activate the electrolytes within them. Then once it is normally used, that is no longer required and charging to a Max of 14.0V / 3.500Vpc will keep everything in optimal condition, as long as the batteries continue to cycle, it all stays good.
Conditions when to charge to 3.650Vpc/14.6V in this instance, is when the following conditions occur;
1) Batts are New or Unused or have been stored for 6 months or more.
2) If Batts have discharged totally to 2.500Vpc/10.0V) and sat disconnected for a period.
3) If Batts got frozen (below -5C/23F) while in Low State of Charge *
* In installations where Batts are subject to Low Temps (but above freezing) for a period of time while functioning, can "slow" electrolytes as they separate a little. Such as in my case where the Powerhouse is only heated to 15C/59F during winter, every spring I ensure I charge the packs in the bank to max and allow Amps Taken to drop to 5A for the entire 1680AH bank combined. (That's a job in itself LOL).
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paulz
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# Posted: 11 Apr 2026 08:23am
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Hi Steve. Yep applies to these new batteries. I don’t know how long they sat at Amazon, at least a few months when here at the cabin. First time one has gone up over 14v.
So this morning WiFi still going, Humsienk at 13.12. It’s been 3 days, and at the 1.3 amps I measured, should be closing in on the 100ah rating.
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Steve_S
Member
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# Posted: 11 Apr 2026 10:17am
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Now you have Direct Observation of an Un-Initiated Battery & its behaviour versus when it has been properly commissioned into operational mode. You may be surprised at how many fail to do so, cause themselves issues, then complain that "it's all bad & I was lied to" because THEY failed to follow standard procedures as outlined in pretty much every companies documentation (which was lacking in the past - earlier days). Don't be too surprised if you get more than 100AH out of that battery pack.
I still peek into some of my former Solar Forums and limitedly interact with them pending on situation. I have for years seen this play out as described above far too many times. Simply put, few actually RTFM even when it is something totally new, different & something they do not understand. Assumptions are the #1 killers of things, including people themselves (self-inflicted stupidity).
Case in point, we (several of us) warned a particular individual that what he was doing, posting, asking questions and then ignoring our recommendations (because he assumed he was better at understanding) was going to cause him pain & suffering. 3 weeks ago he burned his farm to the ground several animals died but so did his wife & 1 child (so we heard). Seems he thought that Grounding & Bonding were not important and that severely overcharging batteries was fine because they somehow stored more evergy ecause of it...
I no longer help ANY of that kind of individual and very selectively help or offer advice to good intelligent critical thinking people like those within THIS community. I tend to focus on African & Europe an serving sites along with a couple of Canadian sites. I barely ever interact with anyone on US Solar Forums anymore... far too challenging and simply not worth the effort anymore. NO OFFENCE INTENDED but you have no idea of the shit & pushback along with threats... and it all came from the most dispical sub-species of hooman.
Thank Goodness there are still refuge's like Small Cabin with great Cabineers.
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gcrank1
Member
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# Posted: 11 Apr 2026 04:12pm
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Thanx for coming around Steve, we can always count on the straight scoop from you 
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paulz
Member
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# Posted: 12 Apr 2026 08:28am - Edited by: paulz
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Still going this morning, watching the news on the WiFi! Probably about done though, Humsienk at 12.85. But it’s been 4 days, about 100 hours, and at 1.3 amps should last only high 70 hours.
The upshot of this is I can leave the cabin for the weekend, put the WiFi on a stand alone battery to keep the cabin battery bank safe, and keep an eye on the place via the WiFi cameras.
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gcrank1
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# Posted: 12 Apr 2026 08:35am - Edited by: gcrank1
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Yep, ime at that voltage there isn't much left, though at that draw it can be like watching grass grow to watch it finally go to lvd. If you can be there for that you will get your real world calc of usable power but it is looking like the Hummer is a good bat.
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paulz
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# Posted: 12 Apr 2026 12:49pm
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Right, WiFi just died, Hummer at half a volt. Best part is I had it just jumpered in with the battery bank feed turned off at the panel switch. Just left it jumpered and turned the switch on, WiFi back up and Hummer charging off bank. Will only get up to bank voltage, bit over 13 depending on the solar coming in but nowhere near the 14+ I had given it. Steve says that should be ok for awhile.
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