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What's your a/c's continuous current draw? Are you calculating a/c runtime based on a 100% compressor duty cycle? We use a 12v Multiplus II 3000 to power the a/c in our small RV with a 304ah lifepo4 battery. A/c's continuous current draw is approx. 8.5a/120vac (approx. 85-95a of 12vdc)...

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Unless you're an avid DIY type, I'd suggest purchasing off-the-shelf. There's a bit of a learning curve with a DIY build. You may get a tad more bang for the buck with a DIY build, but it's nothing like it used to be. Off-the-shelf prices are very competitive these days. That being said...

Lifepo4 cell level high voltage disconnect (HVD) is typically set to 3.650v. It's not necessary to reduce charge current with the active balancer active. However, if you have significantly unbalanced cells (high deltas), you may find the balancing process goes a bit smoother if you use a...

With the BMS and active balancer both installed, we start charging the battery pack with the active balancer off. Once "most" of the cells have risen above 3.450 - 3.500v, we turn-on the balancer. We let the active balancer resolve the delta to as near 0mv as possible using our normal bulk...

We quit formally top-balancing cell packs in a parallel configuration using a power supply a few years ago. We started installing active balancers with an on and off switch. We turn-on the active balancer to perform the initial top-balance, then leave it off until such time as another...

To my knowledge there's no way for the average Joe to accurately determine core temperature. We always assume worst case----the core is at ambient (or the lowest known ambient). Also, to clarify, I believe it's heating "time" that will increase when heating a "frozen" (vs. unfrozen) core...

We did some informal testing with a few 200-300ah 4s cell packs placed outside our home during the winter and inside our home freezer. We found ~1.5w of heat per kg (or ~1w per 1.5 lb.) of cell weight was generally enough to keep the cells heated to 55 - 60f (13c - 16c) when exposed to ambient...

We've been using hard-wired Progressive Industries EMS's for years. They've saved our bacon a number of times. Any particular reason you use the portable version?

We have the latest version of this WFCO 35a converter (and the same 30a power center) in our new teardrop trailer. Have also owned/used a number of other WFCO's through the years--replaced most of them with Progressive Dynamics. WFCO's have a reputation for staying in 13.6v absorption...

Ditto. The 12v Multiplus II 3000 inverter/charger can produce 90-95a of charge current using just 13.5a of 120vac. A Honda 2200 inverter generator can easily do 13.5a (it has a 15a continuous current rating). If you have access to 16.5a via 20/30a shore power or higher capacity generator...

Unless you've got an RV with a huge hydraulic slide system I don't see a problem sourcing 48/12 power. The average slide motor draws less than 30a. Schwintek slide systems, which are very common, typically only draw 10-15a. 30a 48/12 converters are very common. May have to dedicate a...

Without getting too much in the weeds, it would appear you're calculating everything based on max hypotheticals. Perfect sun, max rated output, etc. If you honestly feel you'll be pulling these hypotheticals with the 250/100 and/or you're committed to using only one controller, then 24 might...

A 12v Multiplus II 3000's output is rated at 2400w (3000va) at 25c. At max output it'll probably be drawing 210 - 220a. A 7ft (one-way or 14 ft pos/neg round-trip) run of 4/0 cable at 220a (with excellent terminations) should only experience roughly a 1.3% (.15v) voltage drop. Perfectly...

In terms of overall cost/capability/tech/redundancy, I'd have a tough time justifying going 24/48v on a smaller RV. However, if I had a large 5th wheel or motorhome with tons of solar real estate, with plans to max out one or two Multiplus II 3000's (2400w ea) on a regular basis, I could see...

We use a 12v Victron Multiplus II 3000. Our highest projected continuous load is 175a. Use a 200a Blue Sea MEGA fuse. We prefer to fuse based on highest anticipated load which by design should be less (IMO) than the inverter's maximum rated current. If we're pulling anywhere near the maximum...

If your friend will let you load test these in a 48v configuration prior to purchase, then $400 might be a decent deal. Otherwise, I could see these 4 batteries potentially being more hassle than they're worth in a 48v configuration. One weak battery or reluctant BMS will bring down the...

Lithium Approved means very little. The number of charge stages and the voltage used to support each charge stage determine how safely and how well a given converter or charger will charge a lifepo4 battery/pack. Case in point: Progressive Dynamic makes a number of so-called "Lithium Approved"...

@glennjr1, here's a thread where folks posted their realworld parasitic (no-load) current for various makes and models of inverters they're using. You may find this useful for comparison purposes. Low no-load/parasitic current has always been a big priority for us. We used to use an Aims...

We found 24w of heat would keep a 12v 4s 200ah cell pack (OP's battery is 200ah) at 60f while exposed to ~0f. The cells were placed inside a plastic Group 24 battery box with a top attached. No insulation was used. Four 80x100mm 24w heating pads wired in series/parallel (total combined heat...

We used a battery isolator (BI) to feed 12v to switches we had connected to the Renogy's LC and D+ terminals (switchable off, 20a, & 40a modes). The BI would only pass power to the switches when the primary input voltage to the dc to dc charger was 13.3v or greater (alternator active/online)...

Correct. The Heltec 5a 4s balancer's 5 wires (4 positive cell wires plus neg) will simply parallel with the 4s BMS's 5 sensor wires (also 4 positive cell wires plus neg). Each positive cell wire (from BMS and Heltec) is cell specific (3.2v/6.4v/9.6v/12.8v)---they must be connected in the...

When you're spending just $37 on something that has a no-question, 30 day return policy, what's there to be wary of? No buyer's remorse here--lol! Just a smile! Good luck with your search!

We purchased the same cells from 18650. The voltage was *exactly* the same on all 4 cells (3.302v). Even so, we still needed to top-balance due to excessive deltas (imbalances) when charging above 3.500v. You could always pass on the top-balance and charge your cells normally with the BMS...

Not sure if you noticed, but the reviews for 6 completely different meters are all lumped together . The reviews for the Bside ZT-QS9 are titled Upgraded 600A DC/AC. Regardless, it's your choice to make. I ordered one, use it all the time. Zero risk purchase---I had 30 days to...

Not familiar with your specific model JBD, but our 4s JBD BMS supports calibration of the individual cell voltages. Since you're reading the correct voltage at the cell 1 BMS JST connector, it's possible the cell 1 voltage simply needs to be calibrated.

We purchased a DC power supply to top-balance our first build. Quickly transitioned to installing Heltec 5a active balancers (with an off/on switch) for subsequent builds. The Heltecs do a fine job of top-balancing. Only takes a few hours with large deltas---smaller deltas, less than an hour...

Do you work on your own car? Do you enjoy maintaining most of the plumbing & electrical at home? If yes, you might be a good candidate for a DIY lifepo4 build. In my opinion, purchasing from a reliable, proven source (typically US-based) is your best way to minimize major problems. That goes...

We jumped through all the same hoops as the OP when we assembled and parallel top-balanced our first 200ah 4s pack. Don't do it anymore--just too much hassle. Nowadays, we install the BMS along with a $25-$30 switch-activated Heltec 5a 4s active balancer, charge normally, wait 1-2 hours for...

We typically use an Amprobe 320 for continuous and inrush current readings plus a lower-end Fluke for voltage readings. However, if you're looking for a huge bang-for-the-buck, it's really hard to beat this BSIDE Clamp-On Ammeter currently on sale for $37 (reg $46). It's a true RMS, 6000...

BMS disconnects if the sum/combined/total voltages of all 8 cells in series (for an 8s BMS) exceeds the value set for Sum Volt High Protect.

With 4 separate batteries (and 4 BMS's) in series, there's lots of potential for imbalances (and other assorted problems) to occur. *IF* the warranty claims fall-thru, I wonder if you'd be better served (long-term), opening up the battery cases, removing/disconnecting the (4) 4s BMS'S, wiring...

We just built a 12v 4s lifepo4 battery pack for our RV using 4, 304ah EVE cells from 18650batterystore (came with flexible busbars---nice to have in a mobile RV environment). Cells tested at slightly more than 304ah at .2c . Use a JBD 200a BMS (with bluetooth & heater terminal option). It's...

For what it's worth, we power our 12v Victron Multiplus II 3000 120a charger with a Honda EU2200 often. If we're willing to run the Honda at its max continuous current rating of 15a (1800w), we can get 105-108a of charge current. I believe the Honda is also rated to produce 18.3a (2200w) for...

I've found old-school 3-stage 13.2v/13.6v/14.4v RV lead-cell converters charge 12v lifepo4's to 100% SOC just fine. No downsides. IMO, they're a better charging option than many so-called "Lithium Approved" single-stage (14.6v) and two-stage (13.6v/14.6v) converter/chargers---especially if you...