Battery upgrade to lithium - Wiring size vs circuit protection

[uncle_bob]

Originally Posted by PKI

Bob - Yes, agree totally with the concept that "easy to use" is more likely to become the normal process. Those switch components are quite interesting and significantly lower in cost. Thanks for the link. The T-series price seems higher than what I see for marine applications, but the point remains valid. There is a difference in operating cost for the two different approaches, since a fuse must be replaced, while a breaker just gets reset. Pat

Hi

If you wander into a local store looking for a replacement T series fuse, that's the sort of price you are likely to run into. Everything is cheaper if you buy five or ten at a time, they are not likely to have them in anything other than singles ....

Indeed there are other fuse types (ANL) that are dirt cheap, even in the local store. They may not be as cool as a T, but they do the job perfectly well. Since you don't have to deal with high voltage, a lot of what is designed into the T and missing it them is a "no big deal" sort of thing.

If you *do* head off into the world of car stereo parts (which is what I call all this stuff), be aware that some of the fittings are not up to snuff. You can expect to find this or that un-usable in your application. Since it's all cheap / next day delivery stuff. That's not the disaster it might be.

What am I babbling about? I ran into an ANL fuse holder that simply would *not* properly clamp onto stranded wire. I have no idea what it was designed for, but stranded wire was not going to work with it. Solid wire (or tinned stranded wire ....) worked just fine.

Bob

[gator.bigfoot]

I think that fuses are a lot more reliable than breakers especially with something bouncing down the road. I don't think there are too many cars with breakers. They are all still using fuses (at least mine are). Let's face it if you have one of these high power circuit protectors go you have an issue. Your not just going to reset it or replace it. You've got to figure out why it went. That said I've used the "car stereo parts" circuit breaker for years without issue.

[pdavitt]

I know I'm going to get accused of "over" engineering, but when it comes to circuit protection devices I am very picky. Carling Technologies is the manufacturer of the hydraulic/magnetic class A, C, and F series breakers sold by Blue Seas, Midnite Solar, Outback, Magnum and others. Unless I can find a datasheet like the Series F breaker one shown below, I won't consider other brands.

https://www.carlingtech.com/sites/de...COS_010714.pdf

Being hydraulic/magnetic and not thermal these breakers maintain their trip level through out their operating temperature range; plus they are also rated as switches with a MTBF of thousands of full power actuation's.

Just my thoughts,
Pat

[PKI]

Pat - not quite that over-kill oriented today. Maybe tomorrow ..... Is this an application where cable end lugs could be deleted? Would need a breaker box - power center .....

Bob - the West Marine on-line pricing for a T-series is $51 for 300 amp and $85 for the holder. Do T-series fuses come in different specifications?

Battleborn also suggested the ANL fuse style. West Marine lists the fuses for $25-30 and the holder for $30.

Gater - Not sure about the concern with road vibration. Lots of applications see bumps and jars. But it's a thought I had not investigated and will. Thanks for making the point for folks to consider.

Pat

[rmkrum]

I use ANL fuses with Blue Sea Systems holders, either single or double.

[uncle_bob]

Hi

Both fuses and breakers fail from time to time. Neither one is particularly reliable. If you are designing a high reliability system, fuses and breakers are not going to be part of it. They fail and the system goes down .... not what you are designing it to do.

Operation in a trailer is fairly benign. There isn't a lot of shock or vibration, there also isn't much of a temperature range. It's not a stressful environment compared to a *lot* of other things. That assumes you don't go off road at 60+ MPH ..... Airstreams bottom out before things get really crazy.

Fuses go into a car for one very basic reason - cost. Bought in large volumes, they are cheaper. They also are smaller and lighter. Both of those things do help, but money is the driver.

Unless you are routinely shorting things out/ tripping circuits, all of this stuff is there to protect against a highly unlikely event. If you *are* routinely shorting things out, change your habits. A fuse or breaker should never be what catches your mistakes. Sloppy habits will eventually combine with something a bit more potent voltage wise and get you in serious trouble.

If you look in your basement, your home is most likely run on breakers. If it isn't then it was wired a *long* time ago. Houses do not routinely burn down because they have breakers instead of fuses. Similarly RV's do not catch fire on a regular basis because of breakers. (Airstreams have had breakers in them for ... errr ... forever ...).

Bob

[pdavitt]

Originally Posted by PKI

Pat - not quite that over-kill oriented today. Maybe tomorrow ..... Is this an application where cable end lugs could be deleted? Would need a breaker box - power center .....
Pat

No, lugs are needed the F series breakers have 3/8" studs, the A and C series have 1/4" or 5/16" studs. See below.


Pat

[PKI]

Pat - that configuration is a bit different than expected. Thanks for posting the graphics of the components. More over-kill leaning today.

Bob - very good summary of the considerations. Yes, blowing fuses is not normal operating procedure. Resetting a breaker on a regular basis is also not at all good practice. Thank you for the analysis.

RM - the ANL fuse seems to have a following. A cool design is the LYNX combiner box that has a set of the ANL fuses integral to the internal buss configuration.

Pat

[uncle_bob]

Hi

As far as I know T series comes in one flavor of fuse. The holders come in a couple of sizes and shapes. None of them seem to be cheap. With ANL you *can* get low cost holders and fuses.

Since we seem to be heading into a lot of details:

Crimp lugs on big fat cables are generally a good idea. They give you something very solid to hook to the fixture and a good connection to the wire. We tend to use very fine gauge stranded wire for routing stuff in RV's. That is (in general) not what a lot of "direct connect" fixtures expect to interface with. They are either designed for solid wire or heavy gauge stranded.

Bob

[pdavitt]

Originally Posted by PKI

Pat - that configuration is a bit different than expected. Thanks for posting the graphics of the components. More over-kill leaning today.
Pat

All of these breakers are "panel mount" types. Their ability to also act as switches, keeps the installation nice and clean. Below is a photo of the front of my DC Load Center.

Pat

[PKI]

Bob - Yes, the details are a help to understand the differences in components. That is significantly important due to the limited local availability of some parts or cost differences that challenge the budget.

Pat - Yes, power center mounting is helpful in organizing components. I am currently balancing the hazard of a conductive housing vs the fire protection and organizational value of such an enclosure. Most installations seem to use a non-conductive plywood mounting surface, which provides space for larger cable routing. More details.

Off today to measure existing conditions and lay eyes/hands on existing and proposed components. Pat

[gypsydad]

6V Trojan update: We just returned from a 3 day boondocking trip where we ran the furnace each night in 36-40 degree weather in Glacier at night, and used shower/water heater daily. Started out with 12.6V first day, and ended up with 12.4 when we loaded up and left yesterday...not seeing need for Li's yet...but good to see all the data you'all are sharing!

[PKI]

Originally Posted by gypsydad

-- snip -- good to see all the data you'all are sharing!

Appreciate your encouragement. Circuit protection and wire size review is important for any battery bank upgrade. Pat

[PKI]

OK - a bit of thread shift. Visited Glimmer today and took some measurements so the wire pull distance can be estimated and the wire size established.

Also, visited the local West Marine brick and mortar store to lay eyes on components. They sell Blue Sea parts and Ancor cable.

No issue with respect to lugs and cable sold by the foot. The problem - there is no crimping tool. But we covered that in some prior posts.

The T-series fuse had one option. There was a single 300amp fuse. My preference is to use a 200 or 225 amp fuse for this application. And yes, Bob, they are big and expensive.

The ANL fuses were available in a variety of sizes.

The breakers were available in low amperage type A or 285 styles. Not the plan. Maybe Type C or the 187 style switch thermal breaker.

The bus bar connections were rated for 250 amps. Another reason why I'd like to use a 200 amp primary circuit protection component.

The on-off switch was rated at 300 amps. Maybe OK (have one that may get repurposed).

Now, there are other places to source the parts. I'll check a few. However, the parts availability observed today sends a strong message that some parts are more available than others. Those ANL fuses do have a following.

Also saw a sign. Blue Sea parts packages advertised are not available due to Mfg delivery delay. Wonder? Wonder? Wonder?

The information is growing and the options are becoming clearer. Really appreciate the comments and concepts shared by all. Pat

[Fair_Enough]

I’m perfectly happy designing my own but don’t claim to be an engineer. I’ve put together 4 RV systems. With solar, inverter, and larger than typical battery bank. I’ve learned as I went. No 2 systems are alike.

My current endeavor has 600 W array, 40 A MPPT, 340 Ah LFP (2-170Ah Renogy) in parallel and 3000 W inverter (6000W peak).

I will cook on a 600w to 1800w induction as well as 1000w microwave. Fridge is an Engel that sips 12 volt. AC duties are handled with a Whynter dual hose that will run on the inverter but will not in practice. It’s a bit of a power hog using 8 to 11 amps of ac power. I also have 2 GFCI protected outlets and plan on using a heating pad or blanket for the bed. Fantastic fan handles ventilation duties.

Currently I don’t have a converter, the only charging is solar. If I get a 50-ish amp converter, it would get s 15 amp breaker and be fused at 50 ish amps.

My criteria for voltage drop is no more than 3% for charging sources that includes panels to controller wire run and under 1% battery to inverter run. I use a voltage drop calculator.

Wire runs are quite short. 18” batteries to + bus (individually) using #2/0 protected at each battery with 150 A Blue Sea fuses. Bus to inverter 8” of #1/0 (letting the inverter protect itself). Solar charger 12” of #6 AWG to bus.panels are in series using #10AWG. Since I had left over #2/0 that is what I used batteries to bus and batteries to shunt to (-) bus. I make my own cables.

My thoughts on the inverter size and protection rationale is that I only “needed “
2000 W of inverter (3000 peak) which is around 30 amps at 120 vac and 300 at 12, so my ac main breaker is 30 amps and batteries are fused at 150 A each. The batteries are rated for 100 amps each continuously.

Sorry to ramble. Might be something useful to someone.

Clint

[PKI]

Originally Posted by Wolfwhistle

-- snip -- Sorry to ramble. Might be something useful to someone. Clint

Clint - different perspectives, different implementation ..... always useful as long as it's shared. Short runs, big cable, circuit protection on AC and DC. Yes, helpful to consider. Thanks!

----------------------------------------------------------------------

Camping World has some DC circuit components. Should have known that.

The inverter is just possible to see with a cell phone camera. It has a rats nest of cable but the space is reasonable in size. The heavy cable routing seems to take up most of the room and may be driving long cable length.

Time to get Glimmer home and figure out the details. Pat

[uncle_bob]

Hi

Ok, 200A at 12V is 2.4 KW. 300A is 3.6 KW. Both are a pretty hefty load. Unless you have several hundred AH of *usable* capacity, either one is likely more than you *should* pull from the bank.

Bob

[PKI]

Originally Posted by uncle_bob

-- snip -- more than you *should* pull -- snip --

Bob - Yes, but for our application, consumption will be much less than the connected load. A 240 amp hour capacity should get us through the worst case events. Pat

[PKI]

Originally Posted by PKI

-- snip -- Likely incorrect information - " A 7in length was mentioned as a boat industry requirement." Correct information suspected to be 72 in. -- snip --

OK - both apply, the 7-40-72 rule is how. It says -------

Mounting placement dimensions for a fuse or circuit breaker (7"/40"/72" ABYC rule): 7 inch maximum if the conductor is not housed in a sheath or enclosure in addition to the wire insulation, 40 inch maximum if the conductor is housed in a sheath or enclosure in addition to the wire insulation, 72 inch maximum if the conductor is connected directly to the battery and housed in a sheath or enclosure in addition to the wire insulation.

Enclosure, I understand. To understand the concept of a sheath is going to take a bit more research. Pat

[uncle_bob]

Hi

Sheath = insulating jacket over the assembly. More or less - you put (electrical and mechanical) insulation over the cable.

Have fun when you get to the part about all circuits having disconnects and those disconnects being easily accessible..... The 7000 series from Blue Sea is a good place to start for that part of it. They have matching panels that will accommodate the "couple of dozen" switches involved.

Bob