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Batteries explained

September 26, 2020, 03:51:36 pm

Found this battery write-up to be quite comprehensive, covering many common important questions about batteries.

Attached is from:
Frequently Asked Questions (FAQ) - DC Battery Specialists

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Re: Batteries explained

Reply #1 – September 26, 2020, 08:04:34 pm

Thanks, Barry.  Note this this discussion is for lead batteries.  It does not apply to LiFePO4 (Lithium chemistry) batteries.

Sorry about the ads.

This guy reminds me of Sheldon buy he seems to know his stuff
https://www.youtube.com/watch?v=TxGBde83CXQ

https://www.youtube.com/c/WillProwse/featured

Take everything you see on youtube as someones opinion.

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Re: Batteries explained

Reply #2 – September 26, 2020, 08:46:24 pm

What happened to the battle born 8D's mentioned with internal heaters? 

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Re: Batteries explained

Reply #3 – September 26, 2020, 08:57:29 pm

I think the current situation is holding them back. At the tent the representative said that they would be in production soon, then this happened.

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Re: Batteries explained

Reply #4 – September 26, 2020, 09:44:10 pm

You really don't need Battle Borns in 8D size.  You can get 600 amp hrs in the footprint of 2 8Ds today and same more than 375 lbs compared to 3 8D lead batteries and the heavy racks. There are other LiFePO4 options out there in an 8D size, 300 amp hrs each.  Not with BB 10 yr warranty.

Cold weather limits are for LiFePO4 batteries not being used at sub freezing temperatures. At those temperatures you can discharge them but charge rates need to be low. Using the batteries will warm them up so that charge rates can be increased.  A $10 thin film snowmobile hand warmer heater will heat the batteries up by 30 - 40 degrees when it is close to zero using power from the battery.

BattleBorn makes a heated pad that the batteries sit on now.  Does the same thing but it is $200. 

We have been in Custer State Park for 14 days, no battery charging other than solar.  We are at 100% every day before 10 AM. Start batteries are charged by solar as well.  We have not been charging while driving from the alternator as well on this outing.  After a day of driving we are at or close to 100% just from solar anyway.  Not quite the same in the winter but we are only charging the LiFePO4 batteries at 60 amp max from the alternator then when we drive.

When it is time for new batteries consider LiFePO4 batteries. 

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Re: Batteries explained

Reply #5 – September 26, 2020, 10:04:39 pm

No one seems to touch on lithium batteries for start?.  Is there a reason.?

There are all kinds of safe heat mats on the market. Even heat tape that is designed for usage with pipes. Heat pads are used for seed trays. As mentioned snow mobiles.

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Re: Batteries explained

Reply #6 – September 26, 2020, 10:42:24 pm

Roger, I was hoping that the 8D would be cheaper than 3 100 ahr ones and would require less cable modification.

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Re: Batteries explained

Reply #7 – September 26, 2020, 11:07:43 pm

It might be but you can only get two 8Ds in your battery bay on one level.    Maybe OK if they are 300 amp hrs. The max continuous discharge rate on an 8D LiFePO4 (if they are 300 amp hrs) might be as much as 300 amps and to keep voltage loss to under 1% in 3ft cables to a bus bar they should be 3/0. Four cables for two batteries.

For the 100 amp hr batteries the max continuous discharge rate is 100 amps and for that you could use as small as a 2 ga cable.  Cheaper, easier to connect, lugs are cheaper.  Six batteries, 12 cables.  Bus bars would be the same, switches and fuses the same.

Battery spaces are different in different years and models.  Measure carefully.

It will be interesting to see what the 8D versions look like and what the specs are.

Start batteries are generally high amp, short duration load and quick recharge.  LiFePO4 batteries should be recharged at 20% or less of capacity. You can do it but probably not very cost effective for that function.

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Re: Batteries explained

Reply #8 – September 27, 2020, 01:22:36 am

I understand tesla uses a liquid temp controlling system for their battery cells.  More moderation I assume. 

Newest versions are using a heat pump hvac system. 

That's my point about the internal heating system battle born seems to be considering as the temp restrictions may restrict  them from possible additional future  sales.

The poster here  mentioning silicone batteries seems to have a good option for the temp users.  Hot or cold

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Re: Batteries explained

Reply #9 – September 27, 2020, 09:50:36 am

I thought I read charging below 20 was not recomendations on the Web site.

Roger with 600ah, do you run your AC?

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Re: Batteries explained

Reply #10 – September 27, 2020, 10:04:28 am

Charging at high rates when the batteries (not the outside temperature) are cold can damage the batteries.  You can charge them at low rate it you need to do but LiFePO4 batteries will hold full charge for months.

I could run one AC with a soft start installed from my 600 amphr LiFePO4 battery bank through my inverter for about three hours and go from 100% SOC to about 25% SOC.  My max charge rate while driving is about 60 amps from the alternator and solar might add as much as 50 more on a perfect day.  Even at that it is not enough to run the AC and stay even.  All day on the solar I have would not recover from 3 hrs of AC use.  So I choose not to run AC on the inverter. 

It is not Battle Born Batteries but all Lithium chemistry batteries that have a low charge rate limit at low temps.  Fully charged LiFePO4 batteries can sit for months as it gets colder and still be near 100% SOC when you want to start discharging them and that works, no limits.  Once the battery warms up from use or external heat you can charge normally. 

I tuned my battery heaters on low (18 watts per battery) last winter at single digits above zero. The next morning they were 30° at the terminals, began charging as normal using 40 amp max on LiFePO4 charge profile. Battery heaters were turned off. The AH got turned on electric, thermostat set to 40°.  Easy for it to maintain that temp.  Batteries never got below 40° before we left three days later.

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Batteries explained

Reply #11 – September 27, 2020, 11:13:59 pm

About 50 years ago I passed my my finals for my German University Engineering Degree in Mechanical  Engineering in the subject Electrical Engineering II)  with an A- (just looked it up)
It certainly was one of the easier courses, Thermodynamics, Mathematics  and Physics were much harder.
By now I have forgotten probably 95 % of the subject matter, I worked in management too long.

But I can still learn a new subject. Giving the going rate on my reading (and enjoying the Technical Forum) and taking care of the farm by spring I will be able to truly understand Roger and Susan's comments. (which I appreciate)
 Then I will be able to figure out whether I need new batteries and what type I should buy.

Greetings

Klaus

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