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 > 6 v GC batteries versus 12 v lithium deep cycle batteries

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noteven

Turtle Island

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Posted: 05/15/21 05:26pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

theoldwizard1 wrote:

Ignoring price (very hard to ignore), Lithium Iron Phosphate (LiFePO) batteries are far superior to any lead acid battery for 2 reasons :

• You can discharge them down to almost 0% SOC with no damage (more usable energy for the same rating)


I'm sure Stircrazy would subscribe to this view point--but BattleBorn deliberately derates their 100 amp-hour to 100 from a "real" 120 amp-hour.

So far as I am aware the rest of the Li makers don't protect the end user this way.

Could it be the battery management systems are keeping the bottom 20% from being used?


Hi pt,

Lynac battery Thunder Bay ON rates their Li batteries at "true" available aH's'z as well. 100 aH battery = 100 useable aH's'z.

BFL13

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Posted: 05/15/21 05:46pm Link  |  Quote  |  Print  |  Notify Moderator

jaycocreek wrote:

In an actual capacity test with a heat gun,Will only got 1156 watt hours or 93+ amp hours out of the Battleborn 100ah battery..I only posted because someone here keeps saying Battleborn is 120ah but test clearly show it is not...


Did not see that one, but I doubt a heat gun would be at the 20 hour rate of 5 amps for a 100AH battery to get the AH rating.

WP seems to be pretty good with numbers and is fast talking, so hard to know if he is a flim-flam man or what he is actually doing. I don't "get" WP as a sort of LFP guru/expert for that reason. IMO check his numbers very carefully and still wonder what he might have got past you.

OTOH, you might still win the Kewpie doll! [emoticon]


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Almot

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Posted: 05/15/21 05:46pm Link  |  Quote  |  Print  |  Notify Moderator

Here is what I learned about Li so far.

1) You need to disable Float mode in converter or set it below 13V. Cheaper converters don't have this option and neither do cheap solar chargers. Even not very cheap "Li-compatible" solar chargers will require setting a custom charging profile because the chances that its preset Li profile will match your Li battery are slim.

2) Equalization MUST be disabled. Luckily, most chargers allow this.

3) Li don't need to be charged 100% every time.

3) Li weigh 2 times less than FLA of the same nominal cpacity and "recommended" usable capacity is 80% of nominal, while FLA recommends only 50%. BMS will stop Li from discharging when it's completely empty, this is not recommended in daily use. Nominal capacity of many but not all Li batts = available capacity give or take a few AH, there is no 20% reserve, though some manufacturers provide such a reserve by marketing 120AH Li as 100AH nominal.

4) Li warranties are much longer - typically 3 years warranty for manufacturers defects + 7 years prorated warranty. They typically guarantee 5000-6000 cycles before available capacity drops to 80%, when used properly - meaning charging/discharging as recommended (usually 0.2C). They can take more than 0.2C but this will shorten their life.

5) Li hate being charged and stored in very hot weather, 32-113F is recommended, routinely subjecting them to +100F will shorten their life. Discharging is more tolerable of temps, range 0-130F.

4) In $ per cycle Li cost more than FLA, but in $ per AH through the life of battery Li are cheaper. (Because more cycles and each cycle is 1.6 times deeper).

jaycocreek

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Posted: 05/15/21 05:58pm Link  |  Quote  |  Print  |  Notify Moderator

Will Prowse explains somethings very good and others not so much...For someone completely new to lifepo4 he is about the only one trying to explain things...

Battleborn capacity test with heat gun

BFL13

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Posted: 05/15/21 06:46pm Link  |  Quote  |  Print  |  Notify Moderator

jaycocreek wrote:

Will Prowse explains somethings very good and others not so much...For someone completely new to lifepo4 he is about the only one trying to explain things...

Battleborn capacity test with heat gun


Ok watched that. It was not an actual capacity test wrt the ratings of 100 AH but was a comparative test using Wh. The draw was at 80 amps if I got that right. I missed what that 1200Wh at the start was all about.

It was sort of a blur, but AFAIK he also reduced the amp load before the end for some reason I missed. ?

Anyway, whatever he was doing there was not an AH capacity test using the 20 hr rate.

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3 tons

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Posted: 05/15/21 06:47pm Link  |  Quote  |  Print  |  Notify Moderator

“ 1) You need to disable Float mode in converter or set it below 13V. Cheaper converters don't have this option and neither do cheap solar chargers. Even not very cheap "Li-compatible" solar chargers will require setting a custom charging profile because the chances that its preset Li profile will match your Li battery are slim.

2) Equalization MUST be disabled. Luckily, most chargers allow this.”

Once the LFP is charged (to whatever desired user acceptable level - a LFP thingy...) with an existing multi-stage converter-charger, all you need to do is shut off the converter-charger at the breaker panel (or solar charge controller)...Another option (if so inclined...) would be to install a disconnect switch at the battery terminal, and keep the onboard converter-charger active, Presto, problems solved...

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Almot

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Posted: 05/15/21 06:55pm Link  |  Quote  |  Print  |  Notify Moderator

jaycocreek wrote:

Will Prowse explains somethings very good and others not so much...For someone completely new to lifepo4 he is about the only one trying to explain things...

Battleborn capacity test with heat gun

Confirms that Li available capacity = nominal capacity, more-less.

Offbrand Ruixu - or, let's say, Chinese brand - in this video came up with a slightly higher available capacity per same nominal 100AH.

He is talking how Ruixu will die if you freeze it, but the difference in minimum charging temp btw Ruixu and Battleborn is minor, 25F Battleborn and 32F Ruixu. Minimum temps for discharging and storage are the same 4F for both.

Since the time of this video Battleborn price dropped a little but Chinese brands dropped a lot, you can get 100AH now for less than $600 - this is from established US resellers, not China-direct. They will eventually kill US Li brands same as they killed US and European solar panels. Though I believe Battleborn are only assembled in the US.

steveh27

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Posted: 05/16/21 04:53am Link  |  Quote  |  Print  |  Notify Moderator

I have two 100AH Lifepo4 batteries hooked to make 200 ah available. They have a BMS. I have a PD4635 convertor charger. It works well with these. IF I want to charge them fully I push in the boost button. But I never do that. The charger gets them up to 13.7 volts.

My 130 amp alternator goes through a battery isolator then two 40 amp breakers. It seems to work well. My Trimetric monitor shows the alternator will get them up to 14.4 volts then the BMS shuts down the charging. (At least I think that is what's happening.) I drove 800 miles and it went well.

I have yet to use my portable 120 watt solar suitcase which I mainly use boondocking in the winter in FLA.

BFL13

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Posted: 05/16/21 07:07am Link  |  Quote  |  Print  |  Notify Moderator

Others who have LFP will have to confirm, but AFAIK, the 13.7 is too low for the cell balancing to get started, and that needs to be done every so often. I think the balancing can be observed on the Trimetric.

The 14.4 BMS action seen might be the balancing starting, but if you are driving and stop, I don't know how it can finish balancing.

BB says:
1. passive balancing process is activated by the BMS at the top of each charge cycle, when the battery voltage exceeds around 14V. This ensures that all the cells remain at the same state of charge, which helps for pack longevity and performance.

2.For your Bulk/Absorption stage, the ideal voltage is between 14.2v-14.6v. For full charge and BALANCE, the absorption mode should be set to last for at least 20 minutes per battery (for multiple batteries in parallel).

* This post was edited 05/16/21 07:19am by BFL13 *

Itinerant1

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Posted: 05/16/21 09:30am Link  |  Quote  |  Print  |  Notify Moderator

You wouldn't know cell balancing is happening off a monitor that is showing just pack voltage other than it happens at x-voltage, bms's use individual cell voltages not pack voltages.

"If" you can see individual cell voltages you would be able to see the runners that should slow down after they reach the balancing voltage while the slower cells catch-up.


12v 500ah (5,120Wh usable), 20 cells_ 4s5p (GBS LFMP battery system). 8 CTI 160 watt panels (1,280 watts)2s4p,Panels mounted flat. Magnum PT100 SCC, Magnum 3012 hybrid inverter, ME-ARC 50. Installed 4/2016 been on 24/7/365, daily 35-45% DOD 1,800+ cycles.

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