Smart Shunt and a new battery?

[mpking]

My Group 24 battery finally died.

I went out and bought a Group 31. After evaluating our camping style, we determined our trailer fits into the "Trailer Park Queen" category. Well, not really, but we have electric hook ups at 99% of the places we go, and over the last 4 years, the group 24 has met my needs.

Anyhow, I set the Battery AH setting to 98 (The number on the spec sheet of the battery).

Is there anything else I should do? Any calibration? Any other setting I should change? It's the same chemistry. I know it's trendy to go with a LiFePO4, but I only Paid $160 for the battery and a new Battery box to hold it.

[TucsonJim]

Mike - Great question. I assume that your new Group 31 battery is flooded lead acid. If you want to maximize the life of the new battery, you should not use more than 50% of the available capacity before recharging. I'd set the AH to 49 of 50. That way, when you've used that much power, the meter will say you're depleted.

Jim

[mpking]

Mike - Great question. I assume that your new Group 31 battery is flooded lead acid. If you want to maximize the life of the new battery, you should not use more than 50% of the available capacity before recharging. I'd set the AH to 49 of 50. That way, when you've used that much power, the meter will say you're depleted.

Jim

Interesting.

Victron seems to have taken this into account, sorta...
Yes, don't discharge below 50%. But the "Time To Discharge" is calibrated for this 50% value..

7.2.3. Discharge floor


The “Discharge floor” parameter is used in the "time remaining" calculation. The battery monitor calculates the time it takes until the set “discharge floor” has been reached. It is also used to set the state of charge alarm defaults.

For lead-acid batteries set this to 50% and for lithium set it lower.

I'm going to put in the actual value, and continue with never going below 50% if I can help it.

[ncitro]

mpking It comes down to who is going to be using it. If it was an owner who is very comfortable with his system I set it to 100%, but I have done a few setups for friends who are shall we say a bit less technical. In those cases its easier to set it to 50% capacity then to tell them not to go below 50% SOC.

[mpking]

So I'm back with a follow up question.

The Group 31 battery I bought in May died. Seriously. 10 volts after charging for 3 days. Since I did end up buying the battery from Interstate, I'm attempting a warranty exchange.

The interstate guy indicated they will test the battery for internal failure. He said that improper use validates warranty.

The trailer has been plugged in almost every single day since May. Other than driving from site to site, it's only been off power for about 24 hours one day when I had the bearings repacked. Am I using the battery "Improperly"?

I did some basic tests before I disconnected the battery. When I connect the trailer to power, the SmartShunt shows 13.32V, and POSITIVE 7.10A. When disconnected from power, the Shunt shows 10.52V and -0.45A

I'm assuming this show the charger is putting sufficient power to charger a battery? (He mentioned some chargers don't put out enough amps to charger a group 31 battery).

[howson]

mpking

What are the parameters for your battery? In other words, what does Interstate say is "fully charged" and is there a graph that shows a %-to-voltage (to indicate SoC)?

Approximately 1/2 amp draw when disconnected from shore (with "nothing" on in the camper) is not unusual. (For other readers, "nothing" is even with the battery disconnect OFF or the key can be removed.)

Assuming the battery is a 100aH lead acid, that means in a temperate environment (not too hot or too cold) it should last a little over 4 days until it gets to 50% discharge. .5A x 24H = 12aH/day 50/12 is about 4 days. At the 7 day point the battery will be exhausted and, if left for any period, will likely lose some of it's life-cycle capability.

As you know since you're a regular, I highly recommend a LifePO4. The chart below was developed for the "Solar 102" presentation I'm giving at the rally. Hopefully it's self-explanatory and will justify the lithium's up-front expense.

Howard

[TucsonJim]

Mike,

The converter/charger in your 2800BH should be a WFCO 30 amp AC, 55 amp DC power center. It will provide plenty of current to charge a group 31 battery, so the battery guy is off base with the comment about lack of power. It sounds like that battery should be replaced under warranty.

Jim

[mpking]

Mike,

The converter/charger in your 2800BH should be a WFCO 30 amp AC, 55 amp DC power center. It will provide plenty of current to charge a group 31 battery, so the battery guy is off base with the comment about lack of power. It sounds like that battery should be replaced under warranty.

Jim

That was my take. I was a little salty when I wrote that update. The fact that I'm reading 13.3 and 7amps on the battery shows the charger is doing it's job trying to charge the battery.

howson, I know that Lithium is the better bang for the buck, but the trailer is on shore power 99% of the time. I've only been in a dry campsite once in the last 3 years, and that site is no longer available to me. I couldn't' justify the extra $500 this time around. Next battery replacement We'll see.

[TucsonJim]

Hey Mike mpking - My son just bought one of these Weize batteries for $260. These prices are getting very interesting and I'm wondering how the guys charging $850 or more will be able to compete?

https://www.weizeus.com/collections/...44090015088868

Jim

[mpking]

Hey Mike mpking - My son just bought one of these Weize batteries for $260. These prices are getting very interesting and I'm wondering how the guys charging $850 or more will be able to compete?

https://www.weizeus.com/collections/...44090015088868

Jim

I just heard back from interstate. They are replacing the battery, it had an internal cell failure, and it's covered by warranty.

The lithium market is going to get very interesting. The spec sheet on that battery states it has a low temperature cut off in the BMS. I've watched a few of the Will Prose videos, and when he cuts the batteries open, a lot of times they don't actually have the low temp cutoff.

If I knew about this battery in May, i would have bought it. (I did look at the Li-ion battery brand, but they were still $500-600 at the time). Just comparing the datasheet, the weize states 2000 cycles, and the LION brand states 3500 cycles. So there is a difference.

[Lonestar]

I just heard back from interstate. They are replacing the battery, it had an internal cell failure, and it's covered by warranty.

The lithium market is going to get very interesting. The spec sheet on that battery states it has a low temperature cut off in the BMS. I've watched a few of the Will Prose videos, and when he cuts the batteries open, a lot of times they don't actually have the low temp cutoff.

If I knew about this battery in May, i would have bought it. (I did look at the Li-ion battery brand, but they were still $500-600 at the time). Just comparing the datasheet, the weize states 2000 cycles, and the LION brand states 3500 cycles. So there is a difference.

Obviously LifePO4 is the future, but I'm still not sure it's cost effective at this point for those of us that camp virtually 100% of the time with shore power available. At the price of the battery being 2 to 3 times as expensive as a FLA battery at minimum, and probably needing to replace the converter, I'm still trying to see the benefit.

With that said, when I replaced my WFCO converter, if I had been thoughtful enough to get one compatible with the lithium batteries, I'd probably have to have a LifePO4 just to be state of the art.

[ncitro]

Obviously LifePO4 is the future, but I'm still not sure it's cost effective at this point for those of us that camp virtually 100% of the time with shore power available. At the price of the battery being 2 to 3 times as expensive as a FLA battery at minimum, and probably needing to replace the converter, I'm still trying to see the benefit.

With that said, when I replaced my WFCO converter, if I had been thoughtful enough to get one compatible with the lithium batteries, I'd probably have to have a LifePO4 just to be state of the art.

If you are on shore power 100% of the time you do not need to replace your converter, it will simply not charge them to 100%, which should actually make them last longer. They last 2-3 times as long as a lead acid, so the math is there. A huge number of electrical issues stem from a bad battery, even if you are on shore power. I would just do one, no reason for a huge array of batteries if on shore power, but one Lithium can be a valid option for pretty much anyone at this point.

[Lonestar]

ncitro

I thought about the converter after I made the above post and you are correct. And if the costs of the Lithium batteries keep coming down the math will prove it's a no-brainer.