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Those GBS cells are exactly what I have in my system - and they are NOT low cycle life batteries, they are rated for several thousands of cycles. For them, you need a BMS like the Elite Power Management system I have (https://www.elitepowersolutions.com/bms) - that has a circuit board for each cell of the battery that monitors cell voltage and temperature, and an over-all controller that talks to all the cell management boards, plus a high current contactor to do the disconnects (I use a TE Connectivity such as https://www.mouser.com/ProductDetail/TE-Connectivity-Raychem/LEV200A4NAF01?qs=R3KmN9Esfyu4S3%2BHsvZmmw==) .
I don't think anyone meant to imply low, not me, just lower compared to LiFePO4, of course they are lighter, which is good. From what I understand (not a chemist) the lower weight LiFeMnPO4 would expect a cycle life of 1500-2000 cycles rather than 3000-5000 from the heavier LiFePO4 cells. But I could be wrong. 1500 - 2000 is not low life cycle but are relatively lower. (or course neither has been around long enough for most people to really know if either is real)

I love my lithium batteries. But I think hooking up a BMS with raw cells is beyond beginner stuff. If I did it over I would probably do a custom system myself.
 

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Discussion Starter #22
I don't think anyone meant to imply low, not me, just lower compared to LiFePO4, of course they are lighter, which is good. From what I understand (not a chemist) the lower weight LiFeMnPO4 would expect a cycle life of 1500-2000 cycles rather than 3000-5000 from the heavier LiFePO4 cells. But I could be wrong. 1500 - 2000 is not low life cycle but are relatively lower. (or course neither has been around long enough for most people to really know if either is real)

I love my lithium batteries. But I think hooking up a BMS with raw cells is beyond beginner stuff. If I did it over I would probably do a custom system myself.
Yeah, nice to know someone who has used the batteries I mentioned and they are working well. As for my situation, not only does what Wowbagger said confuse me, it also looks like several hundred dollars to implement. So I don't think I'm the best candidate to try and make these work. Doing my research on venting Flooded to save some money vs AGMs.
 

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Venting kits are available. Build a box that air can enter the bottom and leave (with the hydrogen) at the top. Mine lead to the outside.
 

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Hi,

Or, skip the venting -- this is from a previous post on venting...

Hydrogen vented by the battery is 14 times lighter than air, so it REALLY wants to go upward. A pocket of hydrogen in air will rise at 45 mph. So, I don't think that even a forced vent system that tries to get the H2 to go down would work.

I seriously doubt whether any venting at all is required.
This link was found by Phil a while back -- it provides a calculator to determine how much ventilation is required for a given size battery: Battery Room Hydrogen Gas Ventilation Calculator by SBS Battery

If you take the common two golf cart battery solution and plug it in to the calculator:
6 hr discharge capacity rating: 185 amp-hrs
6 total battery cells

It predicts 0.82 cubic ft of hydrogen per hour (heavy charging)

The volume of the van as 6.5 ft wide, 6.4 ft high, and 14 ft long = 580 cubic ft

The calculator says to maintain the recommended max concentration of H2 at 1%, that you need 1 air change per 427 minutes -- that's 7.1 hours per air change. I doubt whether anyone could build a van anywhere near that tight -- a VERY good house achieves about 0.5 air change per hour.
If you have a roof fan, I'd guess that the H2 will rise rapidly to the roof fan van area and quickly leak out.

In one respect, this calculator has a large margin of safety in that h2 concentrations of less than 4% are not flammable, but the calculator uses 1% as the maximum.

I guess that something like a charger malfunction might lead to higher rates of H2 production, but if you assume the van air change rate is one air change per hour (quite tight), the margin of safety is about a factor of 7 against a 1% concentration. I don't see how alternator or solar charging could come anywhere close to this?

I don't want to encourage anyone to do anything that is unsafe, so if you have a reason why venting is needed, please speak up.

One thing I would not recommend is making the battery compartment air tight, as this could build a high concentration of H2 within the battery compartment.

If you do a vent system, I think an air inlet to the battery compartment from the van that is low in the compartment and an outlet to the sidewall of the van high in the battery compartment would be good. This is the setup I used: Our ProMaster DIY Camper Van Conversion — Electrical and Solar – Build A Green RV


Gary
 

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I've NEVER vented my flooded batteries (in a van) in 30 years or more and I have no plans to ever vent them. As Gary says "I seriously doubt whether any venting at all is required."! If my van explodes from unvented flooded batteries, I'm sure RD will find out sooner or later and report back to you all ;)!
 

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Hi,

Or, skip the venting -- this is from a previous post on venting...

Hydrogen vented by the battery is 14 times lighter than air, so it REALLY wants to go upward. A pocket of hydrogen in air will rise at 45 mph. So, I don't think that even a forced vent system that tries to get the H2 to go down would work.

I seriously doubt whether any venting at all is required.
This link was found by Phil a while back -- it provides a calculator to determine how much ventilation is required for a given size battery: Battery Room Hydrogen Gas Ventilation Calculator by SBS Battery

If you take the common two golf cart battery solution and plug it in to the calculator:
6 hr discharge capacity rating: 185 amp-hrs
6 total battery cells

It predicts 0.82 cubic ft of hydrogen per hour (heavy charging)

The volume of the van as 6.5 ft wide, 6.4 ft high, and 14 ft long = 580 cubic ft

The calculator says to maintain the recommended max concentration of H2 at 1%, that you need 1 air change per 427 minutes -- that's 7.1 hours per air change. I doubt whether anyone could build a van anywhere near that tight -- a VERY good house achieves about 0.5 air change per hour.
If you have a roof fan, I'd guess that the H2 will rise rapidly to the roof fan van area and quickly leak out.

In one respect, this calculator has a large margin of safety in that h2 concentrations of less than 4% are not flammable, but the calculator uses 1% as the maximum.

I guess that something like a charger malfunction might lead to higher rates of H2 production, but if you assume the van air change rate is one air change per hour (quite tight), the margin of safety is about a factor of 7 against a 1% concentration. I don't see how alternator or solar charging could come anywhere close to this?

I don't want to encourage anyone to do anything that is unsafe, so if you have a reason why venting is needed, please speak up.

One thing I would not recommend is making the battery compartment air tight, as this could build a high concentration of H2 within the battery compartment.

If you do a vent system, I think an air inlet to the battery compartment from the van that is low in the compartment and an outlet to the sidewall of the van high in the battery compartment would be good. This is the setup I used: Our ProMaster DIY Camper Van Conversion — Electrical and Solar – Build A Green RV


Gary
hydrogen is one item (which by itself I do not think we can smell). I believe there can be other off gasses other than hydrogen. If you smell “rotten eggs” ever, that is probably not good.



I took a photo of a factory camper vent; I will look for it & post it if I find it; edit found it


64250


64251
 

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Battery venting is simply not needed as Gary mentions. You will never get anywhere near explosive H2 concentrations with modern FLA batteries and regular van charging.
 

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I agree that the venting is not a requirement. I vented mine after I had built a battery box anyway and had it next to the driver’s side wall and realized a $20 kit and an hour would get it done. I cant say it was needed but it did no harm. BTW I did find that my batteries needed topping up from hydrolyzing water (and evaporation?) from the cells once a year and it took about 2-3 quarts of distilled water to top up the two 6 volt 215 A-H batteries. After five years and 4 refills the batteries were pristine clean, no corrosion on anything and performed as well as when new. They were $86 each from Sam’s club when I bought them. As part of my “$500 Solar and $700 complete electrical system” they more than did the job and returned value beyond their cost.
 

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BTW I did find that my batteries needed topping up from hydrolyzing water (and evaporation?) from the cells once a year and it took about 2-3 quarts of distilled water to top up the two 6 volt 215 A-H batteries. After five years and 4 refills the batteries were pristine clean, no corrosion on anything and performed as well as when new. They were $86 each from Sam’s club when I bought them.
Topping Up (if unequal top ups are needed & a pattern can be identified)

I know you take very good care of your FLA batteries, so you may already know this, but I will pass the info on incase others don’t

A Commercial Electrician buddy of mine who has experience with large commercial “electric“ passenger vehicles has loads of experience with FLA batteries (amongst all things electric). He had an issue with large battery banks & “Differential Top Ups” of individual batteries (all same age & purchased all at the same time). As he purchased a major amount of batteries from the manufacturer he had a pretty good business relationship with them & a contact. He phoned them & was told to check the battery post terminals on the ones that required “more top up typically” than the others.

Not as tight, or a small amount of corrosion on the battery terminal was the culprit.

Not as important in our van house banks vs a heavy commercial operation that punishes their batteries and need to get the massive bank up to 100% or to the degraded max capacity over night. Zero of the batteries they use make it to the replacement time (months) under warranty as the cycles are used up far before they time out.
 

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Above is one reason you don’t mix batteries of different ages or capacity.
Even cells will have a differential top up and I don’t know why. Once one cell dries down to the lead plates it will then be much worse. I have a fla battery in my F650GS motorcycle buried under the plastic. It failed after being on the maintainer on and off this winter. I don’t remember checking it last fall- my bad) 5 cells were dry to the top of the lead and the 6th had about 1” of acid in it. DEAD! It was 8 years old (6/2012) so I got good use of it and it was only $53 to replace. I almost got AGM but at twice the price it would never last 16 years. Lithium is now available at $175 but I don’t trust the charging profile.
 

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Discussion Starter #31
Above is one reason you don’t mix batteries of different ages or capacity.
Even cells will have a differential top up and I don’t know why. Once one cell dries down to the lead plates it will then be much worse. I have a fla battery in my F650GS motorcycle buried under the plastic. It failed after being on the maintainer on and off this winter. I don’t remember checking it last fall- my bad) 5 cells were dry to the top of the lead and the 6th had about 1” of acid in it. DEAD! It was 8 years old (6/2012) so I got good use of it and it was only $53 to replace. I almost got AGM but at twice the price it would never last 16 years. Lithium is now available at $175 but I don’t trust the charging profile.
RD- whenever you’ve opened your battery box have you ever noticed a smell? I guess that’s more of a concern for me with FLA than the venting at this point. Especially bc mine would be located in the “garage” aka under our bed. I’m leaning towards AGMs at the moment but you make a strong case.
 

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Hi,
I have a pair of golf cart batteries from Costco -- similar to RD's. My experience is similar. The battery terminals are as clean as the day I put them in -- no corrosion. I do use the battery terminal spray similar to this: Amazon.com: CRC Battery Terminal Protector, 7.5 oz Aerosol Can, Dark Red: Industrial & Scientific

I check the water level about every 3 or 4 months -- sometimes I have to add, sometimes not.

My batteries are vented through the sidewall, but If I were doing it again, I'd not bother with the venting.
I've never detected any kind of odor in or around the battery box.

According to the Trojan battery life cycles chart, the FLA batteries have an about 20% longer cycle life than the same size AGM battery (1200 vs 1000 cycles to 50% depth of discharge) -- half the price with 20% more life -- what a deal :)

Gary
 

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Hi,
I have a pair of golf cart batteries from Costco -- similar to RD's. My experience is similar. The battery terminals are as clean as the day I put them in -- no corrosion. I do use the battery terminal spray similar to this: Amazon.com: CRC Battery Terminal Protector, 7.5 oz Aerosol Can, Dark Red: Industrial & Scientific

I check the water level about every 3 or 4 months -- sometimes I have to add, sometimes not.

My batteries are vented through the sidewall, but If I were doing it again, I'd not bother with the venting.
I've never detected any kind of odor in or around the battery box.

According to the Trojan battery life cycles chart, the FLA batteries have an about 20% longer cycle life than the same size AGM battery (1200 vs 1000 cycles to 50% depth of discharge) -- half the price with 20% more life -- what a deal :)

Gary
In another vehicle I had I used L16 size flooded batteries (420 AH 6 volt) and they lasted longer than the vehicle was in service. Everyone loves the AGM (and now lithium) and we forget flooded batteries work just fine for many (myself included). If I add battery backup to my solar system at my house I will be using flooded batteries. (I don't care about the weight in a stationary application and lead batteries are actually better in floating applications than lithium)

Don't discount flooded batteries, even as just a starter set.
 

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Discussion Starter #35
So I'm estimating about 100Ah/day in usage. Now I'm trying to determine what size I want to make my battery bank. Is 210Ah too small? I'll have the 300w of solar and connecting to the alternator as well. But I guess if I don't run the vehicle and not exposed to sun then I run out in less than two days. For an FLA setup it's easy to put on more Ah for a good price but I'm still reluctant as I won't be venting. Anyone with a similar usage care to chime in on the size of your bank?
 

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No smell ever, venting works!
I’d say it is barely OK as the solar is going to get you full almost everyday before night and you are likely to use 60-70 amp- hours overnight. That gives you enough and recharge won’t be too long, If you don’t have sun or drive you really have only one full day. I’d shoot for 300-350 A-H of battery for 2 full days and discharge of no more than 35-40% SOC once in a while. 100 A-H is a lot. What do you have on the list? Many things use very little because they run only a little. My fan ran on 10% of its max, my refrigerator ran 25-39% of the time, my diesel heater ran on low at 10% of running on high. If you have over estimated (safe) then the 210A-H might be enough.
As a rule of thumb I like to pair the wattage of the solar with the A-H of the battery. So 300 Watts of solar paired with 300+- A-H of battery. This is for Lead-Acid of course. Lithium is a different game.
 

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Discussion Starter #37
No smell ever, venting works!
I’d say it is barely OK as the solar is going to get you full almost everyday before night and you are likely to use 60-70 amp- hours overnight. That gives you enough and recharge won’t be too long, If you don’t have sun or drive you really have only one full day. I’d shoot for 300-350 A-H of battery for 2 full days and discharge of no more than 35-40% SOC once in a while. 100 A-H is a lot. What do you have on the list? Many things use very little because they run only a little. My fan ran on 10% of its max, my refrigerator ran 25-39% of the time, my diesel heater ran on low at 10% of running on high. If you have over estimated (safe) then the 210A-H might be enough.
As a rule of thumb I like to pair the wattage of the solar with the A-H of the battery. So 300 Watts of solar paired with 300+- A-H of battery. This is for Lead-Acid of course. Lithium is a different game.
Thanks for the quick reply. Probably an overestimate and I’m almost strictly on 12v. Fridge, MaxxFan, diesel heater, led lights, water pump, and 12v outlets to charge a couple laptops and phones.
 

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I have those same items and use about 40 A-Hrs overnight, being fully charged when the sun goes down. So, 100 A-H a day may be about right, but would be a full 50% SOC of your battery bank. I would say leave room for 2 more batteries in your build, and add them if needed. I did the 4 x 6V golf batteries from Sams for 430 A-H total capacity (215 A-H usable). I also have 300W of panels, but only get about 230 watts in real life ;-)
 

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That 230 watts is about 20 amps so 2 hours of full high sun will fill the overnight use and even partly sunny should carry you in the day. Try the 210+ A-H of batteries and leave the space for the two extea batteries WanderingWakes advises.
I got along fine 95% of the time with your use and 200 Watts and the 215 A-H golf cart batteries. No amount of either or both will get you to 100%, 10 years off grid taught me that.
 

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I have those same items and use about 40 A-Hrs overnight, being fully charged when the sun goes down. So, 100 A-H a day may be about right, but would be a full 50% SOC of your battery bank. I would say leave room for 2 more batteries in your build, and add them if needed. I did the 4 x 6V golf batteries from Sams for 430 A-H total capacity (215 A-H usable). I also have 300W of panels, but only get about 230 watts in real life ;-)
Doesn't sound like Sam's carries the same options anymore. All Duracell. Is there a risk in quality there? Costco carries Insterstate. I could get 3 x100Ah AGMs (300Ah bank) from Renogy for $700, 4 x 210Ah (420Ah bank) from FLA Costco (Interstate) for around $500. From a local supplier a 370Ah bank of Trojan FLAs would be around $600.

Sam's has good prices, even 12v AGMs but again it's all Duracell branded.
 
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