LifePo4 in the engine room. Heat considerations?

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Portage_Bay

Portage_Bay

Guru
Joined
Oct 19, 2015
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2,670
Location
United States
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Pacific Myst
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West Bay 4500
This renewed thread Eco-worthy batteries has me considering lithium when the big old golf car batteries wear out. Because they are in the engine room that would be the easiest place to install the lithium bank. The other place is the lazarett. I'd have to move some components from the laz to the engine room ex-house bank flat. Not impossible just a lot of extra work. What are your thoughts on LifePo4 tolerance for heat? For this discussion all considerations of BMS, cabling, fusing, charge regulation etc aside.
 
Of course depends upon the actual conditions in your engine room but I don't have any major concerns for mine. For $40 you can get the little Victron Bluetooth voltage/temp monitors. You can adjust the charge rate as needed. Max temp for many is in the 140 degree F range but I would aim for 100-120 max to provide some headroom.
 
READY said:
Of course depends upon the actual conditions in your engine room but I don't have any major concerns for mine. For $40 you can get the little Victron Bluetooth voltage/temp monitors. You can adjust the charge rate as needed. Max temp for many is in the 140 degree F range but I would aim for 100-120 max to provide some headroom.
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Thank you. I was thinking they are much more heat sensitive than that.
 
READY said:
Of course depends upon the actual conditions in your engine room but I don't have any major concerns for mine. For $40 you can get the little Victron Bluetooth voltage/temp monitors. You can adjust the charge rate as needed. Max temp for many is in the 140 degree F range but I would aim for 100-120 max to provide some headroom.
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Something to seriously think about.

I am underway right now in the Sea of Cortez. It is 86 F outside, and 110F in my engine room right now, and it's barely summer.

What happens in two months when it's 100 outside? How will the batteries do then.

This is a serious thought for my cruising. It's probably not an issue but hot temperatures are a fact of life on a boat, and the engine room/lazarette as house battery location is also normal.
 
I think the short answer is that an engine room is not a good place for LFP batteries. Bet there may be more to it if you want to dig in

It’s common for batteries to be located low in the machinery space, in close proximity to the hull which of course is in contact with the sea water. So areas low and near the hull surface will likely be the coolest area in an ER, and may be kept cooler by insulating them from the heat in the rest of the ER.

Assuming you will be using your boat with the existing batteries for a while longer, I would get a remote thermometer, place it next to the batteries, and monitor how warm it gets. The goal would be to stay as much below 100F as possible, preferably below 90F. If the area is getting hotter than that, try building a temporary shelter or baffle out of foam board to see what happens if you insulate the batteries from the engine heat. The hope would be that nothing more than some insulation will keep the existing battery location acceptably cool.
 
Yes insulating from engine heat would be good but I don't think it should be in a sealed box due to heating during charging. I will provide some actual data in a month or two on mine that sit aft of the 2 Ford Lehmans. I will be in the Sacramento delta so should see some hot weather.
 
Another consideration is alternator heat output. My engine room temps are very different when I’m generating 40 amps vs. 400 amps. I bring it up because the alts will probably run longer and harder with the new batts depending on bank size and running them down to 20% vs. 50%
 
The strange part is that LiFePO4 will actually start to perform better in high temperatures. So that is not exactly the problem. The problem is that all you other equipment most likely cannot handle it. You can of course move the LiFePO4 to a different location, but you can also think of cooling down the ER. My ER used to be hot as well, even getting up 140 - 150 Fahrenheit, so that is when I decided to install industrial ventilators in order to get the temperature down to normal levels.
I did not have space in the ER, so my batteries are in the lazarette, but if I would have had space I would not have had a problem putting them in the ER.
 
I converted from 6x6v golf carts to 7x100ah LFP a few years ago (much better options now than multiple 100ah, but a different topic). The 400lbs of golf carts were in the engine room, low. Between the stringers. Prime real estate for a small boat. So I moved them to the lazarette, outboard.

I didn't think about engine room heat but should have. As Ksanders says, it's damn hot down south (my FLA engine start battery is in the engine room and regularly sees 110F while underway - I give it 2-years). I suppose if you're cruising in the PNW which I believe you are, less of an issue.

I wanted to regain space and frankly, LFP are long lived and need near zero maintenance so there's no reason for them to be in an easily accessible space. Cabling is expensive but it's a one shot deal.

One item that hasn't been mentioned is getting the inverter as close as possible to the LFP bank. For the most part, the LFP evolution is being driven by increased 120/240 VAC usage so inverters are getting larger with more usage. Makes sense to have them close to the LFPs. Plus heat affects inverters too - I forget the exact percentage and temp, but at 100F, inverter efficiency drops to something like 80%-85% of it's rated output (someone check this for me).

Good luck with whatever you decide. Personally, while engine room heat is interesting, I think there's a holistic conversation that grabs more than environmentals.

Peter
 
My LFP's are in the ER. The spec says do not charge them if above 122°F. I put a batt temp monitor next to them and during the last 12 months they have not been above 115. I have not run the engines hard, and seldom need too, on hot days. If the ER temp is getting up then I can leave the ER door open to aid ventilation, and that makes quite a difference.

Having said that, it would be best to have the LFP's and inverter out of the ER. My inverter capcity of 3000VA de-rates quite a lot with increased temp.
 
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Insequent said:
My LFP's are in the ER. The spec says do not charge them if above 122°F. I put a batt temp monitor next to them and during the last 12 months they have not been above 115. I have not run the engines hard, and seldom need too, on hot days. If the ER temp is getting up then I lcan leave the ER door open to aid ventilation, and that makes quite a difference.

Havinf siad that, it would be best to have the LFP's and inverter out of the ER. My inverter capcity pf 3000VA de-rates quite a lot with increased temp.
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As an interesting note, running harder doesn't necessarily lead to higher engine room temps. My engine room temps actually drop a couple of degrees up on plane as the engines are pulling significantly more air though the space (and they draw from up high as well). Temp rise after shutdown is a little more if the boat was run on plane shortly before shutdown though.

My AGM start batteries are in the engine room and are on season 7 (installed spring of 2018). My house batteries are outside the engine room, but realistically they should be in the engine room aft of the holding tank for weight distribution purposes. Fortunately that's down low in the hull and easy to shield them from engine heat, so I don't anticipate any issues with keeping them cool enough if I relocate them at some point. Highest engine room temps I've ever recorded were about 110 at the top of the engine room with outside temps in the low 90s and water temps in the low 80s. Worst case I can duct some outside air directly to the battery area.
 
Slight thread drift, but does anyone know if the relevant operating temperature range is ambient (the engine room) or internal (the actual battery temperature)? My victron bms has a setting to prevent charging at +5c but it's clearly using it's own internal measurement of the battery and not room temperature.
 
I had three identical AGM, about 3-years old. Two for bow thruster in forward area under v-berth. One next to engine in engine room for a start battery. Back in Puerto Vallarta I sort of suspected the engine battery was getting anemic so load tested them (thanks Scot/Muirgen). The engine battery was shot, the two in the forward area were mildly depleted but serviceable. I attribute the difference entirely to heat in the engine room. Thinking back, the engine start battery probably didn't get used more than 100 times.

Heat is the enemy......

Peter
 
RobertLeatch said:
Slight thread drift, but does anyone know if the relevant operating temperature range is ambient (the engine room) or internal (the actual battery temperature)? My victron bms has a setting to prevent charging at +5c but it's clearly using it's own internal measurement of the battery and not room temperature.
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I think it’s the battery temp, but the two won’t differ much under most circumstances. Unless you are heavily charging or discharging, say 0.3C or higher for prolonged time, there is very little heating in the batteries. My max charge rate is about .3 C and after 2 hrs I might see a 10F rise in battery temp as reported by the BMS. At slower charge rates the temp barely changes at all.
 
I have a friend that installed a bank of GNB 3.2VDC cells in his 45’ Marine Trader engineroom, in the bilge between the propulsion engines. After about two years he load tested several of the cells and found that they had lost about 18% of their capacity.
 
twistedtree said:
I think it’s the battery temp, but the two won’t differ much under most circumstances. Unless you are heavily charging or discharging, say 0.3C or higher for prolonged time, there is very little heating in the batteries. My max charge rate is about .3 C and after 2 hrs I might see a 10F rise in battery temp as reported by the BMS. At slower charge rates the temp barely changes at all.
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That was my assumption to but I see quite a difference in the ambient/battery temp. My 3 victron 330amp LiFePO4 all show temps in the low 20c but my current room temp is 11c (I'm in southern Tasmania). Current SoC is 100% with minimal load or charge (on shore power). I've played around with the bms setting to test (changing it until it triggers the stop charge circut) and its definitly reading off the internal temp. I prefer it this way because in my location temps below 5c are very likely and would mean I couldn't routinely recharge. Just dont understand it.
 

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CharlieJ said:
I have a friend that installed a bank of GNB 3.2VDC cells in his 45’ Marine Trader engineroom, in the bilge between the propulsion engines. After about two years he load tested several of the cells and found that they had lost about 18% of their capacity.
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Any idea what temps they were experiencing?
 
RobertLeatch said:
That was my assumption to but I see quite a difference in the ambient/battery temp. My 3 victron 330amp LiFePO4 all show temps in the low 20c but my current room temp is 11c (I'm in southern Tasmania). Current SoC is 100% with minimal load or charge (on shore power). I've played around with the bms setting to test (changing it until it triggers the stop charge circut) and its definitly reading off the internal temp. I prefer it this way because in my location temps below 5c are very likely and would mean I couldn't routinely recharge. Just dont understand it.
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That’s odd. What’s he sea temp vs outside ambient temp?
 
twistedtree said:
That’s odd. What’s he sea temp vs outside ambient temp?
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Sea temp is 15.6c. Outside now 12.7c (9:30 in the morning and sunny). My best theory (which I cant test at the moment) is that the normal internal temp of the battery is inherently around 20c. Unless the ambient temp difference is large (perhaps around 10c) then battery doesn't lose much heat. At some point it must because of things tending to equilibrium. When it gets hotter (room above 20c) perhaps it absorbs heat quicker so that you see room and battery temp closer faster. There may be some physics involved to explain how heat moves to/from different objects based on relative size, temp difference, surface area etc.

I'll check next time underway when my engine room will get hotter to see how they align when the ambient temp is greater than battery temp. Just another rabbit hole in the great boating field.
 
Most manufacturers literature show decreasing life with increasing service temperature (above room temp). The optimum service life seems to be fairly low temps, like 40 or 50F, dropping again as you go lower. Same is basically true of lead acid cells as well - high temperature isn't good for batteries.
 
READY said:
Of course depends upon the actual conditions in your engine room but I don't have any major concerns for mine. For $40 you can get the little Victron Bluetooth voltage/temp monitors. You can adjust the charge rate as needed. Max temp for many is in the 140 degree F range but I would aim for 100-120 max to provide some headroom.
Click to expand...
I have one of those on my boat. The idea was to send battery information from the batteries to the Victron Solar Charge controller. Due to issues related to cabling, the charge controller is in the pilothouse. The batteries at in the after lazarette. The bluetooth range isn't good enough for the charge controller to get the signal from the battery monitor.
 
RobertLeatch said:
Slight thread drift, but does anyone know if the relevant operating temperature range is ambient (the engine room) or internal (the actual battery temperature)? My victron bms has a setting to prevent charging at +5c but it's clearly using it's own internal measurement of the battery and not room temperature.
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+5C =41F
That is not hot, why would the BMS prevent charging at these temperatures? Did You mean below 5C/41F?
 
SteveK said:
+5C =41F
That is not hot, why would the BMS prevent charging at these temperatures? Did You mean below 5C/41F?
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No definitely centigrade. See attached. The discharge values are more what you would expect (-20c to +50c ) but the charging range is +5c to +50c. The manual actually say you will void the warranty if you charge below this however (to the ambient / battery topic) I've never seen the battery temp go below about 18c even when the ambient is around 5c.
 
Attachment for above.
 

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twistedtree said:
That’s a new one to me. Never seen that in any of the research. Just that elevated temps are the biggest factor in aging.
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There is a youtube channel that did research on LiFePO4 batteries, in fact did very extensive tests and they found out that these batteries start performing better when the temp gets up.
I will see if I can find the link to this video, is about 30 min video, they did a real scientific set up and the data for the test is thousands of pages. I found the test when I was researching whether I wanted to change to LiFePO4 or not.
 
Lead acid batteries also perform better at high temps. But the lifespan gets significantly shorter.
 
READY said:
For $40 you can get the little Victron Bluetooth voltage/temp monitors.
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Interesting. Can the Smart Battery Sense stand alone and report temperature and voltage via Bluetooth without using a Victron system? We have an older Xantrex inverter charger.
 
Mambo42 said:
There is a youtube channel that did research on LiFePO4 batteries, in fact did very extensive tests and they found out that these batteries start performing better when the temp gets up.
I will see if I can find the link to this video, is about 30 min video, they did a real scientific set up and the data for the test is thousands of pages. I found the test when I was researching whether I wanted to change to LiFePO4 or not.
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I'd be real interested to see that if you can find it. I'd be interested in what aspect of performance improves, and whether there is any indication that it doesn't also cost you in lifespan at the same time. Depending on the application, trading lifespan to greater performance might make sense, but I doubt it's a good choice for a house bank.
 
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