Harmony5000
New Member
- Joined
- Feb 8, 2022
- Messages
- 54
Hi, I have some questions regarding charge/discharge of lifepo4 in hot environments. I’d like to have a better understanding of risks and possible solutions.
Right off the bat does anyone have experience charging/discharging lifepo4 in a van where outdoor temp reaches an average of 80-85f while they are away from the car all doors and windows closed?
Here is the scenario:
Need to charge/discharge 200ah of lifepo4 battery daily in a city environment (L.A.)while I’m away from the vehicle. High daily outdoor temp in summer months (3 months) is steadily 80-85 degrees fahrenheit. Of course there could be days reaching higher or lower but this is about average high temp each day rest of the year seems to be in the 70s. If anyone lives LA let me know if I’m mistaken? I’ll be parked near Venice beach.
From what I understand temperatures in a vehicle parked in direct sunlight under these conditions can reach 130 on days that are 85. 140 if there is something like a 95 degree day. I’m unsure if that is ambient air temp or surface temp (like dashboard/seat). The batteries themselves won’t be in direct sunlight.
Right now my only defense is custom sunshades I’ve built with Reflectix material (sturdy reflective bubble wrap type material) installed on the interior of the windows. They are fit to where absolutely no sunlight comes in. From what I understand this method dramatically lowers surface temperatures but may have little effect on ambient air temperature - the site that gave that report posted a photo with similar material but it was not tightly fit so I have a one up on that. Their report said ambient air temp was only lowered by 1 degree.
Right now I’m choosing my batteries for the project. It seems like trusted manufacturers charging at high temp shuts off at 113 degrees. Reports for cheaper batteries such as zooms, ampertime, chins, 122. Obviously from what I read we can’t trust reports from company’s like those. Also, the bms systems don’t seem to be reliable for low temp cutoff (not a problem in my case) and I’ve seen some reports of low voltage disconnect not working. I will be using 1 battery outside of the van during the day and completely running it out of juice at times so this concerns me. Just the fact that the temperature inside the vehicle may reach 130-140 and if a cheaper batteries bms fails to employ high temp cutoff this concerns me.
Ok so risks/solutions
Risks:
Battery Life- I understand battery life may be shorted in hot environments. This isn’t a concern to me if the batteries can still be used for 1-2 years. Renogy customer service says they can be stored at 149 degrees which might be the very high air temp in the car a few days. In almost all reports I see temperatures like 149 are at the top of surface temp in direct sunlight not ambient air temp.
BMS - if a cheaper battery is chosen and the bms high temp cutoff fails how likely is it that fire, explosion, or fuming could be a thing?
Battery Choice - right now I’m looking at buying 3 units of 100ah SOK on the high end. Weize (low temp cutoff seems to work and high temp cutoff rating is 113f exactly like battleborn and sok maybe I can trust them?) and on the cheaper side zooms, ampertime, chins. Suggestions? Money is extremely tight but safety is most important. I currently do have a 100ah lithium ion battery (not lifepo4) by SmartBattery 6 years old lots of use, should I discard that/not use under these conditions?
Solutions:
I’ve mentioned the reflective shades. Maybe they can lower to 113 but I have no way of testing and that sounds like an iffy bet.
Would installing simple vent/fan to cycle air from the interior to exterior of the van help? I believe I could build some that slot into the driver and passenger window after I park to move air in and out of what I think would be the area of the van most prone to heat build up (windshield).
Insulated battery box, how much would that help if at all I don’t know?
Ac- I don’t believe I have enough AH to run that and meet my charging needs. I had thought of putting a small portable AC and directly aiming it at the batteries but most of those seem to use evaporative moisture so that’s a no go and if they don’t it’s just more power consumption or maybe ineffective (cool breeze?)
At best I’d just like to keep the batteries under the 113 operating range so they can charge all day. At worst I’d like the BMS to safely shut them off and lose some hours of daytime charging. Also are there any recommended fail safes?
Here’s my system 500w renogy solar, 40a mppt renogy charge controller, 200ah battery to be determined, 900watt xantrex inverter connected to 45w 12v fridge and a secondary charger charging the old 100ah lithium ion (SmartBattery brand) if it sounds safe under the circumstances, or new lifepo4 if that’s a better option?
Thanks so much for taking the time with my post!
Right off the bat does anyone have experience charging/discharging lifepo4 in a van where outdoor temp reaches an average of 80-85f while they are away from the car all doors and windows closed?
Here is the scenario:
Need to charge/discharge 200ah of lifepo4 battery daily in a city environment (L.A.)while I’m away from the vehicle. High daily outdoor temp in summer months (3 months) is steadily 80-85 degrees fahrenheit. Of course there could be days reaching higher or lower but this is about average high temp each day rest of the year seems to be in the 70s. If anyone lives LA let me know if I’m mistaken? I’ll be parked near Venice beach.
From what I understand temperatures in a vehicle parked in direct sunlight under these conditions can reach 130 on days that are 85. 140 if there is something like a 95 degree day. I’m unsure if that is ambient air temp or surface temp (like dashboard/seat). The batteries themselves won’t be in direct sunlight.
Right now my only defense is custom sunshades I’ve built with Reflectix material (sturdy reflective bubble wrap type material) installed on the interior of the windows. They are fit to where absolutely no sunlight comes in. From what I understand this method dramatically lowers surface temperatures but may have little effect on ambient air temperature - the site that gave that report posted a photo with similar material but it was not tightly fit so I have a one up on that. Their report said ambient air temp was only lowered by 1 degree.
Right now I’m choosing my batteries for the project. It seems like trusted manufacturers charging at high temp shuts off at 113 degrees. Reports for cheaper batteries such as zooms, ampertime, chins, 122. Obviously from what I read we can’t trust reports from company’s like those. Also, the bms systems don’t seem to be reliable for low temp cutoff (not a problem in my case) and I’ve seen some reports of low voltage disconnect not working. I will be using 1 battery outside of the van during the day and completely running it out of juice at times so this concerns me. Just the fact that the temperature inside the vehicle may reach 130-140 and if a cheaper batteries bms fails to employ high temp cutoff this concerns me.
Ok so risks/solutions
Risks:
Battery Life- I understand battery life may be shorted in hot environments. This isn’t a concern to me if the batteries can still be used for 1-2 years. Renogy customer service says they can be stored at 149 degrees which might be the very high air temp in the car a few days. In almost all reports I see temperatures like 149 are at the top of surface temp in direct sunlight not ambient air temp.
BMS - if a cheaper battery is chosen and the bms high temp cutoff fails how likely is it that fire, explosion, or fuming could be a thing?
Battery Choice - right now I’m looking at buying 3 units of 100ah SOK on the high end. Weize (low temp cutoff seems to work and high temp cutoff rating is 113f exactly like battleborn and sok maybe I can trust them?) and on the cheaper side zooms, ampertime, chins. Suggestions? Money is extremely tight but safety is most important. I currently do have a 100ah lithium ion battery (not lifepo4) by SmartBattery 6 years old lots of use, should I discard that/not use under these conditions?
Solutions:
I’ve mentioned the reflective shades. Maybe they can lower to 113 but I have no way of testing and that sounds like an iffy bet.
Would installing simple vent/fan to cycle air from the interior to exterior of the van help? I believe I could build some that slot into the driver and passenger window after I park to move air in and out of what I think would be the area of the van most prone to heat build up (windshield).
Insulated battery box, how much would that help if at all I don’t know?
Ac- I don’t believe I have enough AH to run that and meet my charging needs. I had thought of putting a small portable AC and directly aiming it at the batteries but most of those seem to use evaporative moisture so that’s a no go and if they don’t it’s just more power consumption or maybe ineffective (cool breeze?)
At best I’d just like to keep the batteries under the 113 operating range so they can charge all day. At worst I’d like the BMS to safely shut them off and lose some hours of daytime charging. Also are there any recommended fail safes?
Here’s my system 500w renogy solar, 40a mppt renogy charge controller, 200ah battery to be determined, 900watt xantrex inverter connected to 45w 12v fridge and a secondary charger charging the old 100ah lithium ion (SmartBattery brand) if it sounds safe under the circumstances, or new lifepo4 if that’s a better option?
Thanks so much for taking the time with my post!
