Parking up your van for the winter Battery advice

[jeffmossy]

Remember if you park your van up for the winter months , don't forget to look after the batteries ......
All batteries, regardless of their chemistry, will self-discharge. The rate of self-discharge for lead acid batteries depends on the storage or operating temperature. At a temperature of 80 degrees F. A lead acid battery will self-discharge at a rate of approximately 4% a week. A battery with a 125-amp hour rating would self-discharge at a rate of approximately five amps per week. Keeping this in mind if a 125 AH battery is stored for four months (16 weeks) winter without being charged, it will lose 80 amps of its 125-amp capacity. It will also have severe sulfation, which causes additional loss of capacity. Keep your batteries charged while not in use.

 

[Steveandjulie]

Thanks for the advice Jeff

 

[Trek]

If your batteries are lead acid and have caps on the top then i would check the water levels in them and top them up as necessary with distilled water and then charge battery

In deepest winter i leave EHU Cable connected but on a timer so its only on for an hour a day

 

[cliveandann]

While it is a good idea to look after your batteries I think your figures need some clarification. Are the batteries disconnected? If so the self discharge figures you quote are excessive. Yes the rate of discharge varies significantly with temperature but why use the rate at 80 degrees F to calculate the amount of discharge during the winter months assuming you are referring to storage in the UK.

From Battery University regarding lead acid batteries
At a room temperature of 20°C (68°F), the self-discharge is roughly 3% per month and the battery can theoretically be stored of 12 months without recharge. With a warm temperature of 30°C (86°F), the self-discharge increases and a recharge will be needed after 6 months
https://batteryuniversity.com/learn/article/elevating_self_discharge
Note these figures refer to the amount of discharge per month not per week. At 0 degrees C the amount of discharge would be around 3% over a period of 3 months. I have left a car for 6 months with a disconnected battery and it started immediately without recharging the battery.

Its a different matter if the battery remains connected. On a modern vehicle there is a constant drain by the vehicle electronics which will vary from vehicle to vehicle. Disconnecting the battery might cause issues with the electronics which would need resetting when the vehicle battery is reconnected. In these circumstances it is best to trickle charge the vehicle battery. The leisure batteries could be disconnected if required .
I agree that if the batteries are allowed to significantly discharge (<60% state of charge) then there will be sulphation.

Remember if you park your van up for the winter months , don't forget to look after the batteries ......
All batteries, regardless of their chemistry, will self-discharge. The rate of self-discharge for lead acid batteries depends on the storage or operating temperature. At a temperature of 80 degrees F. A lead acid battery will self-discharge at a rate of approximately 4% a week. A battery with a 125-amp hour rating would self-discharge at a rate of approximately five amps per week. Keeping this in mind if a 125 AH battery is stored for four months (16 weeks) winter without being charged, it will lose 80 amps of its 125-amp capacity. It will also have severe sulfation, which causes additional loss of capacity. Keep your batteries charged while not in use.

 

[wildebus]

I will be putting a heat pad (like you have for lizards, snakes and the like) in my battery bank to keep them warmer than ambient as during the late autumn to mid-spring, where I am the night temp usually falls below zero and in winter the temp may be below freezing for many consecutive days.

The Solar should provide enough power for this so will be self-substaining.

 

[hairydog]

The rate of self-discharge for lead acid batteries depends on the storage or operating temperature. At a temperature of 80 degrees F. A lead acid battery will self-discharge at a rate of approximately 4% a week.

I don't know where you got those figures from, but I strongly dispute them, even allowing for the fact that more sensible storage temperatures will reduce the self-discharge rate.

This is from the specification sheet of my leisure battery:

Self-Discharge 77℉(25℃)
Capacity after 3 month storage 91%
Capacity after 6 month storage 82%
Capacity after 12 month storage 64%