Charge Batteries as a function of temperature

[martin007]

> http://language.mkbattery.com/images/GE ... arging.pdf


To compensate for battery temperature not at 20°C, subtract 0.005 V/cell for each 1°C above 20°C; add
0.005 V/cell for each 1°C under 20°C.
Applies to East Penn’s 8G product line.

* https://www.mkbattery.com/application/f ... ochure.pdf

* https://www.mkbattery.com/application/f ... teries.pdf

[martin007]

Temperature of the batteries.
* The temperature of the batteries is higher than the ambient temperature when they have been working.

[Burgerman]

Yes. But theres a safe range. (This one should be ignored. download/file.php?id=9483&mode=view )

The other two are MK gel charts. So follow them.

Since your room is usually 20C the battery will be a little higher like 25C while charging and after use. So call your 20C room, 25C for safety. So 28.2V
In summer if its 30C in your room lower the charge voltage to say 27.6 to 27.8V.

[Burgerman]

http://www.wheelchairdriver.com/MK0.pdf tech gel
http://www.wheelchairdriver.com/MK1.pdf Idealized tech charge data gel
http://www.wheelchairdriver.com/MK2.pdf AGM and GEL tech
http://www.wheelchairdriver.com/MK3.pdf Range specs, correct charge info
http://www.wheelchairdriver.com/MK4.pdf Mobility industry flyer and correct charge voltages
http://www.wheelchairdriver.com/MK5.pdf Battery flyer and correct charge voltages

Since you like reading!!!

And:

[martin007]

OK.

Then it could be said that the temperature of the batteries in charge (and use) is 5º higher than the ambient temperature.

[Burgerman]

So with the mobility charger stopping too soon (sulfation remains).
And the Voltage too high (14.4 to 14.7V per battery, you can see why the MKs dont last very well now!

[martin007]

you can see why the MKs dont last very well now!

Yes

Then it could be said that the temperature of the batteries in charge (and use) is 5º higher than the ambient temperature.

Do you do it that way?

[Burgerman]

Yes. If you put your hand on them after a days use they generally feel warm. Compared to sat the bench, or an internal wall. This is because of resistance. And when you charge, that too warms them a little.

The problem is this. The warmer you get the batteries as you charge, the lower the voltage needs to be. But we dont lower that. So then the battery gets even warmer. Which needs an even lower voltage. So its possible that instead of dropping as the battery becomes full, the AMPS begin to increase again... This results in a thermal runaway and ruins the batteries, smells bad...

So if in doubt use a little lower volts. That takes longer but is safe. At 25C the highest is 14.1v per battery. But 14V is safer. And 13.9V is fine too, but charges slower.

[shirley_hkg]

OMG, max CV in sub-tropical area should be 27.6V .

Our bundled chargers are 28.8---29.2V !

[Burgerman]

Yes... Problem.

Why do you think we get "my batteries are not holding up" type posts! The modern generic charger is for AGM and they add gel as an afterthought rather than lose sales. MK are as bad. They know. But dont care! You CAN charge gel at 29.4V, works fine. Mks non tech sell sheet even says so. What they dont tell you is that you have just murdered the cycle life...