Greetings and a quick ?

[rollingcowboy]

I have MK batteries not able to fully charge - 25.5 volts. They are 8 or 10 yrs old, so not a surprise.

controller is MK6i, motors GBHD

my question is what is the low voltage cutoff?
hopefully I can get new batteries here before the cutoff hits me

thanks in advance to all who answer!

RC

[shirley_hkg]

Around 19.

It could easily get there under load.

[rollingcowboy]

Shirley, thanks!

[Burgerman]

A lead battery in use really has no specific voltage. It just depend on internal resistance and actual load (in amps). They may measure 25V when you dont move. As soon as you do, they may drop instantly to below that 18 to 19 volt point. As you stop they will then climb back to that 25V. Or at least 24V initially and then 25 after around 20 hours. Internal resistance causes this and increases severely as they age.

Your batteries were actually knackered after a couple of years use. 500 cycles (days) is the laboritory test absolute maximum and they are then down to 80% of original capability. The industry point where they are considered done for! End of life.
You just didnt notice this or have the test capability to measure it. Thats simply how long a QUALITY correctly charged and used MK Gel battery lasts. Thats just a fact. But... How knackered they really need to get before it interferes with your daily useage all depends on you. You likely are down to a fraction of the original performance. And your requirements V capability have met!

From a previous post:

When I was a bit younger 30 years back, I hammered the chair daily until out of range/lights. I used all of its range most days. Or at least 80 to 90%.
I could easily detect a 10% loss of performance. in 9 to 10 months. Because I could no longer do what I previously could 9 months ago (when new). They were interfering with my day...
How do I know 10%? Because I measured Ah capacity regularly with a hobby charger. At this point I replaced MKs around every 9 to 10 months. I gave my "old" batteries to the retirement home behind my house. They continued to use them for 5 years or longer because they watch TV and drink tea... Cant tell the difference.

Just replace with a set of these HAZE GEL EV:
https://www.ebay.co.uk/itm/131119213209
(You may notice they look identical to these Eternity OEM sunrise ones... https://www.eternitytechnologies.co.za/ ... ge-G04.pdf And theres a reason for that!!! They are the same)

12V 80AH HAZE GEL. They are the same high quality gel, as the factory fitted Eternity ones in a modern sunrise chair. And a bit cheaper than MK. And a fraction more Ah too. Same as the Eternity ones under a different label.

There are also MOVE gel batteries as supplied by DIETZ chairs and also high quality gel.
https://movebatteries.com/producten/mtg-76-12/
https://movebatteries.com/wp-content/up ... -76-12.pdf