Are Lifepo4 cells sensitive to dirty DC ?

[sunsurfer]

I have SOK 12v 206a batts. I have a 75amp 13.8v charger I got for free many years ago. I don't know how clean it is, I have no access to a scope. It gets noisy(sound) at times and I wonder how clean its output is.

I'm hoping to use it this winter off the genny for cloudy days but I have concern about any noise or ripple on its output. Does anyone know if bad DC can damage the prismatic cells?

 

[sunsurfer]

Anyone know?

 

[timselectric]

As long as you don't over charge the batteries, it shouldn't be a problem.
I'm guessing that the charger is not for LiFePo4 batteries. Probably can't set parameters properly.
Just keep an eye on it.

 

[MacGyver]

As long as you don't over charge the batteries, it shouldn't be a problem.
I'm guessing that the charger is not for LiFePo4 batteries. Probably can't set parameters properly.
Just keep an eye on it.

I use a VOM set on the low AC range across the battery to measure ripple/noise. What you really need to know is the DC output of the charger with out a load. It could be > 16 VDC.

 

[timselectric]

I use a VOM set on the low AC range across the battery to measure ripple/noise. What you really need to know is the DC output of the charger with out a load. It could be > 16 VDC.

I wouldn't use it to fully charge. Just to get through bad weather days. Maybe just get them to 80%.

 

[sunshine_eggo]

To answer your subject question:

No.

I have SOK 12v 206a batts. I have a 75amp 13.8v charger I got for free many years ago. I don't know how clean it is, I have no access to a scope. It gets noisy(sound) at times and I wonder how clean its output is.

If it outputs exclusively 13.8V, you can use it with wild abandon.

EDIT: also, if exclusively for genny use, the low charge voltage will likely require longer generator run times. Quality connection to the battery will be critical (do not use alligator clips!). You may find it more practical to only charge to 70-80% SoC or while the charger produces at or near its max output current.

 

[sunsurfer]

I use a VOM set on the low AC range across the battery to measure ripple/noise. What you really need to know is the DC output of the charger with out a load. It could be > 16 VDC.

Charger is set at 13.8v max

 

[MacGyver]

Charger is set at 13.8v max

Just because it has a setting of 13.8 V max, does not mean it could be more than 13.8v. Thats why I think you should make sure.

 

[Vigo]

^ I actually have an old 'EV battery charger' from a 1994 electric car i parted out, which always reads over 100v when open circuit. You set the 'desired voltage' by adjusting a pot inside, but you have no idea if it worked until you connect it to a battery and let the battery rise to that voltage, and then... see if it stops! If it stops, it's set right, but if it doesn't.. well then you gotta adjust it some more! What a method..

 

[toms]

The jury is still out regarding ripple voltage when DC charging. Initial projections suggested AC charging and the associated noise would shorten LiFePO4 lifespan, supercaps in parallel are used to mitigate the risk.

In practice i haven’t seen anything to indicate a problem when not removing the AC ripple.

 

[pollenface]

Could it be pwm noise?

 

[sunsurfer]

Thanks everyone, I check for AC with a Uni-T DVOM but will also check with a fluke when I get a chance. Nothing with the TRMS Uni-T so that is good.

I have heard lead acid can be damaged from AC so I was wondering about the Lifepo4. Allot of us have large amounts of money tied up in them and it would be good to know