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Support and lead time update

  • We are way behind on backorders, but most products are actually in stock at the moment.
  • New BMS orders will still take up to 30 days to ship.
  • Cells will ship within a few days

We are answering emails to in the following order:

(please stop using the old Gmail address)

  1. Incorrect orders / Warranty claims
  2. Customers who have received their items and are having technical difficulties
  3. Status of placed orders / Cancelations
  4. Technical questions from pre-purchase customers
  5. “What is your lead time really?”

Fair warning, #5 will probably never be answered.

Posted on 16 Comments

An apology from Steve at Overkill Solar

You may have noticed that out customer support has been worthless lately.
I deeply regret this, and I am working to improve the situation.

What happened?

When Will Prowse featured our products in a video, the daily number of orders quadrupled instantly.
The result is, we sold out of everything, including all of the new inventory that had already been ordered.
The factory lead time on BMSs is at least 30 days, sometimes longer due to global supply issues.
Yes, China keeps running out of computer chips and circuit boards. Who would have guessed?

At this particular moment, I am working about 24 hours a day to assemble, test, and ship BMS orders, along with all the help I can get.
Yes, I have dreams where I’m packaging BMSs. (and nightmares about answering angry emails, btw.)
This means I had to choose between getting orders out, or keeping up with emails.
Once I sat here for 8 hours just responding to “Where is my order?” emails, the choice was clear.

Why don’t you just hire more people?

This is way easier said than done. The biggest issue is that it takes a BMS expert to answer the technical support questions.
To my knowledge there are 4 people who fit this description, and they all said “hell no” after getting a taste of my inbox.

Getting more people on board to fill the orders will help, and that is happening asap.

Hopefully we will soon run out of inventory again, then I can catch up on support.
Meanwhile, the best resources will be the BMS User Manual ,, and

Again, I know this is disappointing and frustrating. It will get better some day.




Overkill Solar

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How to charge LiFePo4

LiFePO4 does not need a multistage charging profile.

The manufacturer of our 100 ah cells, and the MFG of the common 280ah cells specifies charging at a rate of 0.5c up to a maximum voltage limit of 3.650 per cell.

Based on the LiFePo4 charge curve the cells will reach nearly 100% charge at 3.500v per cell, so this is our recommended target voltage (14.0v per 4-cell battery, 28v per 8 cell battery).

Note that there is no mention of “float” charging. This is only applicable to lead acid yet most charger designs include a float setting for LiFePo4, usually 13.2v for a 4 cell battery.

Why is this a problem? Because at 13.2v the battery will be significantly discharged, and so you will observe the battery going through a deep cycle after every full charge, even though it remains plugged into shore power.

Therefore the ideal charger for LiFePo4 batteries (in our opinion) is a current limited power supply set to 14.0 to 14.2 volts.