[Oeva-list] Anyone familiar with this battery-balancing system?

Gary Graunke gary at whitecape.org
Mon Nov 23 13:33:45 PST 2009

Victor Tikhonov and I have both used Powercheq modules some time ago. 
Mine were beta units, and I had 50 of them for two 26-12V battery 
strings in my old S10 pickup.

I later put them in a 20 12V battery string in my Insight (which is now 
using LiFEPO4 A123 cells, so I can't use the 12V powercheqs very well).

I still have a bunch of these older units. The newer units seem to be 
the same, but have integrated two ATC automotive fuses on the + and - 
leads (but not the middle lead).

I have recommended them for the Zap, though the 2A limit seems a bit too 
small for the large AH batteries in the Zap. One could always put two in 

They work quite well--the move charges from the batteries as they 
increase in voltage. If you are stuck, you can rest for 1/2 an hour a go 
a bit further. Normally, if you have park somewhere without charging, it 
will continue to equalize so that you go farther before the weakest 
battery runs out.

Caveats: For long strings (26 or 28 batteries), a slight bias to the + 
battery accumulates, and so the most positive battery is charged more 
than the most - one in a long string. This can unbalance your pack. 
However, it is not a problem for smaller packs such as the ZAP.

The powercheq module has no way to slow down the charger, so if the 
batteries are really out of balance, they are not powerful enough to 
shuttle the excess of a full constant current phase amperage to prevent 
overcharging. However, if your batteries are reasonably balanced to 
begin with, they will keep them that way!

I have also used Rudman regs, and I find that Powercheqs are better at 
keeping the battery below the maximum voltage (the regs wait until it 
goes up too high and then bring it back down), but the regs have many 
other advantages (especially if linked to a PFC charger to shut it 
off/slow it down).

I'm also still waiting for a Hart balancer to try that approach. I would 
also like to make a parallel system using telephone DC-DC converters to 
do the equalization more efficiently than the powercheqs (direct from 
all to lowest vs bucket brigade).

Again, I have some that I could part with if someone wants to add their 
own fuses to offer the protection. I have them connected to a 3-pin 
Molex to facilitate easy removal or replacement when working on the 
pack. I paid $40 each for them some time ago.

Summary--the powercheq modules are a simple and effective solution. 
There is no excuse why Zap should not have *some* kind of battery 
management system, and the powercheqs are an example of how easy it is 
to do a decent job protecting the batteries against overcharge and 


Philip Kollas wrote:
> Hi,
> Has anyone used, or otherwise learned about first-hand, the PowerCheq 
> battery balancers? I’ve looked at the info available from Grants Pass 
> Electric Vehicles (GPEV) as a source for my Zap Xebra pickup, but I 
> have little other info about this source or the brand name. Can anyone 
> shed any light on this?
> Here’s their link for this product: 
> http://shop.gpev.us/product.sc?productId=100&categoryId=3 
> <http://shop.gpev.us/product.sc?productId=100&categoryId=3>
> Also, I noted on the GPEV site that they encourage volume orders at a 
> discount. If anyone else is interested—and if the product is 
> worthwhile—we might be able to scrounge up a discount for even a 
> couple of orders at once, given the state of the economy. For rough 
> planning purposes, a six-battery pack would need five of the PowerCheq 
> units, which works out to about $354 for the set. That’s for a solo 
> order; I don’t yet know what kind of pricing they would offer for 
> multiple orders sent in at once. I’ve written to them to inquire but 
> don’t have a reply yet.
> Thoughts?
> Cheers,
> Philip Kollas
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