# [EVDL] Smart vs dumb BMS's



## EVDL List (Jul 27, 2007)

The EVPower BMS from Australia and MiniBMS from Florida do a great job of protecting your battery pack.
Both products are simple to install, reliable, and reasonably priced. I've installed quite a few of both these systems.

However, down the road when you have a problem with your cells (which most people do), it can be a pain to troubleshoot with these "analog" BMSs.
For example, if you have one or more bad cells that "craters" under load, there is no easy way of determining the culprit unless you have physical visibility to the BMS board(s) and/or the ability to measure each cell with a voltmeter while driving or charging..not always easy to do.

A digital BMS such as the Eltihion Lite or OrionBMS are much more useful during setup and especially when you have a problem. Their current sensors allow you to have a true "fuel gauge" and know how much energy is in your pack. In addition to being able to alter the default setpoints via software, i.e. LVC and HVC, you can hookup a laptop to the BMS controller and see each and every cell under charge or discharge with a pretty graphical screen. You can even turn on data logging, go for a drive then analyze the file when you get home.....much easier than having a helper try and probe cells with voltmeter while driving the car...BTDT...not very fun, nor safe.

Summary, 
to reduce future headaches, consider a smarter BMS....no matter how much planning you do, you will have problems with your vehicle in the future!

In my opinion smart BMSs are worth the extra cost if you have more than 16 cells or the cells are in multiple banks throughout the vehicle.
For a DIY EV, I like the simplicity of the Elithion Lite. For a Prius PHEV conversion, the Orion has some nice Prius specific features.

If your pack layout is simple and accessible, EVPower or MiniBMS could be sufficient.

Elitihion Lite info here http://lite.elithion.com/description_.php
OrionBMS info here http://www.orionbms.com

-Paul


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## EVDL List (Jul 27, 2007)

I have MiniBMS, and have a cell (or more?) that signal the low voltage alar=
m before they should (voltage under load when it alarms is at 135v on a 48 =
cell pack, 2.81vpc). You are certainly correct that there is no way to t=
ell which cell it is! My plan here is to install a Cellog8s which will m=
onitor 8 cells, and record the data. I have a suspicion which cells are =
bad from back when I cycle tested all my cells with a Powerlab 6. Some c=
ells tested higher IR's than others. But I don't know for sure which exa=
ct cell, or how many of them, are sagging down. I figure I'll just tempo=
rarily mount the Cellog8s and move it around until I find the offending cel=
ls. A bit of work, but cheaper than buying a whole new digital BMS! A=
nd certainly better than making my daughter ride in the trunk with a voltme=
ter checking cells as I accelerate...

When all is working, the MiniBMS gives me everything I need. Which is ba=
sically a low voltage alarm, and a high voltage charger cutoff. The rest=
of the details I don't really need to know unless I'm having a problem. 

david.
http://www.evalbum.com/4021


----- Original Message -----
> From: Paul Guzyk <[email protected]>
> To: [email protected]
> Cc: =

> Sent: Thursday, September 20, 2012 11:12 AM
> Subject: [EVDL] Smart vs dumb BMS's
> =

>T he EVPower BMS from Australia and MiniBMS from Florida do a great job of =

> protecting your battery pack.
> Both products are simple to install, reliable, and reasonably priced. =
I've =

> installed quite a few of both these systems.
> =

> However, down the road when you have a problem with your cells (which mos=
t =

> people do), it can be a pain to troubleshoot with these "analog" BMSs.
> For example, if you have one or more bad cells that "craters" under =

> load, there is no easy way of determining the culprit unless you have phy=
sical =

> visibility to the BMS board(s) and/or the ability to measure each cell wi=
th a =

> voltmeter while driving or charging..not always easy to do.
> =


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| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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## EVDL List (Jul 27, 2007)

> On 20 Sep 2012 at 16:23, David Ladd wrote:
> 
> > A bit of work, but cheaper than buying a whole new digital BMS! And
> > certainly better than making my daughter ride in the trunk with a
> ...


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