# LeadCalcium battery charging and a variable voltage charger.



## djmjnewton (Aug 14, 2008)

Hi.
Some thoughts,
In planning my EV the second decision after the first 20 or so was battery size and type. I chose the best $ per Ahr battery I could find and purchased 7 X 120Ahr Flooded Lead Acid Amptech D87L batteries from Supercharge.(Review here http://www.onlinetoolreviews.com/genreviews/reviews/AmpTechD87L.htm )

What has followed has been a very steep and expensive learning curve. I hope to save someone else the same journey. I purchased a set of smart battery chargers that had a 14.4V Max Voltage. To cut a long story short I found out my “low maintenance “ batteries were lead-calcium rather than the lower voltage when fully charged, lead-antimony or straight lead plate batteries. My brand new chargers would not fully charge the batteries. I needed 14.8V. Neither did I realise the importance of the 15.5V “equalising charge”. This is used periodically to stir up the electrolyte with gas bubbles so the strata of different density acid is broken up so presumably the chemical reaction is optimised and each cell is able to accept and give up Max charge. My search was on. I lucked onto a Meanwell PB360 charger sold by http://www.wellforces.co.nz. These have the ability to change the float and Max Voltage boost charge in a 3 stage smart charger with bulk, boost and float. I am running four; three 24V and one 12V. (NZ$990 vs a Zivan NG1 NZ$1163+freight from USA+GST) Why a variable voltage charger? This allows me to match the voltage output to the particular battery chemistry specified by the battery manufacturer. It also means that later if a better / cheaper / different battery becomes available I wont have to purchase yet another set of battery chargers. You can also wind the voltage up on these to do the 15.5V periodic equalising charge that is certainly specified with my batteries as important maintenance. Why several chargers rather than a single one? Expense. Also it is cheaper to replace one small one than fix a large one. With each pair of batteries getting a charger it would seem to be more probable that each battery would receive better individual attention vv charging in comparison to being in a longer string of seven and therefore be less likely to be under or overcharged. Auckland supplier vs the States so proximity if something does go wrong re freight and warranty issues. Possible problem- this charger doesn’t monitor battery temperature so if a fault develops it will cook. I think the Zivan may be more intelligent about this. 
I will post more about my battery-charging journey of discovery as it unfolds. Hopefully this set up will do the trick and maximise range as well as battery life.
Outstanding issues.
For example I still don’t have a manufacturers spec on max charged battery Voltage for my lead-Calciums, except that mine seem to have a voltage of 13.2V after a four hour rest from charging.(vs 12.8 for lead?) I would love to know what the 80% discharged voltage is. I’m picking it is higher at 11.1 V. Does anyone know? The other critical voltage is 50%DOD, any ideas?
Thanks
David
Refferences 
Calcium Batteries-What are they? http://www.darylrobertsonautoelectrical.com.au/info.htm 
*State-of-charge reading based on terminal voltage http://www.batteryuniversity.com/partone-13.htm *
Car batteries are not 12V http://www.landiss.com/battery.htm 
Typical Lead-calcium Voltage http://qualitymarinechargers.com/Battery%20Handbook.pdf


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## djmjnewton (Aug 14, 2008)

Hi
When charging the original pack one battery became hot to the touch. (40 deg or so) It tested at 12.6V vs the others at 13.2V after 4 hrs rest. I trialed the range of the complete 84V pack and got 24km. removed battery so running at 72V and the pack went 26km. Took battery back and had it replaced under warranty. Pack now does 32km at 50kph to 80%DOD with good long runs but about 15 stops and accel to 50kph. The dud battery was holding the car back but it only became apparent when I tried to charge it at its correct max Voltage. Who would have thought 0.4V would have such a dramatic effect (14.4 vs 14.8V)
regards
David


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## Jens Rekker (Oct 26, 2007)

Good skills at spotting the faulty battery, Dave. Sometimes a weak battery is hard to spot. I saw a neat approach by UK, Canadian and US converters. It's a multi-battery LED bar display that shows battery voltage under acceleration and load. I've seen YouTube of it working on the Project Forkenswift site ( ecomodder.com ).

You can get detailed instructions as to how to make one of the bar graph gizmos at evconvert.com . I have 24 batteries, so the fabriacation of the bar graph device and all of the cabling was a bit daunting for me. But someone with a lessor number of 12V batteries could get some real value at a fraction of the cost of something like PackTrakr.


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## carrott (Aug 19, 2008)

Check out Lee Hart's Batt-Bridge. It will tell you if there is a weak battery, and which half of the battery it's in. The EVision also monitors pack imbalance and will tell you how many volts the two halves of your battery differ by.


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## djmjnewton (Aug 14, 2008)

Hi,
*Battery charger Malfunction*
One of the Meanwell PB-360P-24 battery chargers decided not to float charge. I have sent it back to Welforces in Auckland for checking and repair under warranty. I purchased a replacement in the mean time for $225 NZ delivered after two days off the road. It remains to be seen if the ease of replacing one of many chargers outweighs the longevity and considerable expence of maintaining a Zivan. The charger was returned fixed at no cost within four days. Excellent warranty service and thanks.

*A Caution about Paktraker and Lead Calcium Batteries*
My Pactraker system started showing a fault code about overcharging because for ordinary flooded american lead acids I am. Ken from Paktraker asked for the sensor unit to be sent back so they could reprogram it for a higher voltage and now it seems to work well. Excellent service from Paktraker in the States. For the next one I purchase I need to inform them about the Lead Calcium battery pack I am using so it can be modified before the sender units are shipped. 

yours etc
David
www.greenev.co.nz


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## enp13 (Mar 26, 2009)

(I do plan to do a high performance EV conversion one day - in the mean time, while I save, this thread caught my eye so thought I'd respond.)

I had similar "learning curve" with my ordinary petrol car when I recently accidentally purchased a 12V calcium lead acid battery from Marshall Batteries, assuming it was an ordinary lead acid battery. The problem became apparent recently when, during a few weeks of good cycling weather, the car battery went flat through lack of use. I hooked up my intelligent charger to it but the battery never seemed to reach full capacity, despite leaving it on for several days. The car would start but the starter motor sounded very sluggish. The Marshall guy came out to help ($50 callout fee but I can't complain) and explained that most modern low maintenance car batteries are going the way of lead calcium. They need a high voltage equalisation if deeply discharged and need a higher than usual absorption voltage. If either of these conditions are not met, the battery loses some capacity. A reduction in capacity is probably not a big problem for a petrol car if it is used regularly but is obviously critical for an EV. I then looked up my charger specs and sure enough, it has a float voltage of 14.2V so not only is it not bringing the battery up to the recommended absorption voltage of 14.8V, it is not able to achieve the equalisation voltage of 15.5V which is critical after a deep discharge. I ended up using a bench power supply to manually do absorption and equalisation stages and can now use my automatic charger to maintain the battery at 100% when the car is not being used for long periods. I still need to check my alternator output and am thinking I should raise it to 14.8V if it is set to the more common 14.4V.

The Projecta website has one lead calcium charger. It is expensive but the spec sheet:

http://www.projecta.com.au/documents/item/42.pdf

has a good description of the charging stages. Interestingly they aim for a 14.7V absorption voltage (they don't say how long for - presumably until the current drops to maybe C/10?) and a 16V equalisation target voltage using a 2A constant current. Once charged, they reckon 13.5V is enough to keep it charged when not in use.


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## morvolts (Jun 19, 2008)

I recently did a little research on the Pb/Ca
battery. I have an old Liberty 1000 and wanted to charge it up and see if it still worked. I was amazed as it has been sitting for 10 yrs and had only 4 volts. Long slow trickle charge while in tandem to a lead acid and its up to 12.3v and passes a load test. I ll do a few charge/discharge cycles and see if I can get it up to 2.25v per cell as the manufacturer says.BTW CD says not to equalize at over 14.7 v on this model and dont exceed 25% of rated 20 hr ampere on charge.


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## djmjnewton (Aug 14, 2008)

Hi,
After getting the whole pack of Amptech batteries replaced under warranty by Supercharge Batteries. (thanks guys, excellent service) I have killed them and their replacements in about a year. They did 7500km and are an uneconomic proposition here in NZ despite the very good price Supercharge gave me. 
Symptoms of imminent destruction were a lack of range and when I checked the water in the cells they had black flecks of solid presumably plate material suspended in two or three cells of a battery. Removing a battery actually increased range on occasion. The lead acid batteries were a great cheap start as I would not have coughed for the added expense of Lithium first up but I hope my next and current Corolla conversion with Lithium iron phosphates deliver both range and longevity as promised.
David


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