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Cheapest cart power solution


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I am now using several different batteries from batteryspace.com (Powerizer "brand") and they have all worked out well.

Most of the batteries I am using, for cart power supplies, have been found in the section for 12.8v packs 19.8Ah - 200Ah

they have this note that scares me a little bit.

"Note: balance function will only take place after battery is fully charged and must wait a minimum of 30 minutes for the cells to balance before being use. If use right away, no balance will be taken place."

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Steve, are these PSC battery packs that are on consignment use LiFePO4 batteries? Just curious because I hadn't heard of PSC using LiFePO4 batteries in this box.

Jeff,

I just replaced the SLA in my PowerStation.

Ron offered a LiFe solution, but it was quite expensive, and I use this only for car work or on a hand ruck with my bag if I'm going mobile, so I chose not to go for it.

Since mine would have been the first, these consignment sales are almost definitely SLA.

And I would expect whoever has these on consignment would take an offer of less than $550, unless they can show the batteries are brand new.

Robert

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they have this note that scares me a little bit.

"Note: balance function will only take place after battery is fully charged and must wait a minimum of 30 minutes for the cells to balance before being use. If use right away, no balance will be taken place."

Nothing scary about this --- it is just the way LiFePO4 batteries fitted with the all important PCB protection work if they also include charge balancing circuit. It really depends on how you are going to be using the battery, what sort of design you will be utilizing if you are building a cart power supply. I have been using LiFePO4 batteries with balancing circuit for charging and have not had any trouble. I built a battery block for Moe Chamberlain who never plugs into AC while using the battery but does charge it up during the night. When it is taken off the charger, it is always at least 30 minutes before it is put in service again, so the balancing has plenty of time to do its thing.

As I have said before, I do not design my cart power supplies to actually accomplish charging the battery since I use the float routine which doesn't seem to have any adverse affect on the charge balancing PCB or on a fully charged battery. When I do charge the battery/supply (not powering any equipment) I use the proper LiFePO4 charger and give it the 30 minutes required before putting it back in service.

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Jeff,

Did you experience problems when using the Shorai? Did the battery dip below the recommended voltage sooner than expected?

The only problem was much smaller capacity than expected. When I knew I could run everything on my cart for x number of hours with a 33 Ah SLA battery but discovered that the Shorai 36 Ah battery gave me half that runtime, I knew I had a problem.

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And I would expect whoever has these on consignment would take an offer of less than $550, unless they can show the batteries are brand new.

A new 33Ah SLA costs less than a 100$ (based on a simple google search).

On another note, I have a quote from an Indian tech company for a 35 Ah LiFePo4 battery pack for the equivalent of 400$ based on current forex rates. To be noted that this is not a "PbEq or cranking capacity" rating like the Shorai. I was a little confused about this kind of capacity rating, and thanks to Jeff's telling me about this, i stopped myself from looking at Shorai or Ballistic batteries. This pack weighs 4.5 kg and will fit into a Pelican 1200 case with room to spare (about 1.25 inches) on one side for XLR/Powercon/etc connectors. I am seriously considering these, especially since they are from a local company. Just a comparison of the weight of this pack against a Shorai "36 Ah" battery tells a lot.

-vin

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" A new 33Ah SLA costs less than a 100$ "

might this require (as an accessory) the outboard circuitry to control charging discharging, and voltage regulation..?

to use the oft quoted "it depends" --- what sort of cart power supply you want to build. Something as simple as an SLA battery in a box with connectors charged up after work with an automotive charger from Pep Boys will not require any "accessories". If on the other hand you want a cart power supply that plugs into AC, charges a battery or batteries, switches from AC use to standalone DC, etc., etc., this will require some additional work.

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Steve, are these PSC battery packs that are on consignment use LiFePO4 batteries? Just curious because I hadn't heard of PSC using LiFePO4 batteries in this box.

Earlier in the thread, it was suggested that used lead acid batteries may be an inexpensive option so, I though I would supply a link if there was interest. But coincidentally, I just saw a prototype PSC lithium phosphate battery in a case last week. Only seven lbs. 20 amp hours, Overcharge protection, speak-on connector. Stay tuned for details.

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What Vin says is true. LiFePO4 batteries, most of them, CAN be charged with "standard" battery charger designed for Sealed Lead Acid batteries but the battery charger must not have a few of the charging routines employed by even standard battery chargers. It is well documented that battery chargers that use any kind of staged charging, high voltage, high current at the start, then lower voltage, then "trickle charge" state, all designed for SLA chemistry, will shorten the service life of LiFe batteries. Also, the concern expressed earlier in this thread about balancing PCBs employed in LiFe batteries can be adversely affected by chargers not specifically designed for the LiFe batteries. From my experience, the main reason manufacturers and distributors state that standard SLA chargers can be used, is to expedite a sale and make people more comfortable with this new type of battery.

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" charges with any standard 12 VDC SLA charger "

has been edited:

charges with most basic 12 VDC SLA chargers

I would edit it further to say: "Do not use a standard 12 vdc charger unless you can confirm that it is a CC and CV type charger whose voltage and current through all steps of the charging process matches the requirements of LiFePO4 battery being used." So, that is a few more words than the original statement but these are the words that need to be stated.

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A primary design goal of Lithium Polymer batteries (like the LiFePO) was to be able to use them as direct replacements for lead acid batteries. This means that LiFePO batteries can also be charged with the same charging systems used for lead acid batteries of the same capacity (typically rated in Amp Hours) in the device they are being used in.

That said, LiFePO batteries can be charged at a faster rate than lead acid types of the same Amp/hour rating. Therefor, a charger designed for a LiFePO of a certain capcity should likely not be used for lead acid types of the same capacity. This is one reason the charger inside the Meon LiFe is smaller than it would have to be for LiFePO batteries, so it can also safely charge supplemental lead acid batteries (which also allows it to fit in a single rack space and produce less heat).

The CC/CV term means that the charger supplies constant current of a specific voltage (13.6V) until a low current draw is established, and then a higher constant voltage (~14.6) is maintained until an even lower current draw is established, and which point a "zero-effect" voltage is established to maintain the full charge (float). (It should be said that the self-discharge of LiFePO batteries is so low that some LiFePO chargers just turn off when the battery becomes fully charged). Otherwise, this is not unlike chargers designed for lead acid batteries. The main difference is that chargers designed for LiFe batteries can supply up to the full rated amp capacity for most of the charging cycle, when lead acid batteries should be limited to a maximum charge current of 1/3 of their rated capacity.

Now, with all that said...

Probably the least expensive way to have an uninterruptible 12VDC power supply is to get a AC-DC 13.8V supply with at least a little more than enough capacity to power your gear (8 Amps is probably ideal), connect it in parallel with a lawn tractor lead acid battery (about $20 at Cosco or Sams) and distribute it to your gear through a parallel array of connectors. Other than the inconvenience of a bulky and wiry form factor, and possibly not having the benefit of circuits protected by fuses, this simple system will work just fine. I've built and used them myself. One time that comes to mind was done with a trip to Western Auto when an equipment case didn't make it on the flight to Puerto Rico. This 13.8V system will maintain a fully charged battery indefinitely, and slowly recharge the battery, but only with the amount of current not used by your equipment. Therefore, if you go with this type of system, you should plan to have a second battery charged and ready to go, and a dedicated fast charger for recharging the batteries after a significant period of discharge. This system can use lead acid or LiFePO batteries interchangeably.

A system like this can be put together for probably less than $400 and will work fine, and I encourage people to do this when a more sophisticated self-contained system is financially out of reach. But if it's just a matter of getting by for less money, when considering the direct initial cost savings the cost of the extra weight, extra size, lack of voltage/current/charge status monitoring, and the impact the choice can have on those who are hiring should also be considered.

Glen Trew

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Hi all,

I just received the new PSC Pelican LIFE battery. It's 20AH @12.8V with a Speakon connector. Even though I knew the dimensions when I ordered it, I was very surprised how small (and light 7 lbs.) it actually is!

When it comes to electronics, I'm not much of a "do-it-yourselfer", so this was a great solution for me..for both the mini cart (primary power) and the big cart (aux power with the MeonLIFE)

I have attached some pics, one with an i-phone to give you a sense of scale.

post-1887-0-81448900-1350506205_thumb.jp

post-1887-0-82387400-1350506217_thumb.jp

post-1887-0-35674800-1350506654_thumb.jp

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You can use the hotbox, and probably use the 10amp charger (depending on the charger). The danger with this setup and a lead acid battery is that the charger interpret the current being drawn by your equipment as a battery that needs charging, which could lead to dangerously overcharging the battery. LiFePO batteries typically have a higher safe float charging voltage (14.6, typically, which is often the fast charge voltage of a lead acid charger), so I believe there is a lead acid battery charger that would be safe in this setup. This will also depend on the effect of the PSC circuitry in the Pelican case, which Ron can answer.

Glen Trew

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