Scissors lift batteries

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Galt

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master electrician and refrigeration service tech.
Friend has a scissors lift, the battery charger quit. It has 4 6 volts. The transformer is bad. They are wired in series for 24 volts total.

Can anyone think of a reason why you could not charge them with a 12 volt charger by hooking them series parallel .
 
It's on a job and want to finish up. We both have 12 volt chargers . He did a little searching with his phone 750.00 bucks.
 
Galt said:
Friend has a scissors lift, the battery charger quit. It has 4 6 volts. The transformer is bad. They are wired in series for 24 volts total.

Can anyone think of a reason why you could not charge them with a 12 volt charger by hooking them series parallel .
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The main objection is the general objection to paralleling two lead acid batteries for either use or charging. It is difficult to get equal charging of the two batteries unless you use a current limited charger and long charging times.
A secondary objection is the hassle (and risk of mishap) of rewiring the batteries between use and charging configurations.
I would be inclined to use a single 12V charger in turn on each series pair of batteries.
Some 12V chargers can be "stacked" in a pair to form a 24V charger.

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180127-2332 EST

What is the battery ampere-hour rating? How fast does the battery need to be charged?

How fast you need to charge the battery will determine how small of a charger you can use. You certainly do not need to rewire the 6 V batteries.

.
 
There should be no problem with using two 12v chargers to charge two pairs of 6v batteries while they're still wired for 24v.
 
GoldDigger said:
The main objection is the general objection to paralleling two lead acid batteries for either use or charging. It is difficult to get equal charging of the two batteries unless you use a current limited charger and long charging times.
A secondary objection is the hassle (and risk of mishap) of rewiring the batteries between use and charging configurations.
I would be inclined to use a single 12V charger in turn on each series pair of batteries.
Some 12V chargers can be "stacked" in a pair to form a 24V charger.

Sent from my XT1585 using Tapatalk
Click to expand...

Every diesel pickup I’ve seen has paralleled batteries. Seems to work.

But I agree - in this case it would be easiest to use 2 12 V chargers. No need to reconnect the batteries for charging.
 
retirede said:
Every diesel pickup I’ve seen has paralleled batteries. Seems to work.

But I agree - in this case it would be easiest to use 2 12 V chargers. No need to reconnect the batteries for charging.
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There is a considerable difference between keeping two batteries in parallel for both charging and discharging and taking two batteries which may have different states of charge and connecting them in parallel for charging.
The initial balancing current from battery to battery could be enough to cause problems.

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GoldDigger said:
There is a considerable difference between keeping two batteries in parallel for both charging and discharging and taking two batteries which may have different states of charge and connecting them in parallel for charging.
The initial balancing current from battery to battery could be enough to cause problems.

Sent from my XT1585 using Tapatalk
Click to expand...

If those batteries are identical and have always been in series use, both charge and discharge, I would not expect the states of charge to be appreciably different.
 
charging batts in series is hit/miss. best to charge each one. four 6v batts needs a single 4x 6v batt charger, or four individual 6v chargers. that is the best way to not only get a long MTBF it also allows the "smart" chargers to detect issues or apply a de-sulfur mode (depending on batt type, etc).

four 6's ?? i'd swap that to two 12's if possible, makes having a batt charger a tad easier.
 
Last edited:
thanks guys might have more to say tomorrow evening. hope we get the lights up.
 
LarryFine said:
This would halve the AH capacity.
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That depends entirely on the size of 12V battery you use to replace two 6V.
If you are near the practical limit size of the 6V battery (weight, size) then yes, you are not likely to find a same watt hour combination single twelve volt battery to occupy the space of two sixes.
 
FionaZuppa said:
... four 6's ?? i'd swap that to two 12's if possible, makes having a batt charger a tad easier.
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One of the important skills for an engineer (or wannabe engineer) is the ability to correctly decide when something merely needs repair vs. needing redesign.

Odds are, this scissor lift uses four golf-cart batteries, a popular format that offers good price and availability due to economies of scale. There is a battery box with holddowns configured to fit GC batteries; swapping something different would require changing the dimensions of the battery box and holddowns ... or were you thinking about just plopping them in there loose? Then the cables would need to be reconfigured, both the battery and charger cables. You'd reduce the weight of the lift and raise its center-of-gravity, invalidating the stability calculations that were performed when it was designed.

Or you could replace the non-functional 24-volt charger with a new one. 24-volt chargers are readily available and only occasionally need replacing. They're not a consumable item; there's no need to substitute something that's more widely available.

The original post was about a quick fix to enable finishing up on a jobsite while the replacement charger is in transit. And a suitable solution has been shared: two 12-volt chargers and no wiring changes.
 
If using (2) 12 volt battery chargers in series as a temporary workaround, would there be any detriment or benefit to connecting the charger voltage midpoint to the battery bank voltage midpoint?

Cheers, Wayne
 
180129-1431 EST

wwhitney:

Quite obviously you would connect one 12 V charger to the series connection of two 6 V batteries. Thus, what you mentioned as midpoints would be connected together. Unless you study the operation of the chargers you have no idea what what happens to the 24 V from their series connection. Basically the chargers are designed to be individually loaded with a battery.

.
 
wwhitney said:
If using (2) 12 volt battery chargers in series as a temporary workaround, would there be any detriment or benefit to connecting the charger voltage midpoint to the battery bank voltage midpoint?

Cheers, Wayne
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multi channel smart chargers would perhaps be an issue. dummy chargers with just a form of current limiting probably would work.

but interesting enough, in series [yet parallel] is a common series-battery charging setup
a single 24v charger is not advisable if you want to have good batt maintenance & life.

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wwhitney said:
If using (2) 12 volt battery chargers in series as a temporary workaround, would there be any detriment or benefit to connecting the charger voltage midpoint to the battery bank voltage midpoint?
Click to expand...
I would say that not connecting mid-point to mid-point (i.e., putting chargers in series across batteries in series) would wreak havoc with the charge monitoring of each charger.
 
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