SLA Batteries And How to Charge Them?
Discussion
Hi Guys,
Hope you all are doing well. I need your help to understanding the basics of battery voltage and ampere relationship.
What it is, my nephew has this ride-on car and the charger is misplaced somewhere. It has 2Nos 6v 7Ah SLA batteries. I've got loads of spare chargers and I want your help to find the right one for charging it please. Sorry I've got loads of questions here, just to keep it safe to avoid a fire hazard.
7Ah = 7000mA
1. What charger, with output 6V and 500mA or 12v 500mA or 12v 1500mA or a 12v 7000mA?
2. What difference the above different amperes would make to charging time, in hours?
3. What role ampere plays when riding the car? Say, replacing the batteries with 12v 20Ah would make the car go faster or prolong the riding time or both?
4. Would using a 12v 80Ah car battery do any harm to motors?
5. What would burn the motor, increasing the voltage (12v to 24v) or ampere (7A to 20A)?
6. Out of curiosity, powering the car with 12V AC (with an AC adaptor with cord), what affect would it make?
Many thanks in advance.
Hope you all are doing well. I need your help to understanding the basics of battery voltage and ampere relationship.
What it is, my nephew has this ride-on car and the charger is misplaced somewhere. It has 2Nos 6v 7Ah SLA batteries. I've got loads of spare chargers and I want your help to find the right one for charging it please. Sorry I've got loads of questions here, just to keep it safe to avoid a fire hazard.
7Ah = 7000mA
1. What charger, with output 6V and 500mA or 12v 500mA or 12v 1500mA or a 12v 7000mA?
2. What difference the above different amperes would make to charging time, in hours?
3. What role ampere plays when riding the car? Say, replacing the batteries with 12v 20Ah would make the car go faster or prolong the riding time or both?
4. Would using a 12v 80Ah car battery do any harm to motors?
5. What would burn the motor, increasing the voltage (12v to 24v) or ampere (7A to 20A)?
6. Out of curiosity, powering the car with 12V AC (with an AC adaptor with cord), what affect would it make?
Many thanks in advance.
Always match the voltage - charge it at 6V. Most half-decent battery chargers have a setting for 6/12V switchable. Try Ring if you haven't got one.
Amperes is a measure of how much current a battery can provide - the Ah is effectively a power rating.
You could fit a single or pair of car batteries, but you'd need to be careful wiring up a pair (in parallel, not series), and also watch out that they're sealed too - you wouldn't want him rolling the thing over and getting a battery acid shower.
Amperes is a measure of how much current a battery can provide - the Ah is effectively a power rating.
You could fit a single or pair of car batteries, but you'd need to be careful wiring up a pair (in parallel, not series), and also watch out that they're sealed too - you wouldn't want him rolling the thing over and getting a battery acid shower.
Krikkit said:
Always match the voltage - charge it at 6V......
Amperes is a measure of how much current a battery can provide - the Ah is effectively a power rating.
You could fit a single or pair of car batteries, but you'd need to be careful wiring up a pair (in parallel, not series), and also watch out that they're sealed too - you wouldn't want him rolling the thing over and getting a battery acid shower.
Thanks for your reply Krikkit.Amperes is a measure of how much current a battery can provide - the Ah is effectively a power rating.
You could fit a single or pair of car batteries, but you'd need to be careful wiring up a pair (in parallel, not series), and also watch out that they're sealed too - you wouldn't want him rolling the thing over and getting a battery acid shower.
So you're saying that use a 6v charger. But the there are 2 x 6v batteries, which means it need 12v charging? I just want to understand the reason behind your saying.
If Ah is power rating, then 20Ah would give high power to the motor make the car go faster? Would this still keep the riding time same or reduce it?
Pairing up two car batteries make it 24v?
zakmuh said:
Thanks for your reply Krikkit.
So you're saying that use a 6v charger. But the there are 2 x 6v batteries, which means it need 12v charging? I just want to understand the reason behind your saying.
If Ah is power rating, then 20Ah would give high power to the motor make the car go faster? Would this still keep the riding time same or reduce it?
Pairing up two car batteries make it 24v?
It depends if the batteries are wired in series or parallel.So you're saying that use a 6v charger. But the there are 2 x 6v batteries, which means it need 12v charging? I just want to understand the reason behind your saying.
If Ah is power rating, then 20Ah would give high power to the motor make the car go faster? Would this still keep the riding time same or reduce it?
Pairing up two car batteries make it 24v?
A pair of 6V 7Ah batteries can be used together in two different ways:
- 12V 7Ah (series)
- 6V 14Ah (parallel)
Increasing the amp hours (Ah) will increase the range. The motor power will not be affected.
Increasing the voltage will make the motor turn faster (and likely burn it out).
MatthewH5 said:
zakmuh said:
Thanks for your reply Krikkit.
So you're saying that use a 6v charger. But the there are 2 x 6v batteries, which means it need 12v charging? I just want to understand the reason behind your saying.
If Ah is power rating, then 20Ah would give high power to the motor make the car go faster? Would this still keep the riding time same or reduce it?
Pairing up two car batteries make it 24v?
It depends if the batteries are wired in series or parallel.So you're saying that use a 6v charger. But the there are 2 x 6v batteries, which means it need 12v charging? I just want to understand the reason behind your saying.
If Ah is power rating, then 20Ah would give high power to the motor make the car go faster? Would this still keep the riding time same or reduce it?
Pairing up two car batteries make it 24v?
A pair of 6V 7Ah batteries can be used together in two different ways:
- 12V 7Ah (series)
- 6V 14Ah (parallel)
Increasing the amp hours (Ah) will increase the range. The motor power will not be affected.
Increasing the voltage will make the motor turn faster (and likely burn it out).
The batteries are wired in series in the car. So it has a 12V motor.
To keep the motors safe and increase the run time, I can simply use a car battery which has 80Ah rating- run time will increase by 10 times.
When it comes to charging the car battery though, if I used a 12v 500mA (most of the chargers re...), it'd take like whole day to get fully charged?
Please correct me if I'm wrong.
Cheers
Are they AGM or Gel? If so, then they are pretty recharge sensitive, they ideally need a charger that switches from constant voltage to constant currant and back again. If you over charge them they gas too much and you lose electrolyte that you cant replace. Gel batteries a bit less sensitive, flooded less again.
You can have a punt with the 6V 500ma charger. For AGM, you could damage the batteries through overcharging (they are unlikely to go on fire with such a charger, but they might leak some acid).I wouldn't leave them unattended. Is it cheaper to replace them or buy a proper charger (they may be knackered anyway if they've been left flat for a long time). I think you should see a max voltage of about 7.2 while charging and dropping to about 6.8 when charged. If they get hot, that's not a good sign.
Charge time hard to say as it isn't 100% efficient, energy is used breaking down sulphation and making heat etc as well as actually charging.
Using a car battery is likely to melt the speed controller or motor windings. Normal (flooded) car batteries also don't like being taken to very low charge levels too often, they fail if you keep doing that.
You can have a punt with the 6V 500ma charger. For AGM, you could damage the batteries through overcharging (they are unlikely to go on fire with such a charger, but they might leak some acid).I wouldn't leave them unattended. Is it cheaper to replace them or buy a proper charger (they may be knackered anyway if they've been left flat for a long time). I think you should see a max voltage of about 7.2 while charging and dropping to about 6.8 when charged. If they get hot, that's not a good sign.
Charge time hard to say as it isn't 100% efficient, energy is used breaking down sulphation and making heat etc as well as actually charging.
Using a car battery is likely to melt the speed controller or motor windings. Normal (flooded) car batteries also don't like being taken to very low charge levels too often, they fail if you keep doing that.
Thanks.
please could you advice on these battery and charger?
Battery link- https://www.batterymasters.co.uk/sealed-lead-acid-...
Charger link- https://www.batterymasters.co.uk/battery-chargers/...
I'm thinking of replacing the existing once with two of these ones (ignore the listed price) and do parallel wiring, giving it 12V 45Ah. This will extend riding time to around 90mins?
please could you advice on these battery and charger?
Battery link- https://www.batterymasters.co.uk/sealed-lead-acid-...
Charger link- https://www.batterymasters.co.uk/battery-chargers/...
I'm thinking of replacing the existing once with two of these ones (ignore the listed price) and do parallel wiring, giving it 12V 45Ah. This will extend riding time to around 90mins?
Hungrymc said:
Are they AGM or Gel?
SLA is usually Sealed Lead-Acid.OP - you cannot use the entire nominal capacity of the battery, else you will bugger them in short order. To be safe, work on half of the nominal time - so if you've got 45Ah which you think should give you 90min, work on 45min of actual use.
You can buy "deep discharge" batteries sold for caravan/golf buggy/mobility buggy use, but they're a lot more expensive, and often not actually any different. Keep an eye on the voltage, and compare to that table, and you'll be on the safe side.
Edited by TooMany2cvs on Tuesday 15th May 12:42
TooMany2cvs said:
Hungrymc said:
OP - you cannot use the entire nominal capacity of the battery, else you will bugger them in short order. To be safe, work on half of the nominal time - so if you've got 45Ah which you think should give you 90min, work on 45min of actual use.
Thanks mate. When you say 'work on', you mean don't ride the car for full 90mins - stop at 45 mins, let it cool down then recharge it?Edited by TooMany2cvs on Tuesday 15th May 12:42
From that table, what is ' charge state'? 11.9 = 40, means use it for 40mins max?
Does this vehicle have any sort of low voltage cut-off? If not, you should consider adding that as your SLA batteries will be damaged if they are over-discharged, and there will be a temptation to keep driving until it is dead.
To charge, consider using a battery conditioner with a decent current rating so that it can be left on charge when not in use.
To charge, consider using a battery conditioner with a decent current rating so that it can be left on charge when not in use.
No, it hasn't got a cut off circuit. I'd work until its fully drained.
Batteries are not charging. So its time to replace them. I tried connecting the car battery 12V 80Ah and it worked well, but I had to hold the battery with long wires- car would move very slow due to battery weight.
Batteries are not charging. So its time to replace them. I tried connecting the car battery 12V 80Ah and it worked well, but I had to hold the battery with long wires- car would move very slow due to battery weight.
zakmuh said:
No, it hasn't got a cut off circuit. I'd work until its fully drained.
Fit one. Unless you like buying batteries.zakmuh said:
I tried connecting the car battery 12V 80Ah and it worked well, but I had to hold the battery with long wires- car would move very slow due to battery weight.
A car battery's only about 10kg or so... What does the entire thing, including driver, weigh?More likely that you've got some fairly serious voltage drop over crappy long wires.
Yeah I'll get one fitted. Cheers
Not really, I tested it connecting a 500mm long wires, just about holding the battery right behind the car.
Just a quick one, I can charge a battery using the PC power supply unit, which has 12v 5A output. Would high amp rate charging cause any damages to the battery?
Not really, I tested it connecting a 500mm long wires, just about holding the battery right behind the car.
Just a quick one, I can charge a battery using the PC power supply unit, which has 12v 5A output. Would high amp rate charging cause any damages to the battery?
zakmuh said:
Batteries are not charging. So its time to replace them.
If the vehicle is being driven until it stops, that would account for the batteries dying. They can't be cheap to replace so it seems worth investing in a low voltage cut-off. I see them available 'off the shelf' at Amazon for about ten quid.TooMany2cvs said:
zakmuh said:
Just a quick one, I can charge a battery using the PC power supply unit, which has 12v 5A output.
No, you want about 14.5v to actually charge it. Just get a proper battery charger.Yeah, I'm about to order a cut off circuit
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