Hi Colin
Sounds like you have found the Ultramax 7Ahr LifepO4 being sold discounted at present so I would not wait too long if you want at this reduced price.
I have used this type of battery in a smaller version to power my yachts for a few year and can confirm they do deliver the power.
Cheers
Dave

Hi Colin,
Great Find😀
Trev

Excellent point! A must.

Great! Only suggestion is to n use an XT60 or Deans style connector.
The Tamiya type are trouble

Fantastic Colin,
They should make a great difference for you.

Thanks Jonathan, I have found a direct lifepo replacement for my sla 12v 7ah battery. At only 35% of sla weight.
It has a dedicated charger with it and free postage all for £55.
So won't have to save too long. Cheers Colin.

Colin,
These are what I used. Also, this company posts a ton of information about it's products which you will find when you link to each product. Also, they offer chargers specific for these batteries. Explore the site. Also check out their information on SLA's, especially discharge and charging rates.
Cheers
Jonathan
https://www.power-sonic.com/batteries/psl-sh-series/

good luck Colin. Here is a link to the style of battery I was referring to. I believe I used a different brnd, but you will get the idea.
https://www.wholesalebatteriesdirect.com/lithium-batteries/66438-12-volt-10-ah-lifepo4-lfp12v10-lithium-iron-phosphate-battery.html
Jonathan

Thanks guys for the great information, as most of my fleet are using vintage electronics and it is important to keep this format for my vintage shows.
The few I use for personal pleasure could be converted so I will need to start saving my pocket money or add items to my Xmas list.
The LIFE battery solution sounds really good apart from the cost.
NimH cells could possibly be my option to try as I have a few cell packs from my cars and quad copter.
I'll let you know how I get on.
Cheers Colin.

Colin,
I have a solutioon for your problem, but you will not like it. There are made LIFE batteries that are designed as direct replacements for the standard 7amp 12v SLA batteries that, on this sdide of the pond, are used commonly in alrm systems. They are in the same style case, with the same dimensions, but they weigh a fraction of the SLA, around 50+- % less. They have the advantage that they can provide high discharge currents, much higher than a standard SLA or even a high discharge SLA.
Te BAD news is the cost, on two counts. 1) the batteries are expensive, $180 amnd 2) they require a dedicated charger, around $30.
They do have an additional benefit, in that they do not self discharge as SLA's do, therefore their management is quite a bit easier. I use these in my 1/16th PT boat and they make keeping the weight in tow very nicely.
Sorry if this is a tease, but I am throwing the information out there.

Hi Colin
NiMhs are the best alternative if you don't want to use LiPos.
Problem is they are not cheap as most users have switched to LiPo. A 12v 5AHr NiMh will cost £30+ so I suspect you may have to remain with your SLA's.
If you are happy with shorter running times you could use lower capacity SLA's which would reduce the weight but give less running time. A spare battery could help extend this. Just a thought but might be in your budget.
Should you wish to move to LiPOs then the initial cost would not be cheap. As well as the battery you would require a special balanced charger and you may also need to update your ESC to one designed to protect the LiPO from over discharge.
Used correctly they are perfectly safe but if you overcharge or discharge below the minimum cell voltage they can become unstable.
Hope this helps
Cheers
Dave976

Hi I appreciate where you are coming from but SLAs are measured differently, on a 20 hour discharge rate whereas the others are measured on a 5 hour discharge rate.
If you check out Cyclon cells these are lead acid batteries designed for high discharge rates at the 5 hour rate the same as NiMh cells are. They are much dearer than SLAs. But can be compared directly with NiMh cells.
I am afraid you are going to have to bite the bullet on this one.

A tip might help you, check the various prices of batteries and you will see that the very high Amp hour capacity ones are often dearer than 2 sets of lesser ones giving the same capacity.

If you know what you are doing another option is to get hold of several 'dud' batteries and separate them out to find the dodgy cells and make a working set from the remainder.

I have done this several times in fact I am doing it this minute with some 1400mAh AA batteries a bit of cutting out and soldering will recover a working set of cells to operate my receiver which also drives the sail winch.

It does not matter if for instance you have to make up a battery with a slightly higher capacity cell as long as you think of the battery as the lowest amp hour capacity. After a year or so of operation the actual capacity of cells has changed anyway.

So a bit of learned ability can save you some money, but do not forget you will need a different charger.

Preferably choose an Intelligent charger and make sure it can cope with the number of cells you want to charge, many just cover 4 - 8 cells and for 12 volt batteries you will need a 10 cell charger.

Best of luck
Roy

Thanks Rudy, as I only have 1 boat with a brushless motor I think lipo's can stay in the shop.
Have considered building nimh battery packs and running in parallel to get a better runtime but may end up as heavy as my sla's. A couple of my boats have twin and triple 12v 7ah sla's. It saves on ballast and gives all day usage.
Cheers Colin.

Hi Colin
It seems you have two options left. Life and Lipo. And both are very finicky. Lithium Iron (LIFE) is used in most mobile phones these days. Their counterpart is Lithium Polymer, which is known to cause fires and explosions if over-charged. But, both are more expensive and would require a balanced charger. Neither will give you the runtime you have with the SLA's, but it will surely give you a power boost for shorter periods. I know very little about LIPO, but the little I've learned is that unless you have brushless motors, don't even bother. It's a hype thing IMHO